Article

Los bosques de Tierra del Fuego. Análisis de su estratificación mediante imágenes satelitales para el inventario forestal de la provincia

June 2001

June 2001
10(1)

Authors:

Secretaria de Ambiente, Tierra del Fuego

Los bosques cubren el 35% de la superficie de la parte argentina de la Isla Grande de Tierra del Fuego, representando uno de los recursos genuinos más importantes de la provincia. Sin embargo, no se cuenta con información detallada y clasificada (distribución de las especies, tipos forestales, dominio, estado de conservación, etc.) que pueda ser utilizada como una herramienta base para la ordenación del recurso forestal en Tierra del Fuego. Por lo que el objetivo de este trabajo fue relevar las superficies boscosas mediante imágenes satelitales y clasificarlas. Para tal fin se utilizaron imágenes SPOT del verano de 1995 y fotografías aéreas georreferenciadas por medio de un sistema de información geográfica, con el apoyo de cartografía preexistente e información de campo complementaria. La masa forestal fue clasificada en base a cinco atributos: especie, tipo forestal, situación dominial, estado de conservación y topografía. ISSN 0327-9375 LOS BOSQUES DE TIERRA DEL FUEGO. ANÁLISIS DE SU ESTRATIFICACIÓN MEDIANTE IMÁGENES SATELITALES PARA EL INVENTARIO FORESTAL DE LA PROVINCIA TIERRA DEL FUEGO FOREST. ANALYSIS OF THEIR STRATIFICATION THROUGH SATELLITE IMAGES FOR THE PROVINCE FOREST INVENTORY LEONARDO COLLADO Subsecretaría de Recursos Naturales, Dirección de Bosques, Sistemas de Información Geográfica. San Martín 1401 (9410) Ushuaia - Tierra del Fuego (Argentina). ( tdf-sig@impsat1.com.ar) Los bosques están compuestos básicamente por tres especies Nothofagus pumilio, N. antarctica y N. betuloides. Las dos primeras se presentan en masas puras y ocupan el 44% y 25% de la superficie forestal, respectivamente. El resto corresponde a bosques mixtos, conformados por las tres especies y con una pequeña participación de Drymis winterii y Maytenus magellanica como especies forestales acompañantes. Los bosques de producción están mayoritariamente compuestos por masas puras de Nothofagus pumilio, representando un 30% de la superficie de bosques. Estos bosques productivos han sido

Respuesta anatómica y fisiológica de especies de Nothofagus de Patagonia austral ante la variación de temperatura, humedad, CO2 y nutrientes

Thesis

Apr 2021

Héctor A Bahamonde

The forests of Nothofagus pumilio (Poepp. et Endl.) Krasser. (lenga, deciduous species); N. antarctica (G. Forster) Oerst. (ñire, deciduous species) and N. betuloides (Mirb.) Oerst. (guindo, evergreen species) are of great ecological, environmental and productive importance to the southern hemisphere. In particular, the forests of these species in Southern Patagonia (Santa Cruz and Tierra del Fuego) covering an area of more than 1.2 million hectares and are the southernmost in the world. Likewise, these forests are one of the main carbon (C) reservoirs in Argentina's Southern Patagonia, making them an important element for maintaining the global C balance in response to climate change. Considering Nothofagus native forests of southern Patagonia as central topic, several investigations have been developed, as shown in the different chapters of the thesis, with the aim of evaluating the response of these species to diverse abiotic stress factors, and thus making it possible to predict their possible response to climate change at a functional, structural and production level. The main aspects examined in this PhD thesis are how the edaphic and climatic factors affect the productivity of N. antarctica forests in South Patagonia, how is the response of this species to water stress and growth under variable climatic conditions, if there are alterations in leaf anatomy in response to an increased atmospheric CO2 levels, and what is the rate of nutrient 18 reabsorption these two species of Nothofagus from Southern Patagonia. In Chapter two, the influence of soil factors and climatic variables on the productivity of different N. antarctica forests, estimated by the height of the dominant trees, has been evaluated. The measured productivity data, together with a series of soil and climate variables, were integrated into a mathematical model that relates the productivity of the studied forests with the mentioned variables in a theoretical way. The four most important variables for the model were: altitude, temperature, soil texture and finally the seasonality of temperature. The main finding was to recognise the predominant effect of the soil and temperature variables on productivity was that the availability of water was less important. The functional response of N. antartica seedlings of different provenances to water stress, an increasingly common factor under current global warming conditions, was studied in detail in Chapter three of the thesis, as a preliminary tool for estimating the survival and sustainability of this species' forests. Ecophysiological experiments were carried out with four different N. antarctica provenances under controlled greenhouse conditions. Among the results obtained, differences were observed in the rate of photosynthesis and stomatal conductance between the different provenances, but only when the plants were kept under sufficient water availability conditions. These studies enabled the characterisation of functional responses to drought of the different provenances N. antarctica, concluding that this species has a great capacity for osmotic regulation. The leaf anatomical features and physical-chemical characteristics of the leaf surfaces of N. antarctica and N. betuloides were estimated after growing the plants under normal conditions and at high levels of atmospheric CO2. Keeping the plants in conditions of good water availability, nutrition and photoperiod from the beginning of the experimental period, a treatment of 400 ppm (control) and another one of 800 ppm of CO2 was imposed on several individuals of these two Nothofagus species. After a period of growth under the aforementioned environmental CO2 conditions, leaf samples were taken and various anatomical studies were carried out using scanning electron microscopy, transmission and optical microscopy. The contact angles of three liquids with different degrees of polarity and apolarity were also measured to estimate the wettability and subsequently, the free energy of the leaf surfaces and related parameters. A differential effect of growth at high levels of atmospheric CO2 between the two species and in the proportion of tissues in adaxial and abaxial leaf surfaces was observed (e.g. an increase in the apoplastic 19 space or thickness of the epidermis or cuticle). Transmission electron microscopy also showed increases in the presence of chloroplasts in the mesophyll cells of leaves of N. antarctica plants grown under high levels of atmospheric CO2 and damage to the chloroplasts of both species. Regarding wettability, surface free energy and wax concentration of adaxial and abaxial leaf surfaces of the plants evaluated, differences were observed at the species level and in some cases due to high CO2 conditions. Differences were also observed in terms of surface topography and the presence of structures such as stomata, trichomes or veins. It is concluded that N. antarctica leaves have a greater potential to absorb water deposited as rain, dew or mist than those of N. betuloides.

El bosque como fuente de combustible: análisis antracológico de los sitios de la faja central de la Isla Grande de Tierra del Fuego

Article

Full-text available

Dec 2020

El objetivo de este trabajo es presentar el análisis antracológico de dos sitios de la faja central de la Isla Grande de Tierra del Fuego (Cabo San Pablo 2017 y Kami 7) y discutir la utilización de recursos leñosos por parte de los grupos que habitaron el área durante el Holoceno tardío. Se aplicó una metodología de análisis antracológico estándar, que incluyó la identificación taxonómica, la evaluación de alteraciones en la estructura de los carbones y estimación del calibre original de los leños utilizados. Los resultados demuestran un énfasis en el uso combustible de taxa de la clase fitosociológica Nothofagetea pumilionis-antarcticae, siendo Nothofagus pumilio y N. antartica/betuloides los más abundantes. Se registra una preponderancia de carbones de grandes calibres, de madera colectada en buen estado y alteraciones que reflejan eventos de altas temperaturas de fogón. De los resultados se deduce un aprovechamiento intenso y variado de los bosques cercanos a los sitios.

Historia del bosque en el centro de Tierra del Fuego, Argentina

Article

Full-text available

Feb 2011

Nothofagus pumilio is the most important native forest species in Tierra del Fuego; it covers an area of 214,000 ha and is the main source of wood. In this work a contribution is made with the elements for the reconstruction of the history of the Nothofagus pumilio deciduous forest in the centre of Isla Grande de Tierra del Fuego, at the southeastern end of the American continent. The reconstruction was performed by means of pollen analysis out of a peat bog profile located in the Argentine sector of Isla Grande de Tierra del Fuego. Pollen grains were extracted by physical and chemical techniques; they were determined and counted, and per centual data were statistically treated through ordination analysis (CA programme). Changes in pollen content along the profile show variation of the environmental parameters during the Holocene with relation to the transition from steppe to forest. We demonstrate that in the centre of the isle, between ca 6,800 and 7,775±205 years BP there was a gramineous steppe, later an open forest between 2,340±35 and 2,755±45 years BP, and as from 1,725±35 years BP a closed forest started developing up to now. These changes are related to the increasing precipitation. The asynchrony in the establishment of forests in other sites of Tierra del Fuego is due to humidity gradients of the southern winds.

Las comunidades de aves terrestres como indicadoras de impacto en bosques de Nothofagus antarctica de Tierra del Fuego

Thesis

Dec 2021

Julieta Benitez

El uso ganadero de los bosques de Nothofagus antarctica de Tierra del Fuego (Argentina) ha sido históricamente extensivo y poco planificado, y usualmente basado en la reducción de cobertura arbórea mediante cortas para aumentar la producción de forraje bajo su dosel. El objetivo de esta tesis fue analizar estructura y rasgos funcionales de las comunidades de aves terrestres, diurnas y residentes estivales (principalmente paseriformes), en diferentes estados del bosque de N. antarctica evaluando el efecto de variables ambientales a escala local y de paisaje, así como el potencial uso de las aves como indicadoras de impactos para mejorar las propuestas de estrategias de manejo foresto-ganadero existentes. Este trabajo se realizó en 4 Estancias (Los Cerros, Rolito, Las Hijas y Cabo San Pablo) ubicadas en el centro y este de la Isla Grande de Tierra del Fuego (Argentina). Se estudiaron 4 tipos de bosque: un tipo con raleos (Abiertos) y tres tipos sin raleos (Muy Cerrados, Cerrados y Muy Abiertos). Las aves se estudiaron en puntos de observación fijos, donde se realizaron conteos durante los meses de enero y febrero del 2017 y 2018 en Los Cerros, 2018 y 2019 en Rolito, y 2019 y 2020 en Las Hijas y Cabo San Pablo, para caracterizar estructura (composición, riqueza, densidad, biomasa e índices de diversidad) y rasgos funcionales (grupos tróficos, uso de sustratos, tipo de nidificación y estatus migratorio). En Los Cerros y Rolito también se analizó la susceptibilidad a la depredación de nidos artificiales. Los efectos analizados fueron: a escala local, la estructura forestal (altura dominante, área basal, cobertura de copas, densidad de árboles y diámetro medio), la cobertura del suelo (sotobosque, residuos leñosos, plantas no-vasculares, renovales y suelo sin vegetación), y la oferta alimenticia, vegetal (riqueza y cobertura total, de gramíneas y de dicotiledóneas consumidas por aves) y de la artropofauna (abundancia total y proporción de los órdenes más importantes); y a escala de paisaje, área, perímetro y forma del parche; área, número de parches, índice del parche más grande y conectividad de bosques y áreas abiertas; y total de bordes y densidad de bordes. Las variables fueron evaluadas mediante modelos lineales generalizados (GLM) y generalizados mixtos (GLMM), y multivariados (PCA, MRPP, IndVal, y CCA). Se pudo identificar mayor riqueza y diversidad de especies de aves en bosques Abiertos (raleados) y Muy Abiertos, dadas por la presencia de especies de áreas abiertas o de bordes de bosque. Por otro lado, se identificaron menores densidades de omnívoros y granívoras en bosques Cerrados y Muy Cerrados, respectivamente, vinculadas a los sustratos de alimentación. El uso de los sustratos difirió entre tipos de bosque, estando el uso de sustratos bajos y copas relacionado con su disponibilidad. Mientras que el uso de ramas y fustes, y la densidad de individuos volando se asociaron a la estructura forestal (cobertura de copas y área basal, entre otras). Por otro lado, la densidad de especies que nidifican en huecos y copa abierta, así como la densidad de residentes y migradoras, también difirieron entre tipos de bosque y se asociaron a la altura dominante y a la cobertura de copas. Los bosques raleados, si bien presentaron algunas diferencias con los Cerrados y Muy Cerrados (mayor riqueza de especies, diversidad, uso de sustratos bajos, densidad de aves volando y de migradoras), fueron parecidos en otros rasgos (ej. densidad de aves que utilizan ramas y copas o que nidifican en huecos), observándose en ellos incluso especies especialistas de bosque (Pygarrhichas albogularis y Aphrastura spinicauda). Si bien no se encontraron diferencias significativas en la susceptibilidad a la depredación de nidos artificiales entre tipos de bosque, los nidos que se encontraban en bosques Muy Abiertos fueron depredados más rápido. Este estudio permitió identificar especies indicadoras de bosques Cerrados y Muy Cerrados (A. spinicauda, P. albogularis), Abiertos (Spinus barbatus) y Muy Abiertos (ej. Tachycineta leucopyga). Por lo tanto, estas especies se podrían utilizar para el monitoreo de los raleos en estos bosques. Al analizar variables de diferentes escalas espaciales (local y paisaje), se pudo observar que las mismas influyeron sobre diferentes grupos de especies. Por ejemplo, la estructura forestal (área basal, cobertura de copas) y el área del parche de bosque tuvieron mayor efecto sobre P. albogularis. Se concluye que ciertas características a nivel local (ej. mayor área basal, cobertura de copas y de renovales, y proporción de himenópteros), así como a nivel de paisaje (ej. parches de bosque grandes e irregulares, alternancia con áreas abiertas), favorecen a una mayor diversidad de aves en los bosques de N. antarctica de Tierra del Fuego. El desarrollo de propuestas de manejo forestales y silvopastoriles que preserven o favorezcan la presencia de paisajes y parches de bosque con estas características contribuiría a que el manejo de estos bosques sea más sustentable.

Estimación de la función ambiental de los paisajes boscosos y esteparios de tierra del fuego a través de la caracterización de su avifauna usando datos de eBird

Article

Jul 2017

El objetivo de este trabajo fue evaluar la utilidad de la base de datos provista por la plataforma global eBird6 para estimar la función ambiental de conservación del hábitat natural y de la diversidad biológica de los paisajes boscosos y esteparios de Tierra del Fuego, a través de la caracterización de su avifauna. Usando eBird se recopiló información sobre observaciones de aves (latitud y longitud, fecha de observación y especies) desde 1973 hasta febrero del 2016

Why Do Beavers Leave Home? Lodge Abandonment in an Invasive Population in Patagonia

Article

Full-text available

Oct 2020

Research Highlights: Lodge abandonment by beavers is apparently a common phenomenon in Patagonia, but it is still poorly understood and we ignore what drives it. In relatively slow growth Nothofagus forests, resource depletion can impact abandonment while water availability may be a major driver in the semiarid steppe. Background and Objectives: North American beaver (Castor canadensis) was introduced in 1946 on the island of Tierra del Fuego (TDF) in southern Argentina. Since then, beavers have become a major disturbance affecting not only forest but also treeless steppe landscapes. Our goal was to determine the factors affecting lodge abandonment by beavers in two habitats of TDF: forest and steppe. Materials and Methods: A total of 47 lodges were surveyed between February and March from 2012 to 2014 in both habitat types, 22 in the forest and 25 in the steppe. To explain factors involved in lodge abandonment by beavers, we measured the following variables: water level variation, stream gradient, vegetation cover adjacent to shore and forest structure. Results: We recorded 24 abandonments events, with a similar proportion of lodges abandoned in both habitats. Our results revealed that lodge abandonment was mostly linked to water level fluctuations irrespective of habitat type. The water level at the entrances of the lodge generally decreased in abandoned lodges. Variables that characterize understory cover had some influence on lodge abandonment in the forest, and no effect in the steppe. Conclusions: Water level variation was associated with lodge abandonment in both habitats, and we found some evidence of resource depletion in the forest. However, we caution that changes in water level may be not only due to extrinsic factors but rather to beaver's own activities or to a decay in pond maintenance following abandonment.

Estimación de la función ambiental de los paisajes boscosos y esteparios de Tierra del Fuego a través de la caracterización de su avifauna usando datos de eBird

Article

Dec 2017

Las funciones ambientales de los bosques son afectadas por las actividades productivas y turístico-recreativas que en ellos se realizan, siendo las aves buenos y versátiles indicadores de cambio ambiental. En la Isla Grande de Tierra del Fuego (Argentina), los paisajes boscosos (40% de la superficie en el centro-sur de la Isla) y esteparios (25%, predominantemente en el norte) son los mejor representados, mientras que las aves son los vertebrados más abundantes y diversos que la habitan. El objetivo de este trabajo fue evaluar la utilidad de la base de datos provista por la plataforma global eBird6 para estimar la función ambiental de conservación del hábitat natural y de la diversidad biológica de los paisajes boscosos y esteparios de Tierra del Fuego, a través de la caracterización de su avifauna. Usando eBird se recopiló información sobre observaciones de aves (latitud y longitud, fecha de observación y especies) desde 1973 hasta febrero del 2016. Excluyendo las especies de aves exclusivamente costeras, marinas y dulceacuícolas, la información se resumió en datos mensuales por año de cada especie para cada “localidad” (coordenada geográfica en latitud/longitud), evitando la repetición de observaciones de una misma especie para un determinado punto. Los datos de latitud y longitud se geoprocesaron en una plataforma SIG para determinar el paisaje dominante en cada localidad, clasificándolo en una de cuatro categorías: estepa, bosque de ñire, bosque de lenga y bosque mixto. Se evaluaron cantidad de observaciones, de localidades y de especies en general y para cada categoría, identificando las aves raras o comunes y las más frecuentes en cada paisaje. Asimismo, se identificaron las especies compartidas por todos los paisajes y las exclusivas. Por último, se detectaron los gremios alimenticios más comunes y el número de observaciones de las especies con funciones ecológicas específicas para cada paisaje. La base de datos permitió extraer información sobre 77 especies y 7.984 observaciones en 493 localidades. Se detectaron 44 especies (56%) compartidas en todos los paisajes (ej. Carduelis barbata, Falco sparverius y Vultur gryphus) y 11 (14%) raras (ej. Asthenes pyrrholeuca, Muscisaxicola maculirostris y Phrygilus fruticeti), varias de las cuales se observan circunstancialmente en la Isla pero cuya distribución típica no la incluye. Respecto de la cantidad de observaciones, el 66% se realizó en paisajes dominados por bosques mixtos (42% de las localidades), los cuales incluyeron gran cantidad de observaciones en el Parque Nacional Tierra del Fuego y en la ciudad de Ushuaia, mientras que los otros paisajes solo incluyeron 7-17% de las observaciones (13-23% de las localidades). En cuanto a la riqueza específica, fue mucho mayor en paisajes con predominio de bosque mixto (74 especies) que en los otros paisajes (estepa=59, bosque de ñire y lenga=55 en cada uno), siendo probablemente subestimada en estos por la baja cantidad de observaciones y localidades. Las especies exclusivas fueron 7 en los paisajes con bosque mixto y 3 en estepa, mientras que no se observó ninguna en paisajes dominados por ñire o lenga. Las aves más frecuentes en cada paisaje se encuentran entre las más conspicuas y conocidas y gran cantidad de ellas coincidieron entre paisajes (ej., Chloephaga picta en estepa, ñire y mixto, Zonotrichia capensis en ñire, lenga y mixto, Milvago chimango en lenga y mixto). Todos los gremios y especies con funciones ecológicas específicas presentaron mayor número de observaciones en los bosques mixtos. Aunque eBird permitió encontrar diferencias y similitudes entre paisajes, se observa cierta tendencia espacial de concentración de las observaciones, lo que indicaría que son necesarios estudios mejor distribuidos espacialmente para caracterizar la avifauna y concluir sobre la función ambiental de los paisajes analizados.

Landscape-level impact and habitat factors associated with invasive beaver distribution in Tierra del Fuego

Article

Full-text available

Jun 2016
BIOL INVASIONS

Understanding the amount of impact and distribution of invasive species is important for both basic ecological research and making management decisions. Because of their extensive impacts in southern Patagonia, invasive North American beavers (Castor canadensis) are considered both a scientific and conservation priority. However, little is known about the landscape-scale effects of these exotic ecosystem engineers. Using satellite imagery, we estimated the impact of beavers in the Argentine portion of Tierra del Fuego Island and determined the habitat factors (vegetation cover, forest type, stream presence and topography) related to their presence using both non-parametric statistical and information-theoretic approaches. Results indicated that more than 31,000 ha (1.6 % of the study area) were impacted by beavers and that the presence, but not the amount, of beaver impacts were spatially clustered. Impacts were greater in the Mountain ecoregion (2.8 % of the ecoregion) and lower in the Steppe (0.1 %). The best model for predicting beaver presence included variables related to water availability (presence of peatlands and streams), forage availability (forest type cover), and topography (slope and elevation). These findings support previous assertions that this invasion is the largest alteration to the sub-Antarctic forests in the Holocene. They also serve as a foundation for the development of maps based on habitat- and landscape-scale conditions to assist with the orientation of control, eradication, and restoration efforts currently being planned.

Phytoclimatic characterization and cartography of subantarctic native forests in Isla Grande de Tierra del Fuego (Patagonia, Argentina)

Article

Full-text available

Jul 2010

Isla Grande de Tierra del Fuego is especially peculiar in phytoclimatic terms, situated as it is at an extreme southerly latitude, surrounded by large water masses and close to the great mass of Antarctic ice. Its main peculiarities in this sense are the coolness of its summers and a very narrow temperature range. As a result, the woodland landscapes in the parts with forest cover are dominated by microphyllous broadleaf physiognomies, both evergreen and deciduous, of the Nothofagus genus. This paper reports a more in-depth investigation of the hitherto little-known phytoclimatic conditions in that territory which included calibration and validation of a model of phytoclimatic suitability that addresses the principal plant physiognomic units and phytoclimatic mapping. It discusses the causes behind the presence of broadleaf formations in thermal conditions which in the northern hemisphere would allow only coniferous formations or no tree formations at all, and also the edaphic peculiarities that may explain the presence of a evergreen species like Nothofagus betuloides in subantarctic mixed forests.

Litterfall and nutrients return in Nothofagus antarctica forests growing in a site quality gradient with different management uses in Southern Patagonia

Article

Aug 2014

We evaluated the annual litterfall and nutrients return in primary forests of Nothofagus antarctica growing at three different site classes (SC) (III, IV and V) and compared two of these forests with adjacent stands under silvopastoral use (thinned 40 years ago), in Patagonia, Argentina. Traps were installed in each stand and sampled monthly during the litterfall over 10 years. Sample from the five stands was ground for further analyses of nutrients (N, P, K, Ca, Mg and S). The litterfall varied significantly between SC, but not between years, from 1,306 to 1,972 kg ha-1 in the best site. The nutrients return from litterfall did not change neither between site classes and years in most nutrients. Comparing primary forests with silvopastoral stands, in SCIV, significant differences among uses occurred for litterfall production and nutrients return, being higher in primary forest. While, in SCV, the litterfall and nutrients return practically did not change among uses. The results showed the incidence of site quality and forest use on the litterfall and nutrients return in N. antarctica forests.

Producción de hojarasca en bosques primarios y bajo manejo silvopastoril de Nothofagus antarctica en diferentes clases de sitio.

Article

May 2008

Héctor A Bahamonde

Changes in the bird communities of Nothofagus forests in a long‐term plot in Tierra del Fuego

Article

Dec 2023

Long‐term studies have proven to be important to characterize animal communities and analyse the ecological responses to climate and environmental changes. These studies are necessary to determine the natural community variability (e.g., richness and density) to develop better conservation strategies to face climate changes. Here, we analysed the natural changes in the structure and functional traits of bird communities over 13 consecutive years (2010–2022) and determined the number of years of sampling needed to obtain a good estimation of the community structure variables in deciduous high latitude Nothofagus forests. Using point counts, we studied closed (80% of canopy cover) and open (40% of canopy cover) forests inside the Tierra del Fuego National Park. Species richness, density, biomass, and functional traits (migratory status, trophic groups, nest type, and feeding strata) were analysed using generalized linear models with forest type (closed and open) and year (2010–2022) as the main factors, while the standard error (SE) of sampling obtained from one to 12 sampling years was compared. Richness was significantly higher in open forests ( p < 0.01), while density and biomass were higher in closed forests. Additionally, density and biomass significantly varied among years in both forest types (e.g., lower density in 2013, 2014 and 2015, and higher in 2019). The density of birds for some functional traits also varied among years and forest types (e.g., higher values of cavity nesters in closed forests during 2019). Five to six years of sampling were needed to have an acceptable estimation of richness (20% SE), between 10 and 12 years for density, and >12 years for biomass. This study highlights the importance of long‐term studies to visualize natural variations in undisturbed habitats along time.

Asociación espacial de Nothofagus antarctica y Berberis microphylla: mecanismos de facilitación sobre la regeneración arbórea en sistemas silvopastoriles

Thesis

Jun 2023

Gimena Noemí Bustamante

Chloride nutrition provides a more efficient use of nitrogen (NUE) in tobacco and tomato plants

Chapter

Full-text available

Sep 2014

Chloride (Cl-) is one of the 16 elements essential for plant growth. Because it is supposedly needed in small quantities for healthy growth of higher plants (<50-100 mM in the nutrient media), Cl- is considered a micronutrient (Johnson et al., 1957; Terry, 1977; Whitehead, 1985). Usually non-halophytic plants present critical deficiency contents below 0,2 mg/g shoot dry weight (reviewed in Flowers, 1988; Marschner, 1995; Xu et al., 2000; White and Broadley, 2001), under which, deficient plants show a significant decrease in leaf area as a result of a reduction in cell division rates (Terry, 1977). Chloride is considered however to be an strange micronutrient since actual Cl- concentration in plants is typical of the content of a macronutriente (10-60 mg/g, about 50-300 times higher than the content required is essential micronutrient; Marschner, 1995; Brumós et al., 2010; Franco-Navarro et al., 2012; Franco-Navarro et al., 2013). This is relevant provided that all the other mineral micronutrients (B, Cu, Fe, Mn, Mo, Ni, Zn) are present at much lower concentrations in plant tissues (10-4-10-1 mg/g) and their accumulation to higher levels result in plant toxicity (Hänsch and Mendel, 2009). Besides the micronutrient functions, Cl- is an osmotically active solute in the vacuole. Participation of Cl- in cell osmotic regulation has been largely argued through its involvement in the regulation of cell turgor processes like stomatal movement, and the activity of motor cells controlling nastic movements (Leigh and Wyn Jones, 1985; Flowers 1988 and references therein; Marschner, 1995; Iino et al., 2001; Shabala and Lew 2002). Thereby we proposed and demonstrated that Cl- plays a biological role in controlling water balance and plant water relations (to be published). We observed that in the low millimolar range Cl- promotes plant growth and improves developmental and water relation parameters like leaf expansion, cell elongation, the relative water content, tissue osmolarity, water-use efficiency (WUE) and drought tolerance (Franco-Navarro et al., 2012; FrancoNavarro et al., 2013). But there were left many unsolved questions, i.e., the response of plants to increasing concentration of anions and the correlations with different water parameters, including a complete leaf water/osmotic/turgor potential measurement. In order to elucidate these issues, two independent experiments were done. Tobacco plants were grown under well-irrigated semi-hydroponic conditions for 8 weeks subjected to different treatments: basal nutrient solution (BS); BS supplemented with different concentrations of Cl- salts (CL); BS supplemented with different concentrations of NO3- salts (N); BS supplemented with different concentrations of SO4 2- + PO4 3 salts (SP). All treatments (CL, N and SP) contained the same concentration of charge-balancing cations. Data concerning correlations between anions content vs. water balance parameters will be presented.

Effects of long-term low intensity silviculture and habitat on birds in Nothofagus antarctica forests of south Patagonia

Article

Jul 2022
FOREST ECOL MANAG

Low intensity silviculture has been used to decrease the impact of forest harvesting, for example, on bird species and structural diversity. The objective of this work was to analyse the long-term effect of thinning on bird communities of Nothofagus antarctica forests in Tierra del Fuego (Argentina), compared with unthinned forests at two different locations. Thinning was performed 15 and 50 years ago at each location (ranches), therefore we also evaluated other common forest habitat types to differentiate these effects (location and time). We sampled four habitat types associated to overstory canopy cover (CC) categories: thinned (35–65% CC), and three unthinned forests (open with <35% CC, closed with 65–85% CC, and very closed with >85% CC), totalling 32 sampling sites (2 ranches × 4 canopy cover × 4 replicates). Bird assemblages’ structure and functional traits (e.g., richness, density, trophic groups, use of strata) were surveyed during two consecutive summers (2017–2020) at each site. We also characterized habitats by: (i) forest structure and ground cover (e.g., basal area, debris, and saplings); and (ii) food availability, considering understory plants consumed by birds (e.g., plant richness, grasses and dicots cover) and arthropods (e.g., total abundance). We evaluated the effect of CC, ranch, time, habitat and food availability by Generalised Linear Mixed Models and multivariate analyses (Multiple Response Permutation Procedure, Canonical Correspondence Analysis). In thinned forests, some bird structure and functional traits remained similar to closed forests; however, thinning increased bird species richness, being more similar to open forests. Effect of time could not be detected. CC and ranch were the factors that better described bird community structure, while forest structure, ground cover and food availability (e.g., dominant height, basal area, proportion of Hymenoptera) were the main drivers of most functional traits. The whole bird assemblage was better explained by 4–6 habitat structure and food availability variables depending on location (ranch). Results suggest thinning will benefit bird conservation if thinned forests maintain characteristics of mature forests (e.g., basal area > 40 m²/ha, shrub cover > 5%).

Effects of Long-Term Low Intensity Silviculture and Habitat on Birds in Nothofagus Antarctica Forests of South Patagonia

Article

Jan 2021

Low intensity silviculture has been used to decrease the impact of forest harvesting, for example, on bird species and structural diversity. The objective of this work was to analyse the long-term effect of thinning on bird communities of Nothofagus antarctica forests in Tierra del Fuego (Argentina), compared with unthinned forests at two different locations. Thinning was performed 15 and 50 years ago at each location (ranches), therefore we also evaluated other common forest habitat types to differentiate these effects (location and time). We sampled four habitat types associated to overstory canopy cover (CC) categories: thinned (35–65% CC), and three unthinned forests (open with <35% CC, closed with 65–85% CC, and very closed with >85% CC), totalling 32 sampling sites (2 ranches × 4 canopy cover × 4 replicates). Bird assemblages’ structure and functional traits (e. g., richness, density, trophic groups, use of strata) were surveyed during two consecutive summers (2017–2020) at each site. We also characterized habitats by: (i) forest structure and ground cover (e.g., basal area, debris, and saplings); and (ii) food availability, considering understory plants consumed by birds (e.g., plant richness, grasses and dicots cover) and arthropods (e.g., total abundance). We evaluated the effect of CC, ranch, time, habitat and food availability by Generalised Linear Mixed Models and multivariate analyses (Multiple Response Permutation Procedure, Canonical Correspondence Analysis). In thinned forests, some bird structure and functional traits remained similar to closed forests; however, thinning increased bird species richness, being more similar to open forests. Effect of time could not be detected. CC and ranch were the factors that better described bird community structure, while forest structure, ground cover and food availability (e.g., dominant height, basal area, proportion of Hymenoptera) were the main drivers of most functional traits. The whole bird assemblage was better explained by 4–6 habitat structure and food availability variables depending on location (ranch). Results suggest thinning will benefit bird conservation if thinned forests maintain characteristics of mature forests (e.g., basal area > 40 m2/ha, shrub cover > 5%).

Changes in forest structure values along the natural cycle and different management strategies in Nothofagus antarctica forests

Article

Apr 2021
FOREST ECOL MANAG

Ecologically sustainable forest management aims to preserve ecosystem integrity by providing wood and non-wood values. For this, it is necessary to determine the losses produced by the different management practices in natural forest resilience. The aim was to determine changes in forest structure values along the natural cycle and human impacts generated by rural timber, pastoral and silvopastoral uses in managed, unmanaged, and transformed Nothofagus antarctica forests of Tierra del Fuego (Argentina), as well as in some associated environments (grasslands). We sampled 145 sites to determine landscape characterization, microclimate, soil properties, debris, forest structure and regeneration under different conditions: (i) six phases of natural forest dynamic (even-and uneven-aged), (ii) four types of management and conversion alternatives with and without natural regeneration, and (iii) forest edges and grasslands. Main results showed that stand characteristics (abiotic, soil, forest structure, and regeneration) did not significantly change along the different natural forest phases in even- and uneven-aged structures. However, many studied variables strongly varied depending on harvesting intensities and fire occurrence. The magnitude of these changes was directly related to the impact degree. Multivariate analyses showed a close relationship among the different natural forest phases, and how stands with harvesting or different conversion intensity differ from the control stands, or how much they become similar to openlands. Through different indexes, we related the modifications of the stand characteristics with the magnitude and direction of the changes. Then, these could be used to propose sustainable forest management strategies in the framework of silvopastoral systems.

Fruit provision from Berberis microphylla shrubs as ecosystem service in Nothofagus forest of Tierra del Fuego

Article

Full-text available

Oct 2020

Berry production is a non-wood product worldwide recognized by its nutritional value and taste, but the most studied species are non-native commercial plants in productive areas, leaving aside native berries. We propose that native berries (Berberis microphylla G.Forst) naturally growing in degradation forests areas could diversify livestock establishment production and complement traditional uses (e.g., livestock). The aims of this work were to 1) environmentally characterize (e.g., soil nutrient content and physical conditions, air conditions and photosynthetically active radiation) in three degraded Nothofagus antarctica Oerst. forest (due to past fires and livestock use) of Tierra del Fuego; and 2) evaluate berries production of B. microphylla in terms of quality production (e.g., fruit number and weigh per shrub) and in terms of quality (individual fruit weight, fruit pulp percentage, and soluble solids content) to assess provisioning ecosystem service of this native shrub in different degraded areas. Studied sites were defined as: 1) Severe soil degradation condition (SEV) (high frequency of horses, bulls and some native guanacos year round, severe soil erosion, and shorter herbaceous layer), 2) Moderate soil degradation condition (MOD) (cattle and guanaco year round, intermediate level of soil erosion and intermediate height of herbaceous layer), and 3) Slight soil degradation condition (SLI) (livestock only during winter, but high frequency of native guanacos, lower soil erosion and taller herbaceous layer). (SEV) had the highest air and soil temperature, least soils nutrients content, highest bulk density, the least soil water content and the poorest fruit production. (MOD) had the highest soil water content and nutrient-rich soils, while (SLI) had the highest relative air humidity and PAR. B. microphylla shrubs grow with similar morphology on the different soil degraded condition. The highest fruit production were at (SLI), however the (SEV) had the highest soluble solids. We conclude that calafate shrubs in degraded Nothofagus forests offer a provisioning ecosystem service through their excellent fruits quality. Livestock farms could diversify their production through native fruits taking advantage of the altered areas occupied by B. microphylla. However, we recommend avoiding intensive livestock use in burned forests since it could lead to an irreversible soil erosion. Proper livestock management in Nothofagus burned forest could keep over the time not only the recognized ecosystem provision services (fruits, meat, wood), but also those of regulation and support that calafate shrubs offer and that make the functionality of the ecosystem.

Response of bird communities to native forest urbanization in one of the southernmost city of the world

Article

Oct 2020

Rapid urban development threatens biodiversity, reducing local livelihoods and well-being when replacing natural habitat by urban structures. Although there is a lot of literature on the effects of urbanization on biodiversity, little has been investigated in South America. This study evaluated, for the first-time, bird community variation in an urban gradient of Nothofagus South-Antarctic forest in Ushuaia, the southernmost city of Argentina. We also studied differences during the breeding season and habitat characteristics. We conducted bird surveys monthly from October 2016 to February 2017 in 12 plots classified as (i) urban, (ii) peri-urban and (iii) non-urban forest. We counted birds for 15 min (three times per month) in each plot to obtain assemblage richness, abundance, density and several indices (Shannon-Weiner diversity, Pielou evenness and abundance-based Chao-Sorensen similarity) for the communities and functional groups. We recorded use of strata, weather conditions and human/domestic animal presence during counting, as well as habitat variables (forest structure, ground cover and understory plants) in each plot. We performed univariate and multivariate analyses, which showed that urbanization positively affects bird community structure (all variables increased in urban forest), with a reduction in the abundance of insectivores cavity-nesters that feed on trees (Campephilus magellanicus, Troglodytes aedon, Aphrastura spinicauda and Pygarrhichas albogularis). Bird assemblages changed similarities over the season; non-urban forests were more dissimilar than urban and peri-urban in October and November, but not in the other months, highlighting different roles of each forest in different periods. We found differences in habitats along the urbanization gradient, and discuss possible influences on bird communities, such as more food supply associated with berry shrubs and low overall richness at high latitudes. According to our results, urban forests with native vegetation are useful structures that help to maintain native bird communities and ecological functions in Ushuaia city.

Conservation values of understory vascular plants in even- and uneven-aged Nothofagus antarctica forests

Article

Full-text available

Nov 2020
BIODIVERS CONSERV

Usually, stands with aging trees are considered forests with higher conservation values, regardless their structural diversity and other functional attributes. Natural stands present a wide range of age structures, from even-aged stands growing at different development growth phases (e.g. CO = stands at initial or final optimum development growth phase, MD = stands at mature or decaying development growth phases) to uneven-aged stands with mixed development growth phases (e.g. UOG = stands combining mature or decaying development growth phases with initial or final optimum development growth phases, UMD = stands combining only mature and decaying development growth phases). The aim of this work was to compare richness and cover of understory vascular plants of evenand uneven-aged stands of Nothofagus antarctica (n˜ire) forests in Tierra del Fuego (Argentina), and relate these characteristics with abiotic, soil and forest structure variables. A total of 75 stands were sampled across the natural range distribution of the forests, where understory (point intercept method), forest structure (angle count sampling and eye-fish photos) and environmental (soil) variables were measured. 17 one-way ANOVAs were conducted using Tukey test at p\ 0.05 to compare the means. Among forest structure and environmental variables, cover (F = 4.3, p = 0.007), radiation (F = 4.4, p = 0.006), phosphorous (F = 3.9, p = 0.012), tree density (F = 10.3, p\ 0.001), tree diameter (F = 10.3, p\ 0.001) and stand growth (F = 4.9, p = 0.004) showed significant differences, and in general with a positive or negative trend across the MD—UMD—UOG—CO gradient. Total (F = 6.5, p\ 0.001) and native species richness of the understory (F = 7.2, p\ 0.001) were significantly different among forest types, where UMD [ UOG[ MD[ CO (17–28 total, and 13–24 native species, respectively). Neither exotic species richness (4–5 species) nor understory cover significantly changed among treatments (total, dicots, ferns and bryophytes). However, monocots cover significantly differed among treatments (F = 3.9, p = 0.012), where UMD [MD [ UOG[ CO. Finally, indicator species cover for environmental degradation did not present significant differences (F = 2.1, p = 0.106), but they were positive related to forests growing in mature stages. We concluded that uneven-aged stands presented significantly higher conservation values compared to even-aged stands, where mature/decay stands have better conservation values

Canopy composition and site are indicative of mineral soil conditions in Patagonian mixed Nothofagus forests

Article

Dec 2019

Key message Canopy composition in mixed Patagonian Nothofagus forests has an impact on soil properties like cationic exchange capacity and pH, while most soil variables changed with site [P, cation exchange capacity (CEC), soil moisture (SM), resistance to penetration (R)]. Site conditions and canopy composition need be considered together to better understand the distribution of Nothofagus species. Context Forests can influence soil development, changing main soil properties by several mechanisms, but this has never been investigated in mixed Nothofagus forests. Such influences can be strongly variable depending on local site conditions, and the interactions between both factors need to be clearly established. Aims To reveal the effect on physical and chemical mineral soil properties in mixed Nothofagus forests of canopy composition and their interactions with site conditions. Methods Two sites and three mixed forest types, with different proportion of deciduous-evergreen, were selected in coastal and mountain sites. We evaluated forest structure, litterfall and physico-chemical properties of mineral soil (N = 60), and analyzed these factors with general linear models and multivariate statistics [multi-response permutation procedure (MRPP), principal component analyses (PCA)]. Results Basal area and litterfall were significantly influenced by forest type × sites. CEC and pH value varied among forests types and sites, but sites also influenced other variables (P, SM, R). Multivariate analyses reveals a much stronger effect of site conditions than that of species mixture. Conclusion Forest soil studies must consider environmental factors on different spatial scale and canopy species composition to better understand their influence on soil dynamics in mixed Nothofagus forests.

Efecto de variables ambientales sobre la Productividad Primaria Neta Aérea y la concentración de proteína bruta de gramíneas en Sistemas Silvopastoriles de ñire (Nothofagus antarctica): creación de un modelo de simulación.

Thesis

Full-text available

Nov 2011

Héctor A Bahamonde

Nothofagus antarctica (ñire) ocupa una importante superficie de los bosques de Patagonia Sur, siendo ampliamente usado como sistemas silvopastoriles con ganadería ovina y bovina. Sin embargo, en la mayoría de los casos el uso de estos bosques se realiza sin un manejo que permita optimizar la sustentabilidad del sistema. En esta tesis se estudió el efecto de distintas variables ambientales (temperatura, humedad del suelo, radiación) sobre la productividad y concentración de Proteína bruta (PB) de gramíneas en distintas situaciones de calidad forestal y coberturas de copas de bosques de ñire, así como también procesos asociados: descomposición y dinámica de nutrientes (mineralización-inmovilización) de residuos del estrato arbóreo y graminoso y mineralización de nitrógeno del suelo. La productividad de materia seca (MS) aérea de gramíneas (rango entre 135 a 1863 kg MS ha-1) estuvo positivamente asociada a la calidad forestal de los sitios, mientras que el efecto de las coberturas de copa dependió de la interacción con otras variables ambientales. Los valores de PB variaron principalmente según la cobertura de copa encontrándose los mayores valores en lugares más sombreados (transmisividades < 70 %). La descomposición, tanto en hojas de ñire como en gramíneas, varió según el nivel de radiación, siendo mayores en los lugares con menor cobertura. Por otro lado, la dinámica de nutrientes no fue afectada por la CS o alguna variable estudiada. La mineralización de nitrógeno del suelo fue mayormente afectada por la humedad del suelo y el efecto de la cobertura de copa según la calidad del sitio forestal. Finalmente con los datos obtenidos e información de bibliografía se generó un modelo de simulación de productividad de MS y concentración de PB de gramíneas creciendo en bosques de ñire. El modelo generado después de ser sometido a diferentes pruebas se considera aceptable para ser usado como una herramienta de manejo sustentable en estos sistemas, aportando además nuevos conocimientos sobre las causales en la variación productiva y de calidad de los pastizales en bosques de ñire.

Bosques Mixtos de Nothofagus pumilio y N. betuloides: ¿Son Estables? Aproximación basada en el estudio de las primeras etapas de su ciclo de regeneración natural

Thesis

Mar 2019

Mónica Toro Manríquez

Introduction: Variation in reproductive phenology among species is an important mechanism to maintain species coexistence in mixed forests. In these forests, the impact of the limiting factors (biotic and abiotic) on the reproductive success may influence the proportions of species that conform them, varying between a stable condition and a transition towards monospecific forests. This study offers an approximation based on the first stages of the natural regeneration cycle in mixed deciduos-evergreen Nothofagus forests of Tierra del Fuego, testing the flowering, pre-dispersal and post-dispersal of nuts, recruitment and survival of regeneration seedlings, and loss factors in each stage, in three mixed forest types: with dominance of the deciduous species Nothofagus pumilio, with a dominance of the evergreen species Nothofagus betuloides and with a proportion of approximately 1:1 of both species, comparing two geographical locations (coast and mountain), during three entire regeneration cycles (C1: 2013-2014, C2: 2014-2015, C3: 2015-2016) and two years after the recruitment of the three produced cohorts (until January 2018). Objective: The purpose of this study was to determine whether the mixed Nothofagus forests of Tierra del Fuego, considering three different dominance conditions of N. pumilio and N. betuloides and two characteristic geographical locations, are in a stable state or represent transitions towards forest types with a dominance of single species, through the analysis of the first stages of its natural regener ation cycle (flowering, pre- and post-dispersal of nuts, recruitment and survival of seedlings), and the transition probability from the flower to the seedling. Study area: Mature even-aged Nothofagus forests (>250 years) without harvesting impact at south-west Tierra del Fuego, Argentina. Coastal stands were located close to the Beagle Channel within Tierra del Fuego National Park, while mountain stands were located inner the Island, in Garibaldi Pass (Fuegian Andes Mountains). Methodology: i) Characterization of the forest structure, microclimate, soil physico-chemical variables, and assemblages of understory (vascular and non-vascular) plants; ii) Installation of traps for the monthly collection of aboveground biomass, quantification of reproductive and non-reproductive structures in the stages of flowering, pre- and post-dispersal; iii) Monitoring of permanent regeneration plots to analyze the recruitment and survival of seedlings; (iv) Analysis of transition probabilities through an integrated approach. Results: The three forest types presented different characteristics in forest structure, microclimate, soils, and understory, according to their composition and phases of development. However, the location of the landscape exerted a strong influence on the structure of the canopy, the soils and the plants in the understory. The production of flowers, immature and mature nuts varied interannually for both species in forest types, where cycle 1 had disadvantages in dispersal regarding the other cycles. During flowering, the most vii important limiting factors for both tree species were the losses derived from empty nuts, which were attributed to a mechanism of self-incompatibility during the fertilization of the ovule. During pre-dispersal, the highest losses generated for both species were due to the premature fall of immature nuts, associated mainly with extreme climatic events (e.g., late frosts), but for N. betuloides, losses associated with biotic factors due to birds and insects were also important. In post -dispersal, N. pumilio presented in general higher losses associated with nuts foraging, and mostly in the mountains. For N. betuloides, these losses were similar in the different evaluated factors, although slightly larger by full nuts that do not germinate (due to abortion, dead or non-viable) before the winter stratification. At the end of each cycle, the proportion of potential seedlings for the recruitment was higher for N. pumilio and in mountain forests than for N. betuloides and in coast. However, N. betuloides presented a persistent and permanent bank of older plants, with higher survival over time, and more associated to microsites with bryophytes. Conclusion: The evaluation of biotic and abiotic factors were fundamental to detect the main losses of reproductive structures in regeneration cycle, being in many cases different between both studied species (e.g. greater losses by foraging in the post-dispersion in N. pumilio, but greater due to non-viable nuts and losses in the winter stratification for N. betuloides. The geographic location exerts a strong influence over the reproductive cycle of these species, being as important as forest type. The integrated approach shows that mountain stands had more probabilities to produce a seedling than the coas t, and that N. pumilio has a better transition probability than N. betuloides. Therefore, in mixed forests would tend to be no stable forests. Keywords: deciduous trees, evergreen trees, natural dynamic, geographical location, Tierra del Fuego

The relative importance of soil properties and regional climate as drivers of productivity in southern Patagonia’s Nothofagus antarctica forests

Article

Full-text available

Jun 2018

Key message: Soil texture and temperature-related variables were the variables that most contributed toNothofagus antarcticaforest height in southern Patagonia. This information may be useful for improving forest management, for instance related to the establishment of silvopastoral systems or selection of suitable sites for forest reforestation in southern Patagonia. Context: Changes in forest productivity result from a combination of climate, topography, and soil properties. Aims: The relative importance of edaphic and climatic variables as drivers of productivity in Nothofagus antarctica forests of southern Patagonia, Argentina, was evaluated. Methods: A total of 48 mature stands of N. antarctica were selected. For each study site, we measured the height of three mature dominant trees, as an indicator of productivity. Seven soil, five spatial, and 19 climatic features were determined and related to forest productivity. Through partial least squares regression analyses, we obtained a model that was an effective predictor of height of mature dominant trees in the regional data set presented here. Results: The four variables that most contributed to the predictive power of the model were altitude, temperature annual range, soil texture, and temperature seasonality. Conclusion: The information gathered in this study suggested that the incidence of the soil and temperature-related variables on the height of dominant trees, at the regionally evaluated scale, was higher than the effect of water-related variables. © 2018, INRA and Springer-Verlag France SAS, part of Springer Nature.

Effects of alternative silvicultural systems on litter decomposition and nutrients dynamics in sub-Antarctic forests

Article

Full-text available

Jun 2019
AGROFOREST SYST

Forest harvesting is one of the main economic practices in South Patagonia. The impacts produced by forest harvesting have been studied by numerous investigations. And it is known that forest harvesting affects the decomposition of soil organic matter. However, there is no data about how the harvesting by variable-retentions affect this decomposition. Our objective was to determine how impact variable-retention upon decomposition and nutrient release in Nothofagus pumilio forest soils. We hypothesized that variable-retention accelerate decomposition and nutrient release. We compared primary and harvested forests with two types of retentions (aggregated and dispersed) and two times [1 and 5 years after harvesting (YAH)]. To measure litter decomposition, we used bag technique for to determine organic matter loss. We determined carbon; nitrogen; calcium; potassium; magnesium and lignin concentrations in decomposing material. We analysed the data using linear mixed models ANOVA. Decomposition rates were estimated as derivate of the linear mixed model for the logarithm of the remaining leaf litter weight. We found that dispersed retentions treatment had the highest decomposition rates. Primary forest and aggregated retentions had the smaller slopes of the decomposition model. Dispersed and aggregated retention 5 YAH retained more nitrogen compared to primary forest. Dispersed retention 5 YAH had the lowest C/N ratio. Primary forest had higher Lignin/N ratio at 540 incubation days. Dispersed retention 5 YAH released more phosphorus compared to primary forest. Dispersed and aggregated retention 1 YAH had higher C/P ratio. Dispersed retention 5 YAH presented the most mineralization of potassium in the initial time of decomposition. We conclude that the harvesting by variable-retentions had an immediate negative effect on litter decomposition and the nutrients dynamics.

Thinking in the sustainability of Nothofagus antarctica silvopastoral systems, how differ the responses of seedlings from different provenances to water shortage?

Article

Full-text available

Apr 2019
AGROFOREST SYST

Nothofagus antarctica, is the most important species of the silvopastoral systems of southern Patagonia. However, there is limited information on the ecophysiological response mechanisms of seedlings for survival under different resource availability regimes, and whether such processes may differ between provenances. In this study, we evaluated the functional response to water shortage of seedlings of four N. antarctica provenances grown under controlled conditions. After an initial full irrigation period, seedlings were subjected to a water shortage cycle. Measurements of the diameter at the base of the stem, net photosynthesis (An), stomatal conductance to water vapour (gs), predawn water potential (Ψpd), osmotic potential at maximum and zero turgor (Π100; Π0), relative water content at zero turgor (RWC0) and maximum modulus of elasticity (Emax) were carried out during the experimental period. Differences between provenances concerning An and gs rates were recorded under full irrigation conditions, but were not detected in association with drought stress. All provenances had similar osmotic potential values (Π100 and Π0) at full irrigation, but water shortage led to significant osmotic potential differences between provenances. During the whole experimental period, no significant differences on RWC0 and Emax values were recorded among provenances. Under full irrigation conditions, all N. antarctica provenances had a similar physiological performance which suggests that environmental conditions may be the main driver for phenotypic differences in this species. From the osmotic adjustment results gathered, it is derived that a major osmoregulation capacity in response to water shortage is a common feature of all the N. antarctica provenances evaluated.

Rendimiento de distintos sistemas de aprovechamiento en la corta de protección de un bosque de Nothofagus pumilio

Article

Full-text available

Nov 2017

Nothofagus pumilio is the most important timber native species of south Patagonia in Argentina and Chile. Total volume stock and timber production change according to site quality, occupation degree, growth development phases and management history of the stands. The aim of this work was to evaluate the yield of three different logging systems (short-logs, long-logs and full stems) under a shelterwood cut system of N. pumilio forest growing at a middle site quality stand in Tierra del Fuego (Argentina). Sample plots were obtained in an old-growth two strata stand (3.0 ha) with abundant regeneration (stand density index of 93.8-113.4 %). Total volumes per hectare varied between 726.5 and 850.3 m3 ha-1. The volume/basal area ratio varied from 11.8 to 12.1 m3 m-2. Yield indexes obtained were 45.5 % for full stems, 21.3 % for long-logs and 22.4 % for short-logs logging systems. A model performed to estimate the timber volume for each system shows that full stems is significantly different from the other two. Several studies related to timber production were compared and discussed. Thus, applying full stems system results in a higher timber volume. Considering new alternatives in the planning of N. pumilio forests allows for higher harvest rates, increasing profits for the forestry company and minimizing the damage to the forest.

Litter production in the Nothofagus forests of Tierra del Fuego, Argentina

Article

Oct 2016

2016 Bahamonde semillas ñire

Data

Aug 2016

Ten years of seed production and establishment of regeneration measurements in Nothofagus antarctica forests under different crown cover and quality sites, in Southern Patagonia

Article

Full-text available

Jun 2018
AGROFOREST SYST

This study evaluated the seed production and quality and the subsequent regeneration establishment in five pure Nothofagus antarctica forests growing at different site qualities and crown cover during 10 years, in Southern Patagonia (Argentina). Four traps of 1 m2 were installed in each stand and sampled monthly (between February and May) each year. The incorporation and survival of seedlings were evaluated using four permanent plots of 1 m2 in each stand. The site quality of the studied forests did not influence seed production and regeneration. The amount of seed production and seed quality were proved to have a decisive influence on the N. antarctica seedling establishment in the subsequent years. At the same time, our results suggest that independently of the site class, the canopy openness for silvopastoral use improved the conditions for seedling establishment. However, the success of seedling survival over time would be conditioned for the influence of other factors such as understory competition.

Exportación de nutrientes en bosques de Nothofagus antarctica (ñire) raleados para uso silvopastoril. Pautas para su atenuación.

Conference Paper

Full-text available

May 2015

Este trabajo analizó flujos de nutrientes en bosques de ñire con y sin uso silvopastoril en Patagonia Austral, como base para sugerir pautas de manejo sustentable en estos sistemas. Basados en datos reportados en bibliografía, se calcularon valores de cada nutriente a nivel de árbol individual en función de su edad, clase de copa (CC) y la clase de sitio (CS). Se estimaron los contenidos de nutrientes a nivel rodal para bosques sin intervención (BSI) y las exportaciones generadas por raleos para uso silvopastoril (USP). Similarmente, con datos medidos durante 10 años se calculó la variación en el aporte de nutrientes provenientes de hojarasca en función de raleos en diferentes CS. Los cálculos se hicieron para dos tipos de raleo determinados por diferencias en las proporciones de CC remanentes y dos CS. Los valores de exportación de (C) por raleo tendrían distintas intensidades dependiendo de la CS y de cada tipo de raleo. Al modificar las proporciones de CC remanentes post raleo en ambas CS se redujo la exportación de C, de 31 a 20% y de 16 a 8% para CS IV y V, respectivamente. El porcentaje de exportación de otros nutrientes varió entre CS. La reducción del retorno potencial de nutrientes anual por hojarasca, no varió entre CS para un mismo tipo de raleo. No obstante, tales pérdidas también se verían disminuidas modificando la estructura de los árboles remanentes posterior al raleo para ambas CS. Esta información permite proponer pautas de manejo silvícola que tiendan a disminuir las exportaciones de C y otros nutrientes generadas por los raleos a corto plazo.

Exportación de nutrientes en bosques de Nothofagus antarctica (ñire) raleados para uso silvopastoril. Pautas para su atenuación

Research

Full-text available

Jun 2015

Trabajo presentado en el 3º Congreso nacional de Sistemas Silvopastoriles y VIII Congreso internacional Sistemas Agroforestales, Argentina 2015.

Ecorregión Bosques Patagónicos

Chapter

Full-text available

Jan 2012

Silvia Diana Matteucci

POTENCIALIDAD DE LA COSECHA Y RENDIMIENTO INDUSTRIAL DE BOSQUES DE Nothofagus antarctica EN TIERRA DEL FUEGO (ARGENTINA) (1)

Article

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2) CADIC-CONICET. Casilla 92 (9410) Ushuaia, Argentina. cadicforestal@cadic.gov.ar. (3) UNLP, Cátedra de Biometría Forestal., La Plata, Argentina. (4) UNPA-INTA-CONICET, Río Gallegos, Argentina. RESUMEN: La propuesta silvícola para bosques de Nothofagus antarctica es el manejo silvopastoril, siendo la limitante para su implementación la falta de mercado para los productos madereros generados durante su aplicación. En Tierra del Fuego (Argentina) existen más de 180 mil ha, de las cuales 23% pertenecen a sitios medio-altos (>11,5 m de altura). El potencial de cosecha y el rendimiento industrial fueron analizados en 12 parcelas de 500 m², cuya área basal fue 58,7±11,5 m².ha -1 (promedio ± desvío estándar) con un remanente de 29,9±7,6 m².ha -1 luego de la aplicación de raleos. El volumen cosechado fue 102,2±29,0 m 3 .ha -1 . El rendimiento en aserradero (127 trozas en 20 paquetes de muestreo) varió con la calidad y el tamaño de las trozas. Trozas >30 cm presentaron rendimientos del 34, 10, y 4% para calidades alta, media y baja, respectivamente. Trozas <30 cm de alta calidad presentaron rendimientos del 27%, y 10% para la de calidad media. Las trozas >30 cm de mejor calidad produjeron 9% de tablones, 21% de tablas, 49% de tirantes, 5% de madera corta y 16% de madera para pallet y las trozas <30 cm produjeron 0-1, 8-11%, 30-53%, 7-16% y 32-43%, respectivamente. Los rendimientos sugieren la posibilidad de incorporar al aserrado solo trozas de alta calidad de cualquier diámetro, lo que representa rendimientos de cosecha de 50,0±27,9 m 3 .ha -1 para bosques de calidad de sitio media-alta. Considerando solo el punto de vista maderero, los rendimientos obtenidos pueden solventar la aplicación de los tratamientos silvopastoriles con ingresos brutos de hasta U$S 3500 por hectárea. (1) Estudio financiado por el proyecto PID2005 35648 (SECYT-Argentina), y gracias a la colaboración del Aserradero Kareken y la Consultora "Servicios Forestales" (Tierra del Fuego -Argentina).

Caracterización y cartografía fitoclimáticas del bosque nativo subantártico en la Isla Grande de Tierra del Fuego (Patagonia, Argentina)

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Resumen La Isla Grande de Tierra del Fuego presenta una muy marcada originalidad fitoclimática por su posición en latitu-des muy australes, por estar rodeada de grandes masas de agua y por su cercanía a la gran masa de hielo polar antár-tica. Esta originalidad se traduce en un escaso calor estival y en una oscilación térmica muy reducida como principa-les peculiaridades, dando lugar en sus porciones arboladas a paisajes boscosos dominados por fisionomías planifolias de carácter micrófilo, tanto perennifolias como caducifolias del género Nothofagus. Este trabajo profundiza en las hasta hoy escasamente conocidas condiciones fitoclimáticas de este territorio, mediante la calibración y validación de un modelo de idoneidad fitoclimática respecto de las principales unidades fisionómicas de vegetación y el esta-blecimiento de una cartografía fitoclimática. Se discuten las causas que provocan la existencia de formaciones plani-folias en condiciones térmicas que darían lugar a formaciones aciculifolias o desarboladas en el hemisferio Norte, así como las particularidades edáficas que condicionan la presencia de la estrategia perennifolia representada por No-thofagus betuloides en los bosques mixtos subantárticos. Palabras clave: fitoclimatología, envolvente convexa, modelización, Nothofagus, haya, estepa.

Predicción del diámetro a la altura de pecho en función de las dimensiones del tocón de árboles de lenga (Nothofagus pumilio) en Tierra del Fuego, Argentina

Article

Full-text available

Dec 2006

The lenga state forests of Tierra del Fuego, Argentina, historically have sustained most of the province forest industries. These forests generally were used without appropriate silvicultural criteria and with a harvesting rate that possibly will finish the fiscal reserves of old growth productive forest in the short term. In order to avoid this situation towards a sustainable management, it's necessary to reduce the annual rate of harvesting, to implement silvicultural criteria, to perform a stronger State control and to evaluate the incorporation of harvested areas that have recovered their productivity, defining specific management criteria for these forests. For this last point it's necessary to know the initial characteristics of the stands and the harvesting characteristics. In order to construct a tool that offers basic information for specific decision making at stand level, data of 973 trees (d, dh, h) were collected, distributed in 60 sites throughout the Fagnano lake basin. Predicting models of d, based on the other two variables, were adjusted using the stepwise method. Given the found heterocedasticity, the procedure was repeated with logaritmized variables. Model (R²= 0,971; EEE = 0,0324) was choose. This tool will be useful both to determine the original structure of the forest and to find out the harvesting characteristics. The use of variables such us stump diameter and height, and stand related variables such us site quality and structure is discussed.

Partición diferencial de nutrientes en árboles de Nothofagus antarctica creciendo en un gradiente de calidades de sitio en Patagonia Sur

Article

Full-text available

Dec 2012

Nothofagus antarctica (ñire) es una especie nativa caducifolia que crece al sur de Argentina y Chile. Estudiar la distribución de nutrientes en árboles es importante como base para el entendimiento de la dinámica de los mismos en sistemas forestales. El enfoque alométrico permite evaluar, mediante el estudio de las pendientes, cómo es la distribución de recursos entre los componentes aéreos y subterráneos de ñire. Con datos publicados de contenido nitrógeno, fósforo, potasio, calcio, azufre y magnesio en árboles individuales de diferentes edades (5-220 años) y clases de copas creciendo en distintas calidades de sitio, se ajustaron regresiones que evaluaron las distribuciones: aéreo-subterráneo; hojas-raíces y hojas-tallos. Se compararon las pendientes de dichas regresiones mediante ANDEVA para detectar diferencias según la calidad de sitio. Las relaciones alométricas exploradas mostraron buen ajuste para todos los nutrientes. La partición de nutrientes varió según cada nutriente y según la calidad de sitio. En la relación aéreo-subterráneo, el magnesio fue destinado más a la porción aérea en el mejor sitio, mientras que en la peor calidad de sitio se observó el gradiente calcio > nitrógeno > magnesio > fósforo = potasio = azufre para los exponentes de dicha relación. Asimismo, árboles creciendo en la peor calidad de sitio destinaban mayor proporción de nutrientes hacia las raíces, mientras que el mejor sitio presentó el patrón contrario. Los resultados indican que N. antarctica presentaría cierta plasticidad de distribución de recursos según el sitio donde se desarrolla, característica que le permitiría crecer en una amplia variedad de condiciones ambientales.

Propuesta tipológica forestal para los bosques de Quercus pyrenaica de la comarca del Bierzo del noroeste de España, empleando análisis multivariante

Article

Full-text available

Jan 2009

El objetivo de este trabajo fue proponer una tipología para Quercus pyrenaica en la comarca del Bierzo, España, aplicando estadística multivariante a las parcelas del tercer Inventario Forestal Nacional (IFN3). Fueron seleccionadas seis variables descriptoras y calculadas otras nueve auxiliares; la composición se representó con el valor de cobertura y la estructura de edades con tamaños de los diámetros en cuatro clases. Así, esta tipología se elaboró sobre la base de 15 variables. Las etapas del análisis estadístico fueron análisis factorial y determinación de factores con máxima varianza explicada, confección de dendrograma para determinar el número de tipos, y análisis discriminante para hallar las variables con mayor poder de discriminación. El grupo de variables se consideró adecuado para la determinación de la tipología a la luz de los estadísticos logrados. Así, fueron encontrados seis tipos que describen adecuadamente las condiciones de dehesas, latizales puros o degradados y bosques mixtos que han sido propuestos con frecuencia para la Comunidad de Castilla y León. Esta metodología permitió además establecer una clave dicotómica para asignar nuevas situaciones a los tipos propuestos, mediante el uso de parámetros cuantitativos diferenciadores y de fácil observación en campo. Considerando las similitudes entre los bosques de Nothofagus spp. sudamericanos y los de fagáceas europeas en que se han desarrollado las tipologías, hacen de éstas una prometedora herramienta de gestión forestal para Chile y Argentina.

Phytoclimatic segregation of subAntarctic Nothofagus woodland types in Tierra del Fuego, southern South America

Article

Full-text available

Sep 2012

Background: Climatic variables determining the most suitable sites for the woodlands of Tierra del Fuego are not yet as well understood as those related to their geographical range.Aim: The aim of this paper is to provide some insights into the relationships between climatic niche and current distribution of three Nothofagus species in Tierra del Fuego. Methods: We have identified the climatic variables responsible for the most suitable sites for three sub-Antarctic Nothofagus woodland types within their climatic ranges by calculating suitability indices, using the CLIMPAIR niche-based phytoclimatic model.Results: The distribution range of the major Nothofagus woodlands is mainly driven by variables related to water stress, whereas phytoclimatic suitability is mainly driven by thermal variables related to warm summer temperatures for Nothofagus betuloides and N. pumilio and to winter cold for N. antarctica that are also mainly responsible for the peculiarity of the Fueguian climate.Conclusions: These findings introduce a new perspective in the study of the Nothofagus ecology, based on the climatic traits responsible for the high suitability locations instead of the traditional focus on the overall geographical distribution.

Equivalent impacts of logging and beaver activities on aboveground carbon stock loss in the southernmost forest on Earth

Article

Full-text available

Oct 2023

The conservation of forest landscapes is crucial for global climate strategies, and the forest in Tierra del Fuego, located in Patagonia, represents the southernmost example on Earth. These ecosystems are critical for Chile’s roadmap toward carbon neutrality. Unfortunately, these ecosystems have been impacted by logging and beaver activities. Currently, the precise contribution of each driver to forest cover and carbon stock loss remains insufficiently quantified, impeding effective policymaking and the implementation of strategies to safeguard and enhance carbon stocks in these ecosystems. In this study, we conducted an assessment of forest carbon stock loss resulting from both logging and beaver activities in Chilean Tierra del Fuego from 1986 to 2019. While beavers have received significant attention for their substantial contribution to forest cover loss (56.1% forest cover, ≈ 1.4 MtC), our findings suggest that logging has nearly equally contributed to carbon stock depletion (43.8% forest cover, ≈ 1.2 MtC). Consequently, the prevailing focus on beavers has obscured the ongoing logging-induced carbon stock loss. The implications of our study highlight the urgency for comprehensive consideration of both drivers in Chile’s climate strategy to fulfill the country’s mitigation commitments.

Reproductive rates of invasive Castor canadensis respond to management in Tierra del Fuego, Argentina

Article

Aug 2022

The effects of population management on reproductive traits of invasive mammals are poorly known (specifically concerning trapping aimed to reduce population density). The beaver (Castor canadensis) is an invasive species on Isla Grande de Tierra del Fuego (“Isla Grande”), Argentina, with significant ecological impacts. At seven pilot areas of Isla Grande subject to an experimental eradication program between 2016 and 2018, we assessed the effect of several population management histories (removal intensities of individuals) on age-specific fecundity and fertility rates and reproductive values of beaver females. We also proposed a reproductive schedule for Isla Grande. Reproductive rates were found to increase with population management intensity, by contrasting: (1) areas with historic management (historical trapping) showed high production of kits at earlier ages; (2) areas with focused management diminished the reproductive value; (3) an area reinvaded after an eradication presented higher reproductive values, delays in breeding onset, and late senescence; and (4) areas without or with very low management (without trapping) produced less kits, with later breeding onset and senescence at the middle of the life cycle. Gestation and parturition periods in the pilot areas were longer than previously reported in Tierra del Fuego. When beavers reinvade an area, they express their maximum reproductive potential. Also, the removal of animals at areas without previous management would relax density-dependence of reproductive rates. The value of beaver control by landowners needs to be reevaluated. Focusing trapping effort on the estrus period would reduce beaver fertility while also reducing the impact of capturing lactating females on offspring welfare. Continuity in the active surveillance to remove re-invaders represents the main challenge to restore the Fuegian environment affected by beavers.

Abiotic and Biotic Resources

Chapter

Aug 2021

Hernan De Angelis

It presents the general, environmental and geological framework of the studied area, with special emphasis on recording the biotic and abiotic resources that may become available in the different environments. The hunter-gatherer and fisherman groups that inhabited the Big Island of Tierra del Fuego exploited a wide range of natural resources (Fig. 1.1). It could even be said that they exploited all the resources at their disposal, both biotic (plants, fungi and fauna) and abiotic (e.g. lithic), for a large number of activities: subsistence, technological and symbolic. The knowledge they had about the climatic conditions, the topography and its possibilities of use and exploitation, the available resources distributed throughout the Fuegian archipelago, allowed them to occupy the area for at least 10,000 years. For this reason, it is of fundamental importance that archaeological investigations integrate a detailed and comprehensive study of the geological and climatic aspects, as well as the environment in which the societies under study develop. However, it is advisable that the presentations on the natural part of the environment focus on those characteristics that are either resources (e.g. lithic and food) or can act on human activities such as mobility (e.g. snow load and flood plains). This approach to resources, both biotic and abiotic, chosen and exploited, allows us to understand the relationships between them, the way they are obtained, used and the ends pursued. Within the present work, the study of resource management takes a central role. This is due to the relationship that existed between them, but also, and fundamentally, to the fact that resource management is a process that involves choices and decisions that are deeply embedded in social dynamics.

Variable retention harvesting influences belowground plant-fungal interactions of Nothofagus pumilio seedlings in forests of southern Patagonia

Article

Jul 2018

Background The post-harvest recovery and sustained productivity of Nothofagus pumilio forests in Tierra del Fuego may be affected by the abundance and composition of ectomycorrhizal fungi (EMF). Timber harvesting alters EMF community structure in many managed forests, but the impacts of harvesting can vary with the management strategy. The implementation of variable retention (VR) management can maintain, increase, or decrease the diversity of many species, but the effects of VR on EMF in the forests of southern Patagonia have not been studied, nor has the role of EMF in the regeneration process of these forests. Methods We evaluated the effects of VR management on the EMF community associated with N. pumilio seedlings. We quantified the abundance, composition, and diversity of EMF across aggregate (AR) and dispersed (DR) retention sites within VR managed areas, and compared them to primary forest (PF) unmanaged stands. EMF assemblage and taxonomic identities were determined by ITS-rDNA sequencing of individual root tips sampled from 280 seedlings across three landscape replicates. To better understand seedling performance, we tested the relationships between EMF colonization, EMF taxonomic composition, seedling biomass, and VR treatment. Results The majority of EMF taxa were Basidiomycota belonging to the families Cortinariaceae ( n = 29), Inocybaceae ( n = 16), and Thelephoraceae ( n = 8), which was in agreement with other studies of EMF diversity in Nothofagus forests. EMF richness and colonization was reduced in DR compared to AR and PF. Furthermore, EMF community composition was similar between AR and PF, but differed from the composition in DR. EMF community composition was correlated with seedling biomass and soil moisture. The presence of Peziza depressa was associated with higher seedling biomass and greater soil moisture, while Inocybe fibrillosibrunnea and Cortinarius amoenus were associated with reduced seedling biomass and lower soil moisture. Seedling biomass was more strongly related to retention type than EMF colonization, richness, or composition. Discussion Our results demonstrate reduced EMF attributes and altered composition in VR treatments relative to PF stands, with stronger impacts in DR compared to AR. This suggests that VR has the potential to improve the conservation status of managed stands by supporting native EMF in AR. Our results also demonstrate the complex linkages between retention treatments, fungal community composition, and tree growth at individual and stand scales.

Literature

Chapter

Jan 2008

Bernardo Gut

Silvicultural characterization of the mixed ñire forests of northern Patagonia as a basis for sustainable forestry

Article

Full-text available

Jan 2007

In spite of their wide geographical distribution and use, there are few publications about the silviculture of the forests with Nothofagus antarctica, locally named "ñirantales". The available publications report studies carried out in central to southern Patagonia, where "ñ ires" form forests of relatively tall trees. The traditional management of the ñire forests has been based in fuelwood production and silvopastoralism. Characterization of the forests of Lomatio-Nothofagetum antarcticae of the central basin of the Foyel River (Río Negro, Patagonia, Argentina) was carried out in order to provide methodological skills useful for the sustainable management of "ñirantales". We developed a typologic key, the silvicultural stand characterization of the different forest types present in the area and we established the local dendrometric equations for N. antarctica, Diostea juncea, Lomatia hirsuta, Schinus patagonicus. The studied forests showed a high variability between stands in close distance. Stem diameter distribution of the different forest types indicate that they are even aged groves in an intermediate development phase. Based on the current development stage of the stands, we suggest that it is possible to apply forestry models based on density regulation and complete canopy cover. Based on our results, we preliminary suggest that the implementation of silvicultural systems based on wood extraction can be seen as an alternative to current silvopastoral systems.

Report on basin response for Argentina (Deliverable 18 EPIC FORCE Project - INCO-CT2004-510739 - European Commission

Research

Full-text available

Aug 2015

Respuesta hidrológica de cuencas de Tierra del Fuego a eventos extremos y su vinculación al manejo del bosque y manejo del suelo en el contexto del proyecto UE Evidence-based Policy for Integrated Control of Forested River Catchments in Extreme rainfall and Snowmelt (EPIC FORCE)

PERI P.L.; ORMAECHEA S. (2013) Relevamiento de los bosques nativos de ñire (Nothofagus antarctica) en Santa Cruz: base para su conservación y manejo, 88 pp. Ediciones INTA, Buenos Aires. ISBN 978-987-679-219-6.

Book

Full-text available

Jan 2013

Caracterización silvícola de ñirantales del norte de la Patagonia para la gestión forestal sostenible

Article

Full-text available

Jan 2007

A pesar de la amplia distribución geográfica y uso de los ñirantales, son muy escasos los trabajos descriptivos sobre la silvicultura en estas comunidades forestales, centrándose principalmente en las zonas donde el ñire (Nothofagus antarctica) alcanza un mayor desarrollo arbóreo (centro y sur de la Patagonia). Tradicionalmente, el manejo de los ñirantales se ha basado en la obtención de leña y en la silvopascicultura. Con el objetivo de sentar bases metodológicas para la gestión forestal sostenible de los ñirantales se caracterizaron los bosques de Lomatio-Nothofagetum antarcticae de la cuenca central del río Foyel (Río Negro, Patagonia, Argentina), estableciendo una clave tipológica, así como la caracterización silvícola de los diferentes tipos de masa presentes en la zona y las ecuaciones dendrométricas locales para N. antarctica, Diostea juncea, Lomatia hirsuta y Schinus patagonicus. Los resultados indican que en la zona de estudio existe una marcada variabilidad y heterogeneidad espacial, apareciendo diferencias dasométricas entre rodales en muy corto espacio. Las distribuciones diamétricas de los distintos tipos de ñirantal muestran mayoritariamente formas principales de masa regulares en estado intermedio de desarrollo, abriéndose la posibilidad a considerar la implementación de modelos silvícolas basados en el manejo de la espesura y la ocupación completa del potencial productivo del sitio. Las variables dasométricas indican que además del actual manejo silvopastoril la implementación de modelos de gestión sostenible fundamentados en la obtención de biomasa leñosa puede ser una alternativa de manejo.

Turno de corta y posibilidad de los bosques de lenga (Nothofagus pumilio) en Tierra del Fuego (Argentina)

Article

Full-text available

Apr 2004

Turno de corta y posibilidad de los bosques de lenga (Nothofagus pumilio) en Tierra del Fuego (Argentina) 29 Turno de corta y posibilidad de los bosques de lenga (Nothofagus pumilio) en Tierra del Fuego (Argentina) Rotation length and sustainable use of lenga (Nothofagus pumilio) forests in Tierra del Fuego (Argentina) SUMMARY Forest regional planning is an important tool for developing forest policies for the protection of natural forests, the use of sustainable management and multiple use principles. It is necessary to use parameters and reliable models that simulate forest production and alternative land use capabilities. The forest inventory is the primary tool, but without precise estimations of rotation length it is not possible to obtain reliable data of sustainable forest use. For these reasons, the objective was to define a simple methodology to calculate the rotation length (harvest diameter of 40 cm), by analyzing the interaction and influence of: (a) livestock browsing pressure, (b) site quality, and (c) silvicultural management. Sustainable use of Tierra del Fuego forests in Argentina was investigated using several alternatives. Some assumptions were adopted for the silvicultural system, forest management objectives, stand growths and browsing pressure. These were methodologies and biometrical models selected from the bibliography. The methodology for rotation length estimation was defined and composed of three phases of tree growth, the establishment stage, initial growth and diameter growth. This was undertaken while considering livestock, silvicultural management and site quality. Models for rotation length estimation are presented and the effects of livestock pressure and silviculture (with or without) were analyzed in forests that varied between 94 and 200 years of age. Sustainable forest use calculated for the productive forests varied from 913 ha/year for the current situation to 1692 ha/year with silviculture and without browsing pressure. The rotation length varied considerably according to the site quality and the type of management used for the forest. The application of a single standard rotation length in all forest situations introduced large errors, with the weighted average data obtained being higher than those suggested for lenga. Finally, according to the rotation length values and sustainable forest use of Tierra del Fuego forests, several alternatives are discussed for adjusting harvesting rates toward a sustainable management of the forest resource.

Response of Nothofagus betuloides (MIRB.) oersted to different thinning intensities in Tierra Del Fuego, Argentina

Article

Full-text available

Dec 2002
INTERCIENCIA

El sector forestal de Argentina y Chile se ha desarrollado principalmente sobre la base del cultivo de especies exóticas, ocupando el bosque nativo un lugar secundario en la definición de políticas de investigación y desarrollo. Los bosques de Nothofagus conforman la totalidad del recurso maderero para los aserraderos en Tierra del Fuego. Existen numerosas propuestas de manejo mediante la aplicación de tratamientos intermedios y de ensayos de raleo, pero muy pocas en N. betuloides. Los objetivos de este trabajo fueron determinar el crecimiento y la dinámica forestal de un rodal joven, y evaluar las respuestas del crecimiento a tres niveles de raleo, comparándolas con las de un rodal no intervenido a lo largo de seis años. El rodal sin intervención de 46 años de edad tuvo un incremento diamétrico de 0,1 a 0,2cm/año, un incremento volumétrico de 6,3m³/ha·año y un autoraleo natural de 350 árboles/año. Este bosque respondió favorablemente a la aplicación de distintos niveles de raleo. El incremento en diámetro alcanzó los 0,52cm/año en el tratamiento más intenso (2000 individuos/ha), disminuyendo en proporción a medida que la intensidad del raleo decreció (0,37cm/año y 0,31cm/año para los tratamientos de 3500 individuos/ha y 5000 individuos/ha). En contraposición, la menor intensidad de raleo presentó los mayores incrementos volumétricos (13,6m³/ha·año) comparados con la mayor intensidad (9,5m³/ha·año). Nothofagus betuloides es una especie con un gran potencial para ser incorporada dentro de un manejo forestal intensivo, por los crecimientos que presenta y la respuesta a los tratamientos intermedios.

The alpine flora of Tierra del Fuego

Article

Jan 1975

D.M. Moore

Apuntes del tercer curso de silvicultura de los bosques de lenga

Jan 1994

H Schmidt
Y J Caldentey

SCHMIDT, H, y J. CALDENTEY, 1994. Apuntes del tercer curso de silvicultura de los bosques de lenga. CONAFCORMA-Universidad de Chile. Punta Arenas. 118 pp.

Manual de Utilización de ArcView Image Análisis

Jan 1998

ERDAS, 1998. Manual de Utilización de ArcView Image Análisis. ERDAS, Inc. Atlanta. USA.

Eduardo Martínez Carretero por su estímulo constante. A la Fundación CRICYT por su apoyo en la publicación de los mapas

estilísticas, y al Ing. Eduardo Martínez Carretero por su estímulo constante. A la Fundación CRICYT por su apoyo en la publicación de los mapas.

Explorando Tierra del Fuego. Zaguier & Urruty

Jan 1990
185-195

Bibliografía Borla
M Vereda Collantes
J Ontivero
O Bianciotto

BIBLIOGRAFÍA BORLA, M., M.VEREDA, 2001. Explorando Tierra del Fuego. Zaguier & Urruty. Ushuaia. 416 pp. COLLANTES, M., J. ONTIVERO y O. BIANCIOTTO, 1990. Análisis de las comunidades de Nothofagus en Tierra del Fuego. Parodiana 6: 185-195.

Manual de Utilización de ArcView Gis Enviromental Systems Research Institute

Jan 1996

Ch Usa Fitzgerald

ESRI, 1996. Manual de Utilización de ArcView Gis. Enviromental Systems Research Institute, Inc. Redlands, CA. USA. FITZGERALD, CH., 1997. Plan de manejo: Cuartel Aguas Blancas, cantón b.

Pflanzensociologische studien in Chile

Jan 1960

OBERDORFER, E., 1960. Pflanzensociologische studien in Chile. Fl. Veg. Mundi 2.

Algunos resultados de las investigaciones de manejo silvicultural que se realizan en los bosques andinopatagónicos de Argentina

Jan 1973
69-75

Y E Orfila

MUTARELLI, E.J. Y E. ORFILA, 1973. Algunos resultados de las investigaciones de manejo silvicultural que se realizan en los bosques andinopatagónicos de Argentina. Revista Forestal Argentina 17 (3): 69-75.

Relevamiento de vegetación de la cuenca del río Larsipharshak

Jan 1999

De Recursos Naturales Y Ambiente Subsecretaría
Humano

SUBSECRETARíA DE RECURSOS NATURALES Y AMBIENTE HUMANO, 1999c. Relevamiento de vegetación de la cuenca del río Larsipharshak. Subsecretaría de Recursos Naturales y A.H. Informe interno, inédito.

Inventario Forestal de la Zona Central de Tierra del Fuego

Jan 1978

Instituto Forestal Nacional

INSTITUTO FORESTAL NACIONAL (IFONA), 1978. Inventario Forestal de la Zona Central de Tierra del Fuego. INSTITUTO FORESTAL NACIONAL (IFONA), 1984. Precarta Forestal Nacional, Territorio Nacional de Tierra del Fuego. Instituto Forestal Nacional. 20 Pp.

Rodalización de los bosques de la margen sudeste del lago Fagnano

Jan 1999

De Recursos Naturales Y Ambiente Subsecretaría
Humano

SUBSECRETARíA DE RECURSOS NATURALES Y AMBIENTE HUMANO, 1999d. Rodalización de los bosques de la margen sudeste del lago Fagnano. Subsecretaría de Recursos Naturales y A.H. Informe interno, inédito.

Los bosques de Tierra del Fuego. Análisis de su estratificación mediante imágenes satelitales para el inventario forestal de la provincia

Abstract

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