Figura 10 - uploaded by Jesús Pozo
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3. Restos de madera en el cauce de un río, un recurso alternativo a la hojarasca del que no todos los organismos pueden hacer uso. Se aprecia el efecto sobre la retención de otros materiales y la heterogeneidad que genera en el cauce
Citations
... All these characteristics could promote the movement of genetic material from species present in the mountainous regions of the upper micro-basin towards the river and downstream to the study area. This statement is corroborated by the displacement of organic material, including DNA, in rivers (Pozo et al., 2009;Deiner et al., 2016). Likewise, it is necessary to consider that when working with eDNA in a river transect, it will not have eDNA exclusive to the species of the site. ...
Background
The development of anthropogenic activities has generated a decline in aquatic fauna populations, and amphibians have been the most affected. The decline of batrachofauna is concerning, as 41% of all species worldwide are endangered. For this reason, rapid, efficient, and non-invasive biodiversity monitoring techniques are needed, and environmental DNA (eDNA) is one such tool that has been sparsely applied in Ecuador. This technique has allowed scientists generates information on species diversity and amphibian community composition from a water sample. This study applied eDNA-based biomonitoring analyses and visual encounter surveys (VES) as inventory techniques to identify the diversity of aquatic amphibians in the Tena River micro-basin (TRMB).
Methods
The experimental design was divided into three components: (1) fieldwork: all amphibians were recorded by the VES technique and water samples were collected; (2) laboratory work: DNA isolation from amphibian tissue samples and eDNA-containing filters, amplification, electrophoresis, and sequencing were performed; (3) Data analysis: a local DNA reference database was constructed, and eDNA sequence data were processed for classification, taxonomic assignment, and ecological interpretation.
Results
Using both eDNA and VES, we detected 33 amphibian species (13 with eDNA only, five with VES only, and 15 with both methods). These species belonged to six amphibian families: Hylidae being the richest with 14 species (three eDNA, one VES, and 10 with both methods), followed by Strabomantidae with nine species (six eDNA, one VES, and two with both methods). All families were detected with both methods, except for the Aromobatidae, having one single record ( Allobates aff. insperatus ) by VES. Individually, eDNA detected 28 species and had a detection probability (DP) of 0.42 CI [0.40–0.45], while VES recorded 20 species with a DP of 0.17 CI [0.14–0.20]. Similarly, using VES, Cochranella resplendens was detected for the first time in TRMB, while with eDNA, four mountain frogs Pristimantis acerus, Pristimantis eriphus, Pristimantis mallii , and Pristimantis sp. (INABIO 15591) previously recorded at 1,518 m.a.s.l. at altitudes below 600 m.a.s.l. were detected.
Conclusions
Results obtained in this study showed that eDNA-based detection had a greater capacity to detect amphibians in aquatic environments compared to VES. The combination of VES and eDNA improves the sensitivity of species detection and provides more reliable, robust, and detailed information. The latter is essential for developing conservation strategies in the Ecuadorian Amazon.
... Entradas de MOPG: Con base en la metodología propuesta por Pozo et al. (2009) y Rodríguez-Barrios et al. (2008, en cada una de las quebradas de estudio se seleccionó un tramo de 100 m en el cual se midieron los aportes verticales de hojarasca utilizando 10 canastas de caída de 0.5 x 0.5 m en el centro del cauce. Para los aportes laterales se instalaron 10 trampas de 0.5 x 0.5 m en la margen derecha e izquierda de la fuente de agua, dispuestas cada 10 m, para un total de 30 canastas por quebrada. ...
Introducción:
La materia orgánica particulada gruesa originada en la vegetación ribereña es la fuente principal de energía en muchas cuencas de cabecera. Sin embargo, la transferencia de dicha materia es alterada por la destrucción de los bosques.
Objetivo:
Evaluar diferencias en la materia orgánica en quebradas con bosques y con pastizales.
Métodos:
Comparar las entradas, el almacenamiento y la exportación de esta materia orgánica en el cauce de quebradas con bosques y con pastizales, en la región central de los Andes de Colombia. En cada quebrada, se midieron los aportes verticales y laterales de hojarasca con canastas; hojarasca del lecho de las quebradas con cuadrantes, y la exportación de material con redes de deriva, con un alcance de 100 m.
Resultados:
Las quebradas con bosques ribereños recibieron un promedio anual de 915 g m⁻² de materia orgánica particulada gruesa, exportando un total de 334 g m⁻³ y almacenando 732 g m⁻², valores que fueron significativamente más altos que en quebradas con pastizales, donde los valores correspondientes fueron: 125.4 g m⁻²; 128 g m⁻³ y 205.5 g m⁻².
Conclusiones:
La remoción de cobertura boscosa de la zona ribereña reduce la materia orgánica en estas cuencas de cabecera en Colombia.
... Entradas de MOPG: Con base en la metodología propuesta por Pozo et al. (2009) y Rodríguez-Barrios et al. (2008, en cada una de las quebradas de estudio se seleccionó un tramo de 100 m en el cual se midieron los aportes verticales de hojarasca utilizando 10 canastas de caída de 0.5 x 0.5 m en el centro del cauce. Para los aportes laterales se instalaron 10 trampas de 0.5 x 0.5 m en la margen derecha e izquierda de la fuente de agua, dispuestas cada 10 m, para un total de 30 canastas por quebrada. ...
Introduction: Coarse particulate organic matter originated in riparian vegetation is the main source of energy in many headwater streams. However, the transfer of such material is altered by the destruction of forests. Objective: To assess flow differences of this organic matter in streams with forests and grasslands. Methods: We compared input, storage and export of this organic matter in the riparian belts of streams with forests, and streams with grasslands, in the central Andean region of Colombia. For each stream, we measured vertical and lateral litter with baskets; stream bed litter with a quadrant, and matter export with drift nets, in a 100 m reach. Results: The streams with riparian forest received an average of 915 g m-2 of coarse particulate organic matter annually, exported a total of 334 g m-3 and stored 732 g m-2, values that were significantly higher than in grassland streams, where the corresponding values were: 125.4 g m-2; 128 g m-3 and 205.5 g m-2. Conclusions: The removal of tree cover from the riparian zone reduced the organic matter in these headwater streams of Colombia.
... TP was analysed using acid digestion followed by evaluation of solubilised phosphorus as soluble reactive phosphorus (A.P.H.A. 2005). We estimated Ash Free Dry Weight (AFDW) of the CPOM using the Pozo et al. (2009) methodology. High and fast discharge prevented us from placing Surber sampler nets in G during October. ...
... We did not observe in the monthly samples significant differences in the amount of CPOM exported by the two streams. However, we cannot rule out the possibility that a stratified sample, taken weekly during the leaf fall period (Pozo et al. 2009), would have yielded a different result. However, we highlight the fact that in CP the CPOM was made up mainly of native N. pumilio leaves, while in G the dominant leaves were from the introduced species S. fragilis. ...
Fluvial dynamics are driven by multiple environmental factors and
scales. Studies coupling hydrological and nutrient dynamics of
mountain streams are almost non-existent in the Northern
Patagonian region; which is characterised by a temperate-cold
climate. We studied two adjacent streams with contrasting
drainage basins: Casa de Piedra (41°07′30.11′′S 71°27′13.16′′W),
which originates in a small mountain lake and runs through
pristine landscapes, and Gutiérrez (41°09′36.18′′S 71°24′37.19′′W)
that originates in a large piedmont lake and runs through an
anthropized landscape. The streams displayed contrasting
hydrological and nutrient dynamics. Casa de Piedra had higher
discharge flashiness with shorter response delays to precipitation.
Whereas the hydrology of Gutiérrez was buffered by the
upstream lake, its nutrient exports were not. Differences observed
in quality and timing in the export of coarse particulate organic
matter and levels of phosphorus and nitrogen are explained by
human activities affecting Gutiérrez but not Casa de Piedra.
Moreover, the ratio of nitrogen:phosphorus suggests that
phosphorus may be the limiting nutrient in the future, at the
more densely populated basin. To summarise, Northern
Patagonian streams flowing under marked geological and climate
similarities, display stark differences in dynamics of their adjacent
basins due to differences in topography and land use.
... Coarse particulate organic matter (CPOM) in rivers is composed of particles with a diameter larger than 1 mm (Pozo et al., 2009). CPOM in forest streams is mainly composed of plant materials including leaves, twigs, reproductive structures and fragmented materials that originate in the riparian vegetation that borders the channel (Webster et al., 1990;Pozo et al., 1997). ...
This work studies benthic CPOM in two streams of Ecuador: the Atacames stream, located in a developed watershed, and the Súa stream, located in a rural watershed and used as a reference. It is tested whether the amount, composition and timing of benthic CPOM will differ between them as a function of watershed and riparian land uses. Benthic CPOM was collected at five study sites on each stream with a Surber net and classified into four categories: leaves, twigs and bark, flowers and fruits and debris. Leaves were further identified to genus or species. There were no significant differences in the amount, composition and timing of benthic CPOM between the streams. CPOM storage showed strong seasonality linked to seasonal rainfall and a weak relation with land uses, channel width and stream order. Diversity of the benthic CPOM was high and 30 species contributed to the benthic leaf pool. Presence or absence of Ficus species with heavy leaves that are easily retained in the streambed explained the spatial distribution of benthic CPOM, so spatial differences in the composition of the riparian vegetation in these tropical streams seem to be more important to explain CPOM distribution than in their temperate counterparts.
... Leaves removed after 24 h were dried at 70°C for approximately 72 h, cooled in a desiccator for one hour and weighed to the nearest mg. With this mean air-dried mass and the initial mean mass (after air drying the leaves), we calculated a different coefficient (S) for each size of litter bag to correct for the effect of mass loss due to manipulation, dividing dry mass (DW) between initial (DWi) and air-dried (DWa) leaf mass (Bärlocher 2005;Pozo et al. 2009). Thus S= DWi/DWa. ...
... A second coefficient (C) was calculated as AFDMi / DWi for each litter bag size to further calculate AFDWi from DWi after each litter bag removal. The same process (obtaining of DW and AFDM) was followed after each removal, following the protocol in Benfield (2006) and Pozo et al. (2009) to obtain the percentage of AFDM remaining (%AFDM). Specific coefficients S and C were used for each litter bag size. ...
The goal of this study is to experimentally assess the possible effect of macroinvertebrate predators on the decomposition rate of leaves in a Mediterranean stream and to analyse the pattern of colonization by macroinvertebrates of the litter bags through time. We designed a factorial experiment with three types of litter bags (allowing the entrance of no macroinvertebrates, only small macroinvertebrates and small and large, top‐predators, macroinvertebrates). We measured the percentage of ash‐free dry mass remaining after 15, 30 and 45 days, as well as the macroinvertebrate community composition of the two types of litter bags where they were allowed to enter. We did not find differences in the ash‐free dry mass remaining between the two types that allowed the entrance of macroinvertebrates. The diversity of the community colonizing each type of litter bag was always relatively high and changed significantly with time and, in some cases, with the exclosure treatment studied. These results show the absence of important top‐down control of macroinvertebrates and particularly in those involved in the leaf decomposition in the food web of this Mediterranean stream that could have repercussions on the leaf decomposition process.
... Los bosques son los sistemas más productivos, y gran parte de la materia producida por la vegetación riparia termina en los ríos (Graça & Canhoto, 2006). En los ríos de bajo orden predomina el aporte alóctono de material orgánico (Webster & Benfield, 1974;Vannote et al., 1980;Boulton & Boon, 1991;Casas et al., 2000) siendo principalmente hojarasca, aunque también madera, frutos y flores (Casas et al., 2000;Graça & Canhoto, 2006;Pozo et al., 2009). Esto es debido a las bajas temperaturas del agua y a la sombra de la vegetación riparia (Abelho, 2001) al reducir la producción autóctona del perifiton (Graça & Canhoto, 2006). ...
... Reice, 1974;Abelho, 2001;Hieber & Gessner, 2002;Ferreira et al., 2006). La primera es una rápida pérdida de masa por lixiviación de los compuestos solubles y sencillos (como aminoácidos y carbohidratos) (Boulton & Boon, 1991;Pozo et al., 2009) principalmente en las primeras 24-48 h de inmersión (Webster & Benfield, 1974;De Lagrán et al., 2012), aunque es un proceso mucho más largo (Gessner et al., 1999). ...
... La siguiente fase es la colonización microbiana (bacterias y sobre todo hongos), actuando como descomponedores y alterando los compuestos complejos en otros más asimilables (acondicionamiento) al producir otros compuestos más digeribles para los detritívoros (Allan, 1995;Gessner et al., 1999;Pozo et al., 2009). La tercera fase es la degradación y consumo por parte de macroinvertebrados, con presencia continua de la abrasión física (Reice, 1974;Webster & Benfield, 1974). ...
Existe un gran flujo de energía en los sistemas forestales, siendo la descomposición el proceso encargado de reciclar los nutrientes y de controlar la productividad del sistema, así como la hojarasca el principal aporte de material orgánico en ríos de bajo orden. Esta descomposición depende de una gran variedad de factores y se divide en tres fases (lixiviación, acondicionamiento microbiano y fragmentación física y biológica). Este experimento se ha realizado en el arroyo de la Umbría (Sierra de Guadarrama, Madrid) y se ha estudiado la fase de la fragmentación y los macroinvertebrados asociados, siendo los factores estudiados la cantidad de masa inicial y el tipo de ambiente.
Durante el estudio se utilizaron 50 bolsas de malla con dos masas iniciales (5 y 10 g) de hojarasca senescente de chopo (Populus x canadensis Moench) y se colocaron en dos tipos de ambientes (pozas y rápidos) durante 29 días. Se calculó la cantidad de masa perdida de cada bolsa y se realizó un ANOVA de dos vías para determinar si la masa inicial y el ambiente afectaban a la descomposición. Los efectos de la masa inicial y del hábitat sobre la riqueza, la diversidad, la abundancia total de fauna y la de los taxones más abundantes (> 200 individuos) se testaron mediante un modelo lineal generalizado (GLM), ANOVA de dos vías, non-metric multidimensional scaling (MDS) y ADONIS.
Tanto la masa inicial como la interacción masa*ambiente afectó de manera significativa a la velocidad de descomposición, por lo que las diferencias entre ambientes dependieron de la cantidad de masa inicial. Cumpliendo con las hipótesis propuestas, las bolsas de 10 g perdieron más masa en rápidos que en pozas y, además, en los rápidos se encontró que las bolsas de 10 g se descompusieron más rápidamente que las de 5 g. Ni la masa inicial ni su interacción con el hábitat mostraron una influencia significativa sobre la abundancia, la riqueza, la diversidad total de macroinvertebrados ni la abundancia de los principales taxones. En cuanto al ambiente, únicamente condicionó la riqueza de taxones y afectó a solo dos de los siete taxones más abundantes. Sin embargo, tanto el MDS como el ADONIS muestran que el hábitat tuvo una influencia significativa sobre la composición general de las comunidades que colonizaron las bolsas.
... La cantidad de madera muerta depende tanto de los ciclos de regeneración (Buxó y Piqué 2008), de la composición y estructura del bosque (Pozo et al. 2009), así como del uso o manejo del mismo (Delgado y Pedraza 2002). ...
Para este estudio se cuantificó la biomasa seca acumulada en la capa de mantillo sobre el suelo y en la madera muerta, así como el contenido de carbono orgánico en el suelo (COS), en cuatro estadios de sucesión de bosque: 5 a 15 años, 15 a 30 años, mayores de 30 años y bosque primario. Se estableció un diseño simple aleatorio con sub-muestreo, cuatro tratamientos (estadio sucesional), cinco repeticiones (PPM) y cuatro muestras por PPM. La biomasa acumulada en la capa de mantillo fue mayor en bosques primarios con 9,75 t/ha, seguido por bosques mayores de 30 años con 7,93 t/ha, bosques de 15-30 años con 5,97 t/ha y por último bosques de 5-15 años con 5,60 t/ha. Los valores de biomasa en la madera muerta fueron de 7,80 t/ha en bosques primarios, 3,26 t/ha en bosques mayores de 30 años 5,84 t/ha, en bosques de 15-30 años y de 3,42 en bosques de 5-15 años. El carbono orgánico almacenado en el suelo fue mayor en bosques de más de 30 años (109,24 tC/ha), seguido por bosques primarios (92,29 tC/ha), 15-30 años (88,01 tC/ha) y por último bosques de 5-15 años (78,48 tC/ha-1). Se encontraron diferencias estadísticas (α = 0,05) en la biomasa de mantillo acumulada en bosques primarios respecto bosques de 5-15 años. Las tendencias mostraron un aumento en la cantidad de biomasa acumulada en la capa de mantillo conforme aumenta el estadio sucesional. La biomasa de madera muerta no mostró diferencias estadísticas respecto a la edad del bosque (α = 0,05). El carbono orgánico en el suelo (COS) mostró diferencias estadísticas (α = 0,05) en bosques de 5-15 años respecto a bosques mayores de 30 años.
Background
Cocoa is an important tropical tree crop that is mainly cultivated in agroforestry systems (AFS). This system, known as cabruca in northeastern Brazil, holds promise to reconcile biodiversity conservation and economic development. However, since cocoa AFS alters forest structure composition, it can affect litter dynamics in riparian zones and streams. Thus, our objective was to determine litter inputs and standing stocks in riparian zones and streams under three types of forest: managed cocoa AFS, abandoned cocoa AFS, and secondary forest.
Methods
We determined terrestrial litter fall (TI), vertical (VI) and lateral (LI) litter inputs to streams, and litter standing stocks on streambeds (BS) in the Atlantic Forest of northeastern Brazil. Litter was collected every 30 days from August 2018 to July 2019 using custom-made traps. The litter was dried, separated into four fractions (leaves, branches, reproductive organs, and miscellaneous material) and weighed.
Results
Terrestrial litter fall was similar in all forests, ranging from 89 g m ⁻² month ⁻¹ in secondary forest (SF) to 96 g m ⁻² month ⁻¹ in abandoned cocoa AFS (AC). Vertical input were higher in AC (82 g m ⁻² month ⁻¹ ) and MC (69 g m ⁻² month ⁻¹ ) than in SF (40 g m ⁻² month ⁻¹ ), whereas lateral input were higher in MC (43 g m ⁻² month ⁻¹ ) than in AC (15 g m ⁻² month ⁻¹ ) and SF (24 g m ⁻² month ⁻¹ ). Standing stocks followed the order SF > AC > MC, corresponding to 425, 299 and 152 g m ⁻² . Leaves contributed most to all litter fractions in all forests. Reproductive plant parts accounted for a larger proportion in managed AFS. Branches and miscellaneous litter were also similar in all forests, except for higher benthic standing stocks of miscellaneous litter in the SF. Despite differences in the amounts of litter inputs and standing stocks among the forests, seasonal patterns in the abandoned AFS (AC) were more similar to those of the secondary forest (SF) than the managed AFS, suggesting potential of abandoned AFS to restore litter dynamics resembling those of secondary forests.
Waterways act as integrators of ecosystems, their dynamics driven by multiple environmental factors and scales. To elucidate factors affecting hydrological and nutrient dynamics in Andean streams, we characterized two adjacent North Patagonian streams with contrasting drainage basins: Casa de Piedra (CP), originating in a small mountain lake and running through a pristine landscape, and Gutierrez (G), originating in a large piedmont lake and running through an anthropized landscape. The drainage basins share both temperature and precipitation regimes; however, the streams presented contrasting hydrological dynamics and nutrient export values. CP had higher discharge flashiness with shorter response delays to precipitation, while G showed more stable hydrograms, a difference explained by buffering from a large upstream lake in G&sacute basin. Streams showed differences in the quality and timing of coarse particulate organic matter export and basal export levels of phosphorus and nitrogen that could be explained by human activities affecting G but not CP. Moreover, nitrogen:phosphorus ratio indicates a possible shift to phosphorus as the limiting nutrient in the future in G drainage basin. In summary, our results show that even under a common climatic regime, dynamics of adjacent basins can be strongly driven by topographic and land use factors.
