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Enrichment of Pinus patula plantations with native species in southern Ecuador
Abstract and Figures
Se instalo un ensayo para evaluar el efecto facilitador de elementos arbóreos sobre la sobrevivencia, estado fisiológico y crecimiento de especies forestales nativas. El estudio se lo implemento en la plantación de Pinus patula cerca de la Estación Científica San Francisco; se seleccionaron dos tipos de cobertura: claros naturales y ambientes bajo dosel de la plantación. Para cada tipo cobertura se seleccionaron 4 parcelas; en total se plantaron 648 individuos de 9
especies diferentes. Las especies nativas fueron: Cedrela montana, Heliocarpus americanus, Tabebuia chrysantha, Cinchona officinalis, Piptocoma discolor, Alnus acuminata, Cupania sp.; Myrica pubescens, Isertia laevis; A los 12 meses, se han registrado sobrevivencias superiores al 90% para todas especies nativas a excepción de C. officinalis que alcanzo el 60%. El crecimiento en altura de las plántulas demuestra un evidente efecto positivo de la plantación, sobre todo en los claros naturales, pues a excepción de Cupania, y H. americanus todas las restantes especies nativas crecen mejor en ambientes con mayor cantidad de luz; destacándose A. acuminata. Concluyendo que el manejo silvicultural de plantaciones y la transformación de estos ecosistemas en ambientes mas funcionales y de mayor diversidad puede ser factible y además se puede obtener en menor tiempo debido al mejor crecimiento de las especies nativas.
Palabras claves: restauración, rehabilitación, bosque tropical, silvicultura de transformación.
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... As an example of this approach, in the south of Ecuador, a project started to convert the presented pine plantations into mixed forests by thinning pine plantations and underplanting the native tree species Cedrela montana and Tabebuia chrysantha. Both species exhibit intensive mycorrhization after transplanting in the field [108] and are of a high timber value [109]. Further native species like Alnus acuminata, Podocarpus oleifolius, Podocarpus sprucei, Lafoensio acuminata, Jacaranda mimosifolia, Cordia alliodora, and Triplaris cumingiana also have a high potential in the south of Ecuador [109]. ...
... Both species exhibit intensive mycorrhization after transplanting in the field [108] and are of a high timber value [109]. Further native species like Alnus acuminata, Podocarpus oleifolius, Podocarpus sprucei, Lafoensio acuminata, Jacaranda mimosifolia, Cordia alliodora, and Triplaris cumingiana also have a high potential in the south of Ecuador [109]. However, the effects of pine plantations on the success of the establishment of native tree species will vary with site conditions and the establishment of a forest site classification can help to develop site-specific measures to improve the effectiveness of forest conversion [109][110][111]. ...
... Further native species like Alnus acuminata, Podocarpus oleifolius, Podocarpus sprucei, Lafoensio acuminata, Jacaranda mimosifolia, Cordia alliodora, and Triplaris cumingiana also have a high potential in the south of Ecuador [109]. However, the effects of pine plantations on the success of the establishment of native tree species will vary with site conditions and the establishment of a forest site classification can help to develop site-specific measures to improve the effectiveness of forest conversion [109][110][111]. At sites with properties characteristic of the identified class C with the lowest pine productivity, thinning with the subsequent removal of pine trees will cause strong losses of nutrients, especially K and Ca. ...
Forest site classification adapted to the respective site conditions is one prerequisite for sustainable silviculture. This work aims to initiate the forest site classification for pine plantations in the southern Andean region of Ecuador. Forest productivity, estimated by the dominant height of 20-year-old trees (DH20), was related to data from climate, topography, and soil using 23 plots installed in pine plantations in the province of Loja. Forest site productivity was classified as: low (class C: 13.4 m), middle (class B: 16.6 m), and high (Class A: 22.3 m). Strong determinants to differentiate the forest site classes were: the short to medium term available Ca and K stocks (organic layer + mineral soil standardized to a depth of 60 cm), soil acidity, the C:N ratio, clay and sand content, forest floor thickness, altitude, and slope. The lowest forest productivity (Class C) is mainly associated with the lowest short to medium term available K and Ca stocks. Whereas, in site classes with the highest forest productivity, pines could benefit from a more active microbial community releasing N and P, since the soil pH was about 1 unit less acidic. This is supported by the lowest forest floor thickness and the narrowest C:N ratio.
... At the same time farmers may be able to improve their land yields, and to diversify their sources of income (Dawson et al., 2013;FAO, 2005;Sherr, 1995) [19][23] [59]. Most (90%) of the existing tree plantations in Ecuador are based on introduced species such as Pinus spp and Eucalyptus spp (Aguirre, et al., 2006) [2]. These species present some ecological problems that have caused a shift in interest towards use of native species (Mosandl and Günter, 2008) [11]. ...
... The probability that the central actor may return a tie or ask for information from an actor with less income may be very low. The special case of pine is related directly to timber wood, and therefore to income generation (Aguirre et al., 2006) [2]. This was verified by the negative twopath parameter, η 2P . ...
A case study in South Ecuador serves as an example to understand the dynamics of adoption of agroforestry species. Agroforestry species become
important in land that is totally devoid of forest cover. They can reduce
soil degradation, increase local biodiversity and at the same time increase
household income. Their use can be seen as a new practice that spreads
throughout a region by means of social networks. Sharing information
about this potentially sustainable agricultural innovation has become important in a region like southern Ecuador. In this region there are mainly
two ethnic groups, namely the Saraguro and the Mestizo-colonos. In the
first group are indigenous people and the latter are migrants from other
places of the country that went to settle the region during the agrarian
reform. The two ethnic groups do have different traditions and land use
practices.
Qualitative research shows that there are potential differences in adoption
of agroforestry tree species between two ethnic groups. The low adoption
rate of Saraguro communal leaders may be an indicator of lower contagion than Mestizo-colonos. Contagion refers to actor i adopting the same
innovation as actor j with whom actor i had contacted. It is proposed
a heterogeneous diffusion model that addresses network exposure effects
and a generalized blockmodel for relational data analysis. It was first hypothesized that the Saraguro indigenous group may have lower access to
the information necessary for the adoption of the innovation than MestizoColonos. Nonetheless, the results show that Mestizo-colonos have higher
adoption rate than Saraguros.
The network actors’ behaviour is shaped by local characteristics, for instance their ethnicity. For the analysis it was taken into account the search
for advice for the main agricultural activities for the household. On this
base, it is proved that indeed there are structural differences on search for
advice between ethnic groups. By analyzing ethnic subgroups, the subgroup of Mestizo-colonos has the actors with highest degree of centrality
and betweenness. These actors are in the highest cohesive block in cohesive block analysis. Furthermore, a high Burt’s constraint shows that low
access to structural holes in the network create a differentiation of information sharing between groups. Higher Burt’s constraint indicates less access
to the information located in other clusters in the network. The periphery
of the network plays an important role as a source of advice, as shown
by cohesive bloc analysis, which we complement with a k-core analysis.
The k-core analysis suggests that different and more diverse information is
accessed by Mestizo-colonos as compared to Saraguros. In applied terms
this suggests that Saraguros tend to share more similar information within
their group than do Mestizo-colonos.
In order to understand patterns of network structure the Exponential Random Graph Models (ERGM) become important. For example, ERGMs
help to valuate the importance of reciprocity in the network relations depending on how many reciprocal dyads are found in the observed network.
Fitting an exponential random graph model (ERGM) to the network, it is
shown that indeed there are differences between two ethnic groups in the
way they share information. We explore the network patterns in the sharing on agroforestry species. Sharing information with similar others is
limited to the less commercial tree species. The most commercial tree
species information is concentrated in one actor, who is Mestizo-colono.
Transitive network effects are identified within ethnic groups as long as
they share information on different tree species (others than pine). The
two ethnic groups share information of different tree species. This shows
a different knowledge, where Mestizo-colonos are more related with commercial species.
... Smallholders, who own the largest proportion of these plantations, practice no forest management due to economic and technical assistance deficiencies. In addition, most logging activities are done without considering technical advice (Aguirre et al. 2006). We considered two BAU scenarios for Alnus and Pinus, using a final harvest at 20 and 25 years for each, which was the common rotation time for plantations in the region (see Table 1). ...
Sustainable forest management requires tools to guide optimal silvicultural treatments. Timing and intensity of thinnings and timing of final harvest are key decisions. An Optimized Reforestation Management (herein, an ORM) model was developed to reach the optimal combination of thinning times, thinning intensities and rotation periods for Ecuadorian forest plantations of Alnus acuminata, Kunth and Pinus patula Schltdl. & Cham. The ORM model uses non-linear programing to simultaneously optimize the number of trees to harvest in a certain period in order to maximize the plantations’ annualized net present values (annuities). Results obtained for optimal silvicultural interventions were compared to current management practices in Ecuador, one with no interventions, and a second with a treatment schedule promoted by the Ecuadorian Ministry of Agriculture. ORM model delivered better financial performance for both species, compared to both alternative scenarios, in terms of annuities and payback periods. Thinnings scheduled by ORM tend to be later than recommended by existing schedules. For Alnus, only one thinning was optimal, independent of the discount rate, while for Pinus two thinnings were optimal for higher levels of the discount rate considered. It is recommended for private and public actors to consider these findings for future management of reforestation areas
... La restauración activa va dirigida a restaurar la cobertura vegetal o a recuperar la funcionalidad del ecosistema, el cual es un proceso integral y complejo que implica un gran esfuerzo. La restauración activa suele aplicarse a través de técnicas de enriquecimiento de plantaciones exóticas y mixtas (Aguirre et al., 2006;Beck et al., 2008;Mazón & Aguirre, 2016;Mazón et al., 2017;Murcia et al., 2017). Para la Región Sur del Ecuador, la plantación de enriquecimiento puede resultar una interesante opción para convertir plantaciones de especies exóticas en sistemas o ambientes más naturales, los cuales pueden contribuir a la restauración de la biodiversidad. ...
The planting of three forest species in Andean scrubland in southern Ecuador was experienced in two areas: one carrying out pure planting, planting 20 plants per block species, with three repetitions; and a second area with mixed plantation 20 mixed individuals in each block. Survival, mortality, average growth and annual periodic increase in diameter and height were calculated. Survival at 3 years: Cedrela montana in 37 % pure plantation and mixed 10 %, Jacaranda mimosifolia pure plantation 58 % and mixed 55 % and Lafoensia acuminata pure plantation 93 % and mixed 75 %. Annual mortality: Cedrela montana pure plantation 33 % and mixed 77 %, Jacaranda mimosifolia pure plantation 18 % and mixed 20 % and Lafoensia acuminata pure plantation 2 % and mixed 10 %. Growth in three years: Cedrela montana pure plantation diameter 0,18 cm and height 11,12 cm; mixed plantation diameter 0,36 cm and height 3,08 cm, Jacaranda mimosifolia pure plantation diameter 0,05 cm and height 0,38 cm; mixed plantation diameter - 0,003 cm and height 8,34 cm, Lafoensia acuminata pure plantation diameter 0,08 cm and height 21,95 cm; mixed plantation diameter 0,05 cm and height 4,83 cm. There is decrease in height in Cedrela montana and Jacaranda mimosifolia, this responds to the apical death of some individuals. There are differences in survival and growth between areas, due to the species used and biophysical factors of the sites.
... On the other hand, the facilitating effect of Pinus species in succession processes has already been well explored among restoration strategies such as the reintroduction of endangered tree species through the use of assisted regeneration; thus, the ecological and functional role of certain pioneer species may be of vital importance for the reestablishment of native ecosystems (Aguirre et al. 2006;Arrieta and Suárez 2006;Avendaño-Yáñez et al. 2016). Nevertheless, the use of evergreen conifers as nurse plants to establish Quercus spp. ...
- Key message: A positive effect of mixed pine forests (Pinus sylvestris L. and Pinus pinaster Ait.) on the understory richness and tree regeneration was observed with respect to monospecific stands. Understory species typical of the native Pyrenean oak forests in the Iberian Peninsula contribute to maintaining high understory richness in such mixed pine forests.
- Context: The influence of stands characteristics on the understory in mixtures that combine coniferous tree species of the same genus deserves more study since they are frequent in Spain.
- Aims To assess the effect of mixed versus monospecific stands of Pinus sylvestris L. and Pinus pinaster Ait. on the main tree species regeneration and understory species composition.
- Methods Tree regeneration and understory species composition were inventoried in eighteen forest plots (6 triplets) in North-Central Spain. Each triplet consisted of two plots dominated either by Scots pine or Maritime pine and one mixed plot that contained both species.
- Results The basal area (%) of both Pinus species was the only characteristic of the stands that significantly influenced the understory composition and tree regeneration. Characteristic species of humid and temperate zones, including P. sylvestris regeneration, dominated in Scots pine stands, and typical species of well-drained Mediterranean areas, including P. pinaster regeneration, dominated in Maritime pine stands. In mixed stands, the highest regeneration of the native Pyrenean oak with respect to monospecific stands was accompanied by understory species typical of native oak forests that share the same regeneration niche.
- Conclusion Mixed pine forests allow the development of understory species better than monospecific forests.
... La restauración activa va dirigida a restaurar la cobertura vegetal o a recuperar la funcionalidad del ecosistema, el cual es un proceso integral y complejo que implica un gran esfuerzo. La restauración activa suele aplicarse a través de técnicas de enriquecimiento de plantaciones exóticas y mixtas (Aguirre et al., 2006;Beck et al., 2008;Mazón & Aguirre, 2016;Mazón et al., 2017;Murcia et al., 2017). Para la Región Sur del Ecuador, la plantación de enriquecimiento puede resultar una interesante opción para convertir plantaciones de especies exóticas en sistemas o ambientes más naturales, los cuales pueden contribuir a la restauración de la biodiversidad. ...
Se experimentó la plantación de tres especies forestales en matorral andino en el sur
del Ecuador, en dos áreas: una realizando plantación pura, sembrando 20 plantas
por especie en bloque, con tres repeticiones y otra con plantación mixta, 20
individuos mezclados en cada bloque. Se calculó la sobrevivencia, mortalidad,
crecimiento medio e incremento periódico anual de diámetro y altura. La
sobrevivencia a los tres años: Cedrela montana en plantación pura 37 % y mixta 10
%; Jacaranda mimosifolia en plantación pura 58 % y mixta 55 % y Lafoensia
acuminata en plantación pura 93 % y mixta 75 %. La mortalidad anual: Cedrela
montana en plantación pura 33 % y mixta 77 %; Jacaranda mimosifolia en plantación
pura 18 % y mixta 20 % y Lafoensia acuminata en plantación pura 2 % y mixta 10
%. Crecimiento en tres años: Cedrela montana en plantación pura, diámetro 0,18
cm y altura 11,12 cm; plantación mixta, diámetro 0,36 cm y altura - 3,08 cm;
Jacaranda mimosifolia en plantación pura, diámetro - 0,05 cm y altura - 0,38 cm y
en plantación mixta, diámetro -0,003 cm y altura 8,34 cm; Lafoensia acuminata en
plantación pura, diámetro 0,08 cm y altura 21,95 cm y en plantación mixta diámetro
0,05 cm y altura 4,83 cm. Existe decrecimiento en altura en Cedrela montana y
Jacaranda mimosifolia; esto responde a la muerte apical de algunos individuos.
Existen diferencias de sobrevivencia y crecimiento entre áreas, debido a las especies
utilizadas y a factores biofísicos de los sitios.
... To decide which of the native tree species with higher ecological and/or economic stability (e.g. Cedrela montana, Tabebuia chrysantha, Cupania sp., Heliocarpus americanus, Isertia laevis, Myrica pubescens, Piptocoma discolor, and Cinchona officinalis Aguirre et al. 2006) should be planted under the shelter of pine versus alder further knowledge on the nutritional demands of these native tree species are necessary. ...
Information about nutrient dynamics is of upmost importance in order to contribute to the restoration of degraded forest environments in the Andes of southern Ecuador. This study aims to investigate the differences of nutrient dynamics between a native alder (Alnus acuminata) and an exotic pine (Pinus patula) tree species in this region. Based on litterfall, forest floor and mineral topsoil (0–20 cm) of two pine and two alder plantations, we studied the litterfall production and its seasonality; temporal variations of nutrient concentrations, stoichiometric ratios and potential nutrient return (PNR) of leaf-litterfall; mean residence times (MRT) of nutrients in the forest floor; and assessed soil biogeochemical properties. Our results showed that total litterfall production in pine was twice as high as in alder. Litterfall biomass seasonality was similar for both species and highly associated to periods with less precipitation. Pine exhibited the highest seasonality of nutrient concentrations and stoichiometric ratios. PNR of N, K, Ca, and Mn exhibited the major differences between the species. The annual PNR of N and Ca were higher in alder, while those of K and Mn were higher in pine. Pine exhibited higher MRT values for C, N, P, S, Cu, and Zn, while alder showed the higher for Mg, K, Mn, and Ca. In soils, alder exhibited higher concentrations and stocks of nutrients, but not for C. Although, the soil microbial biomass was similar under both species, microbial activity was different. C and net N mineralization were higher in alder, and nitrification dominated over ammonification processes. In general, our findings show a faster cycling of nutrients in alder than in pine.
... Los procesos antrópicos generalmente van dirigidos a restaurar la cobertura vegetal o a recuperar la funcionalidad del ecosistema, el cual es un proceso más integral y complejo que implica un gran esfuerzo. Esta restauración activa se suele aplicar a través de técnicas de enriquecimiento de plantaciones exóticas y plantaciones mixtas (Aguirre et al., 2006;Beck et al., 2008;Mazón y Aguirre, 2016;Mazón et al., 2017;Murcia et al., 2017). Para la RSE, las plantaciones de enriquecimiento pueden resultar una interesante opción para convertir plantaciones de especies exóticas en sistemas o ambientes más naturales, los cuales pueden contribuir a la restauración de la biodiversidad. ...
En la Región Sur del Ecuador (RSE) que comprende las provincias de Loja El Oro y Zamora Chinchipe, la degradación del patrimonio natural genera la necesidad de recuperarlo mediante estrategias de restauración ecológica (RE), para lo cual es necesario identificar las zonas prioritarias a restaurar, así como los sitios de referencia potenciales. En este contexto la presente investigación se enfocó en identificar áreas prioritarias que necesitan ser restauradas mediante evaluación multicriterio y determinar mediante teledetección los sitios de referencia para las zonas identificadas. Así mediante la clasificación supervisada de imágenes de satélite, la incorporación de criterios de expertos en RE a través de matrices de comparación pareada y mediante el Proceso Analítico Jerarquizado (PAJ) en un entorno de Sistemas de Información Geográfica (SIG), se definió las prioridades de atención o referencia respectivamente. Para las áreas prioritarias se consideraron 5 criterios ambientales, 4 socioeconómicos y 4 intrínsecos y para las referencias 2 criterios de cobertura y uso del suelo, 4 relacionados al Sistema Nacional de Áreas Protegidas y 4 socioeconómicos. Los resultados indican que cerca de 10% de la RSE se clasificó con prioridad máxima a restaurar. La superficie con potencial para referencia es de 2,73% del área evaluada. Finalmente, se determinó que las áreas prioritarias se distribuyeron por toda la RSE, no obstante, presentan una extensión geográfica continua representativa en las provincias de El Oro y Loja. Los sitios de referencia de calidad coinciden con aquellas áreas pertenecientes al SNAP teniendo mayor representatividad en la provincia de Zamora Chinchipe.
Although South America is the fourth largest continent, it houses about 60% of the global terrestrial life and the highest number of plant species. Besides its great native biodiversity, there are an unknown number of introduced non-native plants and at least 2,677 known naturalized non-native plants in South America. Despite the growing knowledge on the richness and general status of non-native species, the real extent of distribution, abundance, and effects of invasive plants in South America are largely unknown. Here, we used country-level data on the number and identity of naturalized plant species to test which factors were related to non-native plant naturalization in the continent. To do so, we (i) compiled a list of the most prominent invasive plants in the continent and (ii) reviewed the existing legislation in place to prevent and manage plant invasions. We found that mean latitude and number of bioclimates were good predictors of naturalized plant richness. We also found that plant invasions have pervasive impacts in South American ecosystems, but that the real magnitude of the impacts was vastly unknown because very few invasive species and invaded ecosystems have been studied. We also found that South American countries have legislations in place to manage plant invasions, but there were no integrated efforts across the countries to collaboratively address biological invasions. In conclusion, we show that there is information about the identity and distribution of most invasive plants, but there is a lack of comprehensive understanding of the impacts and future consequences on biodiversity and human well-being. We also highlight the importance of a more collaborative approach to prevent and manage invasions in the continent.KeywordsBiological invasionsInvasive alien speciesInvasive non-native speciesNaturalized plant speciesEstablished plant species
A tropical mountain ecosystem in one of the "hottest" biodiversity hotspots worldwide was investigated by some 30 research teams of numerous disciplines in the natural and social sciences. Ecosystem analysis followed two gradients: an altitudinal gradient and a gradient of land-use intensity and ecosystem regeneration, respectively.
This volume addresses a multitude of ecologically relevant aspects: macro- and microclimate; physics, chemistry and biology of soils; water relations, matter turnover and nutrient availability; plant growth and biomass partitioning; floral composition and plant life forms; vegetation structure and dynamics; organismic interactions, diversity and population biology of birds, moths and microarthropods; forest management, and reforestation with indigenous species; ethnobotanical and social aspects. New hypotheses are presented with regard to biodiversity and ecosystem functioning, as well as sustainable management of an ecosystem in a biodiversity hotspot.
Vegetation surveys were carried out during 1994 in 0.1. ha plots in abandoned plantations of Pinus radiata, Cupressus lusitanica, Eucalyptus globulus, Alnus acuminata and in a secondary upper montane rain forest in the Central Andes of Colombia. The regeneration forest had the higher number of plant species (33) followed by the E. globulus (26) and A. acuminata (16) plantations. Abandoned plantations of P. radiata and C. lusitanica, had only three species. There were only eleven species in common between the regeneration forest and the plantation of E. globulus (Baccharis latifolia, Cordia cylindrostachya, Dunalia solanacea, Leandra melanodesma, Lippia hirsuta, Monnina angustata, Solanum aff. scorpioideum, S. aphydendron, Sphaeropteris quindiuensis, Tobouchina mollis and Verbesina nudipes), and only seven when compared to the A. acuminata plantation (Abatia parviflora, Asploddianthus pseudostuebelli, Bocconia frutescens, Leandra melanodesma, Lippia hirsuta y Solanum aff. scorpioideum y Verbesina nudipes). With the exception of Cordia cylindrostachya, Bocconia frutescens and Tibouchina mollis, all other species are understory shrubs dispersed by wind or birds. In the understory of the P. radiata plantation there was abundant regeneration of the Colombian national tree, Ceroxylon quindiuensis. Tree height and basal area were significantly higher in the P. radiata and C. lusitanica plantations than in the regeneration forest. Of the environmental and biological variables measured in this study, the accumulation of needles under P. radiata and C. lusitanica plantations, and the high biomass of fine roots under the C. lusitanica plantation, could be the main limiting factors for the establishment of a higher number of species of the native forest. The chemical properties of the soils varied greatly, and there were no consistent differences between the soils under exotic and native species.
It is a widely held view that plantations of exotic tree species in the tropics are harmful to the environment. Arguments are collected here from experience in tropical countries, showing that the canopies of exotic trees can exert protective functions and have a nurse effect for the regeneration of natural forest. This counterbalances the opinion that exotic tree plantations generally are detrimental.
Tropical timber plantations provide a variety of environmental services, including recovery of biodiversity on degraded lands. For example, plantations can speed forest successional processes by improving microsite conditions and attracting seed dispersers, thus promoting woody regeneration. Timber species have been hypothesized to differ in understory recruitment success. In the present research, understory regeneration of woody plants was compared for six native timber species on tropical plantations in the Atlantic humid lowlands of Costa Rica. Timber species compared were: Calophyllum brasiliense Cambess, Hieronyma alchorneoides Allemao, Terminalia amazonia (J.F. Gmel.) Exell, Virola koschnyi Warb., Vochysia ferruginea Mart., and Vochysia guatemalensis Sprague. The six species were present at each of the three sites: one experimental plantation and two small-scale plantations belonging to farmers of the region. All plantations were 9–10 years. The experimental plantation was 100 m from continuous forest (i.e., seed source), and the farmers’ plantations were 1.3 and 2.5 km from continuous forest. Four plots were sampled for each timber species at each site using a randomized block design. All understory woody species were counted, identified, and separated by height class. Canopy openness and leaf litter biomass on the plantation floor were also evaluated.
Se evalúan los efectos de las plantaciones de Pinus patula y Eucalyptus grandes en tres etapas de desarrollo sobre la fauna y flora acompañante. Se encontró que las plantaciones forestales de estas especies causan efectos positivo y negativos. La existencia de una plantación forestal adecuadamente manejada favorece en términos generales la presencia y permanencia de la biota local, si se compara con el uso pecuario. Se hacen recomendaciones para optimizar el manejo de la biota nativa dentro de las área con plantaciones forestales industriales
Species richness and diversity and soil physical and chemical properties were compared between a mature lower montane rain forest (LMRF) and abandoned 21-year-old plantations of introduced Pinus patula and Cupressus lusitanica in the central Andes of Colombia (2000m). In 0.1ha plots, species richness (number of species) and diversity (Shannon and Simpson indexes) were higher in the LMRF, followed by P. patula and C. lusitanica plantations. There were 56species and 30families of higher plants in the LMRF, 26species and 15families in the P. patula plantation, and 18species and 10families in the C. lusitanica plantation. There were no statistically significant differences (p
Andean montane rain forests are among the most species-rich terrestrial habitats. Little is known about their insect communities and how these respond to anthropogenic habitat alteration. We investigated exceptionally speciose ensembles of nocturnal tiger moths (Arctiidae) at 15 anthropogenically disturbed sites, which together depict a gradient of forest recovery and six closed-forest understorey sites in southern Ecuador. At weak light traps we sampled 9211 arctiids, representing 287 species. Arctiid abundance and diversity were highest at advanced succession sites, where secondary scrub or young forest had re-established, followed by early succession sites, and were lowest, but still high, in mature forest understorey. The proportion of rare species showed the reverse pattern. We ordinated moth samples by non-metric multidimensional scaling using the chord-normalized expected species shared index (CNESS) index at various levels of the sample size parameter m. A distinct segregation of arctiid ensembles at succession sites from those in mature forest consistently emerged only at high m-values. Segregation between ensembles of early vs. late succession stages was also clear at high m values only, and was rather weak. Rare species were responsible for much of the faunal difference along the succession gradient, whereas many common arctiid species occurred in all sites. Matrix correlation tests as well as exploration of relationships between ordination axes and environmental variables revealed the degree of habitat openness, and to a lesser extent, elevation, as best predictors of faunal dissimilarity. Faunal differences were not related to geographical distances between sampling sites. Our results suggest that many of the more common tiger moths of Neotropical montane forests have a substantial recolonization potential at the small spatial scale of our study and accordingly occur also in landscape mosaics surrounding nature reserves. These species contribute to the unexpectedly high diversity of arctiid ensembles at disturbed sites, whereas the proportion of rare species declines outside mature forest.
Our study tested the potential for establishing shade-tolerant tree species within different canopy removal treatments of an 18-year-old Pinus caribaea (Caribbean pine) plantation. We investigated whether planting within a Pinus plantation can be a solution to the dispersal, weed competition, and pathogen/insect problems rain forest tree species have during their initial establishment on sites previously cleared of forest. The plantation was originally established on abandoned swidden adjacent to the Sinharaja Man and the Biosphere rain forest reserve in southwestern Sri Lanka. The five species selected for the study were Caryota urens, Dipterocarpus zeylanicus, Pericopsis mooniana, Shorea stipularis, and Swietenia macrophylla. Seedlings were monitored over two years for survival, root collar diameter and height growth along transects that were in seven different environmental treatments within the Pinus plantation. Environmental treatments comprised: (i) under plantings beneath a closed canopy of Pinus that were unaffected by any row removal; (ii) the centres of clearcut strips of Pinus that were 6 m width; (iii–vii) and five treatments across clearcut strips within closed canopy Pinus that were 12 m wide. The five treatments within the 12 m wide clearcut strip included inside edges beneath the Pinus canopy on the eastern (iii) and western (iv) sides of the strip; outside edges on the eastern (v) and western (vi) sides of the strip; and the centre (vii) of the strip opening. At the end of two years, a sample of the seedlings growing within each environmental treatment were taken and measured for dry masses and leaf areas. Results demonstrate that all species grew poorly and had higher mortality in the Pinus understorey than the other environmental treatments. The dipterocarp species (D. zeylanicus, S. stipularis) were slower growing and more site-sensitive to changes in environmental treatment than the non-dipterocarp species. S. macrophylla grew tallest in all environmental treatments as compared to the other species. Overall, the best environments for seedling establishment and growth for all species were in the centres of the canopy strips (6–12 m). This study contributes to investigations testing the feasibility of using Pinus as a nurse for establishing more shade-tolerant species; and as a technique for forest restoration in south and southeast Asia.
Exotic softwood plantations were introduced into the Kibale Forest of western Uganda in the 1960s and early 1970s to convert grassland areas into wood fiber producing sites. Following establishment, few silvicultural activities were initiated within these plantings, and today harvesting operations are planned to remove these over-stocked stands to allow for the development of natural forest communities. During the period May–September, 1994, we inventoried the overstorey and advanced regeneration in plantations of Pinus caribeae and Cupressus lusitanica. Within 92 randomly located 0.01 ha plots per plantation type, we measured the height and diameter of all stems encountered. The pines supported approximately 1.5 times the density and diversity of native woody stems found beneath the cypress (3424 tree and shrub stems ha⁻¹ under the pines), while the pines themselves were characterized by stocking levels, mean heights, and canopy closures which were higher than those of the cypress. We suggest that the greater natural regeneration development observed beneath the pines, when compared with the cypress, is a function of pine development (influence upon competition) and stem characteristics (influence upon seed dispersal mechanisms).
The proliferation of degraded tropical landscapes in need of rehabilitation and the reduction of primary forest area have forced a closer collaboration between ecologists and land managers. This collaboration has led to new paradigms of forest management (combined in the term ecosystem management), new insights into forest ecology through comparative ecological research, a more objective analysis of the ecology of tree plantations and a better understanding of the ecological functioning of these ecosystems. Plantation forests can have the same functions as secondary forest stands. However, because of their species composition, structure and management history, plantations can be more susceptible to disturbances than paired secondary forest stands. Plantations can be designed for maximization of particular outputs such as timber, or for specific land rehabilitation objectives such as protection of soils from erosion. Observations of plantation understories in Puerto Rico suggest that high species richness could occur under the shade of monocultural stands. This led to the hypothesis that reestablishment of tree species richness on degraded sites with arrested succession could be facilitated through plantings of tree monocultures. This phenomena was demonstrated experimentally in small plots and through observations at the landscape scale. Restoring tree species richness by planting tree monocultures works because the manager can match species to particular site conditions and thus overcome limiting factors that prevent the regeneration of species-rich forests on degraded sites. Once a forest canopy is established, microsite conditions change and wildlife is attracted. Animals are likely to disperse tree species from surrounding forest patches and regeneration of shade-intolerant species can be inhibited. Nine lines of research are suggested.