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Forest Regeneration (forest + regeneration)
Selected AbstractsForest Regeneration in a Chronosequence of Tropical Abandoned Pastures: Implications for Restoration EcologyRESTORATION ECOLOGY, Issue 4 2000T. Mitchell Aide Abstract During the mid-1900s, most of the island of Puerto Rico was deforested, but a shift in the economy from agriculture to small industry beginning in the 1950s resulted in the abandonment of agricultural lands and recovery of secondary forest. This unique history provides an excellent opportunity to study secondary forest succession and suggest strategies for tropical forest restoration. To determine the pattern of secondary succession, we describe the woody vegetation in 71 abandoned pastures and forest sites in four regions of Puerto Rico. The density, basal area, aboveground biomass, and species richness of the secondary forest sites were similar to those of the old growth forest sites (>80 yr) after approximately 40 years. The dominant species that colonized recently abandoned pastures occurred over a broad elevational range and are widespread in the neotropics. The species richness of Puerto Rican secondary forests recovered rapidly, but the species composition was quite different in comparison with old growth forest sites, suggesting that enrichment planting will be necessary to restore the original composition. Exotic species were some of the most abundant species in the secondary forest, but their long-term impact depended on life history characteristics of each species. These data demonstrate that one restoration strategy for tropical forest in abandoned pastures is simply to protect the areas from fire, and allow natural regeneration to produce secondary forest. This strategy will be most effective if remnant forest (i.e., seed sources) still exist in the landscape and soils have not been highly degraded. Patterns of forest recovery also suggest strategies for accelerating natural recovery by planting a suite of generalist species that are common in recently abandoned pastures in Puerto Rico and throughout much of the neotropics. [source] Impact of Forest Fragmentation on Understory Plant Species Richness in AmazoniaCONSERVATION BIOLOGY, Issue 2 2003Julieta Benítez-Malvido In Central Amazonia, 9 to 19 years after fragmentation, we recorded species richness and net seedling recruitment rate in forest fragments of 1, 10, and 100 ha and in continuous forest. In 1991 all seedlings 5,100 cm tall within permanent 1-m2 plots in fragments and continuous forest were counted and grouped into tree, liana, palm, and herb life-form classes. In 1993 we manually removed all seedlings that were <1 m tall from the permanent plots. Six years and 5 months later ( 1999 ), all new seedlings recruited into the plots were counted, grouped into different life forms, and classified into distinct morphospecies. The species richness of recruited tree, liana, herb, and palm seedlings was lower in forest fragments than in continuous forest, with the 1-ha fragment having the poorest species richness. The total number of recruited individuals was 40% less than that previously present for all life forms, except lianas. Liana recruitment was 7% to 500% higher than the original abundance in the forest fragments and continuous forest. In general, species similarity was higher among fragments than between fragments and continuous forest, with the 1-ha fragment being less similar. Species rank/abundance curves showed that continuous forest species in all life forms tended to disappear in forest fragments, whereas common species in forest fragments were absent from continuous forest. Overall, our results suggest that the life-form composition and structure of the regenerative plant pool in fragments were shifting toward a species-poor seedling community. Losses of understory species diversity, but especially of tree seedlings, threaten the maintenance of rainforest biodiversity and compromise future forest regeneration. Resumen: La fragmentación de las selvas tropicales afecta severamente a a los árboles de gran porte, sin embargo, su efecto sobre otros estadíos y formas de vida de las plantas es poco conocido. En la Amazonia central, de 9 a 19 años después de la fragmentación, se registró la riqueza de especies y la tasa neta de reclutamiento de plántulas en fragmentos de selva de 1, 10, y 100 ha y en selva contínua. En 1991, todas las plántulas de 5,100 cm de altura dentro de cuadrantes permanentes de 1-m2 en los fragmentos y en la selva contínua, fueron contadas y agrupadas en diferentes formas de vida: árboles, lianas, palmas y hierbas. En 1993 se removieron manualmente todas las plántulas <1 m de altura dentro de los cuadrantes. Seis años y cinco meses más tarde (1999) se contaron todas las plántulas reclutadas dentro de los cuadrantes, se agruparon en diferentes formas de vida v se clasificaron en morfoespecies distintivas. La riqueza de especies de plántulas reclutadas en todas las formas de vida fue menor en los fragmentos que en la selva contínua, con el fragmento de 1 ha presentando la menor riqueza de especies. El número total de individuos reclutados fue 40% menor que los previamente presentes para todas las formas de vida, excepto lianas. El reclutamiento de lianas fué de 7 a 500% mayor que la abundancia original en los fragmentos y en la selva contínua. En general la similitud de especies fué mayor entre fragmentos que entre fragmentos y selva contínua, con el fragmento de 1-ha siendo el menos similar. Las curvas de rango/abundancia de especies, mostraron que las especies de selva contínua en todas las formas de vida tendieron a desaparecer de los fragmentos, mientras que las especies comunes en los fragmentos estuvieron ausentes en la selva contínua. En general, nuestros resultados sugieren que la composición de formas de vida y la estructura del banco regenerativo en fragmentos tienden a convertirse en una comunidad de plántulas pobre en especies. La pérdida de diversidad de especies del sotobosque, pero especialmente de plántulas de árboles, amenaza el mantenimiento de la biodiversidad y pone en peligro la regeneración futura de la selva. [source] Herbivory and plant growth rate determine the success of El Niño Southern Oscillation-driven tree establishment in semiarid South AmericaGLOBAL CHANGE BIOLOGY, Issue 12 2006MILENA HOLMGREN Abstract While climatic extremes are predicted to increase with global warming, we know little about the effect of climatic variability on biome distribution. Here, we show that rainy El Niño Southern Oscillation (ENSO) events can enhance tree recruitment in the arid and semiarid ecosystems of north-central Chile and northwest Peru. Tree-ring studies in natural populations revealed that rainy El Niño episodes have triggered forest regeneration in Peru. Field experiments indicate that tree seedling recruitment in Chile is much less successful than in Peru due mostly to larger mortality caused by herbivores. The dramatic impact of herbivores in Chile was derived from the combined result of slower plant growth and the presence of exotic herbivores (European rabbits and hares). The interplay of herbivory and climatic effects we demonstrated implies that rainy ENSO events may represent ,windows of opportunity' for forest recovery if herbivore pressure is minimized at the right moment. [source] Abandonment of farmland and vegetation succession following the Eurasian plague pandemic of ad 1347,52JOURNAL OF BIOGEOGRAPHY, Issue 4 2007Dan Yeloff Abstract Aim, This paper reviews the available documentary, archaeological and palaeoecological evidence for the abandonment of agricultural land and consequent regeneration of the forest in Europe after the Black Death. Location, Western and northern Europe. Methods, This review is the result of an exhaustive search of the historical, archaeological and palaeoecological literature for evidence indicating agricultural decline and forest regeneration in Eurasia during the 14th century. The available evidence for landscape change can be divided into two categories: (1) documentary and archaeological sources, and (2) palaeoecological reconstructions of past vegetation. In the past few years, several pollen diagrams from north-west Europe have been reported with precise chronologies (decadal and even annual scale) showing the abandonment of farmland and consequent ecological change in the late medieval period. Results and main conclusions, There is strong evidence of agricultural continuity at several sites in Western Europe at the time of the Black Death. The effects of the Black Death on the European rural landscape varied geographically, with major factors probably including the impact of the plague on the local population, and soil quality. At two sites in western and northern Ireland, the late medieval decline in cereal agriculture was probably a direct result of population reduction following the Black Death. In contrast, the decline in cereal production began at sites in Britain and France before the Black Death pandemic of ad 1347,52, and was probably due to the crisis in the agricultural economy, exacerbated by political instability and climate deterioration. Much of the abandoned arable land was probably exploited for grazing during the period between the decline in cereal farming and the Black Death. In the aftermath of the Black Death, grazing pressure was greatly reduced owing to reductions in the grazing animal population and a shortage of farmers. Vegetation succession on the abandoned grazing land resulted in increased cover of woody tree species, particularly Betula and Corylus, by the late 14th century. The cover of woodland was greatest at c.ad 1400, before forest clearance and agriculture increased in intensity. [source] Structure and composition of vegetation along an elevational gradient in Puerto RicoJOURNAL OF VEGETATION SCIENCE, Issue 5 2006W.A. Gould Liogier & Martorrell (1999) Abstract Question: What are the composition, conservation status, and structural and environmental characteristics of eight mature tropical forest plant communities that occur along an elevational gradient. Location: Northeastern Puerto Rico. Methods: We quantified the species composition, diversity, conservation status, and ecological attributes of eight mature tropical forest plant communities in replicated plots located to sample representative components of important forest types occurring along an elevational gradient. A suite of environmental and vegetation characteristics were sampled at each plot and summarized to characterize communities and analyse trends along the elevational gradient. Results: The set of communities included 374 species; 92% were native, 14% endemic, and 4% critical elements (locally endangered) to the island. All communities, occurring within a wide range of patch sizes and degree of conservation protection, showed a high percentage of native species (> 89% per plot). The lowland moist forest communities, occurring within a matrix of urbanization, agriculture, and disturbance, had the highest degree of invasion by exotics. Community descriptions were nested within a variety of hierarchies to facilitate extrapolation of community characteristics to larger ecosystem units. Basal area, above-ground biomass, canopy heights, and mean species richness peaked at mid elevations. Conclusions: It is significant that all of these forest communities continue to be dominated by native species while existing in a matrix of human and natural disturbance, species invasion, and forest regeneration from widespread agriculture. The lowland moist and dry forest types represent a minority of the protected forested areas in Puerto Rico, serve as unique genetic reservoirs, and should be protected. [source] The Role of Frugivorous Bats in Tropical Forest SuccessionBIOLOGICAL REVIEWS, Issue 4 2007Robert Muscarella Abstract Discussion of successional change has traditionally focused on plants. The role of animals in producing and responding to successional change has received far less attention. Dispersal of plant propagules by animals is a fundamental part of successional change in the tropics. Here we review the role played by frugivorous bats in successional change in tropical forests. We explore the similarities and differences of this ecological service provided by New and Old World seed-dispersing bats and conclude with a discussion of their current economic and conservation implications. Our review suggests that frugivorous New World phyllostomid bats play a more important role in early plant succession than their Old World pteropodid counterparts. We propose that phyllostomid bats have shared a long evolutionary history with small-seeded early successional shrubs and treelets while pteropodid bats are principally dispersers of the seeds of later successional canopy fruits. When species of figs (Ficus) are involved in the early stages of primary succession (e.g. in the river meander system in Amazonia and on Krakatau, Indonesia), both groups of bats are important contributors of propagules. Because they disperse and sometimes pollinate canopy trees, pteropodid bats have a considerable impact on the economic value of Old World tropical forests; phyllostomid bats appear to make a more modest direct contribution to the economic value of New World tropical forests. Nonetheless, because they critically influence forest regeneration, phyllostomid bats make an important indirect contribution to the economic value of these forests. Overall, fruit-eating bats play important roles in forest regeneration throughout the tropics, making their conservation highly desirable. [source] Postdispersal Seed Fate of Tropical Montane Trees in an Agricultural Landscape, Southern Costa RicaBIOTROPICA, Issue 3 2009Rebecca J. Cole ABSTRACT Variation in postdispersal seed fate is an important factor driving patterns of forest regeneration. Because most previous studies have not tracked final seed fate and have commonly equated seed removal with predation without considering the possibility of secondary dispersal, little is known about individual seed mortality factors in successional and degraded habitats. This study tracked the postdispersal fate of large-seeded tropical montane trees in abandoned pasture, young secondary forests, and small forest fragments during two consecutive years in an agricultural landscape in southern Costa Rica. The incidence of secondary dispersal by animals, scatterhoarding in particular, and the effects of seed burial on germination were measured. Overall, seeds survived through germination more often in secondary forests with high levels of mortality occurring in abandoned pastures and forest fragments. The majority of seed mortality was caused by rodent predation in forest fragments, insects and fungal pathogens in secondary forests, and a combination of desiccation, insects, and fungal pathogens in pastures. Seeds were frequently secondarily dispersed in larger forest fragments, whereas they were only rarely moved in pastures and secondary forests. Burial tended to improve germination in pastures and was important for an often scatterhoarded species, Otoba novogranatensis, in all habitats. The results of this study suggest that: (1) seed mortality factors differ in response to the type of habitat degradation; (2) large-seeded species have high potential for survival when dispersed to young secondary forests; and (3) seed removal is not a reliable proxy for seed predation, particularly in less degraded forest fragments. RESUMEN La variación en el destino de las semillas posterior a la dispersión es un factor importante que puede determinar patrones de la regeneración de los bosques. Dado que la mayoría de los estudios anteriores no han realizado seguimiento al destino final de las semillas y han equiparado comúnmente la remoción con la predación sobre las mismas, sin tener en cuenta la posibilidad de dispersión secundaria, poco se sabe sobre los factores de la mortalidad de semillas en hábitats sucesionales y degradados. Este estudio hizo seguimiento al destino posterior a la dispersión de semillas grandes de árboles tropicales montanos en pasturas abandonadas, bosques secundarios jóvenes y en pequeños fragmentos de bosque durante dos años consecutivos en un paisaje agrícola del sur de Costa Rica. Se midieron la incidencia de la dispersión secundaria por parte de los animales, particularmente por scatterhoarding (estrategia en la cual se almacenan pequeñas cantidades de alimento en distintos escondites), así como los efectos que tiene el entierro de semillas sobre la germinación. En general, las semillas sobrevivieron hasta la germinación con más frecuencia en los bosques secundarios, teniendo altos niveles de mortalidad en las pasturas abandonadas y en los fragmentos de bosque. Gran parte de la mortalidad de semillas fue causada por la predación de roedores en fragmentos de bosque, de insectos y hongos patógenos en los bosques secundarios, y de una combinación de desecación, insectos y hongos patógenos en los pastos. Las semillas presentaron una frecuente dispersión secundaria en los fragmentos de bosque más grandes, mientras que sólo en raras ocasiones se trasladaron en los pastos y los bosques secundarios. El entierro de semillas mostró tendencia a mejorar la germinación en los pastos y fue importante para Otoba novogranatensis, especie cuyas semillas son en ocasiones dispersadas por scatterhoarding en todos los hábitats. Los resultados de este estudio sugieren que (1) los factores de mortalidad de semillas difieren en respuesta al tipo de degradación del hábitat, (2) las especies con semillas de gran tamaño tienen un alto potencial de supervivencia cuando se dispersan a bosques secundarios jóvenes, y (3) la remoción de semillas no es un indicador confiable de la predación sobre las mismas, particularmente en fragmentos de bosques menos degradados. [source] Research Priorities for Neotropical Dry Forests,BIOTROPICA, Issue 4 2005G. Arturo Sánchez-Azofeifa ABSTRACT Our understanding of the human and biophysical dimensions of tropical dry forest change and its cumulative effects is still in the early stages of academic discovery. The papers in this special section on Neotropical dry forests cover a wide range of sites and problems ranging from the use of multispectral and hyperspectral remote sensing platforms to the impact of hurricanes on tropical dry forest regeneration. Here, we present to the scientific community the results of a workshop on which research priorities for tropical dry forests were discussed. This discussion focuses on the need to develop linkages between remote sensing, ecological, and social science research. The incorporation of social sciences into ecological research could contribute dramatically to our understandings of tropical dry forests by providing important contextual information to ecologists, and by helping to develop an important science,policy,public nexus on which environmental management can succeed. RESUMEN El conocimiento actual de las dimensiones humanas y biofísicas de los cambios en los bosque secos tropicales y sus efectos acumulativos esta en las etapas iniciales del descubrimiento académico. En este articulo, introducimos una serie de artículos científicos asociados a este número especial sobre bosques secos en los Neotropicos. Estos artículos provienen de una distribución muy variada de sitios en las Américas y van desde las aplicaciones de sensores multi- e hiperspectrales, hasta el estudio del efecto que los huracanes causan en la regeneración de los bosques secos. Presentamos a la comunidad científica los resultados de un taller dirigido a la discusión de aquellas prioridades de investigación en bosques secos. La discusión se enfoca a lo largo de los vínculos que se necesitan entre percepción remota, ecología y ciencias sociales. La incorporación las ciencias sociales dentro de la investigación ecológica podría contribuir dramáticamente al entendimiento de los bosque secos tropicales, así como tienen len a posibilidad de ayudar en el desarrollo de vínculos importantes entre ciencia y política dirigida al manejo de los recursos presentes en este importante ecosistema. [source] | ||||||||||