Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 49
Filtrar
1.
Nature ; 620(7975): 807-812, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37612395

RESUMEN

The United Nations recently agreed to major expansions of global protected areas (PAs) to slow biodiversity declines1. However, although reserves often reduce habitat loss, their efficacy at preserving animal diversity and their influence on biodiversity in surrounding unprotected areas remain unclear2-5. Unregulated hunting can empty PAs of large animals6, illegal tree felling can degrade habitat quality7, and parks can simply displace disturbances such as logging and hunting to unprotected areas of the landscape8 (a phenomenon called leakage). Alternatively, well-functioning PAs could enhance animal diversity within reserves as well as in nearby unprotected sites9 (an effect called spillover). Here we test whether PAs across mega-diverse Southeast Asia contribute to vertebrate conservation inside and outside their boundaries. Reserves increased all facets of bird diversity. Large reserves were also associated with substantially enhanced mammal diversity in the adjacent unprotected landscape. Rather than PAs generating leakage that deteriorated ecological conditions elsewhere, our results are consistent with PAs inducing spillover that benefits biodiversity in surrounding areas. These findings support the United Nations goal of achieving 30% PA coverage by 2030 by demonstrating that PAs are associated with higher vertebrate diversity both inside their boundaries and in the broader landscape.


Asunto(s)
Biodiversidad , Conservación de los Recursos Naturales , Objetivos , Clima Tropical , Naciones Unidas , Animales , Conservación de los Recursos Naturales/legislación & jurisprudencia , Conservación de los Recursos Naturales/métodos , Conservación de los Recursos Naturales/tendencias , Mamíferos , Agricultura Forestal/legislación & jurisprudencia , Agricultura Forestal/métodos , Agricultura Forestal/tendencias
4.
Proc Natl Acad Sci U S A ; 118(3)2021 01 19.
Artículo en Inglés | MEDLINE | ID: mdl-33397807

RESUMEN

Biodiversity is declining worldwide. Because species interact with one another and with their environment, losses of particular organisms alter the function of ecosystems. Our understanding of the global rates and specific causes of functional decline remains limited, however. Species losses also reduce the cumulative amount of extant evolutionary history ("phylogenetic diversity" [PD]) in communities-our biodiversity heritage. Here we provide a global assessment of how each known anthropogenic threat is driving declines in functional diversity (FD) and PD, using terrestrial mammals as a case study. We find that habitat loss and harvest (e.g., legal hunting, poaching, snaring) are by far the biggest drivers of ongoing FD and PD loss. Declines in FD in high-biodiversity countries, particularly in Southeast Asia and South America, are greater than would be expected if species losses were random with respect to ecological function. Among functional guilds, herbivores are disproportionately likely to be declining from harvest, with important implications for plant communities and nutrient cycling. Frugivores are particularly likely to be declining from both harvest and habitat loss, with potential ramifications for seed dispersal and even forest carbon storage. Globally, phylogenetically unique species do not have an elevated risk of decline, but in areas such as Australia and parts of Southeast Asia, both habitat loss and harvest are biased toward phylogenetically unique species. Enhanced conservation efforts, including a renewed focus on harvest sustainability, are urgently needed to prevent the deterioration of ecosystem function, especially in the South American and equatorial Asian tropics.


Asunto(s)
Biodiversidad , Evolución Biológica , Conservación de los Recursos Naturales , Ecosistema , Mamíferos/crecimiento & desarrollo , Animales , Asia Sudoriental , Australia , Extinción Biológica , Bosques , Actividades Humanas , Humanos , Mamíferos/genética , Filogenia , América del Sur
5.
Am Nat ; 201(4): 574-585, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36957999

RESUMEN

AbstractCommunity trait assembly, the formation of distributions of phenotypic characteristics across coexisting species, can occur via two main processes: filtering of trait distributions from the regional pool and in situ phenotypic evolution in local communities. But the relative importance of these processes remains unclear, largely because of the difficulty in determining the timing of evolutionary trait changes and biogeographic dispersal events in phylogenies. We assessed evolutionary and biogeographic transitions in woody plant species across the Indo-Malay archipelago, a series of island groups where the same plant lineages interact with different seed disperser and seed predator assemblages. Fruit size in 2,650 taxa spanning the angiosperm tree of life tended to be smaller in the Sulawesi and Maluku island groups, where frugivores are less diverse and smaller bodied, than in the regional source pool. While numerous plant lineages (not just small-fruited ones) reached the isolated islands, colonists tended to be the smaller-fruited members of each clade. Nearly all of the evolutionary transitions to smaller fruit size predated, often substantially, organismal dispersal to the islands. Our results suggest that filtering rather than within-island evolution largely determined the distribution of fruit sizes in these regions.


Asunto(s)
Magnoliopsida , Dispersión de Semillas , Frutas , Semillas , Plantas , Filogenia , Magnoliopsida/genética
6.
Conserv Biol ; 37(2): e14014, 2023 04.
Artículo en Inglés | MEDLINE | ID: mdl-36178021

RESUMEN

The loss of large animals due to overhunting and habitat loss potentially affects tropical tree populations and carbon cycling. Trees reliant on large-bodied seed dispersers are thought to be particularly negatively affected by defaunation. But besides seed dispersal, defaunation can also increase or decrease seed predation. It remains unclear how these different defaunation effects on early life stages ultimately affect tree population dynamics. We reviewed the literature on how tropical animal loss affects different plant life stages, and we conducted a meta-analysis of how defaunation affects seed predation. We used this information to parameterize models that altered matrix projection models from a suite of tree species to simulate defaunation-caused changes in seed dispersal and predation. We assessed how applying these defaunation effects affected population growth rates. On average, population-level effects of defaunation were negligible, suggesting that defaunation may not cause the massive reductions in forest carbon storage that have been predicted. In contrast to previous hypotheses, we did not detect an effect of seed size on changes in seed predation rates. The change in seed predation did not differ significantly between exclosure experiments and observational studies, although the results of observational studies were far more variable. Although defaunation surely affects certain tree taxa, species that benefit or are harmed by it and net changes in forest carbon storage cannot currently be predicted based on available data. Further research on how factors such as seed predation vary across tree species and defaunation scenarios is necessary for understanding cascading changes in species composition and diversity.


Predicciones de cómo los cambios inducidos en la dispersión y depredación de semillas por la pérdida de fauna afectará a las poblaciones de árboles tropicales Resumen La pérdida de animales grandes debido a la caza excesiva y la pérdida del hábitat afecta potencialmente a las poblaciones de árboles tropicales y al ciclo del carbono. Se considera que los árboles que dependen de dispersores de semillas de talla grande son los más afectados negativamente por la pérdida de fauna. La defaunación también puede incrementar o disminuir la depredación de semillas, además de su dispersión. Todavía no está claro cómo afectan al final a las dinámicas poblaciones de los árboles los diferentes efectos de la pérdida de fauna en las etapas temprana de vida. Revisamos la literatura sobre cómo la pérdida de animales tropicales afecta las diferentes etapas de vida de las plantas y realizamos un metaanálisis sobre cómo la pérdida de fauna afecta a la depredación de semillas. Usamos esta información para definir los parámetros de los modelos que alteraron los modelos de proyección de matriz a partir de un conjunto de especies de árboles y así simular los cambios causados por la pérdida de fauna en la dispersión y depredación de semillas. Analizamos cómo la aplicación de estos efectos de pérdida de fauna afectó las tasas de crecimiento poblacional. En promedio, los efectos de la pérdida de fauna a nivel poblacional fueron no significativas, lo que sugiere que la pérdida de fauna puede no ser la causa de las reducciones masivas que se han pronosticado en el almacenamiento de carbono forestal. Contrario a las hipótesis previas, no detectamos ningún efecto del tamaño de las semillas sobre los cambios en las tasas de depredación. El cambio en la depredación de semillas no difirió significativamente entre los experimentos de encierro y los estudios de observación, aunque los resultados de los últimos fueron mucho más variables. Mientras que la pérdida de fauna seguramente afecta a ciertos taxones de árboles, actualmente no se pueden pronosticar, con base en los datos disponibles, las especies que se benefician o perjudican por esta pérdida y los cambios netos en el almacenamiento de carbono forestal. Se necesita una investigación más avanzada sobre cómo varían los factores, como la depredación de semillas, entre especies de árboles y escenarios de pérdida de fauna para entender los cambios en cascada en la composición y diversidad de las especies.


Asunto(s)
Dispersión de Semillas , Árboles , Animales , Conducta Predatoria , Conservación de los Recursos Naturales , Bosques , Ecosistema , Semillas , Clima Tropical
7.
Conserv Biol ; : e14221, 2023 Nov 08.
Artículo en Inglés | MEDLINE | ID: mdl-37937455

RESUMEN

Reliable maps of species distributions are fundamental for biodiversity research and conservation. The International Union for Conservation of Nature (IUCN) range maps are widely recognized as authoritative representations of species' geographic limits, yet they might not always align with actual occurrence data. In recent area of habitat (AOH) maps, areas that are not habitat have been removed from IUCN ranges to reduce commission errors, but their concordance with actual species occurrence also remains untested. We tested concordance between occurrences recorded in camera trap surveys and predicted occurrences from the IUCN and AOH maps for 510 medium- to large-bodied mammalian species in 80 camera trap sampling areas. Across all areas, cameras detected only 39% of species expected to occur based on IUCN ranges and AOH maps; 85% of the IUCN only mismatches occurred within 200 km of range edges. Only 4% of species occurrences were detected by cameras outside IUCN ranges. The probability of mismatches between cameras and the IUCN range was significantly higher for smaller-bodied mammals and habitat specialists in the Neotropics and Indomalaya and in areas with shorter canopy forests. Our findings suggest that range and AOH maps rarely underrepresent areas where species occur, but they may more often overrepresent ranges by including areas where a species may be absent, particularly at range edges. We suggest that combining range maps with data from ground-based biodiversity sensors, such as camera traps, provides a richer knowledge base for conservation mapping and planning.


Combinación de censos con fototrampas y mapas de extensión de la UICN para incrementar el conocimiento sobre la distribución de las especies Resumen Los mapas confiables de la distribución de las especies son fundamentales para la investigación y conservación de la biodiversidad. Los mapas de distribución de la Unión Internacional para la Conservación de la Naturaleza (UICN) están reconocidos como representaciones de autoridad de los límites geográficos de las especies, aunque no siempre se alinean con los datos actuales de su presencia. En los mapas recientes de área de hábitat (ADH), las áreas que no son hábitat han sido eliminadas de la distribución de la UICN para reducir los errores de comisión, pero su concordancia con la presencia actual de las especies tampoco ha sido analizada. Analizamos la concordancia entre la presencia registrada por los censos de fototrampas y pronosticamos la presencia a partir de los mapas de la UICN y de ADH de 510 especies de mamíferos de talla mediana a grande en 80 áreas de muestreo de fototrampas. Las cámaras detectaron sólo el 39% de las especies esperadas con base en la distribución de la UICN y los mapas de ADH en todas las áreas; el 85% de las disparidades con la UICN ocurrieron dentro de los 200 km a partir del borde de la distribución. Sólo el 4% de la presencia de las especies fue detectada por las cámaras ubicadas fuera de la distribución de la UICN. La probabilidad de disparidad entre las cámaras y la UICN fue significativamente mayor para los mamíferos de talla pequeña y para los especialistas de hábitat en las regiones Neotropical e Indomalaya y en áreas con doseles forestales más bajos. Nuestros hallazgos sugieren que los mapas de distribución y ADH pocas veces subrepresentan las áreas con presencia de las especies, pero con frecuencia pueden sobrerrepresentar la distribución al incluir áreas en donde las especies pueden estar ausentes, en particular los bordes de la distribución. Sugerimos que la combinación de los mapas de distribución con los sensores de biodiversidad en tierra, como las fototrampas, proporciona una base más rica de conocimiento para el mapeo y la planeación de la conservación.

8.
J Anim Ecol ; 91(3): 604-617, 2022 03.
Artículo en Inglés | MEDLINE | ID: mdl-34954816

RESUMEN

Conservation outcomes could be greatly enhanced if strategies addressing anthropogenic land-use change considered the impacts of these changes on entire communities as well as on individual species. Examining how species interactions change across gradients of habitat disturbance allows us to predict the cascading consequences of species extinctions and the response of ecological networks to environmental change. We conducted the first detailed study of changes in a commensalist network of mammals and dung beetles across an environmental disturbance gradient, from primary tropical forest to plantations, which varied in above-ground carbon density (ACD) and mammal communities. Mammal diversity changed only slightly across the gradient, remaining high even in oil palm plantations and fragmented forest. Dung beetle species richness, however, declined in response to lower ACD and was particularly low in plantations and the most disturbed forest sites. Three of the five network metrics (nestedness, network specialization and functionality) were significantly affected by changes in dung beetle species richness and ACD, but mammal diversity was not an important predictor of network structure. Overall, the interaction networks remained structurally and functionally similar across the gradient, only becoming simplified (i.e. with fewer dung beetle species and fewer interactions) in the most disturbed sites. We suggest that the high diversity of mammals, even in disturbed forests, combined with the generalist feeding patterns of dung beetles, confer resilience to the commensalist dung beetle-mammal networks. This study highlights the importance of protecting logged and fragmented forests to maintain interaction networks and potentially prevent extinction cascades in human-modified systems.


Asunto(s)
Escarabajos , Animales , Biodiversidad , Escarabajos/fisiología , Ecosistema , Bosques , Mamíferos
9.
Oecologia ; 200(1-2): 169-181, 2022 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-36100723

RESUMEN

Patterns of co-occurrence among species can help reveal the structure and assembly of ecological communities. However, studies have been limited by measuring co-occurrence in either space or time but not both simultaneously. This is especially problematic in systems such as masting forests where resources are highly variable, meaning that spatial use and co-occurrence patterns can change on fine spatiotemporal scales. We develop an analytical framework for assessing species co-occurrence at fine spatial and temporal scales simultaneously and apply these models to a camera trapping dataset from Borneo. We sought to determine how substantial variation in food availability across space and time affects co-occurrence among terrestrial vertebrates. We detect many significant, mostly positive, co-occurrence patterns among species, but almost entirely in unlogged forest and during dipterocarp mast years. The most strongly co-occurring pair of species, bearded pig (Sus barbatus) and sambar (Rusa unicolor), only positively co-occur in areas and years when fruit is locally abundant. Species occurrences in logged forest and non-mast years are mostly random with respect to other species. This suggests that frugivore-granivore species positively co-occur when resources are plentiful (i.e., large trees are present and fruiting), likely because they use the same resources; these patterns disappear when food availability is lower. Our approach demonstrates the utility of measuring co-occurrence in space and time together and highlights the importance of resource abundance for driving the co-occurrence structure of communities. Furthermore, our method could be broadly applied to other systems to assess fine-scale spatiotemporal patterns across a range of taxa.


Asunto(s)
Bosques , Árboles , Animales , Borneo , Ecosistema , Frutas , Porcinos
10.
Conserv Biol ; 35(3): 1009-1018, 2021 06.
Artículo en Inglés | MEDLINE | ID: mdl-32812649

RESUMEN

Mitigating the massive impacts of defaunation on natural ecosystems requires understanding and predicting hunting effort across the landscape. But such understanding has been hindered by the difficulty of assessing the movement patterns of hunters in thick forests and across complex terrain. We statistically tested hypotheses about the spatial distribution of hunting with circuit theory and structural equation models. We used a data set of >7000 known kill locations in Guyana and hunter movement models to test these methods. Comparing models with different resistance layers (i.e., different estimates of how terrain and land cover influence human movement speed) showed that rivers, on average, limited movement rather than serving as transport arteries. Moreover, far more kills occurred close to villages than in remote areas. This, combined with the lack of support for structural equation models that included latent terms for prey depletion driven by past overhunting, suggests that kill locations in this system tended to be driven by where hunters were currently foraging rather than by influences of historical harvest. These analyses are generalizable to a variety of ecosystems, species, and data types, providing a powerful way of enhancing maps and predictions of hunting effort across complex landscapes.


Comprensión de la Distribución de los Esfuerzos por Obtener Carne de Caza a lo largo de un Paisaje Mediante la Comprobación de Hipótesis sobre el Forrajeo Humano Resumen La mitigación de los impactos masivos de la defaunación sobre los ecosistemas naturales requiere de comprensión y predicción de los esfuerzos de caza a lo largo del paisaje. Dicha comprensión se ha visto obstaculizada por la dificultad que representa la evaluación de los patrones de movimiento de los cazadores en bosques densos y a través de un terreno complejo. Analizamos estadísticamente las hipótesis sobre la distribución espacial de la cacería mediante una teoría de circuito y modelos de ecuaciones estructurales. Usamos un conjunto de datos de más de 7000 localidades conocidas de sacrificios en Guayana y los modelos de movimiento de los cazadores para probar estos modelos. La comparación entre modelos con diferentes capas de resistencia (es decir, diferentes estimaciones de cómo el terreno y la cobertura de suelo influyen sobre la velocidad del movimiento humano) mostró que los ríos, en promedio, limitaron el movimiento en lugar de funcionar como arterias de transporte. Además, ocurrieron mucho más sacrificios cerca de las aldeas que en las áreas remotas. Lo anterior, combinado con la falta de apoyo para los modelos de ecuaciones estructurales que incluyeron los términos latentes para la reducción de presas causada por la sobrecaza pasada, sugiere que las localidades de sacrificios en este sistema tendieron a ser seleccionadas por la ubicación actual en la que los cazadores se encontraban forrajeando y no por la influencia de la cosecha histórica. Estos análisis son generalizables para una variedad de ecosistemas, especies y tipos de datos, lo que proporciona una manera poderosa de mejorar los mapas y las predicciones de los esfuerzos de cacería a través de paisajes complejos.


Asunto(s)
Conservación de los Recursos Naturales , Ecosistema , Bosques , Guyana , Humanos
12.
Proc Biol Sci ; 287(1922): 20192677, 2020 03 11.
Artículo en Inglés | MEDLINE | ID: mdl-32156211

RESUMEN

Unsustainable hunting is emptying forests of large animals around the world, but current understanding of how human foraging spreads across landscapes has been stymied by data deficiencies and cryptic hunter behaviour. Unlike other global threats to biodiversity like deforestation, climate change and overfishing, maps of wild meat hunters' movements-often based on forest accessibility-typically cover small scales and are rarely validated with real-world observations. Using camera trapping data from rainforests across Malaysian Borneo, we show that while hunter movements are strongly correlated with the accessibility of different parts of the landscape, accessibility measures are most informative when they integrate fine-scale habitat features like topography and land cover. Measures of accessibility naive to fine-scale habitat complexity, like distance to the nearest road or settlement, generate poor approximations of hunters' movements. In comparison, accessibility as measured by high-resolution movement models based on circuit theory provides vastly better reflections of real-world foraging movements. Our results highlight that simple models incorporating fine-scale landscape heterogeneity can be powerful tools for understanding and predicting widespread threats to biodiversity.


Asunto(s)
Conservación de los Recursos Naturales , Extinción Biológica , Carne , Animales , Biodiversidad , Borneo , Ecosistema , Humanos , Mamíferos , Dinámica Poblacional , Bosque Lluvioso
13.
Conserv Biol ; 34(4): 934-942, 2020 08.
Artículo en Inglés | MEDLINE | ID: mdl-31840279

RESUMEN

Conservation planning tends to focus on protecting species' ranges or landscape connectivity but seldom both-particularly in the case of diverse taxonomic assemblages and multiple planning goals. Therefore, information on potential trade-offs between maintaining landscape connectivity and achieving other conservation objectives is lacking. We developed an optimization approach to prioritize the maximal protection of species' ranges, ecosystem types, and forest carbon stocks, while also including habitat connectivity for range-shifting species and dispersal corridors to link protected area. We applied our approach to Sabah, Malaysia, where the state government mandated an increase in protected-area coverage of approximately 305,000 ha but did not specify where new protected areas should be. Compared with a conservation planning approach that did not incorporate the 2 connectivity features, our approach increased the protection of dispersal corridors and elevational connectivity by 13% and 21%, respectively. Coverage of vertebrate and plant species' ranges and forest types were the same whether connectivity was included or excluded. Our approach protected 2% less forest carbon and 3% less butterfly range than when connectivity features were not included. Hence, the inclusion of connectivity into conservation planning can generate large increases in the protection of landscape connectivity with minimal loss of representation of other conservation targets.


Incorporación de la Conectividad a la Planeación de la Conservación para la Representación Óptima de Especies Múltiples y Servicios Ambientales Resumen Las tendencias de planeación de la conservación tienden a enfocarse en la protección de la distribución geográfica de las especies o en la conectividad de paisajes, pero rara vez se enfocan en ambas - particularmente para el caso de los ensamblajes taxonómicos y las metas múltiples de planeación. Por lo tanto, hay carencias en la información sobre las compensaciones potenciales entre mantener la conectividad de los paisajes y alcanzar otros objetivos de conservación. Desarrollamos una estrategia de optimización para priorizar la protección máxima de la distribución de las especies, los tipos de ecosistemas y los stocks de carbono de los bosques, a la vez que incluimos la conectividad del hábitat para las especies que modifican su distribución y los corredores de dispersión para conectar el área protegida. Aplicamos nuestra estrategia en Sabah, Malasia, en donde el gobierno estatal ordenó un incremento de ∼305, 000 ha en la cobertura de áreas protegidas sin especificar la ubicación de las nuevas áreas protegidas. En comparación con una estrategia de planeación de la conservación que no incorporó las dos características de la conectividad, nuestra estrategia incrementó la protección de los corredores de dispersión y la conectividad altitudinal en un 13% y 21% respectivamente. La cobertura de la distribución de las especies de plantas y vertebrados y de los tipos de bosque fue la misma con o sin la inclusión de la conectividad. Nuestra estrategia protegió 2% menos del carbono forestal y 3% menos de la distribución de mariposas que cuando no se incluyeron las características de conectividad en la estrategia. Por lo tanto, incluir a la conectividad en la planeación de la conservación puede generar grandes incrementos en la protección de la conectividad del paisaje con una pérdida mínima de representación para los demás objetivos de conservación.


Asunto(s)
Conservación de los Recursos Naturales , Ecosistema , Animales , Biodiversidad , Bosques , Malasia , Vertebrados
14.
Proc Natl Acad Sci U S A ; 114(45): 11998-12002, 2017 11 07.
Artículo en Inglés | MEDLINE | ID: mdl-29078339

RESUMEN

Large, fruit-eating vertebrates have been lost from many of the world's ecosystems. The ecological consequences of this defaunation can be severe, but the evolutionary consequences are nearly unknown because it remains unclear whether frugivores exert strong selection on fruit traits. I assessed the macroevolution of fruit traits in response to variation in the diversity and size of seed-dispersing vertebrates. Across the Indo-Malay Archipelago, many of the same plant lineages have been exposed to very different assemblages of seed-dispersing vertebrates. Phylogenetic analysis of >400 plant species in 41 genera and five families revealed that average fruit size tracks the taxonomic and functional diversity of frugivorous birds and mammals. Fruit size was 40.2-46.5% smaller in the Moluccas and Sulawesi (respectively), with relatively depauperate assemblages of mostly small-bodied animals, than in the Sunda Region (Borneo, Sumatra, and Peninsular Malaysia), with a highly diverse suite of large and small animals. Fruit color, however, was unrelated to vertebrate diversity or to the representation of birds versus mammals in the frugivore assemblage. Overhunting of large animals, nearly ubiquitous in tropical forests, could strongly alter selection pressures on plants, resulting in widespread, although trait-specific, morphologic changes.


Asunto(s)
Evolución Biológica , Frutas/fisiología , Herbivoria/fisiología , Sapindaceae/fisiología , Animales , Ecosistema , Frutas/clasificación , Indonesia , Malasia , Modelos Teóricos , Sapindaceae/clasificación , Sapindaceae/genética , Dispersión de Semillas/fisiología , Semillas/fisiología
15.
Ecol Lett ; 22(3): 480-485, 2019 Mar.
Artículo en Inglés | MEDLINE | ID: mdl-30609192

RESUMEN

Understanding the mechanisms driving declines in biodiversity with latitude requires assessing if there are ecological limits to the number of species that can coexist, and if these limits vary with latitude, both of which are long-standing and currently debated questions. Here I show that diversification of North American mammals across the Cenozoic Era slowed as diversity increased. This damping of diversification rates indicates ecological limitation, which occurred even though diversity fluctuated through time and was almost never at an equilibrium 'saturation' point. The estimated environmental carrying capacity was correlated with global temperature positively at high latitudes and negatively at low latitudes. Geographical variation in how standing diversity affects diversification rates could help explain the latitudinal biodiversity gradient as well as changes in the strength of the gradient over time.


Asunto(s)
Biodiversidad , Mamíferos , Temperatura , Animales , Geografía
16.
Am Nat ; 193(5): 748-754, 2019 05.
Artículo en Inglés | MEDLINE | ID: mdl-31002574

RESUMEN

A fundamental tenet of modern ecology and conservation science is the fact that species occurrence in habitat patches can be determined by patch area and isolation. But such island biogeographic models often poorly predict actual species occurrences in structurally complex landscapes that typify most ecosystems. Recent advances in circuit theory have enhanced estimates of species dispersal and can provide powerful ways to predict landscape-scale distribution of species assemblages through integration with island biogeography. Applying such an integrative analytical framework to 43 bird species in Tanzania improved model fit by an average of 2.2-fold over models where patch isolation was estimated without accounting for landscape matrix heterogeneity. This approach also allowed us to assess species-specific dispersal rates and quantify differences among land cover types in their permeability to animal movement. These results reaffirm the utility of foundational island biogeographic principles, yet with an important caveat. Two-thirds of the variance in species occurrence in habitat fragments can be explained simply by patch area and isolation, conditional on isolation explicitly accounting for the spatial configuration of different land cover types in the landscape matrix.


Asunto(s)
Distribución Animal , Aves , Bosques , Modelos Biológicos , Animales , Tanzanía
17.
Proc Biol Sci ; 286(1907): 20190966, 2019 07 24.
Artículo en Inglés | MEDLINE | ID: mdl-31311475

RESUMEN

Wild meat (or 'bushmeat') hunting is nearly ubiquitous across the tropics and is very often unsustainable-driving declines and extirpation of numerous mammal populations. Loss of these animals can alter the transport of nutrients within and between ecosystems. But whether the physical removal of vertebrate carcasses and the nutrients that they store can reduce overall nutrient availability in ecosystems has been little explored. At 32 sites on three continents, we show that annual phosphorus (P) loss via mammal exploitation was low relative to the rate of atmospheric P deposition. But at four sites in Africa and Southeast Asia, removal of P in the skeletons of hunted mammals exceeded the atmospheric input of this nutrient by 10-fold or more. Because P is the growth-limiting nutrient for many tropical terrestrial ecosystems and certain large mammals, the imbalance created by the removal of mammal biomass under very high hunting scenarios could reduce ecosystem carrying capacity if no compensatory P additions occur in the system. This biogeochemical perspective on bushmeat exploitation raises further concerns about harvest sustainability and human food security in areas where hunting rates are high and ecosystem P inputs low.


Asunto(s)
Conservación de los Recursos Naturales , Ecosistema , Actividades Humanas , Mamíferos , Carne , Fósforo/metabolismo , África , Animales , Asia Sudoriental
18.
J Anim Ecol ; 88(6): 892-902, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-30895613

RESUMEN

Periods of extreme food abundance, such as irregular masting events, can dramatically affect animal populations and communities, but the extent to which anthropogenic disturbances alter animal responses to mast events is not clear. In South-East Asia, dipterocarp trees reproduce in mast fruiting events every 2-10 years in some of the largest masting events on the planet. These trees, however, are targeted for selective logging, reducing the intensity of fruit production and potentially affecting multiple trophic levels. Moreover, animal responses to resource pulse events have largely been studied in systems where the major mast consumers have been extirpated. We sought to evaluate the influence of human-induced habitat disturbance on animal responses to masting in a system where key mast consumers remain extant. We used motion-triggered camera traps to quantify terrestrial mammal and bird occurrences in Sabah, Malaysian Borneo, relative to variation in fruit biomass from 69 plant families during a major (2014) and minor (2015) masting event and a non-mast year (2013), in both logged and unlogged forests. Bearded pigs (Sus barbatus) showed the clearest responses to masting and occurrence rates were highest in unlogged forest in the year following the major mast, suggesting that the pulse in fruit availability increased immigration or reproduction. We also detected local-scale spatial tracking of dipterocarp fruits in bearded pigs in unlogged forest, while this was equivocal in other species. In contrast, pigs and other vertebrate taxa in our study showed limited response to spatial or temporal variation in fruit availability in logged forest. Our findings suggest that vertebrates, namely bearded pigs, may respond to masting via movement and increased reproduction, but that these responses may be attenuated by habitat disturbance.


Asunto(s)
Frutas , Árboles , Animales , Borneo , Malasia , Porcinos , Vertebrados
19.
Conserv Biol ; 33(3): 612-622, 2019 06.
Artículo en Inglés | MEDLINE | ID: mdl-30306633

RESUMEN

Management activities such as law enforcement and community outreach are thought to affect conservation outcomes in protected areas, but their importance relative to intrinsic environmental characteristics of the parks and extrinsic human pressures surrounding the parks have not been explored. Furthermore, it is not clear which is more related to conservation outcomes-the management itself or local people's perceptions of the management. We measured objective (reports by park staff) and subjective (reports by local people) levels of community outreach and law enforcement based on responses to 374 questionnaires. We estimated mammal abundance and diversity of 6 protected areas based on data from 115 camera traps in Xishuangbanna, southwest China, a biodiversity hotspot with high hunting and land-conversion pressures. We then examined correlations among them and found that local people's perception of law enforcement was positively related to the local abundance of 2 large, hunted species, wild boar (Sus scrofa) (ß = 15.22) and muntjac (Muntiacus vaginalis) (ß = 14.82), but not related to the abundance of smaller mammals or to objective levels of enforcement. The subjective frequency of outreach by park staff to local communities (ß = 3.42) and park size (ß = 3.28) were significantly and positively related to mammal species richness, whereas elevation, human population density, and subjective frequency of law enforcement were not. We could not conclude that community outreach and law enforcement were directly causing increased mammal abundance and diversity. Nevertheless, the patterns we detected are some of the first empirical evidence consistent with the idea that biodiversity in protected areas may be more positively and strongly related to local perceptions of the intensity of park management than to either intrinsic (e.g., elevation, park size) or extrinsic (e.g., human population density) environmental factors.


Efectos de la Aplicación de la Ley y la Participación de la Comunidad sobre la Diversidad de Mamíferos en un Punto Caliente de Biodiversidad Resumen Las actividades de manejo como la aplicación de la ley y la participación de la comunidad afectan los resultados de conservación dentro de las áreas protegidas, pero su importancia en relación con las características ambientales intrínsecas de los parques y las presiones humanas extrínsecas que rodean a los parques no han sido exploradas. Además, no está claro cuál está más relacionado con los resultados de conservación - el manejo en sí o las percepciones que las personas locales tienen sobre el manejo. Medimos los niveles objetivos (reportes dados por el personal del parque) y subjetivos (reportes dados por los locales) de la participación de la comunidad y la aplicación de la ley con base en las respuestas a 347 cuestionarios. Estimamos la abundancia y diversidad de mamíferos de seis áreas protegidas con base en datos de 115 cámaras trampa en Xishuangbann, al suroeste de China, un punto caliente de biodiversidad con altas presiones causadas por la caza y la conversión del uso de suelo. Después examinamos la correlación entre ellos y encontramos que la percepción que los locales tienen sobre la aplicación de la ley estuvo relacionada positivamente con la abundancia local de dos grandes especies que son cazadas, el jabalí (Sus scrofa) (ß = 15.22) y el muntíaco (Muntiacus vaginalis) (ß = 14.82), pero no estuvo relacionada con la abundancia de mamíferos más pequeños o con los niveles objetivos de la aplicación de la ley. La frecuencia subjetiva del alcance del personal del parque hacia las comunidades locales (ß = 3.42) y el tamaño del parque and (ß = 3.28) estuvieron relacionadas significativa y positivamente con la riqueza de las especies de mamíferos, mientras que la elevación, la densidad de la población humana, y la frecuencia subjetiva de la aplicación de la ley no lo estuvieron. No pudimos concluir que la participación de la comunidad y la aplicación de la ley estuvieran causando directamente una abundancia y diversidad aumentada de mamíferos. Sin embargo, los patrones que detectamos son de las primeras evidencias empíricas consistentes con la idea de que la biodiversidad en las áreas protegidas podría estar relacionada positiva y fuertemente con la percepción que tienen los locales de la intensidad del manejo del parque y no con los factores ambientales intrínsecos (p. ej.: elevación, tamaño del parque) o extrínsecos (p.ej.: densidad de la población humana).


Asunto(s)
Conservación de los Recursos Naturales , Aplicación de la Ley , Animales , Biodiversidad , China , Relaciones Comunidad-Institución , Humanos , Mamíferos
20.
Proc Biol Sci ; 285(1873)2018 02 28.
Artículo en Inglés | MEDLINE | ID: mdl-29491176

RESUMEN

Animals can have both positive (e.g. via seed dispersal) and negative (e.g. via herbivory) impacts on plants. The net effects of these interactions remain difficult to predict and may be affected by overhunting and habitat disturbance, two widespread threats to tropical forests. Recent studies have documented their separate effects on plant recruitment but our understanding of how defaunation and logging interact to influence tropical tree communities is limited. From 2013 to 2016, we followed the fate of marked tree seedlings (n = 1489) from 81 genera in and outside experimental plots. Our plots differentially excluded small, medium and large-bodied mammal herbivores in logged and unlogged forest in Malaysian Borneo. We assessed the effects of experimental defaunation and logging on taxonomic diversity and plant trait (wood density, specific leaf area, fruit size) composition of seedling communities. Although seedling mortality was highest in the presence of all mammal herbivores (44%), defaunation alone did not alter taxonomic diversity nor plant trait composition. However, herbivores (across all body sizes) significantly reduced mean fruit size across the seedling community over time (95% confidence interval (CI): -0.09 to -0.01), particularly in logged forest (95% CI: -0.12 to -0.003). Our findings suggest that impacts of mammal herbivores on plant communities may be greater in forests with a history of disturbance and could subsequently affect plant functional traits and ecological processes associated with forest regeneration.


Asunto(s)
Agricultura Forestal , Herbivoria , Mamíferos/fisiología , Plantones/anatomía & histología , Árboles/anatomía & histología , Árboles/fisiología , Animales , Biodiversidad , Tamaño Corporal , Borneo , Conservación de los Recursos Naturales , Bosques , Rasgos de la Historia de Vida , Malasia , Plantones/crecimiento & desarrollo , Plantones/fisiología , Árboles/crecimiento & desarrollo
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA