Uso de modelos para avaliar a influência da matriz de paisagens fragmentadas sobre aves do Cerrado e da Mata Atlântica

Tese (doutorado)—Universidade de Brasília, Instituto de Ciências Biológicas, Departamento de Ecologia, Programa de Pós-Graduação em Ecologia, 2012.CAPÍTULO 1: Resumo A maximização do potencial de conservação de médio a pequenos fragmentos florestais é tônica para a manutenção das espécies da Mata Atlântica, onde manchas de habitat são relativamente pequenas e as populações que as habitam são suscetíveis à extinção local. Uma estratégia para fazer isso é por meio da restauração da matriz da paisagem com da implantação de sistemas agroflorestais. Foi construído um modelo para identificar as regiões em que a restauração da matriz tem maior efeito sobre a conectividade funcional para aves florestais endêmicas. As hipóteses testadas são de que (1) a eficácia da restauração da matriz é afetada pelo grau de isolamento da paisagem, e que (2) em graus intermediários de isolamento a eficiência de restauração para a conectividade é máxima. Modelamos a conectividade funcional usando o Índice Integral de Conectividade de quatro espécies de aves endêmicas (Chiroxiphia caudata, Sclerurus scansor, Xiphorhynchus fuscus e Pyriglena leucoptera) em três tipos de matrizes em paisagens da Mata Atlântica. Foram ajustados modelos aditivos generalizados mistos para analisar a influência do isolamento sobre a conversão da matriz. Além disso, foi testado se métrica de isolamento seria o melhor preditor da eficácia da restauração de matriz. A primeira hipótese foi corroborada pelo modelo mas, por outro lado, a segunda hipótese foi confirmada por apenas um único cenário de um total 12. Geralmente a eficácia da restauração está negativamente associada ao isolamento, de modo que uma maior eficácia é encontrada em paisagem em que manchas têm mario área e estão mais próximas umas das outras. Apesar disso, houve uma grande variação na resposta, aspecto que dificultou a generalização dos resultados. A média do índice de proximidade foi melhor preditor da eficiência de restauração do que a média do vizinho mais próximo. O modelo pode ser utilizado para tomadores de decisões e gestores definirem áreas prioritárias para a restauração agroflorestal. _____________________________________________________________________________________________CAPÍTULO 2: Resumo Compreender como os diferentes tipos de manejo da matriz de paisagem afetam organismos que habitam manchas de habitat natural é crucial para a conservação biológica. Tal fato se dá uma vez que a maior parte da biodiversidade terrestre habita sistemas agrícolas ou fragmentos de habitat inseridos em uma matriz agrícola. Considerando que a maior parte dessas paisagens agrícolas é composta por sistemas intensivos, ou que correm risco de sofrer intensificação agrícola, uma questão relevante para o manejo é: como a intensificação da matriz agrícola afeta a dinâmica populacional de pássaros habitando fragmentos florestais inseridos nesta matriz? O presente capítulo descreve um modelo qualitativo baseado em Teoria Qualitativa dos Processos e implementado através do software Garp3 para responder esta questão. O modelo descreve uma paisagem composta por um fragmento fonte resistente à extinção e um fragmento alvo no qual eventos populacionais estocásticos podem ocorrer. Se a permeabilidade da matriz exceder um dado limiar espécie específico, propágulos provenientes da fonte alcançam o fragmento alvo. A intensificação agrícola afeta a estrutura espacial da matriz e reduz a permeabilidade da mesma para as aves florestais, reduzindo assim o efeito resgate. Além disso, assume-se que algumas espécies podem usar a matriz como um habitat complementar para a alimentação e que o manejo da matriz pode afetar a base de recursos para essas espécies. Os resultados da simulação sugerem que, se a intensificação da agricultura continuar a ocorrer no domínio Mata Atlântica, as populações de espécies sensíveis que habitam pequenas manchas florestais (situação em que se encontra a maioria das populações que habitam remanescentes florestais) serão altamente suscetíveis à extinção local sem futuros eventos de recolonização. _____________________________________________________________________________________________CAPÍTULO 3: Resumo Uma parte significativa da biodiversidade terrestre do mundo utiliza manchas de habitat naturais inseridas em uma matriz agrícola. Neste capítulo, é apresentado um modelo de raciocínio qualitativo para comparar os impactos da agricultura intensiva e do manejo tradicional em comunidades de aves que habitam um mosaico de savana-floresta na ecorregião do Cerrado brasileiro, através da exploração não-numérica e representação explícita do conhecimento das relações causais. As espécies foram agrupadas com base em seu uso distinto do mosaico floresta-savana: especialistas florestais, generalistas florestais e não-florestais. O modelo qualitativo foi desenvolvido utilizando o programa Garp3. Nossos resultados sugerem que a agricultura intensiva leva ao declínio das aves florestais especialistas e espécies não-florestais, enquanto generalistas florestais se mantêm estáveis. Por outro lado, o manejo tradicional pode levar a uma diminuição ou a manutenção das espécies não-florestais e manutenção de ambos os grupos florestais. A substituição do manejo tradicional pela agricultura intensiva pode afetar negativamente as aves do Cerrado

Conservation on the Frontier: Understanding and Influencing How Cattle Production Impacts Avian Diversity in the Dry Chaco Forests of Argentina

This thesis combines the identification of land-use strategies that provide high yields and high biodiversity with the identification of the psycho-social drivers of land-use decisions in an agricultural landscape. I visited 116 landholdings in two agricultural landscapes of the Dry Chaco region in Argentina. In 27 landholdings producing beef cattle in production systems of different land-use intensity, I collected empirical information on: (i) cattle yields, (ii) avian diversity, density and composition, and (iii) structural attributes of habitat in the agricultural matrix. The Chaco avifauna responded non-linearly to increasing cattle production intensification as bird species richness was relatively unchanged from forests to intermediate-intensity silvopastoral systems and decreased sharply at high-intensity pasture systems. This pattern indicated the presence of a threshold in habitat quality for birds when native tree cover falls below 30%. The concave trade-off function suggests that land-sharing through the integration of native trees and pastures in silvopastoral systems has more potential than land-sparing to simultaneously provide high cattle yields and high bird diversity. Intermediate-intensity silvopastoral systems may represent a matrix type of high habitat quality for most bird species due to the lower frequency and intensity of disturbances resulting from agricultural management, compared to high-intensity systems. Bird functional groups responded differently to agricultural intensification and habitat modification. Forest-restricted and fruit-eating bird species occurred at low density in intermediate-intensity silvopastoral systems and disappeared from high-intensity pasture systems. Therefore, low-intensity systems and forest fragments (larger than 1000 ha) should be maintained in the landscape to provide habitat for species of high conservation concern and potentially contributing to forest regeneration. In 89 landholdings varying in landholding size and land tenure condition, I interviewed landholders and collected information about their beliefs, values and perceptions regarding conservation of remnant forest fragments. Based on this information, I tested the ability of three social psychological models and nine psycho-social constructs to explain landholders’ conservation intentions. The Theory of Planned behaviour provided a parsimonious and plausible explanatory model of landholders’ intentions to conserve remnant forest fragments in their landholdings. A model integrating self-interest and pro-social motives as proximal predictors and self-identity as the ultimate predictor explained 42% of the variance in landholders’ conservation intentions. The perceived pressure from relevant others to conserve forests (i.e. social norms) and the tendency to value forests favourably or unfavourably (i.e. attitudes) directly and significantly influenced landholders’ willingness to set-aside remnant forests in their landholdings. Landholders’ self-identity and their level of awareness of the scale and consequences of deforestation underlay the effects of social norms and attitudes on conservation intentions. Policy interventions aimed at influencing the behaviour of landholders towards more conservation-oriented outcomes would be more effective if tailored to the characteristics of landholder identity groups. Influencing conservation intentions of high-intensity, productivist landholders may require policy incentives and regulations that link better environmental performance with agricultural production outcomes and can become peer-enforced in the long-term. Conservation and development outcomes can be jointly enhanced for low-intensity, pre-productivist landholders through policies that secure their land tenure and facilitate the implementation of silvopastoral systems

Modelling the spatial and temporal dynamics of upland birds in Scotland

Population numbers change in space and time. The construction of models to investigate the spatial and temporal dynamics of populations may offer a means to identify the processes driving this change. In this thesis, we make use of models to examine the population ecology of three species of upland birds: red grouse, meadow pipit and capercaillie. Populations of red grouse in the British Isles exhibit cyclic fluctuations in abundance. Time series data from 287 grouse moors across the United Kingdom were analysed to investigate co-variation in these fluctuations. Results indicate high levels of synchrony between populations on neighbouring moors, with synchrony declining with increasing intermoor distance. At distances greater than 100km, populations exhibit only weak synchrony. Synchrony is shown to be a product of strong coupling events, which occur on average every one in six years. In the absence of such events, synchrony is shown to dissipate within three years. Further, we present evidence which suggests this coupling is driven (at least in part) by dispersal between populations. The density dependent structures are also found to be sufficiently homogeneous to allow correlations in climate to synchronise dynamics, but examination of three climate variables failed to detect a relationship. We also studied the population dynamics of meadow pipits in upland grassland ecosystems. Data, collected as part of an ongoing grazing field experiment, were analysed to construct a Bayesian model of population growth, and predict the effect of grazing intensity on meadow pipit populations. Results suggest grazing has a significant impact on population growth. Grazing may act to improve meadow pipit foraging efficiency and thus productivity. Finally, a spatially explicit population viability model was constructed to predict changes in the future abundance and distribution of capercaillie. Published estimates of key demographic variables were drawn from the literature to parameterise the model. The spatial structure of the population was inferred from spatial data, documenting the extent and configuration of remnant pine woodlands in Scotland. The model predicts a low probability of extinction for capercaillie in the future, and offers insights into key processes affecting the distribution and abundance of this species. The development of these models has advanced our understanding of the environmental processes driving changes in the spatial and temporal dynamics of these species. The results of these studies may be useful in anticipating the future consequences of various drivers of change on the ecology of upland species

The effects of human disturbance on vascular epiphyte in the Brazilian Atlantic Forest

The high pressure that anthropogenic activities places on tropical forests are pushing species and communities to the brink of local, regional or global extinctions. However, the consequences of the loss of species and their ecosystem functions are not well known. My thesis addresses the causes and consequences of human disturbance on vascular epiphytes in the Brazilian Atlantic forest (BAF). I sampled understory and canopy, across a gradient of habitat loss, i.e. pastureland, human-modified forests (HMFs) and old-growth forest. I found that habitat loss has driven a net loss of 91% of species exclusive to old-growth, and 90% of individuals. I also found the edge effect to be a ubiquitous landscape process extending at least 500 m within forests habitats, leaving just 19.4% of the whole of the BAF suitable for forest-dependant epiphytes. However, whilst endemic species (habitat specialised species) are more prone to disappear as consequence of habitat loss, species with larger dispersal ranges and the ability to colonize different forest types flourish or endure the harsh conditions after disturbance. Consequently, HMFs have low functional richness and low functional redundancy, meaning low resilience, whereas old-growth forests exhibit high ecological resilience. Habitat transformation also leads to the loss of a large set of ecosystem functions related to pollination and water cycling across strata. Hence preserving large continuous forests are probably the only pragmatic conservation strategy for vascular epiphytes in highly human-modified landscapes. However, human-modified forests still provide limited ecosystem functions that may increase because of initiatives to improve habitat amount.Open Acces

Human Alteration of a Neotropical Landscape Drives Long-term Changes in its Forest Bird Communities

Human alteration of natural landscapes leads to biodiversity loss, often from a combination of area effects and fragmentation effects. Smaller habitat patches support fewer species than large ones and incur additional consequences from isolation. Efforts to preempt biodiversity loss from insular habitat fragments are complicated by individualistic species responses and time-delayed extinctions. Understanding how human activity affects bird communities in species rich, disturbance sensitive tropical forests is a conservation priority. Nevertheless, tropical ecosystems remain under-studied; long-term species inventory data from tropical forests are rare. This dissertation combines a unique set of spatially extensive avian inventories from lowland forests in central Panama with a long history of bird surveys from Barro Colorado Island (BCI), a well-studied land-bridge island isolated within the Panama Canal, to better inform our understanding of how human-altered environments drive long-term changes in tropical forest bird communities. First, I evaluated trait predictors of species extinctions from BCI. I assessed to what degree changes in BCI’s bird community can be explained by loss of species sensitive to fragmentation-associated environmental drying. In my second data chapter, I examined the pattern of delayed extinctions on BCI among different species groups. I used species-area models and extinction trends to predict how many species BCI might still lose and how long these remaining species losses could take. Lastly, I focused on lowland forest patches within the Canal zone to evaluate how increasing urbanization influences the use of forest patches by tropical birds, with a focus on species composition, traits, and phylogenetic diversity. Birds are likely to have disappeared from BCI if they had small populations in the 1920s, specialize on terrestrial arthropods, and are sensitive to forest moisture conditions. As a consequence of extreme, persistent declines among understory insectivores associated with wet forests, the bird community on BCI has significantly shifted to resemble forest bird communities on the drier portion of the rainfall gradient. Extinctions accelerated 40-60 years following isolation and the island no longer supports the number of species expected for its size and amount of annual precipitation. From six to 92 additional species may be lost from BCI over the next one to nine centuries. Enduring species losses on BCI appear to be a product of habitat loss, edge effects, and negative consequences of isolation for dispersal-limited birds. In lowland forests of the Canal zone, urbanization is associated with community simplification and decreased compositional similarity without subsequent loss of functional diversity. Urban forests broadly favor good dispersers with short development periods, and recent evolutionary histories. My results reveal the important roles of connectivity, dispersal ability, and sensitivity to local habitat conditions structuring avian community composition in tropical forests of central Panama. Limited human activity and access to large, protected forest tracts appear to be key drivers of avian community composition for both BCI and urban forest fragments. Dispersal-limited tropical birds with small populations, especially habitat specialists sensitive to moisture conditions and human disturbance, may be at greatest risk of extinction in insular rainforest fragments

Assessing the ecological significance of linkage and connectivity for avian populations in urban areas

As urbanisation continues to fragment and degrade habitats there is a need to ensure that cities are managed to sustain ecosystem function and high biodiversity. Ecological theories suggest that areas with higher levels of functional connectivity sustain a more diverse avian population. By identifying the key habitat features that dictate the distribution and abundance of avian populations it is possible to inform planning policy to maximise biodiversity. Bird species presence and abundance across an urban gradient in Birmingham (UK) was surveyed at 70 sites over three sampling periods (between 2009 and 2010), in combination with a tree survey and digital analysis of land use. Functional connectivity was shown to increase the abundance of bird species and to ameliorate the impacts of urban development. Bird species were found to vary with their associations with vegetation structure and a proxy for invertebrate productivity. There was clear evidence for increasing native tree species in the urban matrix to support more bird species. Ringing data collected between 2008 and 2011 were used to examine bird movements through the city and the influence of habitat factors such as connectivity and built space in the matrix. Bird movements between ringing sites demonstrated the permeability of the city and the importance of connectivity in the landscape. This work showed that the composition of the matrix influences bird occupancy and turnover of sites. The novel findings presented in this thesis on the influence of the urban landscape on urban avian ecology should make an important contribution to urban conservation methods

Impacts of climate change on the boreal forest ecosystem. Scientific Opinion of the Panel on Alien Organisms and Trade in Endangered species (CITES) of the Norwegian Scientific Committee for Food and Environment

Source at https://vkm.no/</a

Rainforest regeneration in fragmented forest landscapes

Rainforests are severely threatened by agricultural expansion, frequently resulting in the fragmentation of formerly extensive tracts of continuous forest. The immediate and longer-term effects of fragmentation on tree regeneration, and on alpha- and beta-diversity, remain poorly understood. Forest area and isolation can drive changes in diversity, and may be key considerations for conserving forest biodiversity in human-modified landscapes. I studied trees, saplings, and seedlings (pre- and post-fragmentation recruits), in 14 forest fragments and 5 continuous forest sites in Sabah, Malaysian Borneo. Local alpha-diversity of seedlings was significantly lower in fragments than in undisturbed continuous forest, and lowest in the smallest fragments, potentially signalling an extinction debt. However, saplings showed no declines in alpha-diversity, suggesting that density dependent mortality and/or year-to-year variation in recruitment may compensate for reductions in seedling richness: low seedling diversity may not necessarily translate into low sapling diversity. Nonetheless, 57-64% of genera in small fragments occurred only as adult trees, with no seedlings present, indicating a recruitment failure of some genera. This contributed to greater distinctiveness (increased beta-diversity) of seedling communities in small fragments, which were diverging from trees in the same fragment, and from seedlings in other fragments. Divergence, which has not yet been observed in mature trees, may continue as seedling cohorts mature, causing fragment communities to follow different trajectories of change. Regeneration of 25 functionally-important dipterocarp species was reduced in fragments by almost half (comparing four fragments and four continuous forest sites), but some dipterocarps were still recruiting seedlings effectively in fragments. Collectively, the research shows that there may be some taxonomic impoverishment within fragments (reduced plot-scale alpha-diversity; possible losses from entire fragments), but that continued recruitment in fragments is resulting in increasingly divergent plant communities (increased beta-diversity). Hence, forest fragments continue to make a valuable contribution to landscape-scale diversity and warrant future protection

Modeling of Species Distribution and Biodiversity in Forests

Understanding the patterns of biodiversity and their relationship with environmental gradients is a key issue in ecological research and conservation in forests. Several environmental factors can influence species distributions in these complex ecosystems. It is therefore important to distinguish the effects of natural factors from the anthropogenic ones (e.g., environmental pollution, climate change, and forest management) by adopting reliable models able to predict future scenarios of species distribution. In the last 20 years, the use of statistical tools, such as Species Distribution Models (SDM) or Ecological Niche Models (ENM), allowed researchers to make great strides in the subject, with hundreds of scientific research works in this field. This book collects several research articles where these methodological approaches are the starting point to deepen the knowledge in many timely and emerging topics in forest ecosystems around the world, from Eurasia to America