A modelação dinâmico-espacial na gestão do Parque Natural da Madeira: qual a relação da comunidade de passeriformes comuns com a qualidade ecológica dos habitats nativos?
Ficheiros
Data
2017-05-24
Autores
Título da revista
ISSN da revista
Título do Volume
Editora
Resumo
As ilhas oceânicas têm cativado o interesse de biólogos evolucionistas e ecólogos por serem entidades territoriais confinadas mas, em regra, com elevada biodiversidade, funcionando como modelos ideais para o estudo de processos evolutivos e de alteração ambiental. As ilhas são normalmente caracterizadas por um número significativo de espécies endémicas, que surgem por processos de especiação em contextos de isolamento (ecótipos ou neo-endemismos), bem como por habitats/ecossistemas únicos. Nesta perspectiva, a conservação e gestão destes valores ecológicos é crucial para garantir a sua viabilidade e sustentabilidade face às pressões antropogénicas a que estão sujeitos. Na Madeira, este desígnio conservacionista tem sido desenvolvido no seu Parque Natural. No presente trabalho pretende-se demonstrar a aplicabilidade de um protocolo de modelação dinâmico-espacial na previsão de tendências ecológicas relevantes para avaliar o estado de conservação de habitats nativos. A metodologia estocástico-dinâmica (StDM) foi a abordagem seleccionada em virtude de permitir estudar localmente o modo como indicadores ecológicos relevantes, expressos ao nível das comunidades, respondem às alterações do meio envolvente. O principal objetivo deste trabalho consistiu na selecção de indicadores que permitam avaliar qualidade ecológica dos habitats nativos em contraposição com os habitats moldados pela actividade humana, como as áreas periurbanas e agro-florestais. Para este efeito foram selecionados atributos das comunidades de passeriformes comuns (riqueza específica e abundância) como indicadores da presença de habitats humanizados, muito marcados pela presença de espécies exóticas, potenciais ameaças para a integridade dos habitats nativos. Em termos demonstrativos foram considerados dois cenários contrastantes: (1) o cenário de continuidade, tendo em conta o histórico das alterações em curso no território da Madeira, que têm gerado o aumento das espécies exóticas e da sua dispersão; (2) o cenário de gestão dos habitats nativos, com a implementação mais generalizada de medidas de conservação e de controlo de exóticas.
Em termos comparativos, não obstante a degradação implícita no cenário de continuidade (especialmente induzida pela proliferação de espécies exóticas), os passeriformes revelaram-se bons indicadores da prevalência das características associadas a ecossistemas humanizados, com abundâncias relativas mais elevadas nesses contextos. Quando a gestão é simulada de forma a minimizar os efeitos associados às práticas humanas e/ou das suas consequências sobre os ecossistemas nativos (cenário de gestão), onde se privilegiou a manutenção dos habitats nativos e o controlo da expansão de espécies exóticas, as comunidades de passeriformes típicas dos sistemas humanizados reflectem essas tendências diminuindo a sua abundância relativa (embora sem reflexos na riqueza específica) nos ecossistemas/habitats alvo dessas medidas de conservação.
The Ocean islands have captivated the interest of biologists and evolutionary ecologists because, although confined territorial entities, these systems exhibit high biodiversity levels, working as ideal models for the study of evolutionary processes and environmental change. Islands are generally characterized by a significant number of endemic species, which arise from speciation processes in contexts of isolation (ecotypes or neo-endemics) as well as habitats/unique ecosystems. In this perspective, the conservation and management of these ecological values is crucial to ensure its viability and sustainability in face of anthropogenic pressures to which they are subject. In Madeira, this conservationist intent has been developed by its natural park. This work aims to demonstrate the applicability of a spatially explicit dynamic modeling protocol developed for relevant ecological trends in order to assess and predict the state of conservation of native habitats. The stochastic - dynamic methodology (StDM) has been the approach selected by capturing locally how relevant ecological indicators, expressed at the community level, respond to changes of the environment. The main objective of this work was to select indicators to assess ecological quality of native habitats as opposed to the habitats shaped by human activity, such as peri-urban and agro -forestry areas. For this purpose some attributes of common passerine communities were selected (species richness and abundance) as indicators of the presence of humanized habitats, very marked by the presence of exotic species, potential threats to the integrity of native habitats. These hypotheses were tested under two contrasting scenarios: (1) the continuity scenario, given the historic changes under way in the territory of Madeira, which has generated an increase in alien species and their dispersion; (2) the management scenario of native habitats, with the more widespread implementation of conservation measures and alien species control. By comparison, although the implicit degradation of the continuity scenario (especially marked by the proliferation of exotic species), passerines proved to be a good indicator of the prevalence of characteristics associated with humanized ecosystems, with relative abundances higher in these contexts. When management is simulated in order to minimize the effects associated with human practices and/or its consequences on native ecosystems (management scenario), which favored the maintenance of native habitats and control the spread of exotic species, communities passerines typical of humanized systems reflect these trends decreasing their relative abundance (although no effects on the species richness was detected) in ecosystems/habitats targeted these conservation measures.
The Ocean islands have captivated the interest of biologists and evolutionary ecologists because, although confined territorial entities, these systems exhibit high biodiversity levels, working as ideal models for the study of evolutionary processes and environmental change. Islands are generally characterized by a significant number of endemic species, which arise from speciation processes in contexts of isolation (ecotypes or neo-endemics) as well as habitats/unique ecosystems. In this perspective, the conservation and management of these ecological values is crucial to ensure its viability and sustainability in face of anthropogenic pressures to which they are subject. In Madeira, this conservationist intent has been developed by its natural park. This work aims to demonstrate the applicability of a spatially explicit dynamic modeling protocol developed for relevant ecological trends in order to assess and predict the state of conservation of native habitats. The stochastic - dynamic methodology (StDM) has been the approach selected by capturing locally how relevant ecological indicators, expressed at the community level, respond to changes of the environment. The main objective of this work was to select indicators to assess ecological quality of native habitats as opposed to the habitats shaped by human activity, such as peri-urban and agro -forestry areas. For this purpose some attributes of common passerine communities were selected (species richness and abundance) as indicators of the presence of humanized habitats, very marked by the presence of exotic species, potential threats to the integrity of native habitats. These hypotheses were tested under two contrasting scenarios: (1) the continuity scenario, given the historic changes under way in the territory of Madeira, which has generated an increase in alien species and their dispersion; (2) the management scenario of native habitats, with the more widespread implementation of conservation measures and alien species control. By comparison, although the implicit degradation of the continuity scenario (especially marked by the proliferation of exotic species), passerines proved to be a good indicator of the prevalence of characteristics associated with humanized ecosystems, with relative abundances higher in these contexts. When management is simulated in order to minimize the effects associated with human practices and/or its consequences on native ecosystems (management scenario), which favored the maintenance of native habitats and control the spread of exotic species, communities passerines typical of humanized systems reflect these trends decreasing their relative abundance (although no effects on the species richness was detected) in ecosystems/habitats targeted these conservation measures.
Descrição
Dissertação de Mestrado em Gestão de Recursos Naturais
Palavras-chave
Passeriformes , Parque natural , Ilha da Madeira (Portugal) , Conservação , Modelação dinâmico-espacial , Espécies exóticas