Efeito da quantidade de floresta na predação de sementes e frugivoria em diferentes tipos de ambientes
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Data
2020-02-18
Autores
Alves, Rafael Souza Cruz
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Universidade Estadual Paulista (Unesp)
Resumo
Alterações antrópicas no nível de paisagens afetam de maneiras distintas os diversos grupos de animais e plantas. Tais alterações afetam a composição de espécies e estrutura de comunidades de mamíferos e aves, resultando na perda de funções ecológicas essenciais para a manutenção das florestas. Dentre os processos que podem ser mais afetados inclui-se a frugivoria e a predação de sementes. Desta forma, avançar os conhecimentos de como a paisagem e os tipos de ambientes influenciam tais processos é essencial para a proposição de estratégias que beneficiem a conservação da biodiversidade e manutenção de processos ecológicos. Este estudo tem por objetivo responder qual a contribuição relativa da proporção de vegetação florestal, do tipo de ambiente e sua interação sobre a predação de sementes e frugivoria. Estudamos quatro tipos de ambientes: interior de floresta continua, fragmento florestal, borda de floresta e corredor florestal. O estudo foi realizado em uma região de ecótono entre os biomas Amazônia e Cerrado no estado de Mato Grosso, Brasil. Nessa região foram selecionadas 17 paisagens, representando um gradiente de quantidade de floresta de 10% a 86% em um raio de 3 km. Nessas paisagens avaliamos a frugivoria utilizando frutos artificiais e a predação de sementes utilizando sementes de amendoim e girassóis. Nossos resultados sugerem que a frugivoria por aves foi positivamente relacionada a proporção florestal para aves de médio e grande porte, bem como para a frugivoria total por aves, entretanto a magnitude do efeito variou de acordo com o grupo de aves. Já a frugivoria por pequenos mamíferos apresentou relação negativa com a proporção florestal, sem muito efeito acima de 0,3 de quantidade de floresta. A predação foi influenciada apenas marginalmente pela proporção florestal. Em termos gerais observamos que o tipo de ambiente não influenciou a frugivoria e nem a predação de sementes. Com isso, nossos resultados demonstram que a cobertura florestal tem um duplo efeito negativo na dispersão de sementes, uma vez que reduz a frugivoria e aumenta as taxas de predação. Dessa forma, para a manutenção de funções e serviços ecossistêmicos em que a predação e frugivoria são processos importantes, devemos levar em consideração a quantidade de floresta remanescente na região de interesse.
Human changes at the landscape level affect different groups of animals and plants in different ways. Such changes affect species composition and mammal and bird community structure, resulting in the loss of essential ecological functions for forest maintenance. Among the most affected processes are the frugivory and seed predation. Thus, advancing the knowledge of how the landscape and environment types influence such processes is essential for proposing strategies that benefit the conservation of biodiversity and the maintenance of ecological processes. This study aims to assess the relative contribution of forest vegetation proportion, environment type and their interaction on seed predation and frugivory. We studied four environment types: continuous forest interior, forest fragment, forest edge and forest corridor. The study was carried out in an ecotone region between Amazon and Cerrado biomes in Mato Grosso state, Brazil. In this region, 17 landscapes were selected ranging from 10% to 86% of forest cover in a radius of 3 km. In each landscape we evaluated frugivory using artificial fruits and seed predation using peanut and sunflower seeds. Our results suggest that frugivory by birds was positively related to forest proportion for medium and large birds, as well as to total frugivory by birds, however the magnitude of the effect varied according to the group of birds. Frugivory by small mammals, on the other hand, showed a negative relationship with forest proportion, without much effect above 0.3 of forest. Predation was only marginally influenced by forest proportion. In general, we observed that environment type did not influence frugivory or seed predation. Our results demonstrate that forest cover has a double negative effect on seed dispersal, since it reduces frugivory and increases predation rates. Thus, in order to maintain ecosystem functions and services in which predation and frugivory are important processes, we must take into account the remaining forest amount in the region of interest.
Human changes at the landscape level affect different groups of animals and plants in different ways. Such changes affect species composition and mammal and bird community structure, resulting in the loss of essential ecological functions for forest maintenance. Among the most affected processes are the frugivory and seed predation. Thus, advancing the knowledge of how the landscape and environment types influence such processes is essential for proposing strategies that benefit the conservation of biodiversity and the maintenance of ecological processes. This study aims to assess the relative contribution of forest vegetation proportion, environment type and their interaction on seed predation and frugivory. We studied four environment types: continuous forest interior, forest fragment, forest edge and forest corridor. The study was carried out in an ecotone region between Amazon and Cerrado biomes in Mato Grosso state, Brazil. In this region, 17 landscapes were selected ranging from 10% to 86% of forest cover in a radius of 3 km. In each landscape we evaluated frugivory using artificial fruits and seed predation using peanut and sunflower seeds. Our results suggest that frugivory by birds was positively related to forest proportion for medium and large birds, as well as to total frugivory by birds, however the magnitude of the effect varied according to the group of birds. Frugivory by small mammals, on the other hand, showed a negative relationship with forest proportion, without much effect above 0.3 of forest. Predation was only marginally influenced by forest proportion. In general, we observed that environment type did not influence frugivory or seed predation. Our results demonstrate that forest cover has a double negative effect on seed dispersal, since it reduces frugivory and increases predation rates. Thus, in order to maintain ecosystem functions and services in which predation and frugivory are important processes, we must take into account the remaining forest amount in the region of interest.
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Palavras-chave
Processos ecológicos, Frutos artificiais, Perda de habitat, Interações ecológicas, Ecological processes, Artificial fruits, Ecological interactions, Habitat loss