Large mammalian herbivores modulate plant life-form diversity in tropical forests
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Data
2021-03-12
Autores
Souza, Yuri Silva de [UNESP]
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Universidade Estadual Paulista (Unesp)
Resumo
Os biomas terrestres do mundo são amplamente classificados de acordo com as formas de vida de plantas dominantes que definem a estrutura e os processos do ecossistema. Embora a abundância e distribuição dessas formas de vida possam ser fortemente determinadas por fatores como clima e composição do solo, grandes mamíferos herbívoros têm um forte impacto nas comunidades dessas plantas, portanto, a defaunação (a extinção local ou funcional de grandes animais) tem o potencial de alterar a estrutura de composição das formas de vida das plantas em ecossistemas naturais. As florestas tropicais sustentam uma grande diversidade de formas de vida, incluindo árvores, palmeiras, lianas, arbustos, ervas e bambus, todos os quais desempenham funções importantes do ecossistema. Aqui, avaliamos experimentalmente como grandes mamíferos herbívoros afetam a dominância, diversidade e coexistência de formas de vida de plantas em florestas tropicais usando um experimento de exclusão replicado de longo prazo na Mata Atlântica do Brasil. Ao longo de 10 anos, a exclusão de grandes herbívoros diminuiu a diversidade de formas de vida, aumentou a abundância absoluta de palmeiras e árvores (22% e 38%, respectivamente) e aumentou a diversidade de espécies dentro desses dois grupos, em detrimento de outras formas de vida. Além disso, todas as correlações entre formas de vida foram positivas em parcelas onde os herbívoros tinham acesso, enquanto várias relações negativas surgiram em parcelas onde os herbívoros foram excluídos. Isso ocorreu devido a diversos mecanismos temporais que afetou as comunidades de plantas em ambos os tratamentos experimentais. Nosso trabalho indica que a defaunação altera a dominância das formas de vida e diminui a diversidade e coexistência dessas plantas e, portanto, pode levar a impactos profundos em funções importantes do ecossistema e uma simplificação na estrutural vertical das florestas tropicais.
The world’s terrestrial biomes are broadly classified according to the dominant plant-life forms that define ecosystem structure and processes. Although the abundance and distribution of different plant life-forms can be strongly determined by factors as climate and soil composition, large mammalian herbivores have a strong impact on plant communities, thus defaunation (the local or functional extinction of large animals) has the potential to alter the compositional structure of plant life-forms in natural ecosystems. Tropical rainforests sustain a high diversity of life-forms, including trees, palms, lianas, shrubs, herbs, and bamboos, all of which play important ecosystem functions. Here, we experimentally evaluate how large mammalian herbivores affect the dominance, diversity, and coexistence of these major tropical forest plant life-forms in a long-term replicated exclusion experiment in the Atlantic Forest of Brazil. Over the course of 10 years large herbivore exclusion decreased life-form diversity, increased the absolute abundance of palms and trees (22% and 38%, respectively), and increased the diversity of species within these two groups, in the detriment of other life-forms. Furthermore, all pairwise relationships between life-forms were positive on plots where herbivores had access, whereas several strong negative relationships emerged in plots where herbivores were excluded. This occurred despite strong background directional temporal trends affecting plant communities in both experimental treatments across the region. Our work indicates that defaunation alters life-form dominance and erodes life-form diversity and coexistence and hence might lead to profound impacts on important ecosystem functions and a vertical and horizontal structural simplification of tropical rainforests
The world’s terrestrial biomes are broadly classified according to the dominant plant-life forms that define ecosystem structure and processes. Although the abundance and distribution of different plant life-forms can be strongly determined by factors as climate and soil composition, large mammalian herbivores have a strong impact on plant communities, thus defaunation (the local or functional extinction of large animals) has the potential to alter the compositional structure of plant life-forms in natural ecosystems. Tropical rainforests sustain a high diversity of life-forms, including trees, palms, lianas, shrubs, herbs, and bamboos, all of which play important ecosystem functions. Here, we experimentally evaluate how large mammalian herbivores affect the dominance, diversity, and coexistence of these major tropical forest plant life-forms in a long-term replicated exclusion experiment in the Atlantic Forest of Brazil. Over the course of 10 years large herbivore exclusion decreased life-form diversity, increased the absolute abundance of palms and trees (22% and 38%, respectively), and increased the diversity of species within these two groups, in the detriment of other life-forms. Furthermore, all pairwise relationships between life-forms were positive on plots where herbivores had access, whereas several strong negative relationships emerged in plots where herbivores were excluded. This occurred despite strong background directional temporal trends affecting plant communities in both experimental treatments across the region. Our work indicates that defaunation alters life-form dominance and erodes life-form diversity and coexistence and hence might lead to profound impacts on important ecosystem functions and a vertical and horizontal structural simplification of tropical rainforests
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Experimento de longo prazo, Herbivoria, Defaunação, Mudanças climáticas, Dinâmicas competitivas, Long-term experiment, Herbivory, Defaunation, Climate change, Competitive dynamics