A study published in the journal Ecological Monographs indicates that large mammals, such as tapirs, peccaries, agoutis, and deer, alter the chemical composition of litter and soil in tropical forests of the Brazilian Atlantic Forest. As a result, they increase nutrient availability and, possibly, soil fertility.
The study was conducted by members of the Center for Research on Biodiversity and Climate Change (CBioClima), a Research, Innovation, and Dissemination Center (RIDC) supported by FAPESP and based at the Institute of Biosciences of São Paulo State University (IB-UNESP) in Rio Claro. The findings underscore the critical role of these animals, which are heavily targeted by poachers and experiencing population decline, in the long-term survival of the biome, even within areas where forest cover remains intact.
“Most of the mammalian biomass in contiguous areas of the Atlantic Forest consists of peccaries, native wild pigs that live in herds that can exceed 100 individuals,” says Letícia Gonçalves Ribeiro, the lead author of the study. Ribeiro conducted the research as part of her Ph.D. at IB-UNESP with support from FAPESP.
“They arrive in an area and spend a lot of time trampling and rooting around in the ground, searching for fallen fruits and seeds, as well as defecating and urinating. As a result, they end up influencing nutrient cycling, altering soil chemistry and the diversity of the litter – the layer of leaves, twigs, and fruits on the soil surface,” the scientist explains. Other large herbivorous mammals that inhabit the biome include tapirs, deer, and agoutis, another species of wild pig.
To better understand the importance of these animals to the Atlantic Forest ecosystem, the researchers compared soil and litter samples from areas where the mammals roam freely with samples from fenced-off areas where they were temporarily eliminated. The results revealed substantial differences in acidity (pH) – less acidic with animals present and more acidic without – as well as in the availability of nutrients, such as calcium and aluminum.
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