Replacing the natural savanna matrix with eucalyptus plantations and soybean fields changes the seed rain promoted by bats in Amazonian savannas

Abstract

The advance of plantations and croplands into natural areas has catalysed the loss of species and ecosystem functions worldwide. This loss appears to be more intense in tropical regions and may strongly impact groups essential for maintaining forests, such as bats. We evaluated the consequences of land-use changes on seed dispersal carried out by bats in the Savannas of Amapá, northeast of the Brazilian Amazon. More specifically, we compared the metrics of seed dispersal networks of the natural savanna matrix in relation to soybean or eucalyptus matrix, as well as between forest patches inserted in the natural savanna matrix in relation to forest patches inserted in soybean or eucalyptus matrix. Replacing the natural savanna matrix with croplands and plantations in the Savannas of Amapá causes the near disappearance of seed dispersal interactions and a collapse of the network structure in croplands. In addition, the seed dispersal networks in cultivated landscapes were more centered on a few, more abundant and generalist dispersers, which were more linked to pioneer plant species. Our results show that changes in the natural savanna matrix have drastic consequences on the seed rain promoted by bats, which can directly impact the ecological dynamics of the different habitats that comprise this Amazonian ecosystem. Maintaining natural habitats, such as forest and savanna, in cultivated landscapes is crucial and would reduce this negative impact. Savanna remnants can help maintain the original dynamics of bat communities in the landscape and the integrity and robustness of seed dispersal networks promoted by bats.