The broad negative consequences of habitat degradation on biodiversity have been studied, but the complex effects of natural–agricultural landscape matrices remain poorly understood. Here we used stable carbon and nitrogen isotopes to detect changes in mammal resource and habitat use and trophic structure between preserved areas and human-modified landscapes (HMLs) in a biodiversity hot spot in South America. We classified mammals into trophic guilds and compared resource use (in terms of C3- and C4-derived carbon), isotopic niches, and trophic structure across the 2 systems. In HMLs, approximately one-third of individuals fed exclusively on items from the agricultural matrix (C4), while in preserved areas, ∼68% depended on forest remnant resources (C3). Herbivores, omnivores, and carnivores were the guilds that most incorporated C4 carbon in HMLs. Frugivores maintained the same resource use between systems (C3 resources), while insectivores showed no significant difference. All guilds in HMLs except insectivores presented larger isotopic niches than those in preserved areas. We observed a complex trophic structure in preserved areas, with increasing δ15N values from herbivores to insectivores and carnivores, differing from that in HMLs. This difference is partially explained by species loss and turnover and mainly by the behavioral plasticity of resilient species that use nitrogen-enriched food items. We concluded that the landscape cannot be seen as a habitat/nonhabitat dichotomy because the agricultural landscape matrix in HMLs provides mammal habitat and opportunities for food acquisition. Thus, favorable management of the agricultural matrix and slowing the conversion of forests to agriculture are important for conservation in this region. Significance Knowledge of resource and habitat use by wildlife is essential to support conservation actions. Stable isotope analysis (SIA) is a useful method for the acquisition of this type of information. Samples for SIA can be obtained through indirect and noninvasive methods, which is favorable for studies of threatened species. We used SIA to compare the resource and habitat use and trophic structure of mammals between preserved areas and human-modified landscapes in a tropical rainforest. Our study shows that mammals in human-modified landscapes present an altered trophic structure and use food items from the agricultural matrix, while they depend on forest resources in preserved areas. Our findings stress the need for favorable management of the agricultural matrix to support wildlife survival.
22 October 2022 in Journal of Environmental Management
The Brazilian Atlantic Forest (BAF) is one of the most important biodiversity hotspots and species-rich ecosystems globally. Due to human activities, it has been significantly reduced and fragmented. This study examined both biotic (floristic composition, diversity, and structure) and abiotic (topographic and soil) factors in BAF fragments undergoing varying levels and durations of human disturbance cessation: approximately 20 years (20 y), ~30 years (30 y), and over 40 years (>40 y). We aimed to understand the recovery dynamics of floristic composition, diversity, and structure in BAF fragments in relation to abiotic factors. Several statistical tools were employed to examine similarities/differences and relationships. Forests of the 30 y group exhibit significantly greater homogeneity in terms of floristic composition, while forests of the 20 y group are characterized by lower species abundance and diversity. The floristic composition was primarily influenced by soil features and the time of disturbance. Under “Environmental Protection Areas”, soil–vegetation recovery can occur more swiftly than usually observed for BAF. A significant BAF recovery was observed approximately 40 years after the end of human disturbance. A partial recovery featured 30 y disturbed areas, while in 20 y forests, recovery is in its early stages. Human-disturbed BAF can gradually rebound when effective management practices are implemented.
Deforestation and habitat fragmentation affect to a great extent larger wild mammals, which require large areas to establish their populations. These mammals can have important functions in the structure and dynamics of tropical forests, acting as seed dispersers, herbivory regulators, and umbrella species. In the present paper, we characterize the community of medium and large wild mammals in a semi-deciduous seasonal forest fragment, a denominated IB Forest (Institute of Biosciences) in Edgardia Experimental Farm, UNESP, Botucatu, São Paulo State, Brazil. By adopting sand plots on three trails as the main method, we identified the occurrence of nine species, besides the occurrence of one species by direct visualization. Some of these are in national red lists — Leopardus pardalis and Puma concolor are listed as threatened and Sapajus cf. nigritus as Near Threatened in São Paulo State; Puma concolor is also listed as Vulnerable at the national level. Thus, we emphasize the importance of this forest remnant as a wildlife refuge, which makes it necessary to monitor the occurrence of these animals in the area and conserve similar remnants in the region.