Land-use changes lead to functional loss of terrestrial mammals in a Neotropical rainforest

MC, Mandujano S, Martínez-Camilo R, Martínez-Ávalos JG, Martínez-Meléndez N, Monroy-Ojeda A, Mora F, Mora-Olivo A, Muench C, Peña-Mondragón JL, Percino-Daniel R, Ramírez-Marcial N, Reyna-Hurtado R, Rodríguez-Ruíz ER, Sánchez-Cordero V, Suazo-Ortuño I, Terán-Juárez SA, Valdivieso-Pérez IA, Valencia V, Valenzuela-Galván D, Vargas-Contreras JA, Vázquez-Pérez JR, Vega-Rivera JH, Venegas-Barrera CS, Martínez-Ramos M. Underlying and proximate drivers of biodiversity changes in Mesoamerican biosphere reserves

Protected areas are of paramount relevance to conserving wildlife and ecosystem contributions to people. Yet, their conservation success is increasingly threatened by human activities including habitat loss, climate change, pollution, and species overexploitation. Thus, understanding the underlying and proximate drivers of anthropogenic threats is urgently needed to improve protected areas' effectiveness, especially in the biodiversity-rich tropics. We addressed this issue by analyzing expert-provided data on long-term biodiversity change (last three decades) over 14 biosphere reserves from the Mesoamerican Biodiversity Hotspot. Using multivariate analyses and structural equation modeling, we tested the influence of major socioeconomic drivers (demographic, economic, and political factors), spatial indicators of human activities (agriculture expansion and road extension), and forest landscape modifications (forest loss and isolation) as drivers of biodiversity change. We uncovered a significant proliferation of disturbance-tolerant guilds and the loss or decline of disturbance-sensitive guilds within reserves causing a "winner and loser" species replacement over time. Guild change was directly related to forest spatial changes promoted by the expansion of agriculture and roads within reserves. High human population density and low nonfarming occupation were identified as the main underlying drivers of biodiversity change. Our findings suggest that to mitigate anthropogenic threats to biodiversity within biosphere reserves, fostering human population well-being via sustainable, nonfarming livelihood opportunities around reserves is imperative.

Land use and land cover changes implications on biodiversity in the Owabi catchment of Atwima Nwabiagya North District, Ghana

This paper examined land use and land cover (LULC) change and implications to biodiversity in the Owabi catchment of Atwima Nwabiagya North District in Ghana from 1991 to 2021 using remote sensing, and geographic information systems (GIS), with participatory methods such as interviews and questionnaires with a sample size of 200 participants. The use of supervised classification with maximum likelihood algorithm in QGIS was employed to generate LULC maps of 1991, 2001, 2011, and 2021. Molusce Plugin in QGIS was applied to predict probabilities of LULC changes in 10 years (2021-2031). The results showed that high-density forest has disappeared from 1991 to 2021 while built-up has increased and remained the most dominant LULC from 2011 to 2021. There is a continual decline in the number of plant and animal species in and around the Owabi catchment. This can be attributed to the decline of high-density forests and increased built-up in the study area through human actions. The study identified the influence of human activities as the key forces of LULC change to biodiversity loss. This problem stemmed from the taste for housing and trading activities in the Kumasi Metropolitan Area which has resulted in an increasing demand for settlement because of its closeness to Kumasi and its environs. The study recommends that stringent preventive measures should be developed and enforced by various stakeholders including the Forestry Commission, Ghana Water Company Limited, Environmental Protection Agency, as well as the District/Municipal Assemblies to safeguard the forest from human activities. This recommendation will help these agencies to keep abreast with changes in LULC in the various communities and factors such as changes during the planning of the communities.

Body mass determines the role of mammal species in a frugivore-large fruit interaction network in a Neotropical savanna

Frugivorous mammals play an important role in maintaining biodiversity and are considered one of the main dispersers of large seeds. In this study, we describe the structure of the interaction network between non-flying mammals and seven plant species with large fruits in a megadiverse savanna-forest mosaic in the Brazilian Cerrado. We also evaluated the individual contribution of each species to the organization of the interaction network and tested whether body mass determined the mammals’ role in the network. To record frugivory events of mammals with arboreal and terrestrial habits, camera traps were installed at ground and canopy levels. We identified 18 mammal species interacting with seven plant species in 515 frugivory events. Our observations highlight an interaction network with a modular and non-nested topology and the important role of large mammals in the network structure, which reflects the importance of the group in potential seed dispersal. The extinction of large frugivorous mammals can cause several damages to ecosystem services in the Brazilian Cerrado through changes in network structure, especially threatening the survival of plant species with large fruits.

Habitat loss estimation for assessing terrestrial mammalian species extinction risk: an open data framework

Terrestrial mammals face a severe crisis of habitat loss worldwide. Therefore, assessing information on habitat loss throughout different time periods is crucial for assessing species' conservation statuses based on the IUCN Red List system. To support the national extinction risk assessment in Brazil (2016-2022), we developed a script that uses the MapBiomas Project 6.0 data source of land cover and land use (annual maps at 30 m scale) within the Google Earth Engine (GEE) platform to calculate habitat loss. We defined suitable habitats from the MapBiomas Project land cover classification for 190 mammalian taxa, according to each species range map and ecological characteristics. We considered a period of three generation lengths to assess habitat loss in accordance with the Red List assessment criteria. We used the script to estimate changes in available habitat throughout the analyzed period within the species' known ranges. The results indicated that habitat loss occurred within 94.3% of the analyzed taxa range, with the Carnivora order suffering the greatest habitat loss, followed by the Cingulata order. These analyses may be decisive for applying criteria, defining categories during the assessment of at least 17 species (9%), enriching discussions, and raising new questions for several other species. We considered the outcome of estimating habitat loss for various taxa when applying criterion A, which refers to population reduction, thus supporting more accurate inferences about past population declines.

Land reversion and zoonotic spillover risk

Deforestation alters wildlife communities and modifies human-wildlife interactions, often increasing zoonotic spillover potential. When deforested land reverts to forest, species composition differences between primary and regenerating (secondary) forest could alter spillover risk trajectory. We develop a mathematical model of land-use change, where habitats differ in their relative spillover risk, to understand how land reversion influences spillover risk. We apply this framework to scenarios where spillover risk is higher in deforested land than mature forest, reflecting higher relative abundance of highly competent species and/or increased human-wildlife encounters, and where regenerating forest has either very low or high spillover risk. We find the forest regeneration rate, the spillover risk of regenerating forest relative to deforested land, and how rapidly regenerating forest regains attributes of mature forest determine landscape-level spillover risk. When regenerating forest has a much lower spillover risk than deforested land, reversion lowers cumulative spillover risk, but instaneous spillover risk peaks earlier. However, when spillover risk is high in regenerating and cleared habitats, landscape-level spillover risk remains high, especially when cleared land is rapidly abandoned then slowly regenerates to mature forest. These results suggest that proactive wildlife management and awareness of human exposure risk in regenerating forests could be important tools for spillover mitigation.

Intensive human land uses negatively affect vertebrate functional diversity

Land-use change is the leading driver of global biodiversity loss thus characterising its impacts on the functional structure of ecological communities is an urgent challenge. Using a database describing vertebrate assemblages in different land uses, we assess how the type and intensity of land use affect the functional diversity of vertebrates globally. We find that human land uses alter local functional structure by driving declines in functional diversity, with the strongest effects in the most disturbed land uses (intensely used urban sites, cropland and pastures), and among amphibians and birds. Both tropical and temperate areas experience important functional losses, which are only partially offset by functional gains. Tropical assemblages are more likely to show decreases in functional diversity that exceed those expected from species loss alone. Our results indicate that land-use change non-randomly reshapes the functional structure of vertebrate assemblages, raising concerns about the continuation of ecological processes sustained by vertebrates.