Rainho, A. | bioRxiv Science

bioRxiv2024

Unveiling how herpetofauna cope with land-use changes--insights from forest-cashew-rice landscapes in West Africa

Agricultural-induced land-use change comprises a key driver of biodiversity loss across tropical forests. Guinea-Bissau, in West Africa, was formerly occupied by native forest-savanna mosaics. While savannas have long gave place to traditional rice agroecosystems, forests are now being transformed into cashew monocultures at unprecedented rates. The ecological impact of such rapid change is largely unknown. Here, we examined how rarefied species richness, abundance, and composition of amphibians and reptiles varied across forest remnants, cashew orchards and rice paddies in northern Guinea-Bissau. To do so, visual encounter surveys were carried across 21 sampling sites, seven in each habitat type. A total of 703 amphibian and 266 reptile encounters was recorded from nine and 14 taxa, respectively. The results show class-specific responses to habitat type. Amphibian diversity in forest remnants and cashew orchards remained similar, but rice paddies harboured higher abundance and distinct composition compared to forest remnants. Reptile abundance was highest in cashew orchards, which comprised a distinct species composition, when compared to forest remnants. Rice paddies sustained lower reptile richness and abundance. Overall, our results do not support the expected detrimental impacts of cashew expansion, which might be due to the still high heterogeneity of habitat types within the landscape. Rice paddies proved particularly important for amphibians, and for open-habitat reptiles, boosting the landscape-scale species diversity. In face of the eminent habitat conversion, maintaining heterogeneous landscapes, including the persistence of both forest remnants and rice paddies, is critical to minimize biodiversity loss in West Africa.

ecology↗

bioRxiv2023

Urbanisation generates multiple trait syndromes for terrestrial taxa worldwide

Cities can host significant biological diversity. Yet, urbanisation leads to the loss of habitats and, potentially, to local extinctions. Understanding how multiple taxa respond to urbanisation globally is essential to promote and conserve biodiversity in cities and surrounding landscapes. Using a dataset with site-level occurrence and trait data of 5302 species from six terrestrial fauna taxonomic groups across 379 cities on 6 continents, we show that urbanisation produces taxon-specific changes in trait composition, with traits related to reproductive strategy consistently showing the strongest response. The effect of urbanisation on community trait composition is strongest at the largest spatial scale considered, and more closely linked to landscape composition (% urban) than arrangement (aggregation), although latitude and climatic variables remain a stronger influence. This study did not find evidence in support of a global urban taxa syndrome, but instead we suggest that there are four general urban trait syndromes, with resources associated with reproduction and diet likely to be driving patterns in traits associated with mobility and body size. Functional diversity measures showed a wide range of responses, leading to a shift in trait space that is most likely driven by the distribution and abundance of critical resources, and the urban trait syndrome displayed by individual species within a community. Further research is required to understand the interactions between the four general urban trait syndromes, resource distribution and abundance and changes in functional diversity of taxa at different spatial and temporal scales. Maximising opportunities to support species within taxa groups with different urban trait syndromes should be pivotal in conservation and management programmes within and among cities. This will reduce the likelihood of biotic homogenisation at the taxa level, and helps ensure that urban environments have the ecological capacity to respond to challenges such as climate change, further habitat fragmentation and loss, and other disruptions. These actions are critical if we are to reframe the role of cities in global biodiversity loss.

ecology↗