Raquel Carvalho and Ellen Andresen explain new research that evaluates the impact of land use, landscape structure, and their interactions, on dung beetles, a group of insects that provides many ecosystem services. Carvalho et al demonstrated that both factors act together to shape biodiversity patterns, and that the effect of landscape structure often depends on the specific land use studied.

The problem

Understanding the impact of agricultural landscapes on biodiversity is crucial in species-rich tropical regions, where natural areas are being converted to crops and pastures, causing significant losses of diversity and ecosystem services. Balancing agriculture with biodiversity conservation is essential.

Previous studies have shown that biodiversity is affected by the local land use and also by the structure of the surrounding landscape, but not very often are the effects of both these factors assessed together. However, this latter approach is necessary for improving our ability of designing context-specific landscapes that promote ecological conservation effectively.

Our study

Our study assessed the effects of land use, landscape structure, and the interaction between these two factors, on dung beetle assemblages in heterogeneous agricultural landscapes within a biodiversity hotspot – the Brazilian Cerrado.

We assessed how landscape structure can facilitate or hinder the conservation of certain attributes of the dung beetle fauna inhabiting patches of different land uses. We aimed to gather information that could be used to suggest how to arrange different patches of land to promote specific biological goals, such as having a wide variety of species or a mix of functional roles. 

Findings

We found that both the type of land use (forest, savanna, eucalypt, pasture, soybean) and the surrounding landscape structure (% forest cover, % savanna cover, matrix harshness, landscape heterogeneity) act together to affect biodiversity.

We also discovered that the impact of landscape structure can vary depending on the specific land use. This means that we should not extrapolate effects observed in one land use to other land uses. For example, we found when there was more forest in the surrounding landscape, the number of species increased, but only when we sampled in eucalypt plantations.

Similarly, the negative effect of matrix harshness on the abundance of large beetles was only observed for dung beetles inhabiting eucalypt plantations. In contrast, the positive impact of savanna cover on functional diversity was consistent across all land uses.

Recommendations

Our findings can help guide the design of agricultural landscapes that allow for biodiversity conservation. To effectively conserve the dung beetle fauna, it is important to prioritize the protection and restoration of native vegetation patches, to increase habitat availability and reduce the harshness of the surrounding matrix.

Additionally, establishing eucalypt plantations near forest patches can serve as valuable supplementary habitat for forest-specialist beetles and large beetle species that do not utilize other agricultural covers. Moreover, replacing certain areas of cattle pasture and annual crops with eucalypt plantations can also help decrease matrix harshness and provide additional habitat for sensitive beetle species.

Read the full article “Biodiversity in landscape mosaics: The roles of local land use and the surrounding landscape on dung beetle assemblages” in Journal of Applied Ecology