Spatial-temporal scale in landscapes occupied by Scarabaeinae in Amazon

Abstract

The spatial scale is a crucial aspect on the study of Landscape Ecology, one of the main points of the landscape concept itself and from which the biological perception is given in face of land use and cover changes through space and time. From the perspective of biodiversity responses, the scale is expressed in two complementary dimensions: spatial and temporal. Both the temporal and the spatial scales directly influence the shape and magnitude of the impacts of landscape changes, so that research and initiatives on biodiversity conservation in anthropogenic landscapes need to consider these aspects into account. The present thesis addresses the relationship between the two dimensions of the scale (spatial and temporal) and the biological diversity of coprophagous beetles in the Amazon. In the first chapter we discuss how the definition of the scale of effect (i.e. the size of the landscape in which species respond to spatial disturbances) is associated with the ecological level (assembly, functional group and species). We also evaluate how can the type of response variable influence such definition and how can the biomass (a proxy of size) interfere in the relationship between the landscape and the species. In chapter one, we found the ecological level not to affect the definition of the scale of effect hierarchically however, while the species richness was not sensitive to the variability of the spatial scale, we found abundance to be well associated. The effects of landscape change have similar effect on all species, regardless of their size. In chapter two, we study the existence of a delay/relaxation time (“time lag”) of biodiversity responses to disturbances at the level of the landscape, we also assess which ecological level (assembly and functional group) might present a greater delay in these responses. We found that coprophagous beetles do not respond immediately to habitat loss, their abundance takes 9 years to result in effective responses. In addition, functional groups based on resource allocation strategy are more vulnerable to past landscape conditions. Furthermore, the effect of the time scale is constant on beetles regardless of size (small, medium and large), as all species experience the same relaxation time. The conclusions of this thesis point to the impotence of identifying more accurate responses to the relationship between landscape and biodiversity, and of the spatial and temporal scale to adequately understand the impacts of habitat loss and its spread in space and time.