Chapter 14 - Local and Landscape Scale Effects of Heterogeneity in Shaping Bird Communities and Population Dynamics: Crop-Grassland Interactions

Abstract

Understanding the mechanisms that drive the assembly of communities is a long-standing question in ecology. Even in well-known organisms such as birds, there is still a need for clarification of the factors that shape community structure and composition across different spatial scales. This question constitutes both a scientific and societal challenge in the context of the strong decline of farmland birds due to agricultural intensification observed during recent decades. Multiple aspects of heterogeneity, such as landscape habitat composition, spatial organization, and temporal dynamics, are expected to influence biodiversity and population dynamics. However, the inevitable complexity of models that would integrate these three components often means that simpler models are used instead, limiting the inference that is possible. Thus there remains a need to empirically understand how biodiversity responds to landscape spatial and temporal characteristics in agrosystems. In the context of intensive agroecosystems, we review recent advances using multiscale approaches to disentangle different assembly rules in this system, especially in regard to heterogeneity (both composition and configuration) and the balance between local and regional factors. We point out the key roles of natural and seminatural elements, in particular grassland habitats, in shaping the dynamics of bird assemblages in space and time in intensive farming systems, and the potential key roles of agri-environmental schemes in maintaining such grassland habitats. We also suggest some key factors in implementing habitat heterogeneity and diversity to restore bird populations (iconic species) and communities.