Around the world humans modify landscapes through changes to landscape structure – alterations in the composition and configuration of land use and land cover types across landscapes. Often, this takes the form of habitat loss and habitat fragmentation, both of which have important effects on biodiversity and ecosystem function. However, how these changes to landscape structure translate into shifts in ecosystem service provision is still unclear. This limits our ability to effectively manage human-dominated landscapes for different ecosystem services.
I will present results from urban and agricultural systems that demonstrate how landscape structure in these types of human-dominated systems influence biodiversity, ecosystem function, and ultimately ecosystem services. In both landscape types, relationships between patterns of forest fragmentation, biodiversity, and ecosystem service provision were investigated. In the agricultural landscapes of southern Quebec, the focus was on how surrounding landscape structure influences the biodiversity and abundance of important insect functional groups for pest regulation. In the city of Brisbane, Australia, the focus was on how landscape structure at two spatial scales influences vegetation vertical structure, bird functional and species diversity, and the storage of aboveground carbon and flood regulation.
Across both landscapes, landscape structure and fragmentation were important for ecosystem services and biodiversity. In Quebec’s agricultural landscapes, field width had strong negative effects on predator and pest diversity and abundance, while distance from forest had generally positive effects. However, in some cases these patterns for predators and pests opposed each other, resulting in counterintuitive effects on pest regulation. For example, field width significantly reduced the abundance and diversity of both predators and pests. Thus wider fields had reduced potential for pest control from predators, but also decreased herbivory levels.
In the urban landscapes of Brisbane, spatial models incorporating landscape structure variables (tree cover clumpiness, patch size, etc.) best explained the variation in vegetation vertical structure and vegetation height diversity as compared to models incorporating geophysical, soils, socioeconomic, or urban form variables. This variation in vegetation vertical structure, in turn, was highly correlated with the storage of aboveground carbon and the ability of urban vegetation to intercept precipitation and provide flood regulation.
These results across agricultural and urban systems highlight the importance of managing the structure of human-dominated landscapes for biodiversity and multiple ecosystem services. Significant efforts are now required to determine the specific ecological and social processes that underlie these patterns.