Decoupling of the urban vegetation productivity from climate

Abstract

Urbanization is causing profound alterations of ecosystem functions at local and regional scales. The need to maximize ecosystem services to improve the livability of cities is resulting in intensive management of urban vegetation, which is likely generating new conditions for the ecosystem functioning. In this paper, we address the association between vegetation functioning (i.e., primary productivity) and climate in urban and adjacent non-urban areas in Auckland, New Zealand. We used time series analysis of integrated vegetation indices derived from satellite images (MODIS) to estimate a proxy of primary productivity of urban and non-urban vegetation. We analyzed the interannual variability of vegetation productivity in relation to climate fluctuations. In Auckland’s urban area the variability of primary productivity was not associated with any of the climatic variables considered, while in the non-urban area (i.e. reference area) vegetation productivity was strongly associated with cumulative rainfall during the growing season. Our results suggest that the productivity of urban vegetation may be undergoing a decoupling from the regional climate. If a decoupling of ecosystem functions from climate becomes a general pattern in urban areas it could have significant effects on urban vegetation planning and management. In a context of increased variability, urban ecosystems could constitute stable habitats and they will probably contribute to the viability of vulnerable populations.