Landscape structure influences urban vegetation vertical structure.
Abstract
Vegetation vertical structure is important for biodiversity and ecosystem service provision. In cities, however, while variation in the spatial extent and distribution of vegetation has been widely investigated, vertical vegetation structure and its potential drivers have not. Understanding how vegetation vertical structure varies across cities and identifying the potential drivers of this variation will improve the management of urban vegetation for biodiversity and ecosystem services. We used light detection and ranging (LiDAR) data to quantify the vertical structure of vegetation across Brisbane, Australia, at 1-km2 and 1-ha spatial scales and investigated how this structure varied in response to biophysical, socioeconomic, urban form and landscape structure variables. Using model selection techniques, we found that landscape structure variables related to tree cover (tree cover extent and spatial configuration) best explained the vegetation vertical structure at both spatial scales. Biophysical and urban form variables were also important, but only in combination with landscape structure. Mean vegetation vertical complexity, foliage projective cover and canopy height at a site all decreased as the treed proportion of the surrounding urban landscape decreased. In general, these vertical structure variables also increased where patches of vegetation were clustered together spatially. Synthesis and applications. Using light detection and ranging (LiDAR) data and model selection techniques, we show that the extent and vertical structure of urban vegetation are not independent and that reduced extent and increased fragmentation of urban vegetation are associated with simplification of its vertical structure. If common, this relationship means that managing urban vegetation for biodiversity and ecosystem services should not focus solely on the amount of tree cover or green space present across cities, but also on identifying where interventions to improve vegetation vertical complexity are required. Our study provides important insights into where these locations may be in cities.