Patterns and dynamics of urban forests in relation to land use and development history in Guangzhou City, China

Abstract

Trees in cities display a varied pattern that is often moulded by a city's physical fabric and its evolution through time. The town plan expressed in spatial dimension as land use, and in temporal sense as development history, furnishes a framework to evaluate the intricate association between city and trees. Guangzhou city, the premier metropolis of south China, has been established for 2800 years, and has a long history of urban greening and heterogeneous land use. Five urban districts, which represent old, middle-aged and young stages of development and cover the bulk of the city's built-up zones, form the study area. Interpretation of aerial photographs is used as a basis to classify the urban forest into three types, and to design a sampling scheme for studying trees in urban parks, institutional grounds and roadsides. District history has bequeathed a plethora of configurations in terms of buildings, roads and land uses, accompanied by plantable spaces of dissimilar dimensions, geometry and quality. The districts display diverse tree attributes such as frequency, density and species diversity. Young districts, with lower density, more institutional uses and wider roads, present more opportunities for greening. Recent shifts in landscape fashion have introduced a significantly different treescape. A few exceptionally large parks and institutional sites play a pivotal role in the city's tree assets. Parks, roadsides and institutional forests have different tree-stocking rates and species assemblages. Implications for future planting and management of urban trees in different situations, and for the greening of other cities in China, and other developing countries, are explored.