Spatiotemporal dynamics of urban forest biomass in Shanghai, China

Urban forest biomass is a major store of carbon and thus plays an important role in the regional and global carbon cycle. In this paper, the estimating method of urban forest biomass based on the field inventory data, remote sensing data and spatial analysis was explored. The spatiotemporal dynamics of urban forest biomass in Shanghai, China between 2005 and 2012 were analyzed. The results show that (1) The density and amount of forest biomass in Shanghai maintained a steady increase between 2005 and 2012. The mean biomass density across Shanghai increased from 34.82 tlha in 2005 to 37.12 tlha in 201 2,and the amount raised from 3.02 million tons (Tg) in 2005 and 3. 14Tg in 2008 to 3.42Tg in 2012. Of which, the forest biomass increased annually by 0.04 Tg from 2005 to 2008 and 0.07 Tg from 2008 to 2012. The mostly fraction (94 %) of total forest biomass was in the suburban areas and only 6% in the urban areas, which were in accordance with their area proportions to the total Shanghai area ,that was respectively 95.44% and 4.56%. (2) The higher forest biomass density areas concentrated mostly in the urban areas such as the northern Pudong New District and Huangpu District, where there are higher tree planting density , mature trees and elder forests. Suburban districts such as Qingpu District and Jiading District presented the lower forest biomass density, because the landuse types in these areas consisted mainly of industrial and agricultural land and forests are mostly younger managed. The spatial distribution of forest biomass displayed a tendency of high density in northeast area and low in southwest area.(3) The total forest biomass and average biomass density in the urban and suburban areas presented diferent change traces over the past two periods of 2005 -2008 and 20082012. in the urban areas, the total biomass and average biomass density decreased slightly from 2005 to 2008, and increased gradually from 2008 to 2012, whereas the associated value both rose continuously in the suburban areas between 2005 and 2012. This dynamics tendency showed a consistency with the forest change. it was concluded that the urban forest biomass keeps rising stably and modified constantly in the spatial distribution as well with the rapid development of economy and modernization in Shanghai. More emphasis on the harmonious development of economy, social and ecology should be put to make great support to comprehend the regional and global carbon cycle.