Urbanization in China is undergoing rapid development. The urbanization process is characterized by the rapid urban expansion and excessive development, resulting in remarkable negative eco-environmental impacts on urban ecosystems, which include landscape fragmentation, increased ecological footprint in urban area, increased carbon emissions, etc. Forests contributed several crucial ecosystem services to human society, such as biomass, carbon sequestration, water, and recreation opportunities. A few researches indicated that the ecosystem service function is closely related to biomass. While there has been a net gain of forest cover and forest age during the past two decade, changes in forest biomass are rarely concerned in City-and-town Concentrated Area. To evaluate forest biomass dynamics of regional forest based on the data from the forest resource inventory (1990, 2005) and forest area data in 2010, this paper studied the spatial and temporal variation of forest biomass in South Jiangsu. The results show that the area, the total biomass and the average biomass density of forest vegetation in South Jiangsu have increased significantly during the nearly 20 years. The total biomass increased from 7.15 Tg to 16.72 Tg. The average biomass density increased from 29.32 t/hm2 to 39.82 t·hm-2 which is still far below the national average. The biomass is unevenly distributed in different cities. The cities with larger area aslo have higher biomass. Among the five cities, Nanjing possesses the largest forest biomass, followed by Wuxi, Changzhou, Suzhou and Zhenjiang. The total biomass in various cities depend on the forest area and natural condition, such as terrain. Rising of forest biomass density and the increase of the proportion of broad-leaved forest also have boosted the growth of total forest biomass. Human activity played a major role in the rising tide of forest biomass in South Jiangsu. The high level of economic development enhaced the growth of forest resources, high population density did not show significant negative effects on forest area and biomass.%随着我国城镇化进程的快速推进，城镇密集区城市扩张带来的负面生态环境问题得到广泛关注。森林生态系统具有固碳释氧等多种生态服务功能，对减小城市化的负面效应、改善生态环境具有积极作用。近年来我国植树造林成效明显，森林资源总量和质量持续提升，科学评估森林生物量动态对理解碳源汇变化及制定森林保护政策具有重要的意义，但当前对快速城市化地区长时期生物量变化及影响因素研究较少。苏南地区处于我国最大的城镇密集区长江三角洲的中心，近年来该地区森林面积和质量不断增加，而受中低卫星遥感数据分辨率影响，以往对该地区生态系统生物量研究未探测到这种变化。利用1990、2005年江苏省森林资源调查数据及2010年江苏省森林覆盖监测数据，采用换算因子连续函数法和平均生物量法等计算苏南地区三个时期森林生物量，研究20年来苏南快速城市化地区森林植被生物量的时空变化，并结合社会经济数据探讨了生物量变化与经济人口的关联。结果表明：20年来，苏南地区森林植被面积、生物量和生物量密度总体呈显著增加趋势，生物量从7.15 Tg增长到16.72 Tg，乔木林的生物量密度由29.32 t·hm-2上升至39.82 t·hm-2，但远低于同期全国的均值；各市生物量分布不均匀，2010年生物量总量从大到小依次是南京、无锡、镇江、常州和苏州；各市森林生物量总量主要由森林面积和地形决定，森林面积增加是生物量增加的主要因素，阔叶林比例和林龄的增长也促进了生物量增加，随着区域森林林龄不断增长，森林生物量仍将不断增加；政府政策和经济利益等影响下的森林建设是区域森林生物量增加的主要原因，较高的经济发展水平促进了各市森林资源数量增长，而高人口密度未对森林面积和生物量未产生显著负面影响。
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