城市化已成为全球土地覆被变化的主要驱动因素之一.城市化及其引起的土地覆被变化对城市生态系统碳动态具有重要的影响.以快速城市化的典型区域——深圳市为例,采用遥感影像解译与实地生态调查相结合的方法,研究了1986—2015年间城市化引起的土地覆被变化对城市生态系统碳密度和碳储量的影响,旨在加深对城市生态系统碳循环的认知,为城市生态系统碳管理提供科学依据.研究结果显示,(1)研究区城市化过程中土地覆被变化的主要特征是建设用地的急剧扩张.林地、耕地、园地等在面积减少的同时,景观趋于破碎化.(2)研究区植被和土壤的碳密度呈现出明显的空间异质性.研究时段内,植被和土壤的平均碳密度分别减少了约5.1 t·hm-2、11.8 t·hm-2.(3)研究区城市生态系统碳储量的变化大致经历了3个阶段:城市化"初始期"以自然植被和农业用地为主的高碳储量期;城市化"加速期"建设用地快速扩张带来的城市生态系统碳储量急剧下降;城市化"稳定期"城市生态系统碳储量逐渐恢复.(4)研究时段内土地覆被变化造成研究区城市生态系统约16.8 t·hm-2的碳损失,占城市生态系统碳储量的37.7%.虽然城市化总体上导致了城市生态系统碳密度和碳储量的减少,但通过适当的城市植被与土壤的碳管理措施可以使城市生态系统碳库逐渐得到恢复.%Urbanization has becomeone of the major drivers of the global land cover change. Urbanization and associated land cover change have significant impacts on carbon dynamics of urban ecosystems. In this study, we took the case of rapid urbanizing region-Shenzhen as the case study area to study the impacts of urbanization and associated land cover change on carbon dynamics of urban ecosystems from 1986 to2015. The research was carried out based on interpretations of historical remote sensing images and field samples of urban vegetation and soils. The primary objective of this work is to improve understanding of the impacts of urbanization on carbon dynamics of urban ecosystem and providing scientific basis for carbon management of urban ecosystems. The results show that: (1) rapid expansion of urban impervious surface is the main feature of land cover change associated with population urbanization. The areas of forests, cropland, and garden land decreased significantly over the study period, and the patches of them tend to become fragmented; (2) the carbon densities of urban vegetation and soil have complex spatial patterns, and the average values of them decreased about 5.1t·hm-2 and11.8 t·hm-2, respectively; (3) the change of carbon storage of urban ecosystem in the study area has experienced three stages: in the early period of urbanization, natural vegetation and cropland had the dominant carbon storage; in the middle period of urbanization, the rapid increase of built-up land drove the decrease of carbon storage of urban ecosystems; in the late stage of urbanization, carbon storage of urban ecosystem has been gradually recovering; (4) land cover change had caused the loss about16.8 t·hm-2, which approximately accounts for 37.7% of the total carbon storage of urban ecosystems in the study area. Although urbanization causes the decreases in carbon density and carbon storage of urban ecosystems, we can take steps in urban vegetation and soil management to recovering the carbon pool of urban ecosystems.
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