2000-2015年城市和工矿用地扩张对净初级生产力的影响

中国近15 a来快速的城市化和工业化对陆地净初级生产力（Net Primary Productivity，NPP）的影响是关系到碳循环和全球变化效应的重要问题。首先，本文基于VPM（Vegetation Photosynthesis Model）模型得到NPP数据，基于中国土地利用数据集（National Land Use Datasets of China（NLUD-China））获取2000-2015年城市和工矿用地数据，然后通过邻域替代法模拟2000-2015年间因中国城市和工矿用地扩张损失的陆地NPP。结果表明：2015年城市和工矿用地占中国国土总面积的1.2%，在2000-2015年间面积增加了70×10³ km²。城市和工矿用地扩张导致陆地NPP损失1.24 TgC·a^-1到3.14 TgC·a^-1，在2005-2010年损失NPP最多（3.14 TgC·a^-1）。耕地被建设用地占用是造成中国陆地NPP损失的重要原因，在2010-2015年共有13×10³ km²的耕地被城市和工矿用地占用，因此损失的NPP达1.51 TgC·a^-1，占中国城市和工矿用地扩张损失NPP总量的82%。从时空分布特征来看，21世纪初剧烈的城市扩张造成沿海和中部地区NPP损失严重（2000-2005年沿海地区主要因城市扩张损失NPP高达0.82 TgC·a^-1），而2010-2015年主要因工矿用地扩张使西部地区NPP损失升高（在2010-2015年因工矿用地扩张损失NPP 0.46 TgC·a^-1，占中国NPP损失总量的30.81%），NPP损失量呈现出从东高西低逐渐过渡到东西平衡的时空格局。从影响上分析，城市和工矿用地不透水地表比例（0.59±0.19）高于自然植被的不透水地表比例（0.29±0.14），并且城市内部透水地表的平均标准化NPP（0.9）低于自然植被的平均标准化NPP（1.1），是造成城市和工矿用地损失NPP的主要原因。

Impacts of urban and industrial land expansion on net primary productivity of China during 2000-2015

Based on the VPM model,we obtained the NPP data(NPP_u&i)through using the improved neighborhood substitution method(i.e.,the NPP(NPP_pot)of crop land or vegetable land occupied by urban and industrial land which is newly expanded between year t and year t+5(data interval of 5 years)were taken place by the vegetation types in year t within 10 km of the same area)to retrieve NPP_pot during 2000-2015 and further analyzed its spatio-temporal pattern characteristics,and explained the causes of NPP loss caused by urban and industrial land transformation. The results show that urban and industrial land in 2015 accounted for about 1.21% of total land area and the expansion area of urban and industrial land in China during 2000-2015 was 72×10³ km². The loss of net primary productivity due to urban and industrial land expansion was about 1.24×10⁴ tC·a^-1 to 3.14×10⁴ tC·a^-1,the highest loss was in 2005-2010. The major cause of NPP loss was cropland converted into urban and industrial land. During 2010-2015,13.28×10³ km² of cropland had been converted into urban and industrial land,resulting in a NPP loss of 151.09×10⁴ tC·a^-1,accounting for 82% of the total loss of the total ecosystem productivity. From the spatial perspective,severe urban expansion in the early 21^st century resulted in severe NPP losses in the coastal and central regions(up to 81.75×10⁴ tC·a^-1 in coastal areas in 2005)and the NPP losses (45.50×10⁴ tC·a^-1 in 2015,accounting for 30.81% of the total loss)in the western region were mainly due to the expansion of industrial land expansion in the late 21^st century. The loss of ecosystem productivity gradually changed from the pattern of eastern higher than western to the east-west balance. For the mechanism analysis,the percentage of ISA(0.59 ±0.19)was higher than that of natural vegetation(0.29 ±0.14),and the mean normalized NPP(0.9)of permeable surface in the urban interior was lower than that of the natural vegetation(1.1), which was the main reason for the loss of NPP in urban and industrial land. By assessing the ecological and environmental consequences brought by urbanization and industrialization,it is very helpful to optimize the pattern of urban land use rationally and prevent urban ecological environmental risks.