基于LUCC的渭河流域生态系统碳储量动态变化及脆弱性分析

Dynamic Changes and Vulnerability Analysis of Carbon Storage in the Weihe River Basin Ecosystem Based on LUCC

[目的]探究土地利用/覆被变化(LUCC)对陆地生态系统碳储量的影响机制,为有效开展国土空间规划和生态保护修复提供理论依据。[方法]以渭河流域为研究对象,利用InVEST模型定量评估了1980—2020年陆地生态系统碳储量时空演变特征及分布格局,分析土地利用变化对区域碳储量的影响,并结合PI指数探讨了流域生态系统碳储量脆弱性。[结果](1)1980—2020年渭河流域土地利用类型以耕地、林地和草地为主,三大地类的面积占到流域总面积的95%左右。土地利用转移以耕地转为建设用地居多,约为1734.93 km^(2);(2)1980—2020年渭河流域碳储量总体呈现波动式下降趋势,累计减少3.8764×10^(6) t,耕地转为建设用地是导致减少的主要因素。空间分布上总体呈现“南高北低”的分布特征;(3)耕地、林地和草地是渭河流域生态系统碳储量的主要来源,2020年贡献率分别为38.91%,27.60%和30.00%,其他3类土地类型的总贡献率不足4%。(4)1980—1990年渭河流域土地利用变化对碳储量为正向影响,其他时段均为负向影响,下游地区生态系统碳储量更为脆弱。[结论]近40年间渭河流域碳储量随土地利用呈现波动式变化,林地增加将对区域碳汇能力产生正向影响,未来国土空间规划中应注重建设用地与林地、草地等生态用地的合理配置。

[Objective]The aims of this study are to exploring the impact mechanism of land use/cover change(LUCC)on terrestrial ecosystem carbon storage,and to provide theoretical basis for effective national spatial planning and ecological protection and restoration.[Methods]The Weihe River Basin was taken as the research object.The InVEST model was used to quantitatively evaluate the spatiotemporal evolution characteristics and distribution pattern of terrestrial ecosystem carbon storage from 1980 to 2020.The impact of land use change on regional carbon storage was analyzed.The vulnerability of watershed ecosystem carbon storage was explored using the PI index.[Results](1)From 1980 to 2020,the land use types in the Weihe River Basin were mainly cultivated land,forestland and grassland,with the area of the three major land types accounting for about 95% of the total basin area.The majority of land use transfer was from cultivated land to construction land,with the area of approximately 1734.93 km^(2).(2)From 1980 to 2020,the overall carbon storage in the Weihe River Basin showed a fluctuating downward trend,with a cumulative decrease of 3.8764×10^(6) tons,the conversion of arable land to construction land was the main factor leading to the decrease.The overall spatial distribution showed a distribution characteristic of‘high level in the south and low level in the north,.(3)Farmland,forestland,and grassland were the main sources of carbon storage in the Weihe River Basin ecosystem,with contribution rates of 38.91%,27.60% and 30.00% in 2020,respectively.The total contribution rate of the other three types of land was less than 4%.(4)The land use change in the Weihe River Basin from 1980 to 1990 had a positive impact on carbon storage,while it had a negative impact in the other periods.The carbon storage of the downstream ecosystem was more fragile.[Conclusion]In the past 40 years,carbon storage in the Weihe River Basin has shown fluctuating changes with land use.The increase in forestland will have a positive impact on regional carbon sequestration capacity.In future national spatial planning,attention should be paid to the rational allocation of construction land and ecological land such as forestland and grassland.