基于土地利用方式的巢湖流域氮排放情景模拟

Simulation of nitrogen export scenarios in Chaohu Basin based on land use patterns

土地利用方式及其转移对区域氮素迁移和水体氮负荷产生重要影响,但量化自然发展、耕地保护和生态保护等多情景下土地利用方式氮排放时空变化特征,揭示流域水体氮负荷对土地利用变化的响应机制仍面临挑战。本研究以巢湖流域为研究区,通过遥感解译多时相土地利用类型数据,借助PLUS和InVEST模型探索不同情景下氮排放对各土地利用类型变化的响应机制。结果表明:(1)2000-2020年期间,巢湖流域建设用地面积的增加(626.14 km^(2))主要占据的是耕地(减少了775.64 km^(2)),城市化建设成为土地利用方式变化的主要驱动力;(2)PLUS模型多情景预测结果显示:2020-2030年间土地利用变化特征与2000-2020年基本保持一致,但各用地间的转换频率降低;(3)经InVEST模拟,耕地面积缩减而导致氮排放的减少量(340.17 t)大于建设用地等面积增加带来的氮排放增加量(170.11 t),使2000-2020年间巢湖流域土地利用所排放的总氮量呈降低趋势,由2000年的4768.04 t降至2020年的4597.98 t;(4)不同情景下,2030年各土地利用方式的氮排放量较2020年均呈降低趋势。其中,生态保护情景既有效地保障了巢湖流域生态功能又展现出较好的氮减排效果(113.36 t);鉴于此,建议流域管理部门应通过合理规划各用地类型的发展,严格控制建设用地对林草地、水域等生态用地的侵占,以期削减流域水体氮负荷、缓解氮素治理压力。

Land use types and its conversion have a significant impact on nitrogen(N)transport and load for surrounding waterbody.However,quantifying the response of N load to the change of land use patterns under different scenarios is still challenging.This study selected Chaohu Basin as the study area.By interpreting land use data at multiple time periods,the PLUS and InVEST models were used to explore the response of N export to various land use changes under different conditions(natural development,cultivated land protection and ecological protection).The investigation results showed that:1)During 2000-2020,the increase of construction land area(626.14 km^(2))in Chaohu Basin mainly occupied cultivated land(775.64 km^(2)).Urbanization was the main driver of land use change.2)The scenario prediction results of PLUS model showed that the trend of land use change from^(2)020 to 2030 would be generally consistent with that from^(2)000 to 2020.However,the conversion frequency among different land use types would decrease.3)According to the simulations using InVEST,the export of N from Chaohu Basin decreased from 4768.04 t in 2000 to 4597.98 t in 2020.The primary reason was that the reduction of N export(340.17 t)due to the reduction of cultivated land area was greater than the increase of N export due to the increase of construction land(170.11 t).4)N export of all land use modes in 2030 would show a decreasing trend compared with 2020.Under the ecological protection scenario,it not only ensured the preservation of ecological function,but also reduced large amount(113.36 t)of N export.From the perspective of reducing N export,it is recommended that the managers should proper design various land types,and strictly control the use of ecological land(e.g.,forest-grassland and water area)for construction.