基于生态系统服务供需与拓扑结构分析的渭河流域生态网络优化

Optimization of the ecological network in the Weihe River Basin using supply and demand of ecosystem service and topological structure analysis

顾及区域自然资源禀赋和人类活动水平差异,优化生态网络成为缓解景观破碎化、提高连通性的有效途径,更保障了可持续发展目标的实现。在定量测度渭河流域2000、2010及2020年5项生态系统服务供需的基础上,引入景观生态学与复杂网络理论构建并分析该流域生态网络的时空格局及其网络拓扑结构特征,以供需比与源地节点的拓扑结构综合重要性之间的相关性为依据优化生态网络。结果表明:1)与2000年相比,2020年食物生产、土壤保持以及产水的供需比平均值分别上升70%、7%以及215%,而碳固定与生境质量则分别下降97%与1%。2)生态源地数量与占总面积比分别为125个和36%,生态阻力呈现“南低北高”的空间特征,约有280条平均长度为15 km的生态廊道,流域生态质量有所提升。3)2000、2010及2020年生态网络在面对蓄意攻击时,结构连通鲁棒性平均值依次为0.160、0.168以及0.150,说明2010年生态网络具有更稳定的网络结构;源地拓扑结构综合重要性与各类服务供需比均呈正相关,其中与碳固定服务供需比相关性最高,为0.51(P<0.001)。4)优化后的生态网络(2020年)在面对蓄意攻击时具有更高的连通鲁棒性,同时在一定攻击节点范围内表现出更为显著的“涌现”现象,优化后的网络具备更强的恢复力和缓冲力。研究结果可为渭河流域优化生态网络结构、提高生态系统抗干扰能力提供科学依据,也可为流域生态空间规划提供借鉴参考。

Ecological networks can be optimized to mitigate landscape fragmentation for better connectivity in the sustainable development of modern agriculture.Different natural resources and human activities can also be considered in various regions.Taking the Weihe River Basin as the study area,this study aims to optimize ecological networks using supply-demand ecosystem service and topological structure analysis.Firstly,the ecosystem service supply and demand ratio(ESDR)was quantitatively measured for five ecosystem services in 2000,2010,and 2020 using the InVEST model and the ecological process equation.Secondly,the landscape ecology and complex network were introduced to construct the spatial and temporal patterns of the ecological network and the topological structure using morphological spatial pattern analysis(MSPA),connectivity analysis,circuit theory model,and connectivity robustness formula.Thirdly,the ecological network was optimized to rank and screen the ecological pinch points and barriers in the ecological corridor,according to the correlation between the ESDR and the topological comprehensive importance of the nodes at the ecological patches.Finally,the optimization of the ecological network was evaluated on the connectivity robustness The results show that:1)The average ESDR of food production,soil conservation,and water yield in 2020 increased by 70%,7%,and 215%,respectively,compared with 2000.While the carbon storage and habitat quality decreased by 97%and 1%,respectively.There was the most significant increase in the supply or decrease in the demand for water yield services.2)The number and ratio of ecological patches to the total area were 125 and 36%,respectively.The ecological resistance exhibited the spatial patterns of“low in the south and high in the north”,indicating the decreasing trend of resistance in the north.Furthermore,there were approximately 280 ecological corridors with an average length of 15 km.The ecological quality of the basin was improved significantly.However,there was no variation in the number of the ecological network elements.3)The average values were 0.160,0.168,and 0.150,respectively,in the structural connectivity robustness of the ecological network in 2000,2010,and 2020,indicating better stability in the ecological network in 2010.The topological comprehensive importance of ecological patches was positively correlated with the ESDR in each type of service.The highest correlation was with the ESDR of carbon storage at 0.51.4)The optimized ecological network had high connectivity robustness in the face of deliberate attacks.Additionally,there was a more significant“emergence”of the optimized network within a certain range of attacking nodes,indicating the stronger resilience and buffering capacity.The spatial and temporal patterns of the ecological network can be expected to facilitate decisionmaking and strategic planning.The finding can provide a scientific foundation to optimize the ecological network structure for the resistance to the ecosystem in the WRB.Effective support can also be offered for the ecological spatial planning of the basin.