Water conservation is an important part of the ecosystem service function. As a complex ecosystem, forests have different contributions to water conservation. The forest litter plays an important role in the water conservation function, for it directly covers the ground surface. Remote sensing and hyperspectral technology provide a solution for the long-distance detection of water conservation in planar areas. Especially in plateau areas, remote sensing is the most effective way to obtain surface information. In this paper, the hyperspectral data of main tree species were measured by ASD spectrometer in the Grand Canyon research area of Yarlung Zangbo. The litter samples were obtained by sampling on the plot and the water holding capacity of the samples was calculated. Use leaf spectrum information to construct vegetation index related to litter water conservation capacity, then establish multiple regression model of vegetation index and effective retention capacity, and invert the water conservation capacity distribution of main tree species in the Grand Canyon based on Sentinel-2 images. In the end, the accuracy of the inversion model is evaluated based on the verification points. The results showed that : (1) The reflectance of Quercusaqui folioides was the highest, the lowest was the Picea Linzhi, and the total reflectance trend of the three species was similar; (2) The effective interception amount of litter is sorted from large to small as follows: Picea Linzhi (48. 36 t . ha (1))> Quercusaqui folioides (39. 24 t . ha (1))> Pinus densata (32. 32 t . ha (1)). Picea Linzhi leaves are easy to decompose and store, Quercusaqui folioides' leathery leaves and Pinus densata's oily leaves are not conducive to decomposition. Therefore, the litter of Picea Linzhi has the highest effective interception amount. (3) Through the Person correlation coefficient analysis and the multiple linear regression model, it is found that the higher the wax parameters and attenuation degree of leaves, the weaker the water conservation capacity of litter; the better the vegetation growth trend, the higher the pigment and the water content of leaves, the stronger the water conservation capacity. (4) The results of the accuracy evaluation of the inversion model of the water conservation capacity of litter are good. R-2 of the test points of Pinus densata, Picea Linzhi and Quercusaqui folioides is 0. 943, 0. 815 and 0. 812, and RMSE is 1. 597, 2. 270 and 1. 953. It shows that the model can be used for the prediction and distribution of the water conservation capacity of forest litter in Grand Canyon.

“Two ecological barriers and three shelters” (TEBTS), which has the effect of relieving ecological pressure, is the national ecological security pattern in China. Calculating the value of TEBTS ecosystem services, clarifying the synergy/trade-off relationships between ecosystem services, and maximizing the value of regional ecosystem services are of great significance for maintaining the security of the ecological civilization. At present, the research on ecosystem service synergy/trade-off has become the frontier field of ecology and related disciplines at home and abroad, and many research results have been obtained. However, there is still room and significance for continuing research to think about the synergy/trade-off relationship of ecosystems from the perspective of temporal and spatial heterogeneity: clarifying the spatial scope and spatial transmission characteristics of ecosystem service synergy/trade-off; exploring the trend of ecosystem service synergy/trade-off, and simulating the dynamic characteristics of natural factors affecting ecosystem services; and analyzing the characteristics of different spatial attributes that lead to the synergy/trade-off of ecosystem services. In this study, the Songhua River Basin (SRB), where the NFB is located, is used as the research area, the ecosystem services are simulated through the ecosystem assessment model, ecological unit (EU) is constructed as a research carrier, which is used to define the spatial scope of ecosystem services, and the influence of spatial characteristics and attribute characteristics on the change trend of the ecosystem service synergy/trade-off relationship is analyzed. The research found that water retention, soil conservation, and biodiversity did not change much from 2000 to 2015, and these ecosystem services have a greater value in the NFZ. The amount of carbon sequestration increased rapidly from 2010 to 2015. Crop production showed an increasing trend year by year. As the main grain production area, the Songnen Plain provides the main crop production function, which is greatly affected by humans. In the spatial characteristic, water retention, soil sequestration, and biodiversity present a very significant synergistic relationship, which is manifested in the obvious high-value aggregation characteristics in the NFZ, and crop production and the other four types of ecosystem services are in a trade-off relationship. At the time scale, the four types of ecosystem services, including water retention, soil conservation, biodiversity, and carbon sequestration, are synergistic, and crop production and water retention are synergistic. The vegetation types exhibiting a synergy/trade-off relationship are mainly broad-leaved forests, and the soil types are mainly luvisols and phaeozems. These EUs are mainly distributed in the NFZ and have spatial topological characteristics: the area and circumference of these EUs are smaller, the radius of gyration is also significantly smaller than that of other EUs, and the shape is more regular. By focusing on the spatial aggregation characteristics and changing trends of the ecosystem service synergy/trade-off and clarifying the influencing factors of the ecosystem service synergy/trade-off, the ecosystem services can be integrated, and the ecosystem can be optimized. Thus, the value of regional ecosystem services can be maximized, and a certain data foundation and theoretical support can be provided for major projects, such as ecological restoration and ecological environment governance, which is of great significance for improving the pattern of ecological security.

在分析鄂尔多斯市生态空间网络拓扑结构和鲁棒性的基础上,提出节点最低和最大介数增加(Low and maximum betweenness addition,LMBA)增边优化策略,同时与采用RA、LDF和SMB 3种增边策略的优化结果进行了对比.结果表明:鄂尔多斯生态空间网络有262个节点、402条边,网络直径为38,节点最大介数为418,最大连通度为25.网络连通度低,重要节点少且均位于网络西部,网络极不均匀,当网络结构遭到破坏时,进行自我恢复的能力比较强,但维持自身连通性的能力非常弱.增边94条后,LMBA策略优化后网络直径为16、节点最大介数为796、最大连通度为49,网络重要节点增多,网络整体效率明显提升;RA、LDF策略也使网络连通度极大增强,SMB策略的网络连通性增强效果不显著,重要节点增多且东移,网络结构比优化前更均匀.遭到攻击后,网络的连接鲁棒性大大增强,恢复鲁棒性也有所提升.与其他策略对比,LMBA策略的连接鲁棒性在两种攻击模式下、节点恢复鲁棒性在随机攻击模式下表现最优,节点恢复鲁棒性在恶意攻击下、边恢复鲁棒性在两种攻击模式下表现较优且稳定,说明该策略网络连通性强、结构均匀,综合表现最优.在遭受攻击过程中,LMBA策略维持自身连通情况的能力较优且稳定,节点和边的恢复能力也较优.

A scientific and reasonable ecological compensation scheme (ECS) is an important guarantee for promoting coordinated and equitable development between regions. The existing ECSs usually ignore the premise that the ECS can only be accepted by the stakeholders if there are a clear scope and benefit to the ecosystem services (ES). An ecological compensation scheme should be based on the transmission principle of ES so that a scientific and reasonable scheme can be proposed and accepted by the stakeholders. Based on the theory of ecosystem service flow, this paper analyzed the provision‒benefit mechanism of sand-stabilization ecosystem service (SSS) and selected Ordos City, Inner Mongolia, which is located in Northwest China, as the study area. A revised wind erosion equation (RWEQ) model was used to estimate the sand-stabilization amount of Ordos’s ecosystem in 2015, and a hybrid single-particle Lagrangian integrated trajectory (HYSPLIT) model was used to simulate the path of sand-stabilization ecosystem service flow (SSSF). Then, the benefit areas and levels of SSS were identified, and the spatial distribution of land cover, population, and gross domestic product (GDP) in the ecosystem services beneficiary area (SBA) was evaluated. Based on the identified benefit areas and benefit levels, and combined with the investment and income in the ecological construction of the Ordos, a cross‒regional differentiated ECS was proposed. The results show that the Ordos’s ecosystem played a huge role in sand-stabilization, which have brought huge ecological and economic benefits. In 2015, the sand-stabilization amount of Ordos’s ecosystem was about 7.20×108 tons. The area of SBA is1.66×106Km2, accounting for 17.21% of China’s total area, this mainly involves 16 provinces and cities, including Beijing, Tianjin, Hebei, etc. The amount of dust‒fall (ADF) in the beneficiary area was reduced by 28,738.67 ×104 tons, and investment of 4318.51 ×108 RMB (Renminbi) in dust removal would be avoided. For the ECS, based on the principle of “equity, beneficiary compensation, more benefit and more compensation”, Ordos shall take care of the ecological compensation fee (ECF) of about 36.28% of the total. In 16 provinces and cities, Inner Mongolia costs 66,121.03 ×104 RMB, which is the most. The fees are payable by other SBAs decrease with distance. Hubei Province (Suizhou) pays the least in ecological compensation, at 7.5 ×104 RMB. Based on the theory of ecosystem service flow, this paper proposes a research framework of differentiated ECS of SSS, which can provide an accurate scientific basis for determining the SBA and cross-regional ECS of SSS in the future.

The water cycle in the key agricultural and pastoral zones (KAPZs) is an important factor for maintaining the stability of the ecosystem. Groundwater collection and lateral seepage are indispensable parts of the water cycle, and it is difficult to monitor the groundwater situation in each area. The strength of the alternate circulation of groundwater is directly related to the utilization value and development prospects of groundwater; therefore, creating an effective method for the detection of groundwater burial depth has become an issue of increasing concern. In this paper, we attempt to create a method for the detection of groundwater burial depth that combines cokriging interpolation, spatial autocorrelation, geographically weighted regression, and other methods to construct a quantitative relationship between different land cover types and groundwater depth. By calculating the band index of the land cover type, the groundwater depthinformation of the unknown area can be obtained more accurately. Through collaborative kriging interpolation, normalized difference vegetation index (NDVI), precipitation, and hydrogeological conditions were used as covariates. The groundwater burial depth of Wengniute Banner in 2005, 2009, 2013, and 2017 was the response variable, and the groundwater burial depth in the study area was calculated. The groundwater burial depth data after the cokriging interpolation was used to transform the raster data into vector data in space using the improved hydrological response unit (HRU) model to make it more suitable for the actual groundwater confluence. Subsequently, 551 minimum response units (MHRUs) were obtained by division, and the spatial autocorrelation analysis was performed accordingly. The groundwater burial depth in the study area is spatially distinct from east to west, and the groundwater level shows a trend of being high in the west and low in the east, gradually increasing due to precipitation and rivers. The average change of groundwater depth in the time series is not significant, but it does gradually show a trend of accumulation. According to the aggregation characteristics of spatial autocorrelation analysis, a geographically weighted regression model of groundwater depth and NDVI, normalized difference drought index (NDDI), and net relatedness index (NRI) was established. The NDVI representing the forest land and the Adjusted R-2 of the groundwater depth is 0.67. The NRI representing the cultivated land and the Adjusted R-2 of the groundwater depth is 0.8675. The NDDI representing the bare land and the Adjusted R-2 of the groundwater depth is 0.7875. It shows that the band index representing the ground type has a good fitting effect with the groundwater burial depth.