生物土壤结皮研究：进展、前沿与展望

生物土壤结皮是由隐花植物和相关土壤微小生物与表层土壤颗粒胶结而形成的复合体,与维管束植物覆盖一样,它是干旱区地表的重要覆盖类型(其盖度达40%)。生物土壤结皮是荒漠生态系统组成和地表景观的重要特征,在不同生物气候区的荒漠景观过程、土壤生态过程、土壤水文过程、土壤生物过程和地球化学循环过程,以及干旱半干旱地区生态修复过程中发挥着重要作用。关于生物土壤结皮的研究是地学和生物学学科交叉的前沿研究领域,已成为国际干旱区地表过程研究的重要核心科学问题之一。综述了国内外该领域最新研究进展,分析了研究的趋势,讨论了其前沿科学问题和未来研究的重点,以期促进我国生物土壤结皮的研究,加深对我国干旱半干旱区地表过程的认识。

渭河陕西段沉积物中重金属污染综合评价

为分析渭河陕西段沉积物中重金属的污染程度,对沉积物中10种重金属元素Pb、Zn、Cr、Cu、Co、Ni、Cd、As、Sb、Mn的含量进行分析,采用地累积指数、富集系数、污染负荷指数、内梅罗综合污染指数及潜在生态风险指数对沉积物中重金属污染进行综合评价,结果表明:2015年沉积物中除Cr外其他9种重金属均高出陕西土壤背景值1.49%~91.49%,Cd高出最多;2016年只有Pb、Cu、Co、Cd、Mn分别高出陕西土壤背景值6.21%、2.10%、7.92%、17.02%、4.41%,除Cr、Cd外重金属含量年际之间差异均不显著;10种重金属的污染程度及潜在生态风险整体较低,其中Cd及清姜河、灞河断面污染最严重,应加强对渭河周边农业及交通污染的防控,同时密切关注城市生活污水处理及入渭支流对干流的污染输入影响。

Runoff and Soil Erosion on Slope Cropland: A Review

Soil erosion has become a serious environmental problem worldwide,and slope land is the main source of soil erosion. As a primary cover of slope land,crops have an important influence on the occurrence and development of runoff and soil erosion on slope land. This paper reviews the current understanding of runoff and soil erosion on slope cropland. Crops mainly impact splash detachment,slope runoff,and sediment yield. In this review paper,the effects of crop growth and rainfall on the splash detachment rate and the spatial distribution of splash detachment are summarized. Crop growth has a significant impact on runoff and sediment yield. Rainfall intensity and slope gradient can influence the level of erosive energy that causes soil erosion. Furthermore,other factors such as antecedent soil water content,soil properties,soil surface physical crust,and soil surface roughness can affect soil anti-erodibility. The varying effects of different crops and with different influence mechanisms on runoff and soil erosion,as well as changes in their ability to influence erosion under different external conditions should all remain focal points of future research. The effect of crop vegetation on runoff and soil erosion on slope land is a very important factor in understanding large-scale soil erosion systems,and in-depth study of this topic is highly significant for both theory and practice.

Ecological Carrying Capacity and Green Development in the “Belt and Road” Initiative Region

Since the 1970s,resource crisis,environmental pollution and ecological degradation have become prominent globally,and the limits to growth have always been an important theoretical and policy issue.The technological system of early warning and regulation based on carrying capacity evaluation has great potential in natural resource utilization,environmental management and ecosystem conservation.In this paper,the evolution of carrying capacity research and the concept of ecological carrying capacity are summarized,and the existing evaluation methods of ecological carrying capacity are classified into ecological footprint method,comprehensive index system method,ecosystem service analysis method and human appropriation of net primary productivity method.The current problems in ecological carrying capacity study were analyzed and the trend was outlooked.Combined with the special issue,the recent proceeding of ecological carrying capacity study in the Belt and Road Initiative(BRI)region was narrated,from the aspects of ecological carrying capacity evaluation method and application,the supply and consumption of ecosystem services,and the resources use and environment change.Some suggestions have been proposed to improve the accuracy and reliability of ecological carrying capacity evaluation:1)the spatial heterogeneity and temporal dynamic change of ecological carrying capacity should be explored furtherly;2)the interaction between ecological process and human activities should be simulated;3)factors such as climate change,human activities and ecological products and ecological service flows should be integrated into the evaluation system of ecological carrying capacity.

Synergic Relationship between the Grain for Green Program and the Agricultural Eco-economic System in Ansai County based on the VAR model

Understanding the synergic relationship between the Grain for Green Program(GGP)and the agricultural eco-economic system is important for designing an optimized agricultural eco-economic system and developing a highly efficient structure of an agricultural industry chain and a resource chain.This study used Ansai County time series data from 1995 to 2014,applied vector autoregressive(VAR)models and used tools such as Granger causality,impulse response analysis and variance decomposition,to explore the synergy between the GGP and the agricultural eco-economic system.The results revealed a synergic and reciprocal relationship between the GGP and the agroeconomic system.The contribution of the GGP to the agroecosystem reached 34%,which was significantly higher than either its largest contribution to the agroeconomic system(20.8%)or its peak contribution to the agrosocial system(26.7%).The agroeconomic system had the most prominent influence on the GGP,with a year-round stable contribution of up to 55.3%.These results were consistent with reality.However,the impact of the GGP on the agricultural eco-economic system was weaker than the effect of the agricultural eco-economic system on the GGP.The lag of variable stationarity after the shock was relatively short,indicating that optimal coupling had not formed between the GGP and the agricultural eco-economic system.On the basis of enhancing the ecological functions,we should construct the agricultural industry-resource chain such that it focuses on promoting the effective utilization of resources in the region.In addition,the development of a carbon sink industry can be used to manifest the ecological values of ecological functions.

Research on Ecological Carrying Pressure in the Greater Dunhuang Region based on the Relationship between Supply and Consumption

The Greater Dunhuang Region has experienced ecological degradation in the past 100 years caused by human factors such as ecological immigration, expansion of arable land, and the construction of reservoirs. At present, through the restoration of various ecological projects, the progress of ecological deterioration has slowed down. Ensuring that the development and construction of the Greater Dunhuang Region Cultural Tourism Economic Circle does not threaten ecological security is the top priority of the regional sustainable development plan. Based on the balance between supply and consumption of the ecosystem, this study assesses the pressure of ecological consumption in the Greater Dunhuang Region, and analyzes the patterns and trends in the ecological carrying status. The results reveal three important aspects of the ecological carrying pressure in this Region.(1) After 2000,the ecological supply in the Greater Dunhuang Region experienced a fluctuating growth trend. In the entire ecosystem, the farmland ecosystem provides more than 55% of the ecological supply, and areas with relatively high supply capacity are concentrated in a small number of valleys.(2) The Greater Dunhuang Region is under greater production pressure and there is less pressure from living consumption. The production consumption intensity has exceeded the ecological supply since 2014. The production and consumption structure of the Greater Dunhuang Region is dominated by animal husbandry production and consumption, accounting for more than 65% of the total production and consumption.(3) The Greater Dunhuang Region has been in a state of rich and surplus from 2000 to 2017. However, Dunhuang City turned into a surplus state in 2017 due to the pressure of the fast-growing tourist population. The Greater Dunhuang Region urgently needs to alleviate the ecological pressure through the development of eco-friendly industries. It is necessary to develop an ecological protection resource utilization model that focuses on the development of ecological and cultural services in pastoral areas to ease the pressure on the ecosystem from animal husbandry production.