我国北方农牧交错带西段退耕对土壤保持功能影响研究

退耕还林（草）等生态工程对区域用地结构及生态系统服务功能产生了重要影响。本研究基于RUSLE模型,并辅以遥感监测与GIS空间分析方法,对北方农牧交错带西段2000-2015年退耕状况及其引起的土壤保持功能变化分3个时段（2000-2005年、2005-2010年及2010-2015年）进行了探究。结果表明：北方农牧交错带西段地区2000-2015年耕地面积净减少1663.83 km²,以转为林地、草地、建设用地为主,其中耕地转林、草地净减少面积为1113.64 km²,草地和未利用地是新增耕地的主要来源;15年间土壤保持功能提升显著,退耕还林（草）工程的实施使土壤保持量增加了56.50×10⁴ t,2005-2010年由退耕所带来的土壤保持增加量在3段时期中最高;不同坡度等级的生态退耕引起的土壤保持增加量差别较大,总体随着坡度升高呈下降趋势,但在25°以上的陡坡耕地由退耕还林（草）带来的土壤保持效益又有所升高。研究对于评估北方农牧交错带西段地区实施退耕还林（草）等工程的生态效益具有重要意义,并能为区域生态保护与修复工程的建设规划提供科学依据。     

黄土高原生态退耕的时空分异特征

生态退耕是调整陆地生态系统结构与功能以应对土地利用过度干扰的重要途径之一,因此科学掌握退耕格局与耕地格局演变对黄土高原生态环境治理与生态修复具有深远意义。本文以位于黄土高原的延安市为典型区,从生态退耕的整体特征、地形因素及区域差异等角度,探究生态退耕以来其耕地变化及退耕状况的空间分异特征。结果表明：生态退耕致使延安市耕地面积由2000年的11 752.80 km²减少为2013年的9149.93 km²,退耕面积为2756.85 km²,退耕指数为22.15%,且退耕耕地主要转化为林地、草地,占退耕面积的95.29%;耕地与退耕面积主要分布于6~15°、15~25°坡度及第II级（925~1115 m）、第III级（1115~1275 m）,且2005-2013年的生态退耕速率均高于2000-2005年的生态退耕速率;县域退耕面积及退耕程度均呈现由北向南依次递减的分异特征,而退耕重心与耕地重心均在延安市几何中心以北的安塞县与宝塔区边界,且生态退耕的重心由东北向西南方向迁移,耕地重心则由北向南迁移。本文通过对延安市生态退耕的时空分异特征分析可为黄土高原更加科学合理地推进生态保育与生态文明建设提供参考。     

黄土高原丘坡信息DEM提取算法的应用

选择代表黄土地貌类型(丘陵沟壑区、梁峁区、高原丘陵过渡区)的75个样区(每个样区约4km²),以1∶1万水平分辨率为5m的DEM为研究对象,研究不同算法对提取地面坡度精度的影响。采用6种不同算法分别提取坡度。运用方差分析,对比分析,排序分析等方法,通过比较不同算法所提取坡度矩阵的平均值、最大值、标准差,以及坡度中误差等指标,认为在黄土丘陵沟壑区3类地貌类型区域如果整体考虑坡度的以上指标时选用三阶反距离平方权差分算法较为合理。在黄土高原沟壑区与丘陵沟壑区交错过渡地带也可以选用算法4提取坡度。同时,根据水土保持工作实际生产部门需要,提出并实现了对坡度信息评价时须分级别进行的思路。研究认为,在黄土丘陵沟壑区域相同的地貌类型区,算法对所获得的相同的坡度级别面积影响是不同的,并且规律不相同。在前述三种地貌类型区域,如果需要获得坡度分级面积信息,使用三阶反距离平方权差分算法和三阶反距离权差分最为理想。由于简单差分算法小于其他算法提取坡度所涉及的区域单元大小,不适宜在本区域使用。     

Land use and land cover change on slope in Qiandongnan prefecture of Southwest China

This study uses DEM(Digital Elevation Model) data and remote sensing maps of the study area in 1993, 1999, and 2009 to analyze the slope gradient change of land use patterns in Qiandongnan Prefecture, Guizhou province, China. The land use data were classified into five types, forest, farmland, grassland, water and built-up, the slope gradients were divided into four grades. Indices for analyzing land use features were defined by their proportions, transformation matrixes, land use degree and changes.The results showed that all land use types can be found at every gradient. Generally, with the slope degree increased, the area of forest being augmented as well, while the area of the other land use types(farmland, grassland and build-up) declined. Moreover, a mass of farmland were shifted from other land use types from 0° to 25°, while a quantity of forest were transformed from the other land use types on 25° from 1993 to 2009. In terms of land use degree and changes, the area of farmland and buildup land use types decreased when slope degree increased. Finally, we calculated the five landscape pattern metrics: Patch Density(PD) value, Largest Patch Index(LPI), Shannon's Diversity Index(SHDI), Area-Weighted Mean Shape Index(AWMSI) and Contagion Index(CONTAG). The results of metricsanalysis showed that PD values, SHDI values and CONTA values had a similar variation trend, that is, they decreased when slope degree increased. There was no obvious variation trend on LPI value.     

Analysis of comprehensive benefits of transforming slope farmland to terraces on the Loess Plateau: A case study of the Yangou Watershed in Northern Shaanxi Province, China

De-farming slope farmland has been an effective measure in recent years to improve environment and prevent soil and water loss on the Loess Plateau.There are different views about the defarming method,and also various de-farming patterns have been put into practice.This paper takes the Yangou Watershed in Shaanxi Province of China as a case for studying the comprehensive benefits of transforming slope farmland to terraces.Based on the day-by-day meteorological data of the Yan'an station in 2005 and the data...     

Spatial Disparity of Slope Farmland and Food Security in Three Gorges Area

As an important measure of ecoenvironmental construction, the process of de-farming in slope farmland is being undertaken gradually in the whole China. Meanwhile, the problem of reducing in food yield in de-farming areas can not be neglected any more. It is especially the case in areas with concentrated slope farmland and inconvenient transportation. In this paper, we analyze the causes of hidden troubles in food security, and the spatial relationship between farmland and slope farmland in the reservoir area of Three Gorges, and unveil the spatial disparity of contradictions between food supply and demand. Finally, combining the accessibility of areas, three different spatial types of food security, food security area, food alert area, and food crisis area, are divided.     

Quantifying spatial scale of positive and negative terrains pattern at watershed-scale: Case in soil and water conservation region on Loess Plateau

The positive and negative terrains (P-N terrains) widely distributed across China’s Loess Plateau constitute the dual structure characteristic of loess landforms. Analysis of loess P-N terrains at the watershed scale can serve to elucidate the structural characteristics and spatial patterns of P-N terrains, which benefits a better understanding of watershed evolution and suitable scales for loess landform research. The Two-Term Local Quadrat Variance Analysis (TTLQV) is calculated as the average of the square of the difference between the block totals of all possible adjacent pairs of block size, which can be used to detect both the scale and the intensity of landscape patches (e.g., plant/animal communities and gully networks). In this study, we determined the latitudinal and longitudinal spatial scale of P-N terrain patterns within 104 uniformly distributed watersheds in our target soil and water conservation region. The results showed that TTLQV is very effective for examining the scale of P-N terrain patterns. There were apparently three types of P-N terrain pattern in latitudinal direction (i.e., Loess Tableland type, Loess Hill type, and Transitional Form between Sand and Loess type), whereas there were both lower and higher values for P-N terrain pattern scales in all loess landforms in the longitudinal direction. The P-N terrain pattern also clearly presented anisotropy, suggesting that gully networks in the main direction were well-developed while others were relatively undeveloped. In addition, the relationships between the first scales and controlling factors (i.e., gully density, nibble degree, watershed area, mean watershed slope, NDVI, precipitation, loess thickness, and loess landforms) revealed that the first scales are primarily controlled by watershed area and loess landforms. This may indicate that the current spatial pattern of P-N terrains is characterized by internal force. In selecting suitable study areas in China’ Loess Plateau, it is crucial to understand four control variables: the spatial scale of the P-N terrain pattern, the watershed area, the main direction of the watershed, and the loess landforms.     

Storage and density of soil organic carbon in urban topsoil of hilly cities: A case study of Chongqing Municipality of China

Rapid urbanization results in the conversion of natural soil to urban soil,and consequently,the storage and density of the soil carbon pools change.Taking Chongqing Municipality of China as a study case,this investigation attempts to better understand soil carbon pools in hilly cities.First,the vegetated areas in the study area were derived from QuickBird images.Then,topsoil data from 220 soil samples(0-20 cm) in the vegetated areas were collected and their soil organic carbon(SOC) densities were analyzed.Using the Kriging interpolation method,the spatial pattern of SOC was estimated.The results show that the SOC density exhibited high spatial variability in the urban topsoil of Chongqing.First,the SOC density in topsoil decreased according to slope in the order 2°-6° < 25°-90° < 0°-2° < 6°-15° < 15°-25°.Second,the newly developed areas during 2001-2010 had a lower SOC density than the areas built before 1988.Third,urban parks and gardens had a higher SOC density in topsoil,residential green land followed,and scattered street green land ranked last.For hilly cities,the variability of terrain affects the distribution of SOC.The Kriging results indicate that Kriging method combining slope with SOC density produced a high level of accuracy.The Kriging results show that the SOC density to the north of the Jialing River was higher than the south.The vegetated areas were estimated to amount to 73.5 km2 across the study area with an SOC storage of 0.192 Tg and an average density of 2.61 kg/m2.     

烟台市牟平区废弃矿山地质环境问题及生态修复治理措施

本文以烟台市牟平区某废弃矿山为例,介绍了该区域存在的地质环境问题,分析了造成该区域矿山地质环境破坏的原因,以恢复耕地、草地、林地为目的,对区内的现状进行分析,对采坑、残丘、料场提出相应的修复方案。矿山地质环境恢复治理需从科学的角度树立正确的修复理念,落实地貌重塑、土壤重构和植被恢复三大矿山修复核心技术,为矿山地质环境保护与生态恢复治理提供重要的科学依据。     

陕西秦岭国家级生态功能保护区土壤侵蚀的遥感分析

生态环境问题的调查是生态功能保护区规划的基础,本文介绍了利用1∶25万TM卫星遥感图像查明了陕西秦岭山地土壤侵蚀类型、土壤侵蚀强度及空间分布特征,分析了影响土壤侵蚀的主要因素及发展趋势,为生态功能保护区的准确划分提供依据。     

泰安市山水林田湖草生态修复区废弃露天矿山治理模式与技术体系研究

露天矿山对区域土地与环境产生了复杂多样的负面影响,已成为生态系统修复等方面研究解决的焦点问题。本文分析、诊断、识别了废弃露天矿山修复目标、存在问题及特征,归纳总结了常用的治理模式;厘清了废弃露天矿山治理思路与方法,创新构建了更具针对性、实用性的技术体系;针对废弃露天矿山典型现状,归纳总结出研究区几种典型修复方法。旨在为泰安市山水林田湖草生态修复区废弃露天矿山生态修复治理提供技术参考,同时,对我国类似矿山开采区的恢复治理工作也具有一定的借鉴意义。     

基于生态保护格局的省域国土空间生态修复策略——以山东省为例

国土空间生态保护修复是生态文明建设的重要抓手。省域国土空间生态修复需要以维持区域生态保护格局为基础,聚焦核心生态区、重要生态带和重点生态绿心,构建国土空间生态修复格局,实现整体保护、系统修复、综合治理。以山东为例,在生态问题诊断基础上,基于省域生态保护格局,构建了“两核、三带”的生态修复总体格局,提出了“六心、六原、多城”的生态修复关键区域,提出了筑牢生态保护基础框架,锚定重点生态绿心保护修复,因地制宜开展平原土地整治修复,差异化推进城镇生态修复,以期为省域生态修复提供支撑。     

黄河流域下游泰山区域生态地质环境问题及修复模式

泰山区域位于黄河流域下游,是鲁中地区相对独立的一个山水林田湖生态系统,受自然和人类活动共同作用,区内生态地质环境在一定时期内呈现出负效应.本文介绍泰山区域在国家生态格局地位的基础上,阐明了存在的生态地质环境问题及分布特征,分析了产生的原因和危害,提出了总体的治理思路及具体的修复模式.本文研究结果对泰山区域生态地质环境保...     

基于“三调”数据的济南市永久基本农田划定和耕地保护研究

探索永久基本农田划定的有效路径，划定质优、集聚耕地为永久基本农田，有效配置耕地资源，对耕地保护和保障粮食安全具有重要意义。本文基于济南市“三调”成果，从多维度构建耕地综合质量和“可恢复”耕地潜力评价指标体系，根据评价结果将济南市耕地划分为优质、较优质、良好、一般、较差、不稳定与生态保护6种类型，将济南市“可恢复”耕地潜力划分为优先恢复区、适宜恢复区、不宜恢复区。客观反映了耕地综合质量和“可恢复”耕地潜力状况，得到济南市耕地和“可恢复”耕地的资源时空配置，为济南市及其他市县永久基本农田划定提供借鉴，为耕地资源差别化管控和耕地“进出平衡”方案编制实施提供参考。     

南方山地丘陵土地利用类型的地形影响GIS分析——以江西省为例

分布广泛的山地丘陵,地形复杂多样,生态环境脆弱,不合理的土地利用方式会造成生态环境的破坏,导致严重的水土流失。分析山地丘陵区土地利用的地形控制机制,对于山地丘陵区土地利用开发与水土保持等生态保护之间权衡提供科学依据而具有重要现实意义。因此,本文以南方山地丘陵分布较广泛的江西省为例,在SRTM数字高程模型(DEM)的支持下,利用中国资源环境数据中心基于Landsat遥感解译的2000年土地利用数据,分析了江西省土地利用结构与高程、坡度和坡向等地形因子的关系。结果表明地形因子是影响江西省土地利用方式的一个重要因素,具体表现在:(1)随着高程和坡度的增加,耕地面积及占土地总面积的比例都呈下降趋势,南坡耕地面积和比例都大于北坡的耕地面积和比例;(2)在低海拔区,林地面积占土地总面积比例随着海拔高程的增加而增加,当海拔高于400米时,基本稳定;(3)居民点和工矿用地受高程和坡度的影响较大,受坡向影响较小;(4)草地的面积随着海拔的增加呈下降趋势,但其面积比随着高程增加呈缓慢增加,受坡度和坡向的影响较小。     

山东省济宁市历史遗留露天矿山地质环境治理规划研究

矿山地质环境是生态环境的重要组成部分,历史遗留露天矿山地质环境恢复治理工作日益紧迫。本文在查明山东省济宁市历史遗留露天矿山分布、地质环境问题的类型及特征、已开展工程采取的治理措施及存在问题等的基础上,结合城镇、交通、河流、自然保护区等国土空间及生态保护格局,着力构建“一核、一带、两片区”矿山修复总体布局。提出因地制宜选择植被修复措施,设计阶段应重视养护和管护措施的提出和制定,积极吸引社会资金等建议。     

黄土地貌类型的坡谱自动识别分析

地貌形态特征识别与分类,对生态环境、水文研究及地质构造分析等地学研究具有重要意义,已成为现代地貌学的一个研究热点。传统的统计模式识别方法精度较低,难以解决线性不可分的模式分类问题。人工方法虽然识别精度高,但因各人认知偏差导致的识别误差难以控制。人工神经网络作为一种动态信息处理系统,能有效解决线性不可分的地貌类型识别问题。坡谱是利用微观地形定量指标来反映宏观地形特征的有效方法,在地貌学研究中正受到广泛的关注。本文以陕北黄土高原8个不同地貌类型区的数字高程模型（DEM）为实验数据,以流域为分析单元,提取坡谱及其特征指标作为描述地形特征的定量因子,并通过BP神经网络的构建与学习,进行黄土地貌类型自动识别。实验结果表明,在8种地貌类型的样本数据中,第1次实验正确识别率平均值达70%;第2次和第3次实验中,去除相似度较高的峁状丘陵沟壑或峁梁状丘陵沟壑任一种地貌类型后,正确识别率平均提升为80%和85%。经Kappa系数验证,该方法能以DEM数据有效识别不同类型的黄土地貌。     

Assessing the real value of farmland in China

The preservation of farmland is a growing concern in China because the fact that China possesses limited land resources and the world's largest population presents a clear contradiction. Only when the value of farmland is fully appreciated in commercial markets can farmland preservation be effectively achieved. The current study constructed a model to evaluate the economic, social, and ecological value of farmland in China according to the connotation of values. As a case study, the value of Chinese farmland was estimated in 1999, 2002, 2005, 2008, and 2011 using the established model. Although the amount of farmland was greatly reduced from 1999 to 2011 due to constructive occupation, agricultural restructuring, ecological restoration, and disaster destruction, the value of this farmland increased from 220.71×1012 to 736.26×1012 RMB Yuan as a result of the multifunctional nature and scarcity of farmland during the same period. The potential value of farmland in China was huge, but the value in the market was greatly underestimated, especially in regard to its social and ecological value. This study proposes a new method that integrates the discounted value of all future services provided by a natural resource(for the society and individuals) to evaluate the resource assets, provides a scientific foundation for the preservation and operation of farmland assets, and explores ways to increase farmers' property income.     

基于TM遥感数据的汶川地震极重灾区生态恢复研究

本文以地震极重灾区2006、2008和2011年3期Landsat TM遥感影像为数据源,利用GIS提取灾区土地利用信息,结合坡度和高程等地形因子对灾区主要生态系统面积的变化进行综合分析.结果表明:2008年地震对灾区生态环境造成严重破坏,使研究区农田、森林和草地生态系统分别减少了124.6km2、461.6km2和9...     

Response of Soil Moisture to Rainfall Event in Black Locust Plantations at Different Stages of Restoration in Hilly-gully Area of the Loess Plateau,China

Precipitation plays an important role in the water supplies that support ecological restoration by sustaining large-scale artificial plantations in arid and semiarid regions, especially black locust(Robinia pseudoacacia) plantations(RP plantations), which are widely planted due to R. pseudoacacia being an excellent pioneer species. Characterizing the response of soil moisture to rainfall events at different stages of restoration is important for assessing the sustainability of restoration in RP plantations. In this study, we quantified the response of soil moisture to rainfall events at different years of restoration(15, 20 and 30 yr) representing different restoration stages in RP plantations in a typical hilly-gully area, i.e., the Yangjuangou Catchment, of the Loess Plateau, China. Over the growing season(June to September) of 2017, smart probes were placed at nine depths(10, 20, 40, 60, 80, 100, 120, 150, and 180 cm below the soil surface) to obtain volumetric soil water information at 30-min intervals in the three RP plantations. The advance of the wetting front was depicted, and the total cumulative water infiltration was measured. Soil moisture was mainly replenished by eight heavy rainfall events(mean rainfall amount = 46.3 mm), accounting for 88.7% of the rainfall during the growing season. The mean soil moisture content profiles of RP plantations at the three restoration stages were ordered as 30-yr(14.07%) 20-yr(10.12%) 15-yr(8.03%), and this relationship displayed temporal stability. Soil moisture was primarily replenished by rainfall at the 0-60 cm soil depth, and soil moisture remained stable below the 100-cm soil depth. The rainfall regime influenced the advancement of the wetting front. Here, a single rainfall event of 30 mm was the rainfall threshold for infiltration into the 60-cm soil layer. The total infiltration time ranged from 310.5-322.0 h, but no significant differences were found among RP plantations at different restoration stages. Young and old RP plantations had more total infiltration(more than 228.2 mm) and deeper infiltration depths(80-100 cm) than middle-aged plantations. The RP plantation at the intermediate restoration stage exhibited minimal total infiltration(174.2 mm) and a shallow infiltration depth(60 cm) due to the soil physical structure of the plot, which may have limited rain infiltration. More stand conditions that may affect infiltration should be considered for priority afforestation areas.