岷江上游1974-1995年间景观变化

Landscape changes were traced over the 20 years from 1974 to 1995 in the upper Minjiang River basin, one of the most important forest regions in China, based on satellite image interpretation to provide basic data for local decision-making as well as sustainable landscape use and management. Results revealed that landscape from 1974 to 1995 changed at the regional scale as the area of forestland decreased, while cropland, shrubland, economic forest, grassland, and built-up land increased. Landscape changes mainly occurred in forestland, shrubland, grassland, economic forest, and built-up land. Moreover, the changes among forestland, shrubland, and grassland were the largest, influencing the whole characteristics of the changes in the basin. Analysis of the changes between 1974 and 1995 in the study area indicated that landscape heterogeneity and fragmentation increased, whereas landscape connectivity decreased. There were multiple reasons for landscape changes. A principal component analysis （PCA） was used to quantitatively study driving forces of landscape changes. The PCA results showed that economic and population factors were the principal driving forces of landscape changes from 1974 to 1995 in the upper Minjiang River basin, and that PCA was a suitable method for investigating driving forces of landscape changes.     

黄河三角洲耕地变化及其驱动力的卫星遥感分析

Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this study. An interactive interpretation and a manual modification procedure were carried out to acquire cultivated land information. An overlay method based on classification results and a visual change detection method which was supported by land use maps were employed to detect the cultivated land changes. Based on the changes that were revealed and a spatial analysis between cultivated land use and related natural and socio-economic factors, the driving forces for cultivated land use changes in the study area were determined. The results showed a decrease in cultivated land in Kenli County of 5321.8 ha from 1987 to 1998, i.e., an average annual decrement of 483.8 ha, which occurred mainly in the central paddy field region and the northeast dry land region. Adverse human activities, soil salinization and water deficiencies were the driving forces that caused these cultivated land use changes.     

不同轮作制度下土壤中不稳定有机碳组分的变化

Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this study. An interactive interpretation and a manual modification procedure were carried out to acquire cultivated land information. An overlay method based on classification results and a visual change detection method which was supported by land use maps were employed to detect the cultivated land changes. Based on the changes that were revealed and a spatial analysis between cultivated land use and related natural and socio-economic factors, the driving forces for cultivated land use changes in the study area were determined. The results showed a decrease in cultivated land in Kenli County of 5321.8 ha from 1987 to 1998, i.e., an average annual decrement of 483.8 ha, which occurred mainly in the central paddy field region and the northeast dry land region. Adverse human activities, soil salinization and water deficiencies were the driving forces that caused these cultivated land use changes.     

子午岭植被自然恢复过程中土壤有机碳密度的时空变化

To probe the processes and mechanisms of soil organic carbon （SOC） changes during forest recovery, a 150-year chronosequence study on SOC was conducted for various vegetation succession stages at the Ziwuling area, in the central part of the Loess Plateau, China. Results showed that during the 150 years of local vegetation rehabilitation SOC increased significantly （P 〈 0.05） over time in the initial period of 55-59 years, but slightly decreased afterwards. Average SOC densities for the 0-100 cm layer of farmland, grassland, shrubland and forest were 4.46, 5.05, 9.95, and 7.49 kg C m^-3, respectively. The decrease in SOC from 60 to 150 years of abandonment implied that the soil carbon pool was a sink for CO2 before the shrubland stage and became a source in the later period. This change resulted from the spatially varied composition and structure of the vegetation. Vegetation recovery had a maximum effect on the surface （0-20 cm） SOC pool. It was concluded that vegetation recovery on the Loess Plateau could result in significantly increased sequestration of atmospheric CO2 in soil and vegetation, which was ecologically important for mitigating the increase of atmospheric concentration of CO2 and for ameliorating the local eco-environment.     

Estimating Soil Salinity in the Yellow River Delta,Eastern China——An Integrated Approach Using Spectral and Terrain Indices with the Generalized Additive Model

Soil salinity is one of the most severe environmental problems worldwide. It is necessary to develop a soil-salinity-estimation model to project the spatial distribution of soil salinity. The aims of this study were to use remote sensed images and digital elevation model (DEM) to develop quantitative models for estimating soil salinity and to investigate the influence of vegetation on soil salinity estimation. Digital bands of Landsat Thematic Mapper (TM) images, vegetation indices, and terrain indices were selected as predictive variables for the estimation. The generalized additive model (GAM) was used to analyze the quantitative relationship between soil salt content, spectral properties, and terrain indices. Akaike’s information criterion (AIC) was used to select relevant predictive variables for fitted GAMs. A correlation analysis and root mean square error between predicted and observed soil salt contents were used to validate the fitted GAMs. A high ratio of explained deviance suggests that an integrated approach using spectral and terrain indices with GAM was practical and efficient for estimating soil salinity. The performance of the fitted GAMs varied with changes in vegetation cover. Salinity in sparsely vegetated areas was estimated better than in densely vegetated areas. Red, near-infrared, and mid-infrared bands, and the second and third components of the tasseled cap transformation were the most important spectral variables for the estimation. Variable combinations in the fitted GAMs and their contribution varied with changes in vegetation cover. The contribution of terrain indices was smaller than that of spectral indices, possibly due to the low spatial resolution of DEM. This research may provide some beneficial references for regional soil salinity estimation.     

土壤微食物网对旱改水不同稻作年限土地利用变化的响应

Land use changes affect belowground ecosystems.During the past few decades,land use in Northeast China has changed considerably,and the area of paddy fields has increased rapidly from upland.In this study,soil characteristics and soil biotic community in paddy fields with different years of rice cultivation were measured to examine the effects of land use change from upland to paddy fields on soil micro-food web.The upland maize fields were selected as control and the microbial community composition was characterized using phospholipid fatty acids (PLFAs) analysis.The microbial biomass (total PLFA),bacteria biomass,and fungi biomass were higher in the 20-40-year (late-stage) than 1-10-year (early-stage) paddy fields.The abundances of total nematodes and bacterivores were lower in the early-stage than late-stage paddy fields.The abundance of herbivores was the highest in the early-stage paddy fields but that of omnivore-predators was the highest in the late-stage paddy fields.Structural equation model indicated that soil food web was developed and structured after 20 years of paddy cultivation.Our results suggested that soil micro-food web may be a good indicator for soil development and stabilization of paddy fields following land use change.     

巴西东北部地区土地退化对土壤微生物量和活性的影响

Land degradation causes great changes in the soil biological properties.The process of degradation may decrease soil microbial biomass and consequently decrease soil microbial activity.The study was conducted out during 2009 and 2010 at the four sites of land under native vegetation(NV),moderately degraded land(LDL),highly degraded land(HDL) and land under restoration for four years(RL) to evaluate changes in soil microbial biomass and activity in lands with different degradation levels in comparison with both land under native vegetation and land under restoration in Northeast Brazil.Soil samples were collected at 0-10 cm depth.Soil organic carbon(SOC),soil microbial biomass C(MBC) and N(MBN),soil respiration(SR),and hydrolysis of fluorescein diacetate(FDA) and dehydrogenase(DHA) activities were analyzed.After two years of evaluation,soil MBC,MBN,FDA and DHA had higher values in the NV,followed by the RL.The decreases of soil microbial biomass and enzyme activities in the degraded lands were approximately 8-10 times as large as those found in the NV.However,after land restoration,the MBC and MBN increased approximately 5-fold and 2-fold,respectively,compared with the HDL.The results showed that land degradation produced a strong decrease in soil microbial biomass.However,land restoration may promote short-and long-term increases in soil microbial biomass.     

红壤丘陵地区土地利用的生态学效应

Plant biomass and biodiversity,element accumulation and return,water loss and soil erosion,and changes in soil properties were studied for up to 10 years after conversiton of sparse tree-shrubby grass land into the following four land use patterns:masson pine(Pinus massoniana Lamb.) land,beautiful sweetgum(Liquidambar formosana Hance)land,vegetation reservation aldn,and artificial mowing land.Thie annual biomass production of the masson pine land was 5060kg ha^-1,being 4.9,2.1,and 6.0 times that of the beautiful sweetgum land,the vegetation reservation land,and the artificial mowing land,respectively,Compared with the background values,the number of plant species for the vegetation reservation and increased by 10 species after 10 years of land utilization,while for the masson pine and the beautiful weetgum decreased by 4,and for the artifiucial mowing land by 9.For masson pine land,total amount of N,P,K,Ca,and Mg needed for producing 1000kg dry matter was only 3.5kg,annual element return through litter was 22 kg ha^-1,both of which were much lower than those of the other patterns.Vegetation reservation was an effective measure to conserve soil and water and improve soil fertility in the red soil hilly region.Artificial mowing aroused serous degradation of vegetation and soil.Some measures and suggestions for management and exploitation of the red soil hilly region such masson pine planting,closing hills for afforestation,and stereo-agriculture on one hill are proposed.     

中国坡耕地分布特征与退耕还林草政策影响分析

The Grain-for-Green Policy in China could not only improve China's ecological quality, but also influence grain supplies for a short term. Based on data from the detailed nationwide land use survey in 1996 and the steep cultivated land survey update in 2000, a regression model for the driving forces affecting steep cultivated lands was developed, and cluster analysis was used to identify seven steep cultivated land types in order to analyze the grain availability impact of the project with land usage estimates for 2010 and 2030. The results suggested that consecutive days with minimum daily temperature over 10 ℃ and the dominant slope in a county constrained the spatial distribution of steep cultivated lands. In terms of socioeconomic factors, steep cultivated land was a complex interaction of population size, gross domestic production level, and the richness and quality of cultivated lands having slopes less than 15°. The trends for steep cultivated land in 2010 and 2030 were forecast using a driving forces model and China's grain security criteria and showed that the Grain-for-Green Policy at the national level would not cause a grain shortage or threaten food security criteria. However, if steep sloped lands were to be retired from production, some regions would need grain supplements as early as 2010. Also, assuming that only 60% of the cultivated land at the national level was needed, population and economic development pressures in 2030 would require some steep cultivated lands to be used for grain production.     

Utilizing landsat TM imagery to map greenhouses in Qingzhou, Shandong Province, China

To build a rapid and accurate method for greenhouse vegetable land information extraction using an index model derived from TM digital data of Qingzhou City, Shandong Province, based on a systematic analysis of the spectral characteristics of different land use types in the study area, a subset of the image was first made to eliminate the mountainous region not associated with vegetable distribution, and then water body pixels were masked. With this the VI index model for greenhouse vegetable land extraction was developed. The index model indicated greenhouse vegetable land for Qingzhou in April 2002 was concentrated in the southeast and around rural residential areas. Field data used for an accuracy evaluation showed that greenhouse hectares determined with remote sensing were 95.9% accurate, and accuracy for the spatial distribution of greenhouse vegetable land cross checked with a random sample was 96.3%. Therefore, this approach provided an effective method for greenhouse vegetable land information extraction and has potential significance for management of greenhouse vegetable production in the study area, as well as North China.     

黄河流域<河南段>耕地多功能时空格局演变及其权衡协同关系

科学测度耕地多功能权衡与协同关系对于量化和表征耕地隐性形态具有重要意义,可为构建土地利用绿色转型调控路径、揭示人地关系演化过程提供科学依据。该研究以黄河流域（河南段）为研究区域,利用1990－2020年时间序列社会经济发展数据,从耕地的生产、社会、生态以及文化功能4个维度系统构建耕地多功能评价指标体系及土地系统功能权衡度（Land system Function Trade-off Degree,LFTD）模型,测算黄河流域（河南段）耕地多功能指数,解析耕地多功能之间权衡与协同关系时序演化特征,以此揭示耕地利用隐性形态的演变规律。结果表明：1）1990－2020年间黄河流域（河南段）耕地的生产、社会、生态和文化功能均呈增长态势,且生产与文化功能增长较为突出。2）按照功能层次性,将1990－2020年间耕地多功能的变化划分为6个阶段。在1990－2010年的前四个阶段中以生产与生态功能为主,在2010－2020年的后两个阶段中以生产与文化功能为主,并且功能间作用关系较为复杂。3）1990－2020年间,耕地生产、社会、生态和文化功能间相互作用关系呈现\     

干旱内陆河流域土地利用转型的生态环境效应变化特征及其驱动因素探测

为探讨土地利用转型对生态环境质量的影响并明确相关驱动因素作用机理,以黑河流域中游这一典型干旱内陆河为研究对象,利用生态环境质量指数、标准差椭圆模型和地理探测器工具,在对研究区2000—2020年土地利用转型生态环境效应数量变化、空间分布及方向特征进行多维测定基础上,对影响生态质量空间分异的驱动因素及其交互作用机制进行了识别与分析。结果表明：(1) 2000—2020年,研究区土地利用转型频发,林地、灌木和人造地表大幅增加,草地、裸地和湿地减少,“南草北裸”的空间分布特征未发生扭转,草地和裸地是流域其他地类最为重要的转型补给源;(2)黑河流域中游生态环境质量整体处于较低水平但向好发展,“北低南高”的空间分布格局显著,其生态环境质量呈“正西北—正东南”朝向的变化趋势特征;(3)人为活动及高程、植被覆盖和坡度是黑河流域生态环境质量空间分异的主要驱动因子,自然、社会和经济诸因素激烈的交互与协同作用,共同导致流域生态环境质量的空间分异。综上,黑河流域中游生态环境质量趋好,但需严控人为活动,保障流域土地利用与生态安全持续稳定。     

2000-2015年黄河流域植被净初级生产力时空变化特征及其驱动因子

黄河流域区域性差异显著,生态系统环境脆弱敏感,研究植被NPP对其生态环境生产能力的了解具有重要意义。基于MOD17A3 NPP数据、气象数据和土地利用/覆盖类型数据,采用偏差分析、趋势分析、相关性分析及马尔科夫转移模型对黄河流域2000—2015年植被NPP的时空格局、变化趋势及驱动因子进行了研究。结果表明:（1）2000—2015年黄河流域植被年NPP均值为228.2 g C/（m²·a）,变化范围为179.6～258.1 g C/（m²·a）,整体上呈现微小波动增加趋势,植被NPP偏差值呈现先减少后增加的趋势;上中下游植被NPP年均值呈明显的梯度分布,即上游<中游<下游,说明中上游区域生态环境相对脆弱。（2）黄河流域植被NPP具有较强的空间分异性,呈南向北带状递减分布;上中下游植被NPP总量差异显著,其中中上游植被NPP总量约占整个流域的96%,可见中上游对整个黄河流域生态环境的影响举足轻重,故加强对中上游区域生态环境建设与保护至关重要;流域大部分地区植被NPP以增加为主要趋势。（3）流域植被NPP受气候因素中降雨影响较大,以气候因素强驱动的区域主要分布在川西高原、鄂尔多斯高原及华北平原等地区。农用地转建设用地及草地转荒漠是黄河流域植被NPP损失的主要方式,可见城市加速扩张以及过度开垦、放牧等人类活动是植被NPP损失的主要驱动力,近几年林地、草地面积有所增加,植被NPP整体上损失程度有所减小,可见实施退耕还林还草政策已见成效。     

蒲河流域退耕前后降水和植被对土壤侵蚀变化的影响

为了定量评价退耕还林还草前后蒲河流域土壤侵蚀变化特征及降水和植被对土壤侵蚀的影响,运用修正后的通用土壤流失方程(RUSLE模型)探讨1990—2019年流域土壤侵蚀变化,结合LMDI模型评估了1990—2000年、2000—2010年、2010—2019年3个时间段植被和降水对流域土壤侵蚀变化的影响。结果表明：30年来,流域侵蚀强度以微度和轻度侵蚀为主,而中度及以上等级的土壤侵蚀面积有逐渐减小的趋势;流域侵蚀情况总体持续向好,植被覆盖度与降雨侵蚀力相互作用驱动了研究区土壤侵蚀的动态发展;2000年以前,降水是影响土壤侵蚀变化的主导因素,随着退耕还林还草工程的实施,植被作用逐渐凸显。蒲河流域的退耕还林还草成效显著,是流域侵蚀防治的有效措施,应在侵蚀较强的流域中上游地区继续加强植被恢复措施。     

基于遥感黄河流域内蒙古段十大孔兑生态环境质量监测评价

黄河流域生态环境质量的及时、准确监测评价,是对其生态环境保护和建设的重要基础。因此以黄河流域内蒙古段十大孔兑为研究对象,利用Landsat5 TM和Landsat8 OLI数据,基于生态遥感指数对研究区2000—2020年生态环境健康度的分布格局及变化趋势进行了分析。结果表明:(1)2000年、2010年和2020年,十大孔兑的遥感生态指数均值分别为0.31,0.33,0.57,生态环境质量正在不断改善。(2)研究期间,十大孔兑的生态环境质量等级以差到一般为主,差、较差及一般的面积之和占区域总面积的比例依次为79.45%,76.54%,70.16%,面积在不断减少,向良好和优秀等级转移的面积达1 004 km²。(3)在空间分布上,下游平原区的生态环境质量最优,上游丘陵区与中游风沙区相对较差。整体来看,研究区的生态环境治理虽取得了一定的成效,但仍有很大的改善空间。     

黄河口生态脆弱区土地利用时空变化及驱动因素分析

黄河三角洲是典型的生态环境脆弱区,在人类活动及自然环境相互作用下土地利用变化剧烈,是研究土地利用变化的热点地区。该文以黄河口垦利县为研究区,选用1989年、1995年、2000年、2005年及2011年5个时相的遥感影像,获取各时相土地利用信息,利用土地利用变化相关模型,分析了研究区20余年来土地利用的时空变化特点,并对其驱动因素进行了探讨。结果表明:研究区土地利用变化的主要特征是旱地、林草地面积减少和建设用地、水域、盐荒地、滩涂面积的大幅增加。2000年之前总体土地利用变化程度高于后期,单一土地利用动态度,河流水面、水域及建设用地表现较明显。研究时段内旱地、盐荒地、水田、建设用地重心均向西南方向迁移,林草地、河流水面、滩涂重心则向东北方向迁移,水域重心转向西南,但整体地域分布特点变化不大。蒸降比大、偏砂质地土壤、地下水埋深浅且矿化度高、黄河断流等气候水文因素是该区土地利用覆盖变化的主导自然驱动,人类不合理的农业开发活动是主要人为驱动。该研究为黄河口生态脆弱区资源环境的利用保护和社会经济的可持续发展提供依据。     

基于TM图像和GIS的土地利用/覆被变化及其环境效应研究

选择黄河三角洲垦利县为研究区,采用1987～2000年4个时相的TM数字图像,以基于知识与规则的分类方法提取土地利用/覆被信息,分析研究区土地利用/覆被的时空变化。通过筛选环境脆弱性因子,建立评价指标体系,进行了研究区环境脆弱性评价。在此基础上,通过空间叠加、缓冲区及相关分析模型,系统分析了土地利用/覆被及其变化对环境脆弱性的影响。结果显示,从1987～2000年,研究区土地利用/覆被变化明显,尤其旱地、林草地、盐荒地和滩涂转换频繁,总体生态环境表现出较强的脆弱性及明显的空间规律性;环境脆弱程度与林草地、盐荒地、水域和滩涂4种类型的面积,以及与林草地－旱地、盐荒地,盐荒地－滩涂间的转换高度相关。同时土地利用/覆被与离黄河和渤海的距离及相关水土环境条件关系密切。该研究对环境脆弱区土地利用/覆被变化及其环境效应的定量研究有借鉴意义。     

黄河上游玛多县生态环境变化遥感监测及成因分析

玛多县是黄河流经的第一县,是三江源自然保护区的重点地区,生态系统异常敏感和脆弱。在高海拔的生态脆弱区进行生态环境遥感监测,不仅利于高寒脆弱生态体系自然规律的研究,而且可为当地进行生态环境保护与治理提供可操作性强的、科学的决策依据。本文利用1990年和2000年两期最新的卫星影像数据,结合野外调查,对研究区80年代以来生态环境变化过程趋势进行对比分析,并以对70年代以来以气候因子为主导的包含冻土环境与水文条件的自然因素变化和人类活动进行分析为基础,探讨了研究区生态环境变化的成因。     

海河流域生长季植被覆盖度时空变化及驱动力分析

[目的]了解海河流域生长季植被覆盖度(FVC)的时空变化及其驱动力,以期为海河流域的生态保护、建设与可持续发展提供参考。[方法]基于MODIS NDVI遥感数据和同时期的18种影响因子,采用趋势分析法和M-K显著性检验分析了2001—2019年海河流域生长季植被覆盖度的时空变化特征;并利用地理探测器探讨了其空间分异特征与驱动力。[结果]2001—2019年海河流域生长季植被覆盖度总体呈显著上升趋势,线性倾向率为0.063/10 a, 2011年之后增速减缓。空间分布差异明显,植被覆盖度总体较高,仅环渤海湾地带和一些城市区域植被覆盖率较低。改善区域的面积远大于退化面积,其中改善部分以极显著改善为主,占流域总面积的60.42%。海河流域生长季植被覆盖度的空间分布差异主要由林地比例和林草混合地比例所决定,解释力均在30%以上。对海河流域生长季植被覆盖度交互作用解释力最强的是林草混合地比例和农田比例。[结论]海河流域植被覆盖度总体显著上升,空间分布差异主要驱动力为林地比例和林草混合地比例。     

乌江流域土地利用变化的自然因子

自然因素是引起典型山地流域土地利用变化的主要原因,乌江流域作为典型山地流域,明确各自然因子在乌江流域土地利用类型转变中的贡献率,找到关键性驱动因子,从而为合理调整土地利用布局提供借鉴作用。以乌江流域为研究对象,基于时空性和整体性,采用2000年、2010年和2020年三期土地利用数据,综合各自然要素,利用增强回归树模型来分析土地利用变化的自然因子。结果表明:(1)2000—2020年乌江流域土地利用类型变化表现在,林地、灌木地、水体和人造地表面积比重明显增加,耕地、湿地面积显著减少,草地面积变化呈稳定趋势。(2)2000年和2020年对比发现乌江流域中部水体面积扩大,北部林地面积有所增加,东部耕地面积大幅度缩减。草地和灌木地空间变化不明显,呈嵌入式分布。人造地表以东南、西南、东北和西北部增加最为明显。(3)从贡献率方面考虑,降水对草地变化的贡献率最大,坡度对耕地的影响最大,植被类型对林地影响最大,影响湿地最大的自然驱动因子是坡度,气温是制约灌木地发展的最大自然因子,土壤类型对水体变化的贡献率最大,坡度是人造地表变化最大的自然驱动因子。草地变化的特征因子主要是降水、植被类型和气温; 耕地变化特征因子分别是坡度、高程和气温; 林地变化的特征因子是植被类型、高程和气温; 湿地变化的特征因子是坡度; 灌木地变化的特征因子是气温、土壤类型和植被类型; 水体变化的特征因子是土壤类型和植被类型; 人造地表变化的特征因子是坡度和植被类型。