土地状况

截至2006年10月31日,全国31个省(自治区、直辖市)土地调查面积中,农用地98.58亿亩(占69.1%)、建设用地4.85亿亩(占3.4%)、未利用地39.17亿亩(占27.5%)。人均农用地7.50亩,人均建设用地0.37亩。农用地中,耕地18.27亿亩、园地1.77亿亩、林地35.4亿亩、牧草地39.29亿亩、其他农用地3.83亿亩。建设用地中,居民点及独立工矿用地3.95亿亩、交通运输用地0.36亿亩、水利设施用地0.54亿亩。     

从化市土地利用总体规划实施的生态效应评价

从生态系统服务价值的角度对从化市土地利用总体规划（1997-2010年）实施的生态效应进行了定量评价。结果表明，1996-2005年从化市土地利用变化的总体趋势是耕地、林地、牧草地和未利用地面积在减少，园地、建设用地和水域面积在增加；从化市生态系统服务总价值增加了0．0690亿元，增加率为0．21％。从化市土地利用总体规划（1997-2010年）基本可行，其实施虽然取得了一定的生态效应，但与规划预期目标相比尚有一段差距。     

干旱区典型绿洲城市LUCC及社会人文驱动因素分析——以乌鲁木齐市为例

选取2001—2011年的相关数据,采用因子分析、相关性分析的方法对乌鲁木齐市土地利用/土地覆被变化及社会人文因素进行分析。结果表明:①研究区的土地利用类型的整体结构差异明显,农用地占据绝对优势,其比重均在79%以上,但面积和比例持续缩小;建设用地则处于相对劣势的地位,其比重仅为3.2%左右,但规模和比重却在不断扩大。②11年来,研究区土地利用变化的总强度不大,仅为36%,各用地类型的动态度为:建设用地农用地其他用地。③各类用地变化强度的顺序为:交通用地园地居民点工矿用地耕地水域水利设施用地牧草地其他农用地其他建设用地。④影响乌鲁木齐市土地利用类型变化的4个因子及其影响程度由高到低的排序为:区域经济产业结构交通发展社会人口。     

兵团土地利用变化及其生态系统服务价值分析

运用谢高地等人提出的生态服务价值系数,根据土地利用变化研究了新疆生产建设兵团(简称兵团)的生态服务价值变化。结果表明①兵团生态服务价值在2001-2009年呈增加趋势,单位面积生态服务价值从2001年的5234.13元/hm2.a-1增长到2009年的5354.19元/hm2.a-1,增长率为2.29%。②2001-2009年,兵团林地和水域的生态服务价值分别增加了10.73×108元和10.39×108元,牧草地、园地和建设用地的生态服务价值有略微的增加,耕地和未利用地的生态服务价值有略微的减少。③研究区生态经济的发展已经处于协调水平的边缘,需要加强对生态保护的力度。     

基于遥感影像的西安地区土地利用变化分析

以西安地区为研究对象,采用1990年和2000年两期遥感影像,综合遥感与GIS技术、马尔可夫模型,分析了土地利用变化的空间特征。在研究区划分出林地、牧草地、建筑用地、未利用地、耕地、园地和水域共7个土地利用类型,据此建立起1990—2000年土地利用变化转移矩阵,并分析了研究区的土地利用变化幅度。结果表明,10年间西安地区建筑用地、园地呈增长趋势,林地、牧草地、未利用地、耕地、水域呈减少趋势。进一步分析表明,该区土地利用变化的驱动力主要为人口压力、经济因素、宏观政策,这3方面共同影响着土地利用变化。     

煤粮复合地区生态系统服务价值变化研究——以邹城市为例

根据Costanza等人对全球生态系统服务价值的测算结果,分析了1996-2003年邹城市土地利用和生态系统服务价值变化.结果表明,邹城市的耕地、园地和林地土地面积在减少,建设用地和水域用地面积在增加.由于水域单位面积生态系统服务价值较高,7年间邹城市区域生态系统服务价值处于增加状态.邹城市生态系统服务价值从1996年的95.9704×106美元增加到2003年的104.5830×106美元,7年间增加8.6126×106美元,变化率达到8.97%.     

青海省不同土地利用方式碳汇效益分析

文章利用2002~2012年青海省主要土地利用类型面积统计数据,对青海省主要土地利用类型现状进行分析,在此基础上采用碳排放系数法对主要土地利用类型碳汇效益及其空间分布格局进行了分析。结果表明:(1)截至2013年末,青海省总土地面积为71.21万km~2,青海省各类农用地、建设用地和未利用地面积分别占全省土地总面积的66.39%、4.47%和29.14%。在空间上,不同土地利用方式产生的碳排放情况呈现明显的区域差异。(2)2002~2012年青海省耕地、林地和牧草地的碳吸收效应逐年增加,其中林地变化较为明显,2012碳汇量是2002年碳汇量的3.2倍。耕地和牧草地变化不明显,碳汇量分别介于7.155~7.982万t和770.637~804.445万t之间。(3)2002~2012年青海省建设用地碳排放总量为427.75~1 570.286万t,利用同期的耕地、林地和牧草地的碳汇量,分别为7.155~7.982万t、1 210.843~3 936.506万t和770.637~804.445万t。计算得出2002~2012年青海省主要土地利用类型净碳排放量介于802.346~3 178.312万t,近11年平均净碳排放量为1 314.686万t。表明耕地、林地和牧草地碳汇量明显大于建设用地碳吸收量,区域整体表现为碳汇。     

青藏高原湖泊变化监测研究

文章采用多源多时相遥感影像为数据源,以Arc GIS、Erdas、Envi等遥感地信软件为信息提取处理平台,对青海可可西里国家级自然保护区高原湖泊进行遥感监测分析。结果显示:1该区土地利用/覆盖类型主要为草地、水域湿地、人工用地和未利用土地,其中草地为主要类型,占区域总面积的68.04%;2调查区以中、小湖为主,共占全区湖泊总数量的91.46%,其中小湖泊占71.95%,面积大于1km2的湖泊总面积3 018.85km2;32006~2013年间,区域内湖泊数量总体上呈增加趋势,其中较大湖泊保持不变、大湖泊增加1个、中湖泊减少2个、小湖泊增加3个。西北部的勒斜武担湖和东北部的库赛湖变化较为显著。     

青海湿地资源现状及保护管理对策探讨

文章阐述了青海省高原湿地资源类型多样、分布不均衡、地域特征明显、海拔高、结构简单等特点,分析了缺乏统一的协调组织机构、法律法规体系不健全等问题,提出了建立湿地保护与合理利用资源的综合管理协调机制,完善湿地资源利用与管理的有关政策和法制体系,大力加强湿地自然保护区域建设,加强湿地科学研究的发展对策。     

基于CA-Markov模型的新疆克州土地利用动态模拟研究

利用"3S"技术及IDRISI软件中的CA-Markov模型,以2005年为起始时刻,对新疆克州2015年土地利用格局进行模拟预测.研究认为:研究区土地利用覆盖结构呈现"两大、四小"的特点,即:草地及未利用土地面积大,而耕地、林地、水域及城乡居民工矿建设用地面积较小;与2005年相比,模拟的2015年研究区土地利用结构变化不大,仍然是以草地和未利用地面积为主,各土地利用类型面积变化也不大,其中,耕地、林地和城乡建设用地面积将略有增加,而草地、水域面积将有所减少,未利用地面积也有一定的增加,总体上,研究区内生态环境将可能进一步呈恶化趋势.     

AN ECONOMIC AND ENVIRONMENTAL EVALUATION OF ALTERNATIVE LAND DEVELOPMENT AROUND LAKES1

ABSTRACT: The objective of the study was to evaluate alternative land developments around New Hampshire lakes. Alternative development patterns, evaluated by their impacts on the lake area environment and area economy, included residential patterns, commercial patterns, and combinations of these two types. Phosphorus loading of the lake water was used as a proxy variable for changes in the lake water quality. Commercial developments yielded the highest revenues to the town and the local area. It also attracted the most lake users to the area as well as contributing the largest phosphorus loading in the lake waters. Residential developments, although contributing high revenues to the businessmen in the area, yielded less net income to the town. Phosphorus loading levels from residential developments were much lower than lake phosphorus loading by commercial developments.     

Long-Term Effects of Changing Land Use Practices on Surface Water Quality in a Coastal River and Lagoonal Estuary

The watershed of the Neuse River, a major tributary of the largest lagoonal estuary on the U.S. mainland, has sustained rapid growth of human and swine populations. This study integrated a decade of available land cover and water quality data to examine relationships between land use changes and surface water quality. Geographic Information Systems (GIS) analysis was used to characterize 26 subbasins throughout the watershed for changes in land use during 1992–2001, considering urban, agricultural (cropland, animal as pasture, and densities of confined animal feed operations [CAFOs]), forested, grassland, and wetland categories and numbers of wastewater treatment plants (WWTPs). GIS was also used together with longitudinal regression analysis to identify specific land use characteristics that influenced surface water quality. Total phosphorus concentrations were significantly higher during summer in subbasins with high densities of WWTPs and CAFOs. Nitrate was significantly higher during winter in subbasins with high numbers of WWTPs, and organic nitrogen was higher in subbasins with higher agricultural coverage, especially with high coverage of pastures fertilized with animal manure. Ammonium concentrations were elevated after high precipitation. Overall, wastewater discharges in the upper, increasingly urbanized Neuse basin and intensive swine agriculture in the lower basin have been the highest contributors of nitrogen and phosphorus to receiving surface waters. Although nonpoint sources have been emphasized in the eutrophication of rivers and estuaries such as the Neuse, point sources continue to be major nutrient contributors in watersheds sustaining increasing human population growth. The described correlation and regression analyses represent a rapid, reliable method to relate land use patterns to water quality, and they can be adapted to watersheds in any region.     

Lake area changes in the middle Yangtze region of China over the 20th century

The Jianghan Plain and the Dongting lake area, located in the middle reaches of the Yangtze River are famous for their abundant freshwater lakes. The lakes have undergone changes in size and number over thousands of years due to natural causes and human activities. The 20th century particularly, witnessed dramatic changes in the freshwater resources of this region. This paper traces and analyzes lake evolution in the middle reaches of the Yangtze River over the past century. Lakes greater than 0.1 km(2) in size are mapped using Geographic Information System. Data is acquired and integrated from drainage network maps, relief maps, historical maps and remotely sensed images for different time periods. The results indicate that while there has been little change in the number of lakes over the past century, the lake area has experienced a dramatic decrease of 58.06%. The paper also examines the natural processes and human activities that may have contributed to the decrease in lake area. The results show that the decrease in total lake area appears to coincide with periods of rapid land reclamation in the middle reaches of the Yangtze River. Moreover, uncontrolled land reclamation activities can create an increase in sediment deposition in lakes thereby further reducing the lake size. Reduction of the lake area directly affects flood-control and has a negative ecological impact on the environment and on human life and property.     

STREAM PHOSPHORUS EXPORTS FROM WATERSHEDS WITH CONTRASTING LAND USES IN SOUTHERN ONTARIO1

: The export of dissolved molybdate reactive phosphorus (DMRP) from 22 watersheds in the Duffin Creek drainage basin near Toronto Ontario was measured over a 25-month period. The annual average loss varied from 0.027 to 2.11 kg P/ha. Phosphorus levels in a number of watersheds were strongly influenced by effluent from a sewage treatment plant which contributed about 68 percent of the annual DMRP input to Duffin Creek. An analysis of 12 watersheds which did not contain major point pollution sources revealed that DMRP concentration and losses had a significant positive correlation with crop area and a strong negative association with forest, abandoned farm land, and area of sand + sandy loam soils. The causal relationships underlying these simple correlations are difficult to evaluate because of considerable multicollinearity between land use, soil, and topographic variables. Analysis of a mass balance for the downstream reaches of Duffin Creek indicated that there was considerable retention of phosphorus in the river channel particularly during summer low flows.     

Usefulness of natural regions for lake management: Analysis of variation among lakes in northwestern Wisconsin,USA

A map of summer total phosphorus in lakes was compiled recently for a three-state area of the upper Midwest for purposes of identifying regional patterns of total phosphorus in lakes and attainable lake trophic state. Spatial patterns in total phosphorus from approximately 3000 lakes were studied in conjunction with maps of geographic characteristics that tend to affect phosphorus balance in lakes to identify regions of similarity in phosphorus concentrations in lakes or similarity in the mosaic of values as compared to adjacent areas. While degrees of relative homogeneity are apparent at many scales, the map was designed at a scale that would yield regions with sufficient homogeneity to be useful for lake management throughout the area. In this study, data from 210 lakes in a 1560-mi² area in northwestern Wisconsin, sampled by the Wisconsin Department of Natural Resources in the spring of 1988 (subsequent to the compilation of the phosphorus map), were examined to: (1) substantiate the existence of the regions depicted on the map in northwest Wisconsin, (2) determine the nature and relative precision of the regional boundaries, (3) determine the relative importance of natural and anthropogenic watershed characteristics, lake types, lake area, and lake depth in explaining within-region differences in lake phosphorus, and (4) demonstrate how the regions might be used by local lake managers.     

岷江流域三江交汇区景观格局变化研究

本文以生态景观理论为基础,地理信息与遥感技术为支撑,对岷江流域三江交汇区三期遥感数据,1990年TM、2002年TM、2014年ETM+数据进行图像分类、景观指数提取、空间分析,同时采用面积转移矩阵统计各景观面积的转移情况,分析景观格局变化的影响因素,研究结果表明:(1)1990—2014年三江交汇区景观类型面积排序为:农田林地草地水域居民地裸地。优势景观为耕地,所占比例由72.83%下降到63.32%,面积减少了3480hm2。草地所占比例呈现波动变化,总体增加了2.81%。林地比例由15.98%上升到18.79%,增加了700hm2。居民地所占比例升高了4.1%;(2)1990年研究区内草地景观易受到外部干扰,其分布形状复杂。林地景观整体聚合度较高同时具有较低的异质性,分布通透性好、规模连续。农田分布较为分散且斑块较小。2002年农田斑块分布复杂化,同时具有聚集度高的特点。2014年研究区内农田优势地位下降。此时农田分布比较破碎并且呈现集中的态势。草地分布规模性较好、分布较为完整,但是内部存在一定的破碎性;(3)三江交汇区景观类型相互转化的主要原因:一是,退耕还林、还草政策实施,海拔超过500m的丘陵山地区域,建立生态保护区。二是,成绵乐铁路和高速路网的完善,使得三江交汇区的土地类型向建设用地转化加快,主要集中在乐山市中区和周围城镇。     

Improving lake riparian source area management using surface and subsurface runoff indices

Sensitivity indices, which rank factors pertinent to surface and subsurface runoff pathways, were used to identify phosphorus source areas in riparian zones of 15 northern Minnesota lakes. Watershed models were first developed using a geographic information system (GIS). Empirical models were then developed correlating water quality with land use, lake morphometry, and riparian sensitivity. Base models of forested, cultivated, pasture/open, wetland and residential land use within 100, 200, 400, and 2000 m of the study lakes were regressed on total phosphorus and chlorophyll-a. Area-weighted groundwater and surface runoff sensitivity indices were then incorporated into each model and tested for significance. Within the 200-m buffer, the total phosphorus base model was improved by including the groundwater index alone. The chlorophyll-a base model at 200 m was improved by including: (1) the groundwater index alone, and (2) both the groundwater and surface runoff sensitivity indices. Results suggest that surface and subsurface runoff analysis of potential source areas can improve decision making for lake riparian management.     

Land Use and Land Cover Change Analysis and Prediction in the Upper Reaches of the Minjiang River,China

Scientists have aimed at exploring land use and land cover change (LUCC) and modeling future landscape pattern in order to improve our understanding of the causes and consequences of these phenomena. This study addresses LUCC in the upper reaches of Minjiang River, China, from 1974 to 2000. Based on remotely sensed images, LUCC and landscape pattern change were assessed using cross-tabulation and landscape metrics. Then, using the CLUE-S model, changes in area of four types of land cover were predicted for two scenarios considering forest polices over the next 20 years. Results showed that forestland decreased from 1974 to 2000 due to continuous deforestation, while grassland and shrubland increased correspondingly. At the same time, the farmland and settlement land increased dramatically. Landscape fragmentation in the study area accompanied these changes. Forestland, grassland, and farmland take opposite trajectories in the two scenarios, as does landscape fragmentation. LUCC has led to ecological consequences, such as biodiversity loss and lowering of ecological carrying capacity.     

EFFECTS OF PRECIPITATION AND LAND USE ON STORM RUNOFF1

ABSTRACT: Storm-runoff quantity and quality were studied in three watersheds located near St. Paul in Ramsey County, Minnesota, from April 15 through September 15 of 1984, 1985, and 1986 to qualitatively determine the effects of precipitation and selected land uses on storm runoff. In respect to precipitation effects, differences in stormrunoff quantity between years in an urban watershed that lacks wetlands appear to be related to the average storm size (amount of precipitation) during the study period of each year. In contrast, the differences in storm-runoff quantity from watersheds that contain wetlands appear to be related to total precipitation during study period of each year. In respect to land use, the differences in storm-runoff quantity appear to be related to the amounts of impervious and wetland area. The watershed that contains the largest amount of impervious area and smallest amount of wetland area has the largest amount of storm runoff. Differences in storm-runoff quality appear to be related to the amounts of wetland and lake area. The watershed that contains the largest amounts of wetland and lake area has the smallest storm-runoff loading of suspended solids, phosphorus, and nitrogen. The wetland and lake areas likely retain the loading and, subsequently, lower the amount of storm-runoff loading exported from a watershed.     

PHOSPHORUS ACCUMULATION - DISCHARGE CYCLES IN MARSHES1

ABSTRACT: Artificial and natural marshes were studied to determine changes in quality of polluted water passing through them. Phosphorus removal ranged from zero to 64%. Removals in the 35% range were common, however. Much of the phosphorus went into sediments and unharvestable plant parts. Harvesting vegetation removed 6% of the phosphorus put into the system. Accumulation of phosphorus during the growing season was about 20 g*m^?2, much of which was flushed out after the onset of freezing weather. The amount of phosphorus flushed out can be prevented from entering a lake or stream by handling the marsh discharge in one of three ways; irrigate on land, lagoon to recycle later, treat conventionally if facilities are available.