【作者】 董琼；

【导师】 马履一；

【作者基本信息】 北京林业大学 ， 森林培育， 2009， 博士

【摘要】 土地利用变化(LUCC)是全球变化研究的热点问题,不同空间时间尺度的土地利用变化引起的环境效应及生态安全也是研究的热点问题之一。本文选择我国高原湖泊杞麓湖流域为研究区,对流域内1989-2005年的土地利用变化及其驱动力作了探讨;对土地利用变化的景观格局及其环境效应进行了分析;运用RS和GIS技术及L-thia模型对1989年和2005年两个时段的土地利用变化引起的面源污染变化进行了初步估算;运用压力-状态-响应(P-S-R)模型对杞麓湖流域的生态安全进行了定性分析。根据地理学、土壤学、生态学及相关学科的基本理论,依靠数学、遥感和地理信息系统为分析手段,首先在行政机关收集统计资料,根据影像资料、统计资料和图件结合实地调查,采用遥感(RS)与地理信息系统(GIS)技术以及相关方法,研究杞麓湖流域土地利用变化的历史过程。通过对数据的提炼分析,建立主要土地利用类型数量变化的时间序列,分析其变化的趋势和特点;并研究其空间格局的变化;然后根据收集到的资料,并运用主成分分析、筛选人类活动驱动力因子,从人口的数量构成,国家政策制度和科技进步等人文因子、社会经济因子详细地研究,创建人类活动影响土地利用变化的数量模型,模拟人类活动对土地利用变化的影响。运用景观格局指数分析比较两个时期景观格局变化,并运用生态系统服务功能对两个时期的土地利用生态服务功能进行了分析,评价土地利用变化的环境效应。通过长周期水文模型模拟土地利用变化引起的面源污染响应。先根据长周期水文模型计算出流域内不同土壤类型上不同土地利用类型的产流量,结合径流产出的污染物浓度负荷,估算典型时段1989年和2005年流域内面源污染的负荷的空间分布。运用修正的压力—状态—响应模型,筛选合适的指标对流域进行生态安全评价,为流域的可持续发展提供指导并提出有利于区域生态安全的土地利用策略与建议。研究结果表明:17a来流域综合土地利用动态度年变化率为0.66%,土地利用变化速度相对于云南高原其他流域如洱海流域要快;单一土地利用动态度来说,从大到小依次是有林地、建设用地、灌木林地、耕地、荒草地和水域。在杞麓湖流域这个相对较小区域,自然驱动因子对土地利用的影响较小。影响土地利用变化最主要的因素是人口的增长、经济的发展以及城镇化进程的加快。景观格局研究表明,研究区景观多样性指数提高,优势度指数减少,均匀度指数相应增大,破碎度指数减小,2005年流域的总体生态服务功能价值为比1989年减少了24.15%,总体生态服务功能呈下降趋势,生态环境质量降低。土地利用变化引起的面源污染输出模拟表明,农用地和城镇居民点的总氮、总磷输出为主要贡献,有林地和荒草地的贡献最小,有林地和荒草地对各种污染物截留的效果较好。通过对杞麓湖流域生态安全结果的检验和分析,1989年和2005年杞麓湖流域生态安全指数分别为0.5912和0.5845,均处于“较差”安全状态。2005年杞麓湖流域自然人文压力比1989年有所增高,且生态系统状态和社会对流域生态所采取的响应均有所减弱,导致生态安全状况下降。从系统总体来看,自然人文的压力对流域生态安全评价的影响程度最大。本论文主要创新点在:选择了人类活动剧烈的高原湖泊流域—杞麓湖流域作为研究区域,以17年时间尺度的土地利用变化进行研究并进行了探讨,丰富了我国的LUCC的研究成果,并运用RS、GIS空间信息技术对高原湖泊流域不同时段的土地利用变化的面源污染变化进行了对比研究;从土地利用变化角度研究生态安全并进行动态评价,进一步分析了不同土地利用格局与区域生态安全的关系,从而为土地利用变化生态安全评价的研究提供理论基础。更多还原

【Abstract】 Land-use change and land-cover change is a core field of global environmental change research.Study on land-use and land-cover change of different spatial and time scale is also one focus of geography recently.Land-use change,due to modern agriculture development,industrialization and urbanization,has lots of impacts on water balance and environment,such as increasing downstream flooding,decreasing groundwater supply, drying wetlands,soil erosion,non-point source pollutant increasing and so on.Soil erosion and non-point source pollution are two serious environmental issues.So it is very important to analyze water environment impacts and soil loss of land use change for land use plan and watershed management.By selecting Qilu lake basin as study area,this paper analyzed the land use change of the basin and found the key driving forces in 17 years firstly.Secondly landscape patterns and its environmental effect were analyzed,then,under the support of technology of remote sensing and geographical information system,this paper analyzed the land use changes and its non-point source pollutant in 1989 and 2005.Finally,to use modified pressure-status-response(P-S-R) model,ecological security status of Qilu lake basin was qualitatively assessed.The land map of 1989 and 2005 are acquired by explaining the TM image.Some conclusions are drawn out.The land use had changed greatly from 1989 to 2005 in Qilu lake basin.Agricultural land and waste-grassland areas reduced largely,forest land and construction-use land increased considerably during the period.The land use changes speed is higher than other Yunnan plateau lake basin’s,such as Erhai basin,and its changes ratio is 0.66%annually. So far as the dynamic degrees of certain land types are concerned,forest land areas’ annual change ratio is the maximum,the second is construction-use land areas,then are shrub land and agricultural land,the minimum is waste-grassland and water-body.As far as land-use conversion target is concerned,forest land converted to shrub land mainly,shrub land converted to forestland,waste-grassland to shrub land,water body converted to agricultural land lightly.Agricultural land area change is the maximum and it convened to construction-use land.So far as the source is concerned,forestland area increase is due to shrub protection and forestation on waste-grassland,the part of shrub land was destroyed and convened to waste-grassland.Agricultural land and waste-grassland area decrease are the major contributors to construction-use land area increase because of population increase and economic growth.In the relatively small region,Qilu lake basin,nature driving forces had little effect on land-use change during 17 years.By the methods of Factor Analysis,it is found that there are several main human factors including population growth,economic growth and fast urbanization process.Landscape patterns changed with land use/cover changes because of human activities. The landscape diversity index and evenness index increased,dominance index and fragmentation index decreased from 1989 to 2005.The total patch density decreased because that some similar patch in forest land and construction-use land combined to a bigger patch.Landscape diversity index increased because of agricultural land and shrub land area decrease greatly,in addition forest land,construction-use land and waste-grassland area increase.The degree of every landscape types’ control decreased and the evenness index increase.The degree of landscape fragmentation decreased was due to the number of all land-use patch decrease.As far as landscape structure and change feature was concerned,fragmentation degree of construction-use land is the quickest decrease because of urbanization and economic development,and fractal dimensions is increasing with the constant strengthen of human activities.Vegetation restoration and lake environmental protection made forest land have concentrated continuous tendency,moreover,agricultural land and shrub land trended separated tendency as human activities.As a result of landscape element changes,shortage of water resources,serious water pollution,water degradation,humid area decrease,loss in ecological function of wetland and serious soil erosion etc,these ecological environment effects lead the ecological services function decreased.The total ecological services value of Qilu lake basin is 2.37×10~8 yuan,which decreased by 24.15 percentage than 1989.In general,the system services function decreased.Using precipitation daily serial(from 1985 to 2004),and soil category map,the average annual runoff of 1989 and 2005 can be stimulated based on different land use distribution by L-thia(Long-term Hydrologic Impact Assessment ).The model result express there is prominence pollution impacts of land use change.The runoff in 1989 is 9599.52×10~4m~3,and 9344.43×10~4m~3 in 2005.The total nitrogen and total phosphorus of agricultural land and constructional-use land are the main contributor to the non-point source pollution.The simulated pollutant loads of different land use result show that the total nitrogen and total phosphorus loads is most serious in agricultural land, constructional-use land take the second place.Forest land and waste-grassland can prevent pollutant to a certain extent.The ecological security assessment result showed that Qilu lake basin located unsafe status both 1989 and 2005.The main reason is that humanity pressure increased.Human activities changed the land use construction,and the bearing capacity of the ground is limited.Although economic growth can ease the conflict between land and ecological environment to a certain degree,there is still some measure to promote ecological security construction of Qilu lake basin.更多还原