【作者】 贾俊姝；

【导师】 周心澄；

【作者基本信息】 北京林业大学 ， 工程绿化， 2009， 博士

【摘要】 大通县地处青藏高原与黄土高原过渡地带,生态区位十分重要。本文基于多源数据,运用遥感、GIS技术与数学建模等方法,以景观生态学、土壤侵蚀学等综合学科为理论依据,研究1995年到2005年大通县土地利用/覆被10年期间时空变化特征和规律并预测其未来土地利用/覆被变化趋势;在试验数据和观测资料的基础上分析了土地利用/覆被与土壤侵蚀的关系;运用RUSLE土壤侵蚀预测模型,综合评价了大通县土壤侵蚀状况,主要结论如下:1、土地利用/覆被的数量结构变化特征是林地、水域及建设用地呈现增长趋势,其中林地增长最显著,增长成为2005年最大的土地利用/覆被类型。林地主要分布在半浅山半脑山、脑山及高山地区,所有乡镇的林地均呈现不同程度的增加:草地、耕地及未利用地均呈减少趋势,其中草地减少最明显,由1995年的优势类型减少成为第二位。草地与林地的空间分布基本一致,大部分乡镇草地呈现不同程度的减少;耕地主要分布北川河及其支流两岸的川水地区、浅山地区及半浅山半脑山区,大部分乡镇的耕地面积呈现不同程度的减少。不同土地利用/覆被类型之间的转换很强烈,相互转换的面积186894.97hm~2,占总面积的60.18%:转换数量最显著的草地转出为林地,转换面积为68040.88hm~2,占发生转变总量的36.41%。2、土地利用/覆被空间格局变化特征是:斑块密度PD、最大斑块指数LPI及边缘密度ED的减少,反映了该景观的破碎化程度和生境斑块相互之间的隔离程度在减小;随着景观中斑块形状更趋于简单化,面积加权平均形状指数AWMSI和面积加权平均分维数AWMPFD在研究时段内也减小;蔓延度指数CONTAG增加,整个景观受林地、草地和耕地这几大类斑块的控制,虽然优势斑块类型逐渐形成了良好的连通性、斑块面积趋于均匀。Shannon多样性指数SHDI和Shannon均匀度指数的减小,表明景观异质性下降,破碎化程度及景观多样性降低。3、土壤质量综合指数在不同土地利用类型之间的比较是青海云杉(0.80)＞华北落叶松(0.73)＞中国沙棘(0.57)＞紫花苜蓿(0.36)＞青稞(0.31),其优化排序几乎与抗冲性指数的优化排序完全一致,土壤质量综合指数与抗冲性指数的变化趋势呈显著正相关。4、土地利用变化对降雨量-径流量关系、径流量-输沙量关系的影响都比较明显,1991-1995年期间的输沙量增加速度大于2001-2005年期间的输沙量增加速度;在相同径流条件下,由于2001-2005年期间坡度大于15°以上地区有许多草地和耕地转变为林地,植被覆盖度明显提高,截留能力增强,减弱雨滴对地面的击溅侵蚀,产生的输沙量将会明显减少。5、运用GIS技术基于RUSLE土壤侵蚀预报模型阐明大通县土壤侵蚀状况:2005年土壤侵蚀总量为2160.07×10~4t/a,平均土壤侵蚀模数为51.83t/hm~2.a,按照土壤侵蚀强度等级划分标准属于强度侵蚀区。土地利用类型中旱地的年侵蚀总量是最高的,侵蚀模数达到199.97t/hm~2.a,属于剧烈侵蚀强度;强度侵蚀区域主要分布在高程带为2500-2700m和2700-2900m的浅山到脑山地区、坡度在15-25°和25-35°的陡坡以上及南坡向,这些地区也是防治土壤侵蚀的重点区域。1995年与2005年土壤侵蚀状况相比土壤流失总量的减少778.1×10~4t,土壤侵蚀有所减轻。更多还原

【Abstract】 Datong is located in the transition zone of Qing-Tibet Plateau and the Loess Plateau,a very important ecological area.Based on multi-source data as well as comprehensive academic comprising theoretics of landscape ecology and soil erosion,by using various method such as remote sensing and GIS technology and mathematical modeling,the paper studies the space-time characteristics of Land-use/cover change(LUCC) during the past 10-year from 1995 to 2005 and forecast the future trend of LUCC in Datong County;analyzes the trial data and observational data for the relationship between land-use/cover and soil erosion;builds soil erosion prediction model RUSLE in order to comprehensively evaluate soil erosion conditions of Datong County.The main conclusions are listed as follows:1、The characteristics of land-use/cover changes on quantitative structure:Woodland,water and construction land take on a growth trend,of which woodland becomes the largest land-use/cover types with the most significant increase in 2005.Woodland distributes mainly in the semi-hilly and semi-mountain,the hilly and unbroken mountain areas,showing the rise of various magnitudes in every town;Grassland,cultivated land and unused land display a decreasing trend,in which the grassland turn into the second from the advantage types of 1995,because of a remarkable reduction.Grassland of spatial distribution are basically the same as woodland,the majority towns have different decreases;In the most of town,cultivated land show a various degree of reduction,and mostly position valley areas of the Beichuan River and its tributaries on both sides.The mutual conversion between different land-use/cover type is strong,the area 186894.97hm~2,accounting for the total area of 60.18%;The transition of grassland to woodland,area of 68040.88hm~2,is the most amount accounting for the total change of 36.41%.2、The characteristics of land-use/cover changes on spatial pattern:The degree of landscape fragmentation and habitat isolation is falling because of the reduction in Patch density(PD),Largest patch index(LPI)and Edge density(ED);With the patch shape becoming simplistic,Area-weighted mean shape index(AWMSI) and Area-weighted mean patch fractal dimension(AWMPFD) is also reduced during the study period;Owing to the landscape being controlled by woodland,grassland and cultivated land,Contagion index(CONTAG) increase in the spread,although the advantage of patch gradually form a good connectivity and patch area tend to uniformity.The decrease of Shannon’s diversity index(SHDI) and Shannon’s evenness index(SHEI) indicates that decline in landscape heterogeneity, moreover reduce in the degree of fragmentation and landscape diversity. 3、The optimization sequencing of SQI on different land-use types is Picea crassifo1lia(0.80)＞Larix Principis～rupprechii(0.73)＞Hippophae rharnnoides ssp.sinensis(0.57)＞Medicago etiva(0.36)＞highland barley(0.31),which is the same as the soil anti-scourability indexes,and the two indexes is a significant positive correlation.4、The influence of land-use change on the rainfall-runoff relationship or runoff-sediment relations are more obvious,the growth rate of sediment transport in the period 1991-1995 is greater than 2001-2005;Under the same conditions of run-off,in the period 2001-2005 the sediment transport will be significantly reduced.There are many conversions from cultivated land and grassland into woodland in＞15°areas,so as to improve vegetation cover and rainfall interception capability,reduce the splash erosion of raindrops.5、Depend on soil erosion prediction model(RUSLE) and GIS technology to estimate the soil-erosion status in Datong County:Intensity soil-erosion belongs to Datong County with 2160.07×10~4t/.a of soil-erosion quantity and 51.83t/hm~2.a of soil erosion modulus in 2005.Cultivated land being acuity soil-erosion has the highest soil-erosion quantity in various land-use types,while its soil erosion modulus gets 199.97t/hm~2.a;the areas of intensity soil-erosion distribute mainly in the elevations of 2500-2700m and 2700-2900m,the steep slopes of 15-25°and 25-35°,as well as the southern aspect;moreover,these regions are intensive to prevent soil-erosion.And by contrast with 1995-yaer,the soil-erosion status is improving gradually with the reduction of 778.1×10~4t on soil-erosion quantity.更多还原