在黄土高原地区,交通路网是影响地球关键带过程的一个重要人类活动影响因素,通常与暴雨叠加作用加速黄土关键带水土流失和物质迁移。董志塬是黄土高原面积最大、最连续的塬面,素有“天下黄土第一塬”之称。随着城市化进程的加快,董志塬交通道路网络快速扩张,对塬区景观生态和水土流失产生了重要影响。本数据集基于多源数据,包括历史文献、实地调查、Open Street Map(OSM)数据,利用Arc GIS软件进行目视解译、数据矢量化,并叠加高精度影像对数据进行逐一核对,最终得到了董志塬1975、2005和2020年三期路网矢量数据。本数据集从收集、处理分析到验证均控制严格,数据解译完成后再进行分幅检查,保证数据精度。本数据集的建立与共享,期望为董志塬固沟保塬工程和土地资源管理提供重要的数据支持。
In order to measure the impact of changes in the marsh on breeding Red-crowned Cranes (Grus japonensis) and White-naped Cranes (***) in the Sanjiang Plain,we conducted a complete crane súrvey in each of the summe...
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In order to measure the impact of changes in the marsh on breeding Red-crowned Cranes (Grus japonensis) and White-naped Cranes (***) in the Sanjiang Plain,we conducted a complete crane súrvey in each of the summers of 2007 and 2008,and obtained information on the changes in its marsh through interpretation of satellite images in 1986,1995,2000 and 2005.A comparison between the 1984 and 2008 census shows that:1) the number of Red-crowned Cranes remained stable at about 300 birds,while the number of White-naped Cranes increased markedly; 2) the estimates of nests of Red-crowned cranes are close to the numbers of 1984,while approximately 90％ of the nests of these two crane species were distributed over five national nature reserves (NNRs); 3) the two crane species became more concentrated in three regions,i.e.,the Fuyuan Delta,the middle reaches of the Naoli and Qixing rivers,and the Xingkai Lake wetlands,rather as formerly in six *** area of the marsh decreased by 45％ within the 20-year period from 1986 to *** major loss of the marsh area was in the form of a conversion to paddy fields and dry land,which can be primarily attributed to direct human activity under various economic and policy *** disappearance of cranes in the Dulu and Abuqin rivers was induced by large-scale agricultural *** fragmentation into and isolation of small areas of the marsh became increasingly more serious,which resulted in unsuitable condtions for crane breeding in small patches of the *** number of cranes declined from 1984-1995 but had recovered remarkably by 2008,which may be due to theestablishment of a system of nature reserves,in place since *** land ownership of the reserve plays a key role in maintaining the integrity of the wetland ecosystem,especially in Sanjiang,Honghe,Naolihe and Qixinghe NNRs,which together accommodated approximately 80％ of the population of ***,we did not discover any nests at all in the provincial and
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