| Heterogeneity and stability of the agricultural landscape is the premise to maintain the stability andhigh-efficient of agricultural ecosystem. Agricultural landscape ecological system is the main body of thelower reaches of the Yellow River plains for a long time, and agricultural production is the main productionactivities in this region. FengQiu County in the lower reaches of the Yellow River plains is selected as theresearch object in this study. Landsat TM images of Fengqiu County of1990,2002,2009were selected asthe main data source. By using Erdas9.2software and combining with the land utilization present situationchart, digital elevation model and datas of field survey with GPS as well as other information, thelandscape classification system and the interpretation key were established. And according to the needs,study area was divided into seven kinds of landscape types: Irrigated land, garden and forest land, puddlesand ponds, rivers and canals, bare land, residential and construction land, paddy field. With the aid oflandscape heterogeneity index, Quantitative analysis was carried out on the landscape heterogeneitychanges in the studied area. In this paper, the research content mainly includes the following aspects: Onthe time gradient, dynamic changes of landscape pattern and types of the study area were analyzed; byusing semivariance function, characteristic dimension of the study area was determined; through thecharacteristic scales, spatial differerce of the landscape pattern and interference intensity in the study areawere explored; with ArcGIS9.3software (from Yellow River to the north) six buffers of the study weredivisioned, the changes of landscape patter and types under different disturbance gradient on the space wereanalyed. At same time the gradient changes of spatial disturbance intensity and the disturbance intensity ofspace differences (the space distribution uniformity of disturbance activities) were analyed.Through data analysis, the following content can be got:(1)Agricultural landscape is the main landscape type in FengQiu county for a long time, and landscapematrix is the irrigable land. Among two decades irrigated area by8064hm~2increased to88412hm~2. So thesubject status of the irrigated land is more pronounced. In terms of landscape types, the area, patch numbers,shape etc of each landscape type were changed in different degrees. Inhomogeneity of the distribution ofdistabance intensity between the landscape types is reflected. At the landscape level, landscape evenness index increased from0.5931in1990to0.6105in2002, and in2009decreased to0.4719; contagion indexis decreased from54.2309in1990to53.95in2002, and then increased to65.3333in2009. In addition,landscape diversity and dominance index also revealed a certain changes in volatility in20years. Thedistribution inhomogeneity of distabance activities on time is reflected by the changes of landscape indexes,as well as the nature of the disturbance activities (positive and negative effect) on the different time.(2) Landscape heterogeneity index have certain dependence on the scale, arbitrarily determiningdimensions will lead to the analysis results can not be trusted. Using semivariance function and slidingwindow method algorithm, determine that2500m is the characteristic dimension in the study area.(3) Spatial difference of landscape pattern is obvious under the characteristic scale. The region with ahigh complexity level of landscape patch shape has a high uniform level of landscape composition.Uniformity of landscape patches in high degree distributed mainly in: south of study area (A large area ofpaddy field is distributed here), the region Fengqiu county is located, east of the country (the canals andpits have a large area), the region in the southeast area (the garden land have a large area), the landscapeconfiguration of these areas are more complicated relatively. And other areas are in contrast with them.(4) Conbining with characteristic scales, from the Yellow River to the north, the spatial difference ofdistraction intensity is decreasing gradually; Intensity of distraction is increased continually, and then itremains stable when it is increased to a certain degree. Landscape configuration is more and more sensitivefor the change of landscape composition. |
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