河西走廊山地-绿洲-荒漠复合生态系统的景观异质性分析

采用GIS技术,以相对频率和平均信息量为指标对河西走廊山地-绿洲-荒漠复合生态系统的景观异质性进行了研究。研究结果表明:在复合系统中,荒漠、山地、绿洲、水域、道路的平均相对频率(f)分别为57.5 %、20.7 %、23.4 %、8.1 %、7.3 %,反映出该复合系统的景观结构中,荒漠是最主要的景观类型或结构成分,处于绝对优势地位,是基质,是影响复合系统的结构、功能、动态的决定性因素。山地、荒漠、绿洲、水域、道路平均信息量(H)的平均值分别为22.10、35.50、29.00、17.81和16.80;荒漠景观的异质性最高,其次是绿洲景观,水域景观的空间异质性最低。平均信息量H值的空间变化中,山地景观的变异程度最高,为83.12 %;其次是绿洲,为64.07 %;荒漠景观的异质性空间变化程度最低,为45.21 %,说明荒漠景观在复合系统中的景观空间异质性最稳定,山地景观的空间异质性变化最大。由于荒漠景观的相对频率在50 % 以上,所以,其景观异质性是均质化方向上的空间异质性,而其它景观类型的空间异质性由于相对频率均小于50 %,是异质化方向上的空间异质性。因此以50 % 为相对频率的控制界限,提高道路、水域、绿洲的相对频率,降低荒漠的相对频率有助于提高整个复合系统的景观异质性。

Landscape heterogeneity of the meta-ecosystem consisted of mountain, desert and oasis in Hexi corridor, Gansu, China

Landscape heterogeneity of the meta-ecosystem consisted of mountain, desert and oasis in Hexi corridor, Gansu,China was studied with GIS and indixes of relative frequency (f) and coverage information amount (H). The results show that relative frequency of desert, mountain, oasis, water region and road in meta-landscape ecosystem are 57.5 %, 20.7 %, 23.4 %, 8.1 % and 7.3 %, respectively, which suggests that desert is the dominate landscape element and plays the matrix which controlling the function and pattern of the meta-landscape ecosystem. The coverage information amount of thesis landscape elements are 22.10, 35.50, 29.00, 17.81 and 16.80 bite, respectively, desert has the highest volume of H, while water region gets the smallest. Mountain has the biggest change value (CV) of H, 83.12 %; oasis gets the secondary CV, 64.07 %; desert gets the smallest, 45.21 %; which suggests that the desert is the most stable landscape element, spatial heterogeneity of mountain gets more changes than the other elements in the meta-landscape ecosystem. The spatial heterogeneity of desert is homogeneous heterogeneity because its relative frequency is bigger than 50 %, however, the spatial heterogeneity of other landscape elements in meta-landscape ecosystem is heterogeneous heterogeneity. So, increasing the relative frequency of oasis, water region and road or decreasing the relative frequency of desert to 50 % around is practical ways to maintain and progress the entire spatial heterogeneity of the meta-landscape ecosystem.