嘉陵江流域3大水系的植被景观异质性差异

Differences in Vegetation Landscape Heterogeneity among Three Water Systems in Jialing River Basin

利用景观指数从景观空间组分、空间构型以及空间梯度变化3方面比较和分析了嘉陵江流域内3大水系的植被景观异质性差异。结果表明:(1)涪江水系和嘉陵江干流以栽培植被和针叶林为优势,渠江水系则以栽培植被和阔叶林为主。针叶林和草甸在涪江水系中的破碎化程度较高,而嘉陵江干流和渠江水系中针叶林和灌丛的破碎化程度较高。(2)嘉陵江干流水系在植被景观总体上破碎化程度高、斑块聚合性弱,景观多样性高,而渠江水系则表现为景观破碎化较高,斑块聚合性强,景观多样性低的分布特点。除景观破碎化程度最低外,涪江水系在其它方面均处于前两者之间。(3)沿着河流汇聚方向,3水系在异质性方面均表现出斑块数量减少、斑块间距缩小、聚合性增强、植被景观破碎化和多样性明显降低的总趋势。

The heterogeneity differences of three water systems in Jialing river basin were compared and analyzed on the basis of remote sensing images by applying GIS technology. The results showed that ： （1） There were significant differences in landscape status, fragmentation degree and congregation index at the landscape components scale among thee water system regions. The ＂cultivated vegetation＂ ＆ ＂needleleaf forests＂ were two dominant components in Fujiang river water system and the mainstream of Jialing river region, while the most land cover types were ＂cultivated vegetation＂ and ＂broadleaf forests＂ in Qujiang river water system. Although ＂needleleaf forests＂ ＆ ＂meadows＂ were associated with higher values of fragmentation and ＂cultivated vegetation＂ ＆ ＂needleleaf forests＂ were linked with higher values of aggregation in Fujiang river water system, they were substituted respectively by landscape components ＂needleleaf forests＂ ＆ ＂shrubs＂ with more fragmentation and ＂cultivated vegetation＂ ＆ ＂broadleaf forests＂ with more aggregation in mainstream of Jialing river region and Qujiang river water system. （2） The spatial structure of vegetation landscape in different water systems of Jialing river basin was quite different at the landscape scale. Landscape of vegetation in mainstream of Jialing river region had the character of more fragmentation, higher value of diversity and lower degree of congregation. On the contrary, vegetation landscape in Qujiang river water system had the character of less fragmentation, lower value of diversity and higher degree of congregation. Comparing with the two water systems, vegetation landscape had a mediate value of congregation and fragmentation except for lowest value of landscape diversity in Fujiang river water system. （3） It was found that there existed the same trend of change on vegetation landscape heterogeneity in different water systems by comparing spatial gradient change of landscape indices. Although with the gathering of rivers the distance between patches was becoming shorter, the capacity of congregation was building up, the patch number as well as value of landscape fragmentation and landscape diversity was decreasing down, there were significant differences in three water systems in Jialing river basin.