阿尔泰狗哇花型退化草地植物功能群特征初探

采用空间序列代替时间序列的方法，以石羊河上游重度放牧条件下形成的阿尔泰狗哇花型退化草地及其原生群落（阿尔泰针茅Stipa krylovii+扁穗冰草Agropyron cristatum-冷蒿Artemisia frigida+阿尔泰狗哇花Heteropappus altaicus）为研究对象，对2种草地植物功能群的季节动态特征进行初探。结果表明：草地退化使禾本科牧草的平均盖度、密度和高度依次降低20.4%33.6%、24.0%34.6%、36.2%59.9%，而杂类草的平均盖度、密度和高度依次升高18.1%63.0%、26.7%82.8%、6.9%80.8%；由此推断随时间推移，禾本科功能群较杂类草空间拓殖速率降低，在群落中的地位下降，此特征与功能群所处的退化阶段无关；禾本科功能群在原生植被中始终保持优势地位，而在退化草地中其地位在7月上旬后被杂类草取代，导致群落成员型发生改变。造成该区草地退化的主要原因很可能同放牧干扰与植物功能群季节生长特性相叠加有关，家畜选择性采食和践踏的双重作用，降低了禾本科功能群对资源空间占有的能力，为杂类草生长提供更多的资源空间，造成了杂类草生长势更强，导致其在群落中地位上升，最终形成以杂类草为景观的退化草地。

Preliminary study on characteristics of plant functional types in deteriorated Heteropappus altaicus grassland

The method of spatial-temporal substitution was used to study the characteristics of plant functional types in deteriorated Heteropappus altaicus grassland caused by heavy grazing and its original vegetation community(Stipa krylovii + Agropyron cristatum-Artemisia frigida + H.altaicus) in the upstream of Shiyang River.The results showed that the coverage,density and height of gramineous plants decreased in deteriorated grassland,and their variation ranges were 20.4% to 33.6%,24.0% to 34.6% and 36.2% to 59.9...