中国北部六种沙蒿的地理替代规律及其主导生态因子

An analysis of the geographical substitute law and driven factors for six sandy plants of genus Artemisia in Northern China

对广泛分布于中国北部草原区沙地与荒漠区的6种沙蒿进行野外实地考察、标本查阅、分布区气象数据搜集与土壤成分测定,通过分析得到以下结果:1差不嘎蒿为东蒙古-科尔沁分布种,褐沙蒿是浑善达克沙地分布种,黑沙蒿为腾格里-鄂尔多斯分布种,白沙蒿为戈壁-蒙古种,准噶尔沙蒿为中亚种,乌丹蒿为科尔沁沙地西部种。2黑沙蒿、褐沙蒿、差不嘎蒿呈现出从西南向东北的地理替代分布,白沙蒿与准噶尔沙蒿构成东西向的地理替代分布。乌丹蒿由于与另几个种的亲缘关系较远,不作为这几个种的地理替代种。3利用方差分析的方法分析了5种沙蒿分布区内的热量、水分及土壤指标的差异,在黑沙蒿、褐沙蒿与差不嘎蒿这一地理替代中,黑沙蒿在年均温、最冷月均温、年较差、寒冷指数、6～7月份降水、湿润指数、水热综合因子、土壤酸碱度、土壤全磷含量上均与另两个种存在着显著差异。黑沙蒿向东北被褐沙蒿所替代,应该是水热以及土壤因子的综合作用。褐沙蒿与差不嘎蒿分布区内,主要是5～6月份的降水存在着显著差异,也就是生长季前半期的干旱是褐沙蒿区别于差不嘎蒿并使两者之间发生替代的原因。对于白沙蒿与准噶尔沙蒿这一对地理替代种,同样是降水的变率是两者发生替代的原因。

This paper focuses on studing the six sand plants of genus Artemisia L.——A. halodendron Turcz. ex Bess., A. halodendron Turcz. ex Bess., A. intramongolica H. C. Fu, A. ordosica Krasch., A. sphaerocephala Krasch., A. songarica Schrenk. and A. wudanica Liou et W. Wang. They are semi-shrub derived from the same section Dracunculus of genus Artemisia with close kinships and quite similar morphological characteristics. Distributed in sandy land of steppe and desert region in northern China, they are edificators or dominant species of sandy vegetation and play important roles in wind break and sand dune fixation. Their distributions have remarkable regional characteristics and replace each other in space, and thus become geographical replacement species. The distribution regions of the six species were identified and mapped by analyzing a large number of specimens and reviewing floras and correspond references. Meteorological data and soil samples from areas of the six species were collected for determining driven factors.According to geographical distribution of the six species, Artemisia halodendron Turcz.ex Bess. was referred to as East-Mongolia Kerqin distributive species, A. intramongolica H.C.Fu as Hunshandake sandy land distributive species, A. ordosica Krasch. as Tengeli-Erdos species, A. sphaerocephala Krasch. as Gobi-Mongolia species, A. songarica Schrenk. as Central-Asia species, A. wudanica Liou et W. Wang as west Kerqin sandy land species. The substitutions among these species showed that A. ordosica replaced A. intramongolica and A. intramongolica replaced A. halodendron from southwest to northeast and that A. sphaerocephala replaced A. songarica from west to east. The kinships between A. wudanica and others were far, so A. wudanica was not geographical replacement species for others. The differences among these five species in terms of temperatures, precipitation and soil property were examined with variance analysis. In the geographical replacement of A.ordosica, A.intramongolica and A.halodendron, A.ordosica, comparing with two other species showed significant differences in annual mean temperature, the coldest month mean temperature, annual temperature range, Kira's coldness index, the precipitation in June and July, humidity index, Humid/arid index, soil pH, the content of total phosphorus. It was caused by the synthetic effects of water, heat and soils that A. ordosica was replaced gradually in northeast by A.intramongolica. In the areas of A.intramongolica and A.halodendron, the precipitation of May and June was different significantly. Drought in the former half period of growing season characterized A.intramongolica region other than A.halodendron region, which was likely to be the reason of replacement between them. Similarly, the variation of precipitation played an important role in the replacement between A. sphaerocephala and A. songarica.