东昆仑山及其毗邻地区蕨类植物的生态和地理分布特点

THE CHARACTERISTICS OF ECOLOGY AND GEOGRAPHICAL DISTRIBUTION OF PTERIDOPHYTE FROM EASTERN KUNLUN MOUNTAINS AND ADJOINING AREA IN CHINA

东昆仑山及其毗邻地区位于青藏高原的东北隅，约占北纬３１°３９′－３９°１９′，东经８５°３５′－１０３°０４′，面积约７２万ｋｍ￣２。本区的蕨类植物就目前所知有４８种。隶属于１３科１９属，分别占全国蕨类植物总科数的２１．３１％，总属数的８．５２％，总种数的１．９２％，集中分布于本区东部的高山峡谷区。其分布区北起本区北部的祁连山东段，向南经西倾山、阿尼玛卿山和巴颜喀喇山至唐古拉山东段，呈孤形围绕在本区的东部。其中分布种类较多的科有蹄盖蕨科（３属／１０种）、鳞毛蕨科（２／８）、中国蕨科（３／７）、木贼科（２／４）、铁角蕨科（１／４）、岩蕨科（１／４）等。所含种数较多的属有冷蕨属Ｃｙｓｔｏｐｔｅｒｉｓ（８种）、鳞毛蕨属Ｄｒｙｏｐｔｅｒｉｓ（５种）、岩蕨属Ｗｏｏｄｓｉａ（４）、粉背蕨属Ａｌｅｕｒｉｌｏｐｔｅｒｉｓ（４）、铁角蕨属Ａｓｐｌｅ－ｎｉｕｍ（４）、耳蕨属ｐｏｌｙｓｔｉｃｈｕｍ（３）等。种的地理成分分析表明：来自我国西南的山地成分在本区占全部种数的２７．０８％；来自华北的温带成分占１８．７５％；我国南北共有的成分占到４３．７５％。大多数种类分布于高海拔地区。其中分布于海拔３６００－５０００ｍ的就有３３种，占６?

The eastern Kunlun Mt. and adjoining area is situated at the northeastern of Qinghai-Xizang(Tibet) plateau in China, The square between latitude 3l°39′degrees to 39°19′degreesof north and longitude 89°35′ degrees to l03°04′ degrees of east. The area is about 720000km￣2. There are 48 species of pteridophyte,which belongs to l3 families and l9 genera,and re-spectively has a percentage of 21.31%of total families ,and 8.52%of total genera,and l.92% of total species of China. The distribution of the pteridophyte in the alpine canyon ofeastern of this area around in arched,where from eastern Qilian Mt.turn towards south,andpass through Xiqing Mt. and Animaqing Mt. and Bayankala Mt. to eastern Tanggula Mt.,Pteridophyte in this area,the families which occur more species there are Athyriaceae(3 gen-era/l0 species),Dryopteridaceae(2/8),Sinopteridaceae(3/7),Equisetaceae(2/4),Aspleni-aceae( l/4)and Woodsiaceae ( l/4)atc..The genera which contain more species there areQstopteris(8 )species ), Dryopteris(5),Woodsia(4),Aleuritopteris(4), Asplenium(4) andPolystichum(3)act. Analysising of the geographical elements on the species indicated :theelements of mountainous region come from southwestern of China has apercentage of 27.08%of total species.The temperate elements come from northern China has a percentage of18.75%of total species. The common elements of northern and southern China has a percentage of 43.75%of total species. The majority of species are distributed over the high re-gion in elevation. Among which summed up to 33 species( about 68.75%of the totalspecies)occur in the mountainous region between 3600m and 5000m alt..There are l5species(about 3l.25%of the total species)occur in the region below 3600 m alt.. In thesoutheastern of this area,the species are primaryly elements of mountainous region comefrom southwestern China,And in the northeastern of this area,the species are primaryly tem-perate elements come from northern China. Analysising is indicated :The flora of pterido-phyte in eastern Kunlun Mt.and adjoining area is a yoting flora which poor species,ecologicalforms are simple,small scope of distribution,and converged by wide temperate and cold resis-tant terrestrial species come from around floras. The distributive altitude of this flora wasreached the highest height that the pteridophyte can distributed.The lowest temperature inthis flora is the limite value that the pteridophyte can endured.And this area is the westboundary of some geographical elements.Therefore,we think this flora is a border distribu-tive district of pteridophyte in China. Among the ecological factores,the low temperature isthe key factor to restrict the growth and the development and to form the ecological characteristics and the distributive pattern of pteridophyte in this area.