中国东北植被生态学研究中的焦点问题

中国东北植被经过半个多世纪的系统研究，但有关植被生态学一些争论性问题尚未统一．本文仅就作者近年来研究工作涉及到的内容和关注的问题，提出一些看法：1)中国东北植被地带性分布规律可用Kira的温暖指数(WI）、寒冷指数(CI）和作者的湿度指数(HI)进行定量解释．2)大兴安岭北部山地，在海拔1400m以上存在冻原植被，是作者于1963年首次发现的我国第三块冻原植被，其WI<15℃·月．3)大小兴安岭植被分界线是我国植被区划中第一级分区界线，其位置在爱辉-果松沟-嫩江以南附近，WI为45℃·月．4)大兴安岭植被地带性分异显著，南段、中段为典型草原地带和森林草原地带，北段为针叶林地带，HI值分别为3．5～5．5、5．5～7．5、>7．5mm／℃·月．大兴安岭东麓阔叶林是森林草原带上的森林植被类型．5)东北东部山地岳桦林是山地植被垂直带谱重要组成部分之一，是山地森林垂直分布林线，WI为20～15℃·月为地带性植被类型，而WI>20℃·月为非地带性植被类型．6)内蒙古浑善达克沙地云杉林是陆地上非常罕见的森林生态系统类型，但这种云杉林究竟是哪一树种组成，在中国植物分类上一直是个争论性问题，作者通过核型分析和同工酶实验进一步证明是一个新种即沙地云杉Picea mongolica(H．Q．Wu)W．D．Xu，cmb．NOV．-Picea meyeri Rehd．et Wils var．mogolica(H．Q．Wu)．

Key problems in ecological research on vegetations in Northeast China

There exist many controversial problems in ecological research on vegetations in Northeast China, in spite of systemic studies for half century. In this paper, some comments were put forward on the recent researches of our concerned problems: 1) The zonal distribution pattern of vegetations in Northeast China could be quantificationally explained according to Kira's warmth index (WI), coldness index (CI), and Xu Wenduo's humidity index (HI). 2) There exists tundra vegetation in the north of Daxinganling Mountains with 1400 m altitude and above, which is the third tundra in China found by us firstly in 1963, and its WI < 15 degrees C x month. 3) The vegetation boundary between Daxinganling and Xiaoxinganling Mountains is one of the first class lines in vegetation sub-area. It locates in Aihui-Guosonggou-the Nen River, and the WI here is 45 degrees C x month. 4) In Daxinganling Mountains, the vegetation has significant zonal differentiation. In the south, the vegetation is typical steppe; in the middle, the vegetation is forest-steppe; and in the north, the vegetation is boreal coniferous forest. The HI here are 3.5-5.5, 5.5-7.5, and > 7.5 mm/degree C x month, respectively. The broadleaved forest in the east of Daxinganling Mountains is the forest vegetation type in forest-steppe zone. 5) In the eastern mountains of Northeast China, Betula ermanii forest is an important composition of vegetation vertical zone in mountains, and it is the timberline. The forest (WI is 20-15 degrees C x month) is the zonal vegetation type, whereas the forest (WI > 20 degrees C x month) is the non-zonal vegetation type. 6) In Hunshandake Sandy Land in Inner Mongolia Autonomous Region, spruce forest is the peculiar forest ecosystem type in continent, but which composition the spruce species belongs to is a controversial problem in plant class in China for a long time. It is proved further that it is a new species, namely, Picea mongolica (H. Q. Wu) W. D. Xu, cmb. nov.-Picea meyeri Rehd. et Wils var. mongolica (H. Q. Wu), according to the karyotype analysis and isozyme experiment.