【摘要】 为研究林线种群对气候变化的差异性响应方式,以长白山西坡林线为研究区,选择4个样地(220个样方)内牛皮杜鹃与小叶章为研究对象,以盖度和生长高度为指标,地形坡度为影响因素,对两种植物的扩张程度与动态对比进行分析,利用常规统计法分析牛皮杜鹃与小叶章向苔原扩张的态势,多种数学方程结合逐步剔除回归等方法分析两种植物在扩张时的相互关系。结果表明在气温上升的条件下,林线牛皮杜鹃与小叶章的盖度与生长高度都很大(盖度之和>79%),是林线上移的主力。在坡度较小(<5°)和较大(>42°)时,小叶章通过生长高度的优势排挤牛皮杜鹃成为唯一优势种,而在坡度12°~42°之间牛皮杜鹃又排斥小叶章成为占据这一坡度范围的主力。更多还原

【Abstract】 Plants population’s dynamics at the treeline are very sensitive to climate change and may vary with changes in air temperature. In the Changbai Mountains in China, Rhododendron chrysanthum and Deyeuxia angustifolia thrive as the two main understory plants of Betula ermanii forest growing at the treeline. Studying the dynamics of these two populations at the treeline in response to climate change can provide meaningful data. Therefore, the treeline of the western slope of the Changbai Mountains was selected as the primary research object. Four plots(220 quadrats) were established to study the responses of Rhododendron chrysanthum and Deyeuxia angustifolia populations to increasing temperature, based on two indices of plant growth(vegetation coverage and height) and one factor that influences plant growth(terrain slope). The expansions of Rhododendron chrysanthum and Deyeuxia angustifolia populations to the tundra zone were revealed using standard statistical analysis techniques. The contrasting relationships of the two populations were discovered using the trend lines, which were selected by the highest values of increase in amplitude from one- to six-order trend lines. The expansion of relationships between the two populations were analyzed using multiple mathematical equations and regression models with a gradual rejection. Weather data from three stations surrounding the treeline showed that temperature has increased at the treeline on the western slope of the Changbai Mountains since the 1950 s. Data from the three weather stations had slope values for the trend lines of annual mean temperatures of 0.0196(Donggang, 1957- 2012),0.0249(Changbai, 1957- 2012) and 0.0237(Tianchi, 1959- 2012). Rhododendron chrysanthum and Deyeuxia angustifolia populations created a high percentage of vegetation cover(> 79%)when both species were considered. These two pioneer species are expected to shift their populations as the treeline increases in elevation with increasing temperatures. As their populations expand, their interspecific relationship was observed to change from coexistence to competition. Coexistence occurs on terrain slopes from 5° to 12°, while competition occurred on slopes < 5° and > 12°. Populations of Deyeuxia angustifolia become a single dominant species as it uses its height advantage to outcompete Rhododendron chrysanthum when slopes range of < 5° or > 42°. However, Rhododendron chrysanthum becomes the single dominant species by outcompeting Deyeuxia angustifolia when slopes range from 12° to 42°. For the two species,different species became dominant in different domains, suggesting that one species occupied all the niches in its domain by outcompeting plants of the other species as temperatures increase,which caused a corresponding increase in the probability of local extirpation of endangered species. Otherwise, as the opportunity of coexistence decreases for these two species, this may disturb the flux of energy and will lead to an increase in the frangibility of the original ecosystem. The conclusions play a positive role in understanding the interspecific relationships of a changing environment as the treeline ecosystem shifts with a changing climate.更多还原