大青沟自然保护区主要森林群落优势种的叶性状

植物功能性状是近年来生态学研究的热点。其中叶功能性状与植株生物量和植物对资源的获得、利用及利用效率的关系最为密切。大青沟森林植物群落分布于科尔沁沙地,生境条件非常特殊,在沙沟里存在着一片茂密的森林,与周围浩瀚无垠的沙坨景观形成极为鲜明的对照。从沟底到沟顶,虽然海拔高度仅相差六、七十米,但由于距离沟底水源不同,土壤条件差异大,形成了不同的森林植物群落类型。大果榆群落、蒙古栎群落和水曲柳群落分别分布在大青沟自然保护区的沟顶、沟中和沟底。为了对大青沟自然保护区,不同环境梯度下的森林植物群落叶片功能性状进行研究,以大青沟自然保护区大果榆、蒙古栎、水曲柳3种主要森林群落为研究对象,分别测定不同群落优势种的叶厚度、比叶面积、叶干物质含量、叶大小和叶干重等5项叶功能性状,研究叶功能性状之间的关系,并对不同生长型、不同群落叶功能性状进行比较。相关分析结果表明,叶厚度与比叶面积呈极显著负相关,与叶大小和叶干重呈极显著正相关;比叶面积与叶干物质含量、叶干重呈极显著负相关,与叶大小呈显著正相关;叶干物质含量与叶大小呈极显著负相关,与叶干重呈极显著正相关;叶大小与叶干重呈极显著正相关。不同生长型植物叶片性状的分析表明,草本植物的叶干物质含量比乔木和灌木低,而其比叶面积高于乔木和灌木;对不同群落叶功能性状进行比较发现,大果榆群落和蒙古栎群落乔木、灌木叶厚度与干物质含量显著高于水曲柳群落的叶厚度与干物质含量,二者比叶面积显著低于水曲柳群落。大果榆群落和蒙古栎群落从叶功能性状的角度,它们具有较高的叶干物质含量和较低的比叶面积,体现出适应干旱生境叶片的特征。水曲柳群落呈现出低叶干物质含量、高比叶面积的特征,体现出适应湿润、土壤水分较好生境的特征。不同群落通过调节自身的物种组成,形成不同的功能性状组合来适应环境。

Leaf traits of dominant plants of main forest communities in Daqinggou Nature Reserve

Plant functional traits have been important issues in ecological research in recent years. Leaf functional traits have close relationships with the biomass, resource acquisition and utilization, and resource-use efficiency of plants. Daqinggou forest plant communities are located in the Horqin Desert, where the habitat conditions are very distinctive. There is a dense forest in the sand ditch, which forms a sharp contrast with the surrounding dune landscape. Although the difference in elevation from the bottom to the top of the ditch is only 60-70 m, different forest communities have developed because of differences in soil conditions that have arisen at different distance from the water source in the bottom of the ditch. Ulmus macrocarpa, Quercus mongolica, and Fraxinus mandshurica communities are respectively located in the top, middle and bottom of the ditch in Daqinggou Nature Reserve. In order to study the different environmental conditions in the Daqinggou Nature Reserve, U. macrocarpa, Q. mongolica, and F. mandshurica communities were selected as the three main research objects. We measured five functional traits of dominant species in the main forest communities, namely, leaf thickness, specific leaf area, leaf dry matter content, leaf size, and leaf dry weight. The relationships between the different leaf functional traits were studied, and the leaf functional traits of different growth forms and different communities were compared. Correlation analysis showed that leaf thickness was significantly negatively correlated with specific leaf area and significantly positively correlated with leaf size and leaf dry weight. Specific leaf area was significantly negatively correlated with leaf dry matter content and leaf dry weight, and positively correlated with leaf size. Leaf dry matter content was significantly negatively correlated with leaf size and significantly positively correlated with leaf dry weight, whereas leaf size was significantly positively correlated with leaf dry weight. Analysis of the different growth forms showed that the leaf dry matter content of herbs was lower than that of trees and shrubs. However, the specific leaf area of herbs was higher than that of trees and shrubs. Comparison of the functional traits of different communities showed that in the U. macrocarpa and Q. mongolica communities, the leaf thickness and leaf dry matter content of trees and shrubs were significantly higher than those in the F. mandshurica community. In contrast, the specific leaf area of trees and shrubs in the U. macrocarpa and Q. mongolica communities were significantly lower than those in the F. mandshurica community. The higher leaf dry matter content and lower specific leaf area of trees and shrubs in the U. macrocarpa and Q. mongolica communities reflect their adaptation to a more arid environment. Similarly, the lower leaf dry matter content and higher specific leaf area of trees and shrubs in the F. mandshurica community reflect their adaptation to a moister environment. The species compositions in three main forest communities in the Daqinggou Nature Reserve have been regulated by the development of specific combinations of functional traits, which have enabled these species to adapt to the specific local environments.