滇南3种不同类型热带森林优势种幼树树干生态化学计量特征

Sapling Stem Stoichiometry of Dominant Species in Three Types of Tropical Forests in Southern Yunnan

[目的]探讨滇南地区热带、亚热带森林物种养分元素分配模式、受限制状况、吸收利用资源能力等特征,以期揭示外界环境变化下物种的适应性机制。[方法]以滇南区域热带季节雨林、热带山地雨林和中山湿性常绿阔叶林3种热带森林主要优势种为研究对象,分析不同类型森林不同层次优势种幼树树干C、N、P化学计量特征变化。[结果]1)3种森林优势种幼树树干全C含量随海拔梯度的增加总体呈增加趋势,全N含量和全P含量随海拔梯度的增加呈降低趋势;2)中山湿性常绿阔叶林的C:N、C:P相对较高,热带季节雨林和热带山地雨林N:P均小于14,中山湿性常绿阔叶林大于16;3)森林上层优势种幼树树干全C、全N含量均低于下层树种,全P含量则高于下层树种,上层优势种N:P均小于14,下层优势种大于16,说明上层优势种生长主要受到N元素的限制,且吸收和利用养分能力高于下层优势种;4)冗余分析表明:海拔和层次对优势种幼树树干养分含量及化学计量比的影响较大。[结论]滇南地区3种森林中,中山湿性常绿阔叶林拥有相对较高的氮、磷利用效率,本区生态系统主要受到N、P元素的共同限制作用。不同生长环境条件下植物体内养分元素生态化学计量特征的差异性,可以进一步揭示物种适应各种生态环境的应对机制。

[Objective]The aim this study was to explore the distribution patterns and limitation of nutrient elements in subtropical forest species in southern Yunnan,for revealing the adaptive mechanism of tree species under a changing environment.[Method]The dominant species in three types of tropical forests,i.e.,tropical seasonal rain forests,tropical montane rain forests and montane moist evergreen broadleaved forests,were sampled in southern Yunnan to analyze C,N,P and their stoichiometric ratios in sapling stems.[Result]1)The total C of sapling stems of dominant species in the three types of tropical forests generally increased,but total N and P decreased with increasing elevation.2)The ratios of stem C:N and C:P in montane moist evergreen broad-leaved forests were relatively high compared to other two types of forests.The ratio of stem N:P both in tropical seasonal rain forests and tropical montane rain forests were less than 14,while this value in montane moist evergreen broad-leaved forests was higher than 16.3)The stem C and N of dominant species in upper canopy were smaller than lower canopy.However,total P contents in upper canopy was higher than those in lower canopy.The value of N:P in upper canopy was less than 14,whereas it was higher than 16 in lower canopy.These results suggested that the growth of dominant species in upper canopy was mainly limited by N.4)The results of Redundancy analysis revealed that elevation and community had a great effect on C,N and P contents and their stoichiometric ratios in sapling stems of dominant species.[Conclusion]Montane moist evergreen broadleaved forest has a relatively high nutrient efficiency,and the forest ecosystems in southern Yunnan are mainly limited by N and P contents.The difference of ecological stoichiometric characteristics in trees under different environments can reveal the coping mechanisms of species adaptating to changing environments.