横断山脉亚高山带高山栎叶片生态化学计量及内稳性特征

Ecological Stoichiometry and Homeostasis of Alpine Quercus semicarpifolia Leaves in Subalpine Zone of Hengduan Mountains

为揭示横断山脉亚高山带高山栎(Quercus semicarpifolia)的生态适应性机制,选取该地区8个样地的高山栎叶片和生长基质土壤为研究对象,分别测定C、N、P含量及其比例特征,并对生长限制性元素进行判断,利用生态化学计量内稳性模型拟合判断高山栎叶片所处状态。结果表明8个样地土壤C、N、P质量分数分别为38.86~70.19、3.54~9.46、0.61~2.05 g∙kg^(-1),土壤ω(C)∶ω(N)为5.65~16.07,ω(C):ω(P)为36.98~74.42,ω(N)∶ω(P)为4.41~12.90,均值分别为9.48、51.79和6.54。叶片C、N、P质量分数分别为428.31~473.86、21.22~31.68、2.21~3.68 g∙kg^(-1),叶片ω(C)∶ω(N)、ω(C)∶ω(P)和ω(N)∶ω(P)分别为14.16~22.46,121.41~215.86和6.99~12.84,均值分别为17.36、164.39和9.68。叶片N、P含量均高于全球平均水平。各样地中叶N与土壤P、叶N与土壤ω(C)∶ω(N)、叶ω(C)∶ω(P)与土壤ω(N)∶ω(P)、叶ω(C)∶ω(N)与土壤ω(N)∶ω(P),以及叶ω(C)∶ω(P)与叶ω(N)∶ω(P)极显著正相关(P<0.01)。此外,高山栎叶片化学计量内稳性指数以1/H进行探讨,1/H_(ω(N))为-0.181~0.141、1/H_(ω(P))为-1.255~1.206、1/H_([ω(N)∶ω(P)])为0.391~0.960,表明各高山栎1/Hω(N)处于稳态、1/H_(ω(P))和1/H_([ω(N)∶ω(P)])多处于弱稳态、弱敏感和敏感态。高山栎叶片ω(N)∶ω(P)小于或接近16,说明该地区对高山栎N、P两种元素供应充足。高山栎能够过量贮存N、P元素以适应变化的外界生境,但对于外界P元素的利用策略更为保守。该地区高山栎林在长期演替进程中与土壤形成了良好的养分供给与归还关系,已形成相对完整稳定的亚高山带森林生态系统。

To reveal the ecological adaptation mechanism of Quercus semicarpifolia in the subalpine zone of the Hengduan Mountains,the leaves and growing soil of eight plots were selected,and the C,N and P contents and their stoichiometric characteristics of leaves and growing substrate soil were measured,and the growth-limiting elements were determined.The ecological stoichiometry homeostasis model was used to determine the state of the alpine Quercus leaves.The soil C,N and P contents of the selected eight plots ranged from 38.86-70.19,3.54-9.46 and 0.61-2.05 g∙kg^(-1),with soilω(C)∶ω(N)5.65-16.07,ω(C)∶ω(P)36.98-74.42 andω(N)∶ω(P)4.41-12.90,mean values were 9.48,51.79 and 6.54,respectively.Leaf C,N and P contents ranged from 428.31-473.86,21.22-31.68 and 2.21-3.68 g∙kg^(-1),leafω(C)∶ω(N),ω(C)∶ω(P),andω(N)∶ω(P)were 14.16-22.46,121.41-215.86 and 6.99-12.84,with mean values of 17.36,164.39 and 9.68,respectively.The alpine Quercus leaf N and P contents were higher than the global average.Leaf N and soil P,leaf N and soilω(C)∶ω(N),leafω(C)∶ω(P)and soilω(N)∶ω(P),leafω(C)∶ω(N)and soilω(N)∶ω(P),and leafω(C)∶ω(P)and leafω(N)∶ω(P)were highly significantly and positively correlated in each plot(P<0.01).In addition,the leaf stoichiometric homeostasis index of alpine Quercus were probed in terms of 1/H absolute values,while 1/H_(ω(N))was-0.181-0.141,1/H_(ω(P))was-1.255-1.206,and 1/H_([ω(N)∶ω(P)])was 0.391-0.960.The results indicated that each alpine Quercus 1/Hω(N)was in the homeostasis state,1/H_(ω(P))and 1/H_([ω(N)∶ω(P)])were mostly in the weakly homeostasis state,weakly sensitive and sensitive state.Leafω(N)∶ω(P)ratio was less than or close to 16,illustrating that alpine Quercus in this region tended to be not deficient in both N and P elements.Alpine Quercus might overstore N and P elements to adapt to the changing external habitat,but still had a more conservative strategy for the use of external P elements.The alpine Quercus forests in this region had formed a good nutrient supply and return relationship with the soil in the long-term succession process,which had formed a relatively complete and stable subalpine forest ecosystem.