**叶尔羌河流域荒漠河岸林胡杨叶片和凋落叶的生态化学计量特征**

**Ecological stoichiometric characteristics of leaf and litter leaf of Populus euphratica from desert riparian forest in Yarkant River Basin**

摘要 | 以叶尔羌河流域荒漠河岸林胡杨（Populus euphratica Oliv.）为研究对象，比较了胡杨叶片和凋落叶及不同类型叶片间C、N和P的生态化学计量特征差异，并对N和P的再吸收率及其与叶片和凋落叶N和P含量的相关性进行了分析。结果表明：胡杨叶片C、N和P含量的均值（分别为404.00、43.75和0.81 mg·g^{-1}）均大于凋落叶（分别为373.45、42.83和0.78 mg·g^{-1}）；叶片C/N比、C/P比和N/P比的均值（分别为10.50、511.49和56.15）也均大于凋落叶（分别为8.12、492.72和54.90），其中，叶片C含量的均值显著（P＜0.05）大于凋落叶，而叶片与凋落叶其他5个生态化学计量指标的均值均无显著差异。披针形、卵圆形和阔卵形叶片C、N和P含量的均值分别为399.03~408.76、37.12~47.60和0.78~0.84 mg·g-1，C/N比、C/P比和N/P比的均值分别为8.68~13.92、495.19~533.32和52.05~62.11；其中，阔卵形叶片C和N含量的均值均最大，卵圆形叶片P含量的均值最大，披针形叶片C、N和P含量的均值均最小，披针形叶片C/N比和C/P比的均值均最大，阔卵形叶片N/P比的均值最大；阔卵形叶片与披针形叶片N含量的均值差异显著，3类叶片其他5个生态化学计量指标的均值均无显著差异。胡杨叶片和凋落叶C含量的变异系数均最小，表明胡杨叶片中C含量相对稳定；在3类叶片中，披针形叶片C、N和P含量及C/P比、C/N比和N/P比的变异系数均最大，表明披针形叶片的生态化学计量特征变幅较大。胡杨叶片N和P再吸收率分别为2.10%和3.70%；N再吸收率与凋落叶N含量呈显著负相关，N再吸收率与叶片N含量呈不显著负相关，P再吸收率与叶片和凋落叶P含量均呈不显著正相关。综合分析结果显示：叶尔羌河流域荒漠河岸林胡杨叶片和凋落叶及3类叶片间的生态化学计量特征差异明显，根据生态化学计量特征推测该区域胡杨生长主要受到P元素限制；胡杨凋落叶的分解速率较为缓慢，导致其N和P的再吸收能力均较弱；在胡杨的3类叶片中，披针形叶片的养分吸收和转化能力均较弱。 |

Abstract | Taking Populus euphratica Oliv. from desert riparian forest in Yarkant River Basin as the research object， the differences in ecological stoichiometric characteristics of C， N and P between leaf and litter leaf and among different types of leaves of P. euphratica were compared， and the reabsorption rates of N and P and their correlations with N and P contents in leaf and litter leaf were analyzed. The results show that the averages of C， N and P contents in leaf of P. euphratica （which are 404.00， 43.75 and 0.81 mg·g^{-1}， respectively） are larger than those in litter leaf （which are 373.45， 42.83 and 0.78 mg·g^{-1}， respectively）； the averages of C/N ratio， C/P ratio and N/P ratio of leaf （which are 10.50， 511.49 and 56.15， respectively） are also larger than those of litter leaf （which are 8.12， 492.72 and 54.90， respectively）， in which， the average of C content in leaf is significantly （P＜0.05） larger than that in litter leaf， while there is no significant difference in the averages of other five ecological stoichiometric indexes between leaf and litter leaf. The averages of C， N and P contents in lanceolate， oval and broadovate leaves are 399.03-408.76， 37.12-47.60 and 0.78-0.84 mg·g^{-1}， respectively， and those of C/N ratio， C/P ratio and N/P ratio are 8.68-13.92， 495.19-533.32 and 52.05-62.11， respectively； in which， the averages of C and N contents in broadovate leaf are the largest， the average of P content in oval leaf is the largest， the averages of C， N and P contents in lanceolate leaf are the smallest， the averages of C/N ratio and C/P ratio of lanceolate leaf are the largest， and the average of N/P ratio of broad-ovate leaf is the largest； there is a significant difference in the average of N content between broad-ovate leaf and lanceolate leaf， while there is no significant difference in the averages of other five ecological stoichiometric indexes among three types of leaves. The coefficients of variation of C content in leaf and litter leaf of P. euphratica are the smallest， indicating that the C content in leaf of P. euphratica is relatively stable； among three types of leaves， the coefficients of variation of C， N and P contents and C/P ratio， C/N ratio and N/P ratio of lanceolate leaf are the largest， indicating that the variation degrees of ecological stoichiometric characteristics of lanceolate leaf are relatively great. The reabsorption rates of N and P of leaf of P. euphratica are 2.10% and 3.70%， respectively； there is a significant negative correlation between N reabsorption rate and N content in litter leaf， a non-significant negative correlation between N reabsorption rate and N content in leaf， and a non-significant positive correlation between P reabsorption rate and P content in leaf and litter leaf. The result of comprehensive analysis shows that there are obvious differences in ecological stoichiometric characteristics between leaf and litter leaf and among three types of leaves of P. euphratica in desert riparian forest in Yarkant River Basin， and it is speculated that the growth of P. euphratica in this area is mainly constrained by P element according to the ecological stoichiometric characteristics； the decomposition rate of litter leaf of P. euphratica is relatively slow， resulting in weak reabsorption capacities of N and P； among three types of leaves of P. euphratica， the nutrient absorption and transformation capacities of lanceolate leaf are relatively weak. |