阿拉尔垦区新疆杨防护林化学计量特征分析

Analysis on Stoichiometric Characteristics of a Populus Alba L. var Pyramidalis Protective Forest in Alar Reclamation Area

[目的]以新疆阿拉尔垦区不同龄级新疆杨防护林为研究对象,对不同龄级新疆杨叶—枝—凋落物—土壤的C,N,P含量及化学计量特征进行分析比较,为新疆南部农田防护林后期保育的可持续发展提供理论基础数据。[结果]C,N,P含量与化学计算学特征为:(1)C含量为凋落物(395.14 g/kg)>叶(365.29 g/kg)>枝(363.84 g/kg)>土壤(9.47 g/kg),N含量为叶(13.37 g/kg)>凋落物(9.10 g/kg)>枝(7.31 g/kg)>土壤(0.72 g/kg),P含量为叶(0.46 g/kg)>枝(0.43 g/kg)>土壤(0.37 g/kg)>凋落物(0.27 g/kg)。(2)叶—土壤与全国平均值相比呈现出低C,低N,低P的格局。土壤C含量随龄级的增加呈“升—降—升”趋势,除第Ⅲ龄级外,其他龄级土壤N含量均表现出随土层加深而逐渐降低的趋势。土壤P含量随龄级的增加整体呈上升趋势,且同一土层不同龄级之间存在显著差异(p<0.05)。(3)土壤C∶N(13.05)高于中国土壤均值(C∶N 11.90),C∶P,N∶P(24.04,1.83)均值低于中国土壤均值(C∶P=60.0,N∶P=5.20)。(4)新疆杨0—80 cm土层N,P含量与叶N含量呈极显著负相关(p<0.01)与叶P呈极显著正相关(p<0.01),凋落物N含量与表层土壤N含量呈极显著正相关关系(p<0.01)。凋落物P含量与20—40 cm土壤P含量呈极显著负相关关系(p<0.01)。[结论]由于缺乏对新疆杨防护林后期的管护,导致阿拉尔垦区新疆杨防护林在生长过程中受N,P元素的限制。因此,需适当增添N,P肥,以此来改善土壤肥力,提高林分质量。

[Objective] The contents of C, N, P, and their ecological stoichiometry characteristic contained in foliage, branches, litter, and soil of different age grades of Populus alba L. var pyramidalis stands were determined in order to provide a theoretical basis for the sustainable development of farmland shelterbelts in the Alar Reclamation Area, South of Xinjiang Wei Autonomous Region. [Results] The contents of C, N, P, and stoichiometric characteristics were:(1) C content followed the order of litter(395.14 g/kg)>foliage(365.29 g/kg)>branch(363.84 g/kg)>soil(9.47 g/kg);N content followed the order of foliage(13.37 g/kg)>litter(9.10 g/kg)>branch(7.31 g/kg)>soil(0.72 g/kg);P content followed the order of foliage(0.46 g/kg)>branch(0.43 g/kg)>soil(0.37 g/kg)>litter(0.27 g/kg).(2) Compared with the national average value, foliage-branch-litter-soil showed a pattern of low C, low N, low P. The total C content showed a trend of “increasing-decreasing-increasing” with the age grades. The total content of N in the four age-grades showed a trend of decreasing with increasing soil depth except for the third age grades. The total contents of P generally increased with increasing age grades, and were significant between different age grades in the same soil layer(p<0.05).(3) The soil C∶N ratio(13.05) was higher than C∶N(11.9) in China. The C∶P and N∶P ratios(24.04, 1.83) were lower than those of soil C∶P and N∶P ratios(60.0, 5.20) in China.(4) Soil N and P contents in the 0—80 cm soil layer of Populus alba L. var pyramidalis were significantly negatively correlated with foliar N content(p<0.01), and positively correlated with foliar P content(p<0.01). Litter N content was significantly positively correlated with surface soil N content(p<0.01). There was a significant negative correlation between litter P content and 20—40 cm soil P content(p<0.01). [Conclusion] N and P contents are the limiting factors for the growth of Populus alba L. var pyramidalis shelterbelts because of lack of management and protection in the Alar Reclamation Area. Therefore, N and P must be added appropriately by artificial measures so as to improve soil fertility and the quality of farmland shelterbelt stands.