甘肃省典型林区主要优势树种养分含量变化特征分析

The Variation Characteristics of Nutrients Contents of Main Dominant Tree Species in Gansu Province

林木养分含量是研究森林生态系统物流和能流的基础,养分分布是揭示生态系统中养分循环功能过程的一个重要参数,了解养分含量变化是合理计算植物群落内养分储量的有效途径,对合理评价植物生长潜力有重要意义。利用动态取样法重点选择祁连山、小陇山、白龙江林区的优势树种青海云杉(Picea crassifolia)、华山松(Pinus armandii Franch)、油松(Pinus tabulaeformis)作为研究对象,按照不同起源、不同林龄、不同部位对各树种的叶、枝、干、根进行动态取样,测定各器官N、P、K含量和土壤理化指标等,共获取24个标准地的数据。结果表明:3种乔木叶的N、P、K质量分数分别为1.26%、0.20%、0.65%;枝的分别为0.46%、0.09%、0.34%;干的分别为0.27%、0.07%、0.20%;根的分别为0.37%、0.10%、0.27%。各器官养分含量顺序为叶>根>枝。油松幼林龄N、P、K质量分数分别为0.62%、0.22%、1.08%;中幼林分别为1.24%、0.18%、1.62%;近熟林分别为0.85%、0.26%、1.08%;成熟林分别为0.77%、0.15%、1.04%;过熟林分别为0.70%、0.17%、0.70%,不同林龄养分含量顺序表现为中幼林>近熟林>成熟林>幼林龄>过熟林。油松天然林叶中含N量最高,为0.39%;根中含P量最低,为0.03%;人工林叶中含K量最高,为0.75%,干中含P量最低,为0.04%。华山松天然林叶中含N量最高,为1.61%;干中含K量最低,为0.10%;人工林叶中含N量最高,为1.83%;干中含K最低,为0.09%。土壤N与林木N差异不显著,具有相关性,枝N和根N较强,系数为0.84和0.97;土壤P、土壤K含量均显著高于林木P、K含量,是林木P、K含量的数倍,也具有相关性,相关性最强的为土壤K与叶K,系数为0.98。

Forest nutrient content is the basis of matter and energy flows in forest ecosystem. Nutrient distribution is an important parameter to reveal the nutrient cycling function of ecosystem processes. To understand the nutrient content change is the effective way to reasonably calculate the nutrient reserves in plant communities, and it is important to evaluate the potential of plant growth. In this paper, we use the dynamic sampling method to focus on Picea crassifolia, Pinus armandii Franch and Pinus tabulaeformis in Qianlian Mountain, Xiaolongshan Mountain and Bailongjiang forest, which are the dominant tree species in these area. The dynamic sampling was carried out from leaf, branch, stem and root of the trees according to the different parts of different origin, different ages and of various species, the N, P, and K contents of and determination of these samples were measured, and 24 standard data were obtained. The results showed that the N, P, K content in leaf of the three tree leaf are 1.26%, 0.20%and 0.65%respectively;0.46%, 0.09%and 0.46%in the branches respectively;0.27%, 0.07%and 0.20%in the trunk respectively;0.37%, 0.10%and 0.27%in the root respectively. For organs, the sequence of nutrient contents was leaves, roots and branches from highest to lowest value;for Pinus tabulaeformis in young forest age, N, P, K content of 0.62%, 0.22%and 1.08%respectively;for the young and middle aged forests, 1.24%, 0.18%and 1.24%respectively;for the nearly ripe forest, 0.85%, 0.26%and 1.08%respectively;for the mature forest, 0.77%, 0.15%, 0.15%respectively;for the overmature forest, 0.70%, 0.17%and 0.17%respectively;the order of the nutrient content for the different age forest was middle-aged, nearly ripe, mature, young and overmature forests from the highest to lowest value. The N content of leaf in the natural forest of Pinus tabulaeformis is the highest and reaches 0.39%;the P content of root is the lowest, 0.03%. For artificial forest, the K content of leaf was the highest, 0.75%, and the P content of stem was the lowest, 0.04%. For Pinus armandii Franch, the N content of leaf is the highest, 1.61%;The lowest K content is in trunk, 0.10%;Artificial forest containing N was the highest, 1.83%; stem K content is the minimum, 0.09%. This study indicates that there is no significant differences and relatively strong correlation （0.84） in the N content between soil and trees. There is strong correlation （0.97） between branch and root N content. The P and K content of soil were higher than ones of tree.