子午岭林区人工与天然油松林(Pinus tabulaeformis)养分库和碳库特征

Nutrient and carbon pools in both natural and artificial Pinus tabulaeformis in Ziwuling Region

为了揭示黄土高原地区人工油松林自然化发育过程中的植物叶片与土壤养分库和碳库的变化规律,采用典型样地法,以子午岭林区天然油松群落为参照,选择了不同立地条件的人工油松林,分别对其土壤的氮库、碳库及植物叶片养分库和碳库进行了分析。结果表明,该区油松针叶C、N、P的含量平均值分别为(499.5±63.75)mg/g、(8.53±0.50)mg/g和(0.94±0.64)mg/g,叶片C含量大小依次为阳坡天然林>阴坡天然林>阴坡人工林>阳坡人工林,阳坡人工林叶片N、P含量显著高于阳坡天然林。不同立地条件下油松林叶片C/N、C/P差异显著,叶片N、P和N/P均达到极显著水平,但是叶片C含量差异不显著。油松叶片C含量与N、P含量均呈极显著负相关,N和P之间的呈显著正相关。不同立地的油松林除40～60cm土层土壤C、N含量无显著差异外,0～20cm和20～40cm两个土层的人工林土壤C、N含量显著高于天然林,同时阳坡人工林土壤C、N含量显著高于阴坡人工林。0～20cm、20～40cm两个土层土壤C含量与N含量均呈极显著正相关,与植物N、P均呈显著正相关。子午岭林区阳坡的人工油松林不仅叶片养分含量较高,而且林地土壤是该区土壤的最大养分库和碳库。

Plot-sampling method was used to determine the influence of different site conditions on the plants and soil organic nutrients and carbon pools of the natural P.tabulaeformis and artificial P. tabulaeformis in Ziwuling region. With the natural P. tabulaeformis community as the control standard, artificial P. tabulaeformis communities. Under different site conditions were investigated to study their soil nitrogen pools, soil carbon pools and plant nutrient pools, plant carbon pools. The study showed that in the region the average C, N and P contents of P. tabulaeformis needles were （4995±6375） mg/g, （8.53±0.50） mg/g and （0.94±0.64） mg/g, respectively. The C contents of plant leaves decreased in the order of natural forest on sunny slope〉 natural forest on shade slope〉 plantation on shade slope〉 plantation on sunny slopes. The N and P content of plantation leaves in sunny slopes were obviously higher than that of the natural forest in sunny slope. There were significant differences in leaf C/N, C/P, N, P and N/P among the four types of P. tabulaeformis communities under different site conditions. The leaf C contents were negatively correlated with the leaf N and P contents. And the leaf N contents were observably positively correlated with the leaf P contents. There was no significant difference in C and N content in 40-60 cm soil, but in the other soil layers, the C and N contents in the plantation soil was significantly higher than those in the soil of the natural forest. The C and N content of the plantation on sunny slope soil was significantly higher than that on shade slope soil. Soil C both in 0-20 cm soil and 20-40 cm soil were positively correlated with soil N, and plant N and P. The leaf nutrient content were the maximum in the plantation sunny slope, the soil communities in this region were the greatest soil nutrient pools and carbon pools. The obvious correlation of soil C and N with the C,N and P in P. tabulaeformis leaves showed that there were interactive relations between P. tabulaeformis and soil.