黄土丘陵区微地形梯度下草地群落植物与土壤碳、氮、磷化学计量学特征

论文以黄土丘陵区安塞实验站微地形(阳坡坡上、中、下部,坡顶,阴坡坡上、中、下部)条件下的草地群落为研究对象,测定群落叶片及不同土层根系和土壤碳(C)、氮(N)、磷(P)含量,试图揭示微地形(坡向和坡位)对植物叶片、根系和土壤生态化学计量特征的影响。结果表明:研究区草本群落叶片C、N、P含量和C/N、C/P、N/P化学计量比的平均值分别为433.47、24.84、1.61 g/kg和18.18、320.36、17.41,叶片N/P值表明黄土丘陵区植物生长更易受P限制;根系C、N、P含量及C/N、C/P、N/P计量比的平均值分别为380.05、9.07、0.31 g/kg和49.61、1 326.64、30.73。叶片及根系C、N、P含量在不同坡向都表现出阴坡大于阳坡的现象。植物与土壤作为生物地球化学循环的不同环节,两者之间必然存在联系。论文相关分析表明:0~20、20~50、50~80、80~100 cm 4个分层的土壤C、N、P含量与叶片及根系化学计量特征之间都有不同程度的相关关系,特别是表层土壤C、N、P含量与叶片及根系C、N、P含量相关性较好。

Plant and Soil C,N, P Stoichiometric Characteristics in Relation to Micro-topography in the Hilly Loess Plateau Region,China

The research measured the carbon (C), nitrogen (N), phosphorus (P) content of plant leaf, root and soil at different slope aspects (sunny slope & shady slope) and different slope positions (top, upper, middle and lower) at Ansai Experiment Station. The effects of micro-topography on stoichiometric characteristics of plants and soil in the hilly Loess Plateau region were revealed. The results showed that the average leaf C, N and P contents were 433.47, 24.84 and 1.61 g/kg respectively, the leaf C/N, C/P and N/P stoichiometric ratios were 18.18, 320.36 and 17.41 respectively. The value of leaf N/P showed that the growth of plants was restricted by P in hilly Loess Plateau region. The root C, N and P contents were 380.05, 9.07 and 0.31 g/kg respectively, and the stoichiometric ratios of root C/N, C/P and N/P were 49.61, 1 326.64 and 30.73 respectively. Leaf and root C, N and P contents in shady slope were all greater than those in sunny slope, and those in top slope were the least. In shady slope, the C, N and P contents of leaf and root in different positions were in the order of lower slope > middle slope > upper slope > top slope. Soil C, N and P contents at different slope aspects were in the order of shady slope > sunny slope > top slope. Soil C, N and P contents concentrated in the 0-20 cm soil layer and decreased with soil depth. As the different part of biogeochemical cycle, plant and soil must have the contact. Correlation analysis showed that soil nutrients at different soil layers were correlated with the stoichiometric characteristics of leaf and root. Especially, the soil C, N and P contents at 0-20 cm layer had significantly positive correlation with leaf C, N and P contents (P<0.05), and also had significantly positive correlation with root N and P content (P<0.05), but had no significant correlation with root C content.