高山草甸坡向梯度上植物群落与土壤中的N,P化学计量学特征

选择甘南亚高山草甸坡向梯度(阴坡、半阴半阳坡和阳坡)的草地为研究对象,测定植物与土壤中全N、全P等的养分,阐明在不同生境下植物与土壤的N,P化学计量特征.结果显示:1)0～20 cm土壤中ω(N)和ω(有机质)在不同坡向阴坡>阳坡>半阴半阳坡,土壤ω(P)以及土壤水分从阳坡、半阴半阳坡到阴坡逐渐递增,土壤的ω(N):ω(P)在半阴半阳坡最低为6.23;20～40 cm土壤中ω(N),ω(P),ω(有机质),土壤水分,ω(N):ω(P)及pH值在不同坡向的变化趋势与0～20 cm的相同,但ω(N),ω(P),ω(有机质)及ω(N):ω(P)均低于0～20 cm土壤的,20～40 cm土壤水分在不同坡向均高于0～20 cm土壤的,不同土层土壤的pH值变化不大.2)植物叶片ω(P)在阳坡为(0.137±0.033)%、半阴半阳坡为(0.163±0.039)%、阴坡为(0.168±0.045)%,不同坡向差异显著(P<0.05);植物叶片ω(N)在坡向上差异不显著,植物的比叶面积从阳坡到阴坡分别为121.58±35.40,143.80±43.53,153.64±41.19 cm~2/g、阴坡、半阴半阳与阳坡差异显著(P<0.05);植物叶片的ω(N):ω(P)在阳坡为17.10,半阴半阳坡为15.4,而在阴坡为13.22,阳坡明显大于阴坡.植物群落在阳坡是P限制,而在阴坡是N限制,在一定程度上体现了植物群落对不同生境的一种适应.

N and P stoichiometry of plant and soil on slope direction gradient of sub-alpine meadows

Some nutrients of w(N) and w(P) of plant and soil at different slope gradients(south-facing slope, west-facing slope,north-facing slope) in sub-alpine meadow of Gannan were measured.w(N) and w(P) stoichiometry features of plant and soil in different habitats were also expounded.The results showed that 1) soil w(N) and w(SOC) in the 0～20 cm soil layer were north-facing slope>south-facing slope>west-facing slope in different slopes.Soil w(P) and soil water content were increasing from the south-facing slope,west-facing slope and north-facing slope.Soil w(N):w(P) was lower in the west-facing slope.The change trend of soil w(N), w(P),w(SOC),water content,w(N):w(P) and pH in the 20～40 cm were identical with 0～20 cm,but they were less than 0～20 cm except water content and pH.2) Foliar w(P) were(0.137±0.033)%in the south-facing slope, (0.163±0.039)%in the west-facing slope and(0.168±0.045)%in the north-facing slope..The slope direction showed a significant difference(P<0.05).Foliar N content did not show any significant difference from the south-facing slope to north-facing slope.Plant SLA were 121.58±35.40,143.80±43.53 and 153.64±41.19 cm~2/g from the south-facing slope to north-facing slope respectively.The north-facing slope,west-facing slope and south-facing slope showed a significant difference(P<0.05).Foliar w(N):w(P) were 17.10 in the south-facing slope,15.4 in the west-facing slope,but 13.22 in the north-facing slope.The south-facing slope was obviously greater than the north-facing slope.We deduced that the plant community was the limiting effect of P in the south-facing slope and the limiting effect of N in the north-facing slope.To some extent,the stoichiometric traits at the community level were adaptive to different environmental conditions.