高寒草甸恢复演替过程中生产力与植物功能特征关系的研究

研究选择甘肃省玛曲县阿孜牧场高寒草甸,利用空间序列代替时间序列的方法,分别于同质高寒草甸内选择弃耕后恢复1,3,7,10,15年的5个演替梯度的草地各0.5 hm²,于每梯度样地内选5个0.5 m×0.5 m的样方,分别于2010年5月(牧草萌发期)和8月底(生物量高峰期)分种测定植物高度、盖度、密度和生物量。同时按照生物量比率理论,测定样方中生物量之和达80%的优势物种的株高、相对生长率、叶面积、叶鲜重等,就高寒草甸恢复演替过程中生态系统初级生产力与4种涉及养分获取及养分利用且简单易测的植物功能特征(植株高度、相对生长率、比叶面积和叶干物质含量)的关系进行了研究。 结果表明, 植株高度(y=-12.299x+410.3, R²=0.678 2, P<0.001)、相对生长率 (y=-0.022 9x+0.624 7, R²=0.699 2, P<0.001)、以及比叶面积(y=-61.171x+2 756.5, R²=0.595 6, P<0.001)等功能特征均与演替时间呈显著负相关关系,叶干物质含量与演替时间呈显著的正相关关系(y=0.170 5x+0.106 3, R²=0.506 5, P<0.001)。地上净初级生产力也与演替时间呈显著负相关关系(y=-0.228x+7.386 7, R²=0.495 4, P<0.01)。同时, 地上净初级生产力与株高(y=0.014 7x+0.942 6, R²=0.457 5, P<0.01)、相对生长率(y=8.695 4x+1.869 9, R²=0.519 1, P<0.001)和比叶面积(y=0.002 4x+0.942 6, R²=0.361 7, P<0.01)间呈显著正相关关系,与叶干物质含量的相关性不显著(y=-0.435 5x+6.797, R²=0.101 5, P>0.05)。此结果证明,植株高度、相对生长率、比叶面积等功能特征对高寒草甸生态系统生产力响应演替变化具有一定的指示意义。 在高寒草地生态系统管理和利用中, 可将此特征作为预测草地系统功能响应环境变化的参考依据。

Relationship between productivity and plant functional traits along successive recovery stages in an alpine meadow

Using a spatial sequence approach instead of a temporal one, plant functional traits and aboveground primary productivity were investigated along successive recovery stages in an alpine meadow on the Qinghai-Tibetan plateau. The functional traits, including plant height, relative growth rate, special leaf area, leaf dry mass content, and total biomass of dominant plant species at the individual and community levels were measured at recovery succession stages of 1, 3, 7, 10, and 15 years. The recovery succession significantly reduced the value of plant functional traits such as plant height, relative growth rate and special leaf area, but increased the value of leaf dry mass content (y=0.170 5x+0.106 3, R²=0.506 5, P<0.001). There were negative relationships between plant height (y=-12.299x+410.3, R²=0.678 2, P<0.001), relative growth rate (y=-0.022 9x+0.624 7, R²=0.699 2, P<0.001), special leaf area (y=-61.171x+2 756.5, R²=0.595 6, P<0.001) and succession stage, but a positive relationship between leaf dry mass content (y=0.170 5x+0.106 3, R²=0.506 5, P<0.001) and succession stage. A negative relationship also emerged between above-ground net primary productivity (ANPP) and succession stage (y=-0.228x+7.386 7, R²=0.495 4, P<0.01). Plant height (y=0.014 7x+0.942 6, R²=0.457 5, P<0.01), relative growth rate (y=8.695 4x+1.869 9, R²=0.519 1, P<0.001) and special leaf area (y=0.002 4x+0.942 6, R²=0.361 7, P<0.01) all had significantly positive effects on ANPP, while leaf dry mass content had no significant effect on ANPP (y=-0.435 5x+6.797, R²=0.101 5, P>0.05). The plant height, relative growth rate and special leaf area could be used as predicting traits for ecosystem productivity response to succession in the alpine meadow. In the management and utilization of alpine meadow ecosystems, these three functional traits could be used to describe and predict ecosystem function response to environmental changes.