高寒草甸主要植物地上地下生物量分布及退化对根冠比和根系表面积的影响

Above-and below-ground biomass distribution of main alpine meadow plants and impact of degradation on root/shoot ratio and root area

关键词:  高寒草甸  地上地下生物量  根冠比  根系表面积  退化  影响

Key words:  alpine meadow  above-and below-ground biomass  root/shoot ratio  root surface area  degradation  impact

摘要:

研究高寒草甸主要植物地上地下生物量的分布及其对退化的响应有利于了解高寒草甸的退化过程。该研究首先在西藏那曲生态环境综合观测研究站小嵩草围栏内(2009年围封)选择原生植被较好的地点随机选择小嵩草(Kobresia pygmaea)、矮嵩草(K. humilis)、紫花针茅(Stipa purpurea)、二裂委陵菜(Potentilla bifurca)和青藏苔草(Carex moorcroftii)等5种植物斑块,选择退化斑块上(与原生植被相比)的二裂委陵菜和青藏苔草; 然后用烘箱烘至恒重并称重,用扫描仪对根系进行扫描用于估算根系表面积; 最后利用2因子方差分析检验不同物种个体、不同取样层次对地上和地下生物量的影响,利用物种和退化状态2因子方差分析检验对地上生物量的影响,以及利用物种、取样层次和退化状态3因子方差分析检验对二裂委陵菜和青藏苔草地下生物量、根冠比和根系表面积的影响。结果表明:在未退化条件下,小嵩草、矮嵩草和紫花针茅0～10 cm地下生物量占0～30 cm地下生物量的70%以上,0～30 cm地下生物量占其地上地下总生物量的96%以上; 二裂委陵菜(Potentilla bifurca)和青藏苔草(Carex moorcroftii)0～10 cm地下生物量占0～30 cm地下生物量的50%以上,其中二裂委陵菜0～30 cm地下生物量占其地上地下总生物量的57%,青藏苔草0～30 cm地下生物量占其地上地下总生物量的87%; 对于退化草甸的主要植物,退化显著降低了二裂委陵菜的地上生物量、地下生物量和根冠比,对其根系表面积影响不大,但显著增加了青藏苔草的地上生物量,降低了其根冠比,对其地下生物量和根系表面积影响不大。

Abstract:

Understanding on distribution of above-and below-ground biomass and the effects of degradation on root/shoot ratio and root area is crucial to predict the degraded processes in the alpine meadow. First, In Naqu Ecological and Environmental Observation and Research Station of Kobresia pygmaea Fence(2009 enclosed)select native vegetation place randomly selected Kobresia pygmaea, K. humilis, Stipa purpurea, Potentilla bifurca and Carex moorcroftii five species, degradation choice(compared with native vegetation)of Potentilla bifurca and Carex moorcroftii, then drying to constant weight and using a scanner to scan the surface area of roots. Finally, the use of different species and different levels of sampling two-way ANOVA to test the effects of above-and below-ground biomass, according to species and degraded state, the use of two-way ANOVA to test effects on aboveground biomass, and the use of the species, sampling levels and degraded state three-way ANOVA to examine the influence of biomass, root and shoot ratio and root surface area on Potentilla bifurca and Carex moorcroftii. Our results showed that belowground biomass of Kobresia pygmaea, K. humilis and Stipa purpurea mainly concentrated in the 0-10 cm soil layer which was about 70% of total belowground biomass of 0-30 cm, and belowground of 0-30 cm was about 96% of the total above-and below-ground biomass. Belowground biomass of 0-10 cm for Potentilla bifurca and Carex moorcroftii was about 50% of the total belowground biomass of 0-30 cm. Belowground biomass of 0-30 cm for Potentilla bifurca and Carex moorcroftii was about 57% and 85% of total above-and below-ground biomass respectively. As main plant species for the degraded alpine meadow, we found that degradation decreased aboveground biomass, belowground biomass, its root/shoot ratio and root surface area for Potentilla bifurca; and it increased aboveground biomass but reduced root/shoot ratio for C. moorcroftii, whereas there was no significant effect on its belowground biomass and root surface area.