青藏高原东缘垂穗披碱草草地群落组成及生产力

Study on the composition and productivity of the eastern Qinghai-Tibetan Elymusnutansgrassland community

本研究于2015-2017年对青藏高原东缘垂穗披碱草(Elymus nutans)草地群落结构特征、种群和生物群落生物量及其构成进行了分析。草地植被主要由耐寒中生和中旱生植物种组成,以蒲公英(Taraxacum mongolicum)为优势种,垂穗披碱草、铁杆蒿(Artemisia sacrorum)和甘肃马先蒿(Pedicularic kansuensis)为亚优势种;平均优势度>0.20的植物有10种,伴生种种类多。主要物种地上生物量月动态均呈先增加后降低的单峰曲线模式,于生长旺盛期的7-8月达到峰值;同一物种不同年份间的生物量月动态曲线相似,相同年份的种群生物量月动态存在植物种间分异;随着生长季节的延伸,草地植物组成呈现出由简单趋向复杂、再趋向简单的变化过程。个别植物种的地上生物量表现出了年际间的显著性差异(P<0.05),植物种数和地上总生物量的年际变化不显著(P>0.05),但不同月份间有极显著差异(P<0.001)。草地中原生禾草植被已经受到破坏,草地植被正在从禾草草地向杂草草地退化,应采取措施恢复。

We examined structural traits(i.e.,community total biomass and its ecological dominance,species number and each species’biomass,and population dominance)of the grassland community dominated by Elymus nutans in the eastern Qinghai-Tibetan Plateau during2015and2017.The results showed that the community was composed mainly of meso-xerophtyes and cold-resistant mesophytes,in which Taraxacum mongolicum was the dominant species,and E.nutans,Artemisia sacrorum,and Pedicularis kansuensis were sub-dominant species.Ten species with dominance>0.2coexisted with many other companion species in the same community.Along with growth stage,monthly change pattern of above-ground biomass for the main species and plant community were both unimodal with the maximum during June and August.Moreover,the monthly biomass dynamic curves of the same species were similar in different years,but the monthly dynamic curves of plant biomass were different among species in the same year.With the extension of the growing season,the community has gone through a succession process from simple to complex to simple.The inter-annual variation of plant species and above-ground biomass was not significant,but there were significant differences between different months.Primary grassland vegetation has been destroyed and grassland vegetation is degenerating from grasslands to weed grasslands;therefore,conservation measures should be taken to restore the grasslands.