古尔班通古特沙漠南部植物多样性及群落分类

采用分层取样的方法,以1000m2/样地为最小观测面积,对古尔班通古特沙漠南部61样地植物多样性进行了调查。发现92个物种,隶属于22科71属,单种科、单种属多,区系优势现象明显。草本植物占总物种数的81.5%,短命植物占43.5%,对物种丰富度和盖度的空间变化起决定作用。属的区系成分分析表明地中海、西亚至中亚分布型成分占大多数,具有典型的地中海旱生植物区系分布特征。总物种数,草本物种数,短命植物物种数与纬度显著负相关,与经度和海拔显著正相关。从南到北,总盖度、草本盖度和短命植物的盖度显著下降,灌木的盖度则增加,从西到东,总盖度、草本盖度和短命植物的盖度显著增加,而灌木的盖度则减少。采用多元回归树(Multivariate regression trees,MRT)方法,根据纬度、土壤pH值和海拔,将61样地分为4个群落。结合降水在古尔班通古特沙漠由西到东,由南到北梯度变化所导致的物种多样性的变化,推测如果未来降水持续增加,古尔班通古特沙漠草本植物的优势将更加明显。

Plant species diversity and community classification in the southern Gurbantunggut Desert

Gurbantunggut desert is the second largest desert in China after Taklimakan desert, with an area of 48,800 square kilometers, of which 97% is covered with fixed and semi-fixed sand dunes. From May to June in 2009, plant diversity was surveyed in 61 sites in the southern Gurbantunggut Desert using a stratified random sampling design. The sampling plot at each site is 1000 m². 92 plants belonging to 71 genera and 22 families were observed. With many families and genera including only one species, the flora dominance is obvious. Among these species, 75 species are herbs, accounted for 81.5% of the total number of species; 40 species are ephemeral plants, accounted for 43.5% of the total number of species, and the cover accounted for 54% of total canopy cover of the desert. The flora analysis showed that most species belonged to Mediterranean, and West Asia to Central Asia (areal-type 12) areal-types, reflecting the arid and semi-arid geographical features of the area. The total number of species, the number of herbs and the number of ephemeral plants correlated negatively with latitude but positively correlated with longitude and altitude. From south to north, total coverage, herb coverage and the coverage of ephemeral plants declined significantly, but the coverage of shrubs increased. From west to east, total coverage, herb coverage and the coverage of ephemeral plants increased, shrub coverage is on the contrary. Multivariate regression trees were used to expound on the relationships between plant communities and 18 environmental variables (including soil, geography and climate). The MRT categorized communities into four groups in terms of latitude, pH of soil and elevation. The community group in higher precipitation had higher species richness. Taking the variation in species richness and coverage caused by precipitation difference in the spatial into consideration, it is predicted that the herbs advantage will be more obvious with increased precipitation in the future.