Abstract:

Measuring plant heights one by one is an important way to explore the height structure of grassland plant communities, and can be used to analyze the universal rules and regional variations of vegetation growth under environmental change. We chose grasslands in three plateaus, namely Tibetan Plateau (TP), Mongolian Plateau (MP) and Loess Plateau (LP), and set up three grassland transects along the precipitation gradients from meadow, steppe to desert. The mean height of grassland vegetation was 30.38 ± 22.44 cm, and the mean height from TP, MP to LP increased significantly. The aggregation of grassland vegetation exhibited a positive skew distribution (0.91, 3.60), and the community aggregation from TP, MP to LP tended to a normal distribution (0, 3). However, for TP, there was an exponential distribution in community aggregation of meadows, and a uniform distribution in that of desert. The explanatory effect of climate and soil nutrients on the variation of mean height in each region was more than 70%, while the explanatory effect on the community aggregation was the highest at TP, only 29%. From TP, MP to LP, response intensity of mean height to environmental changes increased significantly, and the influence of temperature and precipitation gradually increased, the influence of radiation, wind speed, and nutrients gradually weakened, and the synergy among environmental factors strengthened. Our study shows that normal distribution is a universal rule of grassland height construction, and that the synergy of environmental factors varies from region to region.

Key words: grassland, vegetation height, community structure, environmental change, transect