Water-energy Dynamics Model And Elevational Patterns Of Plant Species Richness In Mountainous Areas Of Northwest China

Altitude pattern of plant species richness in mountainous areas and its relationship with climate change are the hotspot of ecology and biogeography.However,there are few related studies in arid and semi-arid areas.In this paper,Ningxia mountain and Kunlun mountain in arid and semi-arid climatic environment are selected as the study areas.Principal component analysis(PCA)was used to study the altitude pattern of plant species richness and the applicability of the water-energy dynamic hypothesis in the study areas.The main conclusions are as follows:(1)With the increase of altitude,the variation trend of species richness of different plant groups in the two study areas are single-peak patterns.For Ningxia mountain,the peak of species richness of woody plants,trees,shrubs and herbs reached the highest in the range of 2000-2200 m.For Kunlun mountain,the peak values of species richness of seed plants,trees,shrubs and herbs ranged from 3600 to 3700 m.3300 to 3400 m,3500 to 3600 m and 3600 to 3700 m,respectively.(2)The plant species richness of different life forms have significant quadratic relationships with the annual mean temperature,the maximum temperature of warmest month,the warmest index,the potential transpiration,the maximum monthly potential transpiration and water deficit in Ningxia Mountain,respectively.The plant species richness of different life forms have significant quadratic relationships with the annual mean temperature,the maximum temperature of warmest month,the cold index,the potential transpiration,water deficit in Kunlun Mountain,respectively.(3)The principal component model 2 is a suitable model for the altitude pattern of plant species richness in Ningxia mountain.The explanatory power of species richness of woody plants,trees,shrubs and vine is 62.2%,73.0%,60.9%and 87.3%respectively,which largely supports the water-energy dynamic hypothesis.Principal Component Model 2 is also a suitable model for the altitude pattern of plant species richness in Kunlun mountain.Its explanatory power for species richness of seed plants,trees,shrubs and herb plants is 85.3%,49.6%,77.4%and 87.1%respectively,which largely supports the water-energy dynamic hypothesis.(4)At the same time,different life forms of plants are affected by energy and water factors.For Ningxia mountain,energy is better than water for the interpretation of shrubs.The interpretation of water to trees and vine is superior to energy,but the difference is not significant in general.Among them,the unexplained part of the model fitting for altitude pattern of species richness for different life forms occupies a large proportion.The explanations of water for species richness of trees,shrubs and herb plants in Kunlun mountain are higher than those of energy factors.However,there is little difference on the whole.Among them,the unexplained part of the altitude pattern fitting of species richness for trees and shrubs accounts for a large proportion.The purpose of this paper is to study the altitude pattern of mountain plants in arid and semi-arid areas,analyze the explanatory effect of climate factors on the species distribution pattern from two aspects of water and energy,and to some extent provide theoretical basis for understanding the law of biodiversity affected by climate factors,plant diversity protection and vegetation restoration.