Analysis of Dominant Factors Influencing Moisture Change of Broad-ovate Leaves of Populus euphratica Oliv. in Extremely Arid Region

During the past 50 years, highly intensive human economic and social activities on development and utilization of water resources in Tarim River desert have dramatically changed its natural ecological processes, causing significant ecosystem degradation including dry rivers and lakes, greatly dropped groundwater level, declined vegetation and increased desertification. Therefore, restoration and reconstruction of severely degraded desert ecosystems are urgent scientific issues. Species selection is critical for restoring the ecosystem. In addition to consider the photosynthetic capacity, water utilization ability is particularly important.

Populus euphratica Oliv. is the oldest species of P. euphratica species. It is distinct from other species by its resistance to high temperature and salinity, plays important roles in maintenance of ecological balance in arid and semiarid regions, protection of agricultural production in oasis and is a good timber source for residents. Its water status and growth rate are affected by multiple environmental factors. However, Most of the previous studies only did single factor correlation analysis rather than a comprehensive and systematic analysis of the effects of environmental factors on P. euphratica in arid region, not to mention the dominant environmental factors and their threshold values.

Therefore, researchers from Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, studied the dominant environmental factors that affect the gas-exchange characteristics and water potential (ψ) of broad-ovate leaves of Populus euphratica Oliv. in extreme arid area of Tarim River, China, and their correlation to water status of P. euphratica by analyzing on-field monitored meteorological data, soil moisture and salinity, P. euphratica leaf gas exchange and ψ, and revealed the indicative threshold of environmental factors for P. euphratica leaf water changes and growth.

The results indicated that meteorological factors such as air relative humidity (RH), air temperature (T_air), etc. are the dominant factors. The threshold value of RH is (48.19 ± 1.06) % for P. euphratica growth, i.e. RH from 10.69% to 48.19% is suitable for P. euphratica growth in extremely arid region of Tarim River. This study provides a theoretical basis for reducing drought damage to P. euphratica and maintaining normal growth of P. euphratica by in-time watering.

This study was supported by National Natural Science Foundation of China (Grant No. 91025025, 40901105), Funded Projects of West Light Foundation of the Chinese Academy of Sciences (XBBS201026) and National Basic Research Program of China (973 Program) (2010CB951003). The related research has been published on Photosynthetica, 2011, 49 (2): 295-308. It can be link from: http://www.springerlink.com/content/t8u24134488t6hp7/.