Characteristics of biomass allocation and root distribution of Halogeton glomeratus under different rainfall conditions

摘要

Water is the limited factor in arid and semi-arid regions. Precipitation, as the sole source of water replenishment in arid area, plays an important role in sustaining the desert ecosystem. With the trend of global warming, precipitation is increasing in arid region recently, especially in the extremely arid region at the south rim of Tarim Basin. Halogeton glomeratus (Bieb.) C. A.Mey is the key species of Gobi desert at the south rim of Tarim Basin, which use the scarce and irregular rainfall for survival in greatest possible. There was little research on characteristics of H. glomeratus involving biomass allocation and root distribution under different rainfall conditions in extremely arid regions. Our objective was to study the response for H. glomeratus to the global precipitation change. Artificial controlling water supply was conducted at three levels in experimental fields in Cele Gobi desert. Additionally, the natural precipitation control plot was analyzed for comparison. Frequent harvests were used to determine the response of biomass allocation and root distribution of H. glomeratus during a growing season under extreme rainfall conditions. Biomass of H. glomeratus increased as rainfall increased in the prophase of the growing season, but decreased in the later half phase of the growing season. Biomass allocation showed no significant difference among the treatments. However, H. glomeratus with higher level of rainfall allocates more biomass to roots. H. glomeratus adapts to the lower water condition by means of modulating roots distribution with deeper vertical main root and extent horizontal lateral roots.