Study On The Physiological Characters Related Water Condition And Water Balance For Three Shrubs In The Mu Us Sandy Land

The Mu Us Sandy Land is one of the four major sandlands in China,and its ecological environment is relatively fragile.The problems of shrub water physiology and woodland water balance are particularly important in the process of ecological restoration.In this paper,through two consecutive years of field observation experiments in 2018-2019,the water use characteristics and drought-resistant physiological indicators of the three sandy shrubs of Caragana intermedia Kuang et H.C.Fu,Artemisia ordosica and Hedysarum mongolicum Turez in the middle of Yanchi in Ningxia were studied,and the water balance of bushland was estimated situation.From the perspective of plant water physiology and water balance,it provides a certain theoretical basis for the protection and restoration of the Mu Us sandy plants,and provides a theoretical reference for ecological management in arid and semi-arid transitional areas.The main findings are as follows:(1)in the whole growing season of 2018 and 2019,the soil water content of semi-fixed sandy land was higher than that of fixed sandy land,and the soil water content of different shrubs was the lowest in Caragana intermedia and the highest in Hedysarum mongolicum shrub.In terms of vertical change,the soil water content of Caragana intermedia and Artemisia ordosica in fixed sandy land decreased at first and then increased with the increase of depth in 2018 and 2019,and the soil water content of Hedysarum mongolicum varied greatly in 100-200cm soil layer.The soil water content of different shrubs in semi-fixed sandy land increased with the increase of depth in 2018 and 2019.(2)the net photosynthetic rate and transpiration rate of Hedysarum mongolicum in each vegetation restoration stage were higher,which were significantly different from those of the other two shrubs.The stem water potential of Caragana intermedia is larger in all vegetation restoration stages,which is significantly different from that of the other two shrubs.The vegetation restoration stages of the three shrubs ?13C showed that the semi-fixed sandy land was smaller,the middle Caragana plant water use efficiency was the highest,and the Hedysarum mongolicum was the smallest.In the fixed sandy land stage,the three shrubs mainly used the soil water of 20-50 cm soil layer,while in the semi-fixed sandy land stage,the three shrubs mainly used the soil water of 0-20 cm soil layer in July,Caragana intermedia and Artemisia ordosica mainly used the soil water of 50-100 cm soil layer in the middle of May,the three shrubs mainly used the soil water of 20-50 cm soil layer in the fixed sandy land stage,while in the semi-fixed sandy land stage,the three shrubs mainly used the soil water of 0-20 cm soil layer in July.(3)the overall change trend of Fm,Fv and PI in fixed sandy land and semi-fixed sandy land of three kinds of shrubs was the same,and increased with the increase of rainfall.Compared with the two vegetation restoration stages,it was found that the chlorophyll fluorescence parameters of semi-fixed sandy land were higher than those of fixed sandy land,and the leaf cell membrane permeability,MDA content,POD and SOD enzyme activity of three shrubs increased with the increase of drought stress,and these physiological indexes had certain dynamic changes.When plant cells are damaged by lack of water,the malondialdehyde produced by them has strong cytotoxicity and affects the normal growth of plants.(4)soil water storage and soil evapotranspiration showed that Caragana intermedia was the smallest and Hedysarum mongolicum was the largest.In the growing season,soil evapotranspiration reached a small peak in June and a maximum in August.There were significant differences in plant water use efficiency among the three shrubs,with Caragana intermedia being the largest and Artemisia ordosica the smallest.