Informations et ressources scientifiques
sur le développement des zones arides et semi-arides

Titre : Effects of Drought and Its Soil Legacy Effects on Plant Growth in Typical Steppe on Loess Plateau,China

Auteur : 段东东

Grade : Doctoral Dissertation 2022

Université : Lanzhou University

Résumé partiel
Drought events frequently occur due to global climate changes,which directly affect the plant growth and community dynamics as well as the structure and function of grassland ecosystems through soil legacy effects.In the present study,the field experiment was conducted at the experimental station of arid and semi-arid natural grassland in Huan County,Gansu Province,China.We studied the effects of drought and its soil legacy effects on plant community in typical steppe on Loess Plateau and their response to the subsequent drought by in situ drought experiments in the field（completely intercepting rainwater with a rainout shelter from June to August [FD],with natural precipitation as the control [FU]）and glasshouse drought experiments（the soils from FD and FU treatments in the field were collected,and the plant communities were constructed in glasshouse,with 20% soil water holding capacity [WHC] as the drought treatment,and 60% WHC as control）.We also investigated the effects of soil sterilization on the growth of plants with different root system types（taproot system and fibrous root system）and plant community productivity under drought conditions.The main findings were as follows :（1）Drought treatment significantly reduced the aboveground biomass of plant community in typical steppe but showed no significant effect on plant diversity.Compared with the FU plot,the plant community aboveground biomass in the FD plot was decreased significantly by 48.59%（p < 0.05）,and the aboveground biomass proportion of subordinate species in the community（i.e.,other than the three dominant species of Lespedeza davurica,Stipa bungeana and Artemisia capillaris）in the FD plot was increased significantly by 30.71%（p < 0.05）.The FD treatment significantly increased the concentrations of soil nitrate nitrogen and available phosphorus（p < 0.05）,but significantly decreased the concentration of soil microbial biomass carbon（p <0.05）.These findings suggested that the drought treatment inhibited the uptake of soil nutrients by plants and thus reduced community biomass productivity,but subordinate species in plant community might be more resistant in response to drought.（2）The net soil legacy effects induced by drought decreased the plant community biomass,but enhanced the resistance of plant community to the subsequent drought.Under the 60% WHC,the total community biomass in the FD soil was decreased significantly by 36.52% compared to the FU soil（p < 0.05）.In addition,under the 20%WHC,plant community biomass showed no significant difference between the FD and FU soils（p > 0.05）

Mots clés : drought ;soil legacy effects ;arbuscular mycorrhizal fungi ;nutrient availability ;root system types ;plant community biomass production ;

Présentation (CNKI)