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sur le développement des zones arides et semi-arides

Titre : Effects of Nitrogen Deposition and Rainfall Changes on Soil Organic Carbon and Its Stability in Desert Steppe

Auteur : 梁志伟

Grade : Master 2022

Université : Inner Mongolia Agricultural University

Résumé partiel
Desert steppe ecosystem plays an important role in the terrestrial carbon cycle.As two key driving factors of global change,nitrogen deposition and rainfall change affect the distribution of soil aggregates,active organic carbon components and soil organic carbon mineralization through changing soil physical and chemical properties and vegetation biomass,and then change the stability of soil organic carbon and affect the soil carbon cycle.In order to explore how nitrogen deposition and rainfall change affect soil organic carbon and its stability in desert steppe,this study relied on the multi-year water and nitrogen control experiment platform,and adopted split zone design.The main zone was three water treatments:natural rainfall（CK）,rainfall enhancement 30%（W）and rainfall reduction 30%（R）.The sub-plots were treated with 0（N0）,30(N30),50(N50)and 100(N100)kg·hm-2·a-14nitrogen,and the effects of nitrogen deposition and rainfall on soil aggregates,soil active carbon components and soil organic carbon mineralization were studied in laboratory culture experiments.The main results are as follows :（1）Nitrogen deposition and rainfall had no significant effect on soil total organic carbon content（P＞0.05）,but increased above-ground biomass.N100 treatment significantly increased soil nitrate,ammonium and total nitrogen contents,and decreased soil p H（P＜0.05）under the three water conditions.Water content had no significant effect on the activities of enzymes involved in carbon cycling（P＞0.05）.Under the same water condition,nitrogen deposition significantly increased soil sucrase activity,but had no significant effect on soil cellulase,polyphenol oxidase and peroxidase.（2）Nitrogen deposition and rainfall significantly affected the distribution of soil aggregates.Rainfall increased the proportion of large aggregates（22.6%）,and decreased the proportion of micro aggregates and silt（20.1%and 12.8%）.In addition,with the increase of nitrogen deposition,the proportion of soil large aggregates increased,while the proportion of soil micro aggregates decreased,resulting in the increase of the average weight diameter of soil aggregates.Nitrogen deposition and rainfall had no significant effect on the organic carbon content of soil aggregates.The organic carbon content of microaggregates was higher than that of large aggregates,and the organic carbon content of powder clay was the lowest

Mots clés : Nitrogen deposition ;Rainfall change ;Desert steppe ;Soil organic carbon ;Soil aggregates ;Soil active organic carbon ;Soil organic carbon mineralization ;

Présentation (CNKI)