甘肃景电灌区次生盐碱地枸杞土壤有机碳库的动态模拟

Dynamic simulation of soil organic carbon pool of wolfberry forest in the secondary saline-alkali land in the arid regions in Jingtai,Gansu——Take Jingtai electricity-powered irrigation zone as a case study

以景泰红跃村典型次生盐碱地枸杞（Lycium barbarum）林为研究对象,基于CENTURY模型模拟枸杞生长过程中表层0-20 cm土壤有机碳库的变化,模拟研究结果表明,1）次生盐碱地开垦种植枸杞使得土壤总有机碳发生了显著变化,呈先增后减的倒＂V＂型变化趋势。枸杞林土壤有机碳在幼苗生长阶段（1-4年）快速增加,呈＂碳汇＂趋势,在成熟阶段土壤总有机碳逐渐降低,随着枸杞生长衰老（8-12年）,土壤有机碳降低到开垦前土地的水平。2）土壤碳库活度、碳库指数和碳库管理指数的变化也呈先升后降的趋势,表明次生盐碱地种植枸杞在生长初期可提高土壤肥力,但是随着枸杞生长年限的增加,土壤肥力逐渐下降,土壤性质呈恶化的趋势,这种变化过程与当前大量灌水、施化肥有极大的关系。如果不改变当前的农田管理措施,在未来20-30年内枸杞林地极有可能转变为一个弱的碳排放源。因此,改变当前的农田耕作方式,增加有机肥投入,采用科学灌水设备等对提高枸杞林土壤质量,增加固碳效益和减缓温室效应具有重要的作用。

The dynamics variations of soil carbon pool were simulated using CENTURY modelbased on the soil layer of 0- 20 cm in wolfberry forest growing in the typical secondary saline-alkali land in Hongyue Village of Jingtai County,Gansu. The simulation results showed that there were significant changes in total soil organic matter after planting wolfberry in the reclaimed secondary saline-alkali land which increased firstly and then decreased like the inverted ＂V. ＂After the reclamation of secondary saline-alkali land,the soil organic carbon of wolfberry forest rapidly increased during seedling growth stage（ 1st ~ 4th year old） as ＂carbon sink stage＂,then,it declined gradually during mature stage（ 8th ~ 12 th years old） which reached the level of before land reclamation. Carbon pool activity,carbon pool index（ CPI） and carbon pool management index（ CPMI） also increased firstly and then decreased,which suggested that soil quality firstly improved through planting wolfberry and then gradually declined with wolfberry growth. These variations closely related with the current farmland management and crops cultivation like irrigation,fertilizer. The wolfberry forest possibly converts to weak carbon emission source in the next 20 to 30 years without change of the current farmland conditions. Therefore,it is very important to employ different measures like changing farmland management,increasing organic fertilizer input,adopting scientific irrigation equipments,and replacing the old seedlings,and so on,to improve the quality of wolfberry forest soil,and increase soil carbon reservation,and reduce the greenhouse effects.