退耕还果对黄土高原沟壑区坡地土壤和植被碳、氮储量的影响

摘要

土地利用方式变化是影响陆地生态系统碳储量的重要因素。试验以黄土高原沟壑区王东沟小流域杜家坪坡地果园和邻近农田为对象,分析了坡地退耕还果20年后,地上植被生物量、地下根系生物量以及0—100 cm土层有机碳氮储量的变化及其影响因素。结果表明,坡地果园0—100 cm土层有机碳（SOC）储量为C 50.7 t/hm2低于农田（C 57.3 t/hm2）,但0—20 cm土层,果园SOC储量为C 16.7 t/hm2高于农田（C 15.3 t/hm2）,增幅为9.2%;而在20—100 cm土层,SOC含量基本%Land use change plays an important role in organic carbon and total nitrogen storage in a terrestrial system.To better understanding the mechanism of organic carbon in the terrestrial system,soil organic carbon（SOC）,total nitrogen（TN） in 0-100 cm soil layer,aboveground and belowground biomasses of apple trees were studied in a 20-year of apple orchard converted from croplands,and the effects of converting cropland to apple orchard on carbon and total N storage were evaluated in a terrestrial system in slopping cultivated land of the Loess Gully Region.The results show that the SOC storage in 0-100 cm soil in the apple orchard is C 50.7 t/ha,which is lower than that in the cropland.For topsoil（0-20 cm）,SOC storage in the apple orchard is increased by 9.2% compared to the cropland,while for subsoil（20-100 cm）,SOC storage in the cropland is more than that in the apple orchard.Total N in 0-100 cm soil layer of the apple orchard is lower than that in the cropland（P 0.05）.Carbon and nitrogen storages in aboveground and root of apple trees are 5.8 and 1.7 times of the crop plants after the 20 year conversion of cropland to apple orchard in the sloping cultivated land.The apple tree stem,branch and root contribute much to the changes in C and N storages in the terrestrial system.