生态学报2018，Vol.38Issue(2)：689-697,9.DOI:10.5846/stxb201701110088
黄土丘陵区退耕地土壤可溶性氮组分季节变化与水热关系
Dynamic change in soil soluble nitrogen under farmland converted to forest in the Loess Hilly Region
摘要
Abstract
Soil soluble and available nitrogen are considered to be limiting nutritional factors for the productivity of plants in terrestrial ecosystems.Land-use change has a significant impact on the physical and chemical properties of soil,particularly nitrogen pools.Furthermore,although the amounts of soil soluble nitrogen are generally very small,they can change rapidly during the plant growing season.However,the changes in soil soluble nitrogen dynamics associated with different vegetation restoration patterns are still poorly understood.Therefore,more information is essential to gain a better understanding of the changes in ecosystems dynamics that occur following the conversion of farmland to forest in the Loess Hilly Region.We studied the dynamic changes in soil soluble nitrogen from April to October,and their relation to soil moisture and temperature under three converted land types in the Loess Hilly Region [Robinia pseudoacacia (RP),Caragana korshinskii (CK),and abandoned farmland (AF)],which have undergone conversion from slope farmland (SF) for 15 years.The average densities of nitrate nitrogen (NO3--N),soluble organic nitrogen (SON),and soluble total nitrogen (STN) changed significantly from April to October in the 0-30 cm soil layer (P＜0.05),although only NO3--N varied significantly with soil depth (P＜O.05).During the sampling period (April to October),the average NO3--N density accounted for 5.1％-52.1％ of STN,ranging from 0.13 g/m2(in April) to 1.71 g/m2(in October).The average density of SON varied significantly from 0.29 g/m2(in April) to 2.92 g/m2(in August),which accounted for 30.9％-85.3％ of STN.Although the variation in ammonium nitrogen (NH4+-N) was not significant,it ranged from 0.17 g/m2(in October) to 0.74 g/m2(in April) and accounted for 6.4％-21.4％ of STN.After long-term vegetation restoration,the average densities of NO3+-N in RP,CK,and AF were 3.42,2.54,and 1.26 times higher,respectively,than that of SF in the 0-30 cm soil layer,whereas those of NH4+-N in RP,CK,and AF were increased by 1.71,1.37,and 1.30 times,respectively,and those of SON were increased by 1.64,1.31,and 1.23 times,respectively,compared to SF.Correlation analyses indicated that the dynamic change in soil soluble nitrogen was affected by soil moisture and temperature,and that soluble nitrogen was more sensitive to soil moisture than to temperature.Moreover,NO3--N was more sensitive than SON and STN to soil moisture changes,whereas STN was the most sensitive to soil temperature.Collectively,these findings indicate that converting farm to forest can improve the density of soil soluble nitrogen,and increase the availability of soil nitrogen.It was also observed that the amounts of soil soluble nitrogen change significantly with different seasons.关键词
退耕地/可溶性有机氮/季节动态/水热变化Key words
vegetation restoration/soluble organic nitrogen/dynamic change/soil moisture and temperature引用本文复制引用
赵路红,李昌珍,康迪,任成杰,韩新辉,佟小刚,冯永忠..黄土丘陵区退耕地土壤可溶性氮组分季节变化与水热关系[J].生态学报,2018,38(2):689-697,9.基金项目
国家自然科学青年基金项目(41301601) （41301601）
陕西省科技统筹创新工程项目(2015KTCL02-07) （2015KTCL02-07）
国家自然科学基金项目(41571501) （41571501）
