中国生态农业学报Issue(2)：192-200,9.DOI:10.13930/j.cnki.cjea.150636
水氮添加对内蒙古多伦县退耕还草地生物量、生产力及其分配的影响
Responses of plant biomass and net primary production to nitrogen fertilization and increased precipitation in re-grassed croplands in Duolun County of Inner Mongolia, China
摘要
Abstract
Biomass and NPP (net primary productivity) are the primary data which describe the structure and function of ecosystems. The allocations of biomass and NPP are related to nutrient, water use efficiencies and the ability to resist erosion of ecosystems. Excessive farming has intensified wind-erosion desertification in northern China, which has not only affected local economic development and ecological conditions, but also posed threat to the ecological state of the inland areas. Re-grassing abandoned croplands has been a common measure to prevent wind-erosion-caused desertification in the agro-pastoral ecotone of northern China. Grassland vegetation is very sensitive to nitrogen and water in arid and semiarid areas, but is unclear whether and how nitrogen (N) fertilization and increased precipitation affect the restoration of vegetation in re-grassed croplands. The responses of biomass and NPP to N fertilization [N10: 10 g(N)·m-2·a-1] and irrigation (irrigation amount was 180 mm to simulate 50% increase in precipitation) were investigated in a re-grassed abandoned cropland in Duolun County of Inner Mongolia, China. The results showed that fertilization increased the aboveground biomass of re-grassed croplands by nearly 100% while irrigation increased aboveground biomass by only 17%-37%. Either fertilization or irrigation had no significant effect on belowground biomass in re-grassed croplands (P > 0.05) while irrigation enhanced belowground NPP (BNPP) by 35%-90%. Fertilization reduced root-to-shoot ratio (R︰S) and ratio of BNPP to aboveground NPP (ANPP) in re-grassed cropland but increased precipitation had no significant effect on the two indicators (P > 0.05). The dominant species (Agropyron mongolicum and Artemisia scoparia) had significant positive responses to fertilization, respectively with 130% and 70% increase in biomass in the second year. However, fertilization had no significant effect on biomass of forbs (P > 0.05). Asymmetric competition for fertilizer among plant species increased the proportion of perennial grass and decreased the proportion of forbs in vegetation community of re-grassed cropland. In contrast, forbs were very sensitive to irrigation, with 128% increase in biomass in the second year of treatments. Increased precipitation enhanced the proportion of forbs in the community by 13%. A. mongolicum and A. scoparia biomass was not affected by increased summer precipitation. Belowground biomass, BNPP, total NPP (TNPP) and R︰S ratio of treated or untreated re-grassed croplands were much lower than those of fenced grassland. The results indicated that fertilization significantly increased aboveground biomass and changed the proportions of biomass and NPP in re-grassed farmlands. The results also suggested that increased precipitation hastened vegetation restoration in abandoned croplands. This strongly depended on functional types of dominant species due to the distinct sensitivity of plant species to increased precipitation.关键词
退耕还草地/施肥/增加降水/植被恢复/群落组成/生物量分配/草地生物量Key words
Re-grassing cropland/Fertilization/Increased precipitation/Vegetation restoration/Community composition/Biomass allocation/Biomass of grassland分类
农业科技引用本文复制引用
张金凤,徐雨晴..水氮添加对内蒙古多伦县退耕还草地生物量、生产力及其分配的影响[J].中国生态农业学报,2016,(2):192-200,9.基金项目
国家自然科学基金项目(31200475)和福建省教育厅科研项目(JA12085)资助* This study was supported by the National Natural Science Foundation of China (No.31200475) and Foundation of Education Department of Fujian Province (No. JA12085) （31200475）
