Conversion of alpine pastureland to artificial grassland altered CO 2 and N 2 O emissions by decreasing C and N in different soil aggregates

PeerJ

article

Mei Zhang¹  Dianpeng Li¹  Xuyang Wang¹  Maidinuer Abulaiz¹  Pujia Yu²  Jun Li³  Xinping Zhu¹  Hongtao Jia¹ 

[1] College of Grassland and Environment Sciences, Xinjiang Agricultural University;School of Geographical Sciences, Southwest University;Akesu National Station of Observation and Research for Oasis Agro-ecosystem;Xinjiang Key Laboratory of Soil and Plant Ecological Processes

关键词: CO2 and N2O emissions;    Soil organic carbon;    Total nitrogen;    Soil aggregate structure;    Alpine grassland;   

DOI  :  10.7717/peerj.11807

学科分类：社会科学、人文和艺术（综合）

来源: Inra

【 摘 要 】

BackgroundThe impacts of land use on greenhouse gases (GHGs) emissions have been extensively studied. However, the underlying mechanisms on how soil aggregate structure, soil organic carbon (SOC) and total N (TN) distributions in different soil aggregate sizes influencing carbon dioxide (CO2), and nitrous oxide (N2O) emissions from alpine grassland ecosystems remain largely unexplored.MethodsA microcosm experiment was conducted to investigate the effect of land use change on CO2and N2O emissions from different soil aggregate fractions. Soil samples were collected from three land use types, i.e., non-grazing natural grassland (CK), grazing grassland (GG), and artificial grassland (GC) in the Bayinbuluk alpine pastureland. Soil aggregate fractionation was performed using a wet-sieving method. The variations of soil aggregate structure, SOC, and TN in different soil aggregates were measured. The fluxes of CO2 and N2O were measured by a gas chromatograph.ResultsCompared to CK and GG, GC treatment significantly decreased SOC (by 24.9–45.2%) and TN (by 20.6–41.6%) across all soil aggregate sizes, and altered their distributions among soil aggregate fractions. The cumulative emissions of CO2 and N2O in soil aggregate fractions in the treatments of CK and GG were 39.5–76.1% and 92.7–96.7% higher than in the GC treatment, respectively. Moreover, cumulative CO2 clay +silt (< 0.053 mm), whereas it decreased with aggregate sizes decreasing in the GC treatment. Additionally, soil CO2 emissions were positively correlated with SOC and TN contents. The highest cumulative N2O emission occurred in micro aggregates under the treatments of CK and GG, and N2O emissions among different aggregate sizes almost no significant difference under the GC treatment.ConclusionsConversion of natural grassland to artificial grassland changed the pattern of CO2 emissions from different soil aggregate fractions by deteriorating soil aggregate structure and altering soil SOC and TN distributions. Our findings will be helpful to develop a pragmatic management strategy for mitigating GHGs emissions from alpine grassland.

【 授权许可】

CC BY