基于DNDC模型分析降水变化对黄土丘陵区草地生物量和土壤有机碳的影响  

Analysis of the response of grassland biomass and soil organic carbon to precipitation changes based on the DNDC model in the loess hilly region

作　　者：马露露 徐婷 李泽森 焦峰[1] MA Lulu;XU Ting;LI Zesen;JIAO Feng(Institute of Soil and Water Conservation,Northwest A&F University,Yangling 712100,Shaanxi,China)

机构地区：[1]西北农林科技大学水土保持研究所,陕西杨凌712100

出　　处：《草业科学》2023年第1期25-36,共12页Pratacultural Science

基　　金：国家重点研发计划项目(2016YFA0600801)。

摘　　要：草地生态系统作为黄土高原半干旱区重要的陆地生态系统,降水格局改变对该区域的碳循环过程产生影响。通过在自然恢复草地(NR)和白羊草(Bothriochloa ischaemum)栽培恢复草地(BI)进行原位降水梯度试验,设置了减少自然降水量的80%、60%、40%、20%,自然降水和增加自然降水量的20%、40%、60%、80%(即P–80、P–60、P–40、P–20、CK、P+20、P+40、P+60、P+80)的9种降水梯度,并运用DNDC (denitrification-decomposition)模型进行模拟验证,分析降水改变对土壤有机碳(SOC)、地上和地下生物量的影响。结果表明:1)与自然降水相比,增减降水80%时自然恢复草地的SOC含量增幅最大(21.4%和21.5%),但不同处理间无显著差异(P> 0.05);白羊草地SOC含量在减少降水20%时达到“峰”值(13.41 g·kg^(-1)),整体上白羊草地SOC含量高于自然恢复草地。2)两种草地恢复类型的生物量都随降水量变化而波动起伏,自然恢复草地减少降水20%地下生物量和增加降水40%地上生物量增幅分别为53.6%和52.4%,白羊草地在增加降水20%和减少降水40%时地下、地上生物量各达到最大值;且自然恢复草地地上生物量明显高于白羊草地,地下生物量则相反。3) DNDC模型模拟结果显示自然恢复草地和白羊草地的SOC含量、地上和地下生物量模拟值的变化趋势与实测结果基本一致:均方根误差RMSE%分别为10.0、7.5、6.7和11.7、1.3、1.0,决定系数R2分别为0.578、0.989、0.989和0.776、0.998、0.999,点位模拟效果整体良好;但模型对生物量的模拟吻合程度更高,且在白羊草地的模拟更具优势;因此运用模型模拟黄土丘陵区草地生态系统的土壤有机碳和草地生物量是可行的。Grassland ecosystems represent an important terrestrial ecosystem in the semi-arid region of the Loess Plateau,and changes in precipitation patterns have an impact on the carbon cycle process in this region. In situ precipitation gradient experiments were carried out in naturally restored grassland(NR) and Bothriochloa ischaemum artificially restored grassland(BI). Natural precipitation was used as a control, and nine precipitation gradients(P – 80, P – 60, P – 40, P – 20, CK, P + 20,P + 40, P + 60, P + 80) were established by decreasing the natural value by 80%, 60%, 40% and 20% and increasing this value by 20%, 40%, 60% and 80%. In addition, a denitrification-decomposition(DNDC) model was used to simulate and analyze the effects of precipitation change on soil organic carbon(SOC) and aboveground and underground biomass. The results showed that 1) compared with natural precipitation, the SOC content of NR presented the greatest increase(21.4%and 21.5%) when the precipitation increased or decreased by 80%, respectively, although significant differences were not observed between these two treatments(P > 0.05). The SOC content of BI reached the peak value(13.41 g·kg^(-1)) when the rainfall decreased by 20%. Overall, the SOC content of BI was higher than that of NR. 2) The biomass of the two types of grassland restoration fluctuated with rainfall changes. When the rainfall decreased by 20% and increased by 40%, the underground and aboveground biomass of NR increased by 53.6% and 52.4%, respectively, whereas when the rainfall increased by 20% and decreased by 40%, these parameters achieved the maximum values in BI. Moreover, the aboveground biomass of NR was obviously higher than that of BI, while the underground biomass presented the opposite results. 3) The DNDC model results showed that the change trends of SOC content and simulated aboveground and underground biomass values of NR and BI were basically consistent with the measured results, with RMSE% values of 10.0, 7.5, and 6.7 for NR and 11.7, 1.3, and

关 键 词：降水梯度 土壤有机碳 生物量 DNDC模型 黄土高原 自然恢复草地 栽培恢复草地 

分 类 号：S812[农业科学—草业科学]