甘肃兴隆山不同演替阶段群落土壤氮素矿化对温度的响应

Response of soil nitrogen mineralization to temperature along the differentsuccessional stages in Xinglong Mountain, Gansu Province, China

土壤氮素矿化是土壤中氮素循环的关键过程,而温度是影响土壤氮素矿化的最重要的因素之一,研究温度变化对不同演替阶段群落土壤氮素矿化特征的影响,对于明确陆地生态系统中土壤氮素循环过程具有重要意义。本研究以甘肃兴隆山不同演替阶段群落为研究对象,采用室内恒温好气培养法,研究不同演替阶段群落[草地、灌丛林、白桦林(Betula platyphylla forest)、青杄-白桦林(Picea wilsonii-Betula platyphylla forest)和青杄林(Picea wilsonii forest)]在不同温度(15℃、25℃和35℃)下的土壤氮素矿化特征。结果表明:(1)除草地的0~20 cm土层外,其余演替阶段群落土壤氮素矿化速率随着温度(15~35℃)的增加而增大,且不同演替阶段群落土壤氮素累积矿化量随着温度的增加而增加;(2)随着演替的正向推进,不同演替阶段群落土壤氮素矿化速率与累积矿化量均呈先升高后降低趋势,白桦林的土壤氮素矿化速率最大,分别均是草地、灌丛林、青杄-白桦林、青杄林的1.63倍、1.61倍、1.25倍、1.47倍;而青杄-白桦林的累积矿化量最高,分别是草地、灌丛林、白桦林、青杄林的0.68倍、0.72倍、0.84倍、0.97倍;(3)随着土壤深度的增加,土壤氮素矿化速率与累积矿化量均呈降低趋势,以0~20 cm土层的最大;(4)不同演替阶段群落在15℃培养和25℃培养下的温度敏感系数Q10均有显著差异(P<0.05),随着演替的正向进行,温度敏感系数Q10呈先降低后增加趋势,而不同演替阶段群落在25℃培养和35℃培养下的温度敏感系数Q10均无显著差异(P>0.05)。研究结果将为群落土壤的质量演变和土壤供氮能力的动态变化提供理论依据。

Soil nitrogen mineralization is a crucial process of the soil nitrogen cycle,with temperature being one of the most important factors affecting soil nitrogen mineralization.Studying the effect of temperature on soil nitrogen mineralization characteristics in different successional stages is of great significance for understanding the soil nitrogen cycle in terrestrial ecosystems.In this study,the communities in different successional stages of Xinglong Mountain in Gansu Province were selected as the research objects.The indoor,constant temperature,aerobic culture method was used to study the soil nitrogen mineralization characteristics of five successional stages:grasslands,shrub forests,Betula platyphylla forests,Picea wilsonii-Betula platyphylla forests,and Picea wilsonii forests under temperatures of 15℃,25℃,and 35℃.The results showed that(1)except for the soil at a depth of 0-20 cm in grasslands,the increase in the soil nitrogen mineralization rate of the other successional stages was directly proportional to the temperature,and the cumulative mineralization of soil nitrogen in the different successional stages showed a similar trend.(2)with the positive advancement of succession,the soil nitrogen mineralization rate and cumulative mineralization amount of different successional stages initially enhanced but then diminished.The soil nitrogen mineralization rate of B.platyphylla forests was the highest,which was 1.63-,1.61-,1.25-,and 1.47-times more than that of grasslands,shrub forests,P.wilsonii-B.platyphylla forests,and P.wilsonii forests,respectively.The soil nitrogen mineralization rate and cumulative mineralization amount of P.wilsonii-B.platyphylla forest were the highest,which were 0.68-,0.72-,0.84-,and 0.97-times greater than those of grasslands,shrub forests,B.platyphylla forests,and P.wilsonii forests,respectively.(3)the soil nitrogen mineralization rate and cumulative mineralization were inversely proportional to the soil depth,with the maximum detected at a depth of 0-20 cm.(4)the temperature sensitivity coefficient(Q10)at 15℃and 25℃in different successional stages varied markedly(P<0.05).The Q10 at first decreased and then increased in relation to the positive succession.The Q10 between the communities in different succession stages at 25℃and 35℃did not alter remarkably(P>0.05).The results of this study provide a theoretical basis for evaluating the evolution of soil quality and the dynamic changes in the soil nitrogen supply capacities in the community.