Temperature sensitivity of C and N mineralization in temperate forest soils at low temperatures
Temperature sensitivity of C and N mineralization in temperate forest soils at low temperatures
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DOI：
10.1016/j.soilbio.2013.11.014
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发表时间：
2014-02
影响因子：
9.7
通讯作者：
M. Schütt;W. Borken;O. Spott;C. F. Stange;E. Matzner
中科院分区：
文献类型：
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作者：
M. Schütt;W. Borken;O. Spott;C. F. Stange;E. Matzner
气候模型预测温带地区冬季会变暖，但人们对低温下土壤碳 (C) 和氮 (N) 矿化的温度敏感性知之甚少。在这里，我们评估了欧洲山毛榉和挪威云杉温带森林表层土壤的总氨化、总硝化、碳和净氮矿化的温度敏感性。我们测试了以下假设：(1) 基质质量影响 C 和 N 矿化的温度敏感性，(2) C 矿化的温度敏感性高于总氨化的温度敏感性。土壤培养在-4、-1、+2、+5和+8°C的恒定温度下进行。通过15N池稀释技术测量总氨化作用和硝化作用。使用阿累尼乌斯方程计算了 C、总氮矿化度和净氮矿化度的温度敏感性，并将 C 矿化度作为基质质量的代表。山毛榉土壤中的总氨化度和 C 矿化度比云杉土壤中大得多，而总硝化作用处于同一数量级。总氨化作用、硝化作用和碳矿化作用在 -4 °C 时几乎停止，但在 -1 °C 时已经增加。 Oi/Oe 层位中的净氨化作用在 -4 和 -1 °C 时较低，在 +2 和 +8 °C 之间急剧增加。两种土壤的净硝化作用均较低，但在温度 >2°C 时，云杉土壤的净硝化作用有所增加，而山毛榉土壤则没有温度响应。在 -4 至 +8°C 的温度范围内，总氨化作用和碳矿化的表观 Q10 值在 3–18 范围内。Q10 在低基质质量的土壤层中最低。 C矿化与总氨化的比率在0.5和2.9之间变化，表明富含氮的有机底物的优先矿化或微生物生物质中氮库的快速周转。冬季气温升高可能会对净氮矿化产生重大影响，但影响随着土壤深度的增加而减弱，这可能是由于土壤有机质的基质质量下降所致。
Climate models predict warmer winter in temperate regions, but little is known about the temperature sensitivity of soil carbon (C) and nitrogen (N) mineralization at low temperatures. Here, we assess the temperature sensitivities of gross ammonification, gross nitrification, C and net N mineralization of top soil horizons, under a European beech and a Norway spruce temperate forest. We tested the hypotheses that (1) substrate quality affects the temperature sensitivity of C and N mineralization and (2) that temperature sensitivity of C mineralization is higher than of gross ammonification. Soil incubations were conducted at constant temperatures of −4, −1, +2, +5 and +8 °C. Gross ammonification and nitrification were measured by the15N pool dilution technique. Temperature sensitivities of C, gross and net N mineralization were calculated using the Arrhenius equation and C mineralization was taken as proxy for substrate quality.Gross ammonification and C mineralization was much larger in the beech than in the spruce soil, while gross nitrification was in the same order of magnitude. Gross ammonification, nitrification and C mineralization almost ceased at −4 °C, but already increased at −1 °C. Net ammonification in Oi/Oe horizons was low at −4 and −1 °C and increased strongly between +2 and +8 °C. Net nitrification was low in both soils, but increased in the spruce soil at temperatures >2 °C whereas no temperature response occurred in the beech soil.ApparentQ10values of gross ammonification and C mineralization in the temperature range of −4 to +8 °C were in the range of 3–18.Q10were lowest in soil horizons of low substrate quality. The ratio of C mineralization to gross ammonification varied between 0.5 and 2.9, suggesting preferential mineralization of N rich organic substrates or rapid turnover of the N pool in microbial biomass. Rising winter temperatures might have substantial effects on net N mineralization, but effects decrease with soil depth, likely due to decreasing substrate quality of soil organic matter.