ABSTRACT

To evaluate the effects of land-use types on the temporal dynamics of soil active carbon (C) and nitrogen (N), a field experiment was conducted from five adjacent sites, farmland (FL), abandoned land (AL), Platycladus orientalis artificial forest (PO), Robinia pseudoacacia artificial forest (RP) and Quercus variabilis artificial forest (QV) in the rocky mountainous of North China. Soil dissolved organic C and N (DOC, DON), soil microbial biomass C and N (MBC, MBN), ammonium-N (NH₄⁺-N) and nitrate-N (NO₃⁻-N) were determined during four seasons. The results showed that soil DOC, DON, MBC, MBN, NH₄⁺-N, and NO₃⁻-N contents in PO were higher than other land-use types, especially in QV. Soil DOC, DON, MBC, and MBN contents all showed a higher value in March. Both soil DOC/DON and MBC/MBN showed peak values in June. With the increase of soil depth, soil DOC, DON, MBC, and MBN contents all tended to decrease. Most of soil active C and N components had significant correlations with SOC, TN, AP, soil particle volume fraction and the activities of BG and PROT, while the main influencing factors for soil active C and N components were various. The key contributing factors to soil DOC and MBC was SOC, accounting for 62.6% and 67.9%, respectively. Soil TN was the main affecting factor of soil DON (98.4%) and MBN (75.7%). Soil NH₄⁺-N and NO₃⁻-N were, respectively, affected by volume fraction of silt particles (10.3%) and AP (15.0%). In conclusion, soil active C and N components are more likely to accumulate in the PO soil in spring, indicating tree species and temperature are the key factors driving soil active C and N turnover in this area.

摘要

为了评估土地利用类型对土壤活性碳 (C) 和氮 (N) 时间动态的影响，在五个相邻地点进行了田间试验，农田 (FL)、废弃土地 (AL)、侧柏人工华北岩石山区的森林（PO）、刺槐人工林（RP）和栓皮栎人工林（QV）。土壤溶解有机碳和氮（DOC，DON），土壤微生物生物量碳和氮（MBC，MBN），铵-N（NH ₄ ⁺ -N）和硝酸盐-N（NO ₃ ^- -N）在四个季节测定. 结果表明，土壤 DOC、DON、MBC、MBN、NH ₄ ⁺ -N 和 NO ₃ ^-PO 中的 -N 含量高于其他土地利用类型，尤其是 QV。3月份土壤DOC、DON、MBC和MBN含量均呈较高值。土壤 DOC/DON 和 MBC/MBN 均在 6 月份出现峰值。随着土壤深度的增加，土壤DOC、DON、MBC和MBN含量均呈下降趋势。大部分土壤活性C、N成分与SOC、TN、AP、土壤颗粒体积分数及BG、PROT活性显着相关，而土壤活性C、N成分的主要影响因素多样。土壤 DOC 和 MBC 的主要影响因素是 SOC，分别占 62.6% 和 67.9%。土壤TN是土壤DON（98.4%）和MBN（75.7%）的主要影响因素。土壤 NH ₄ ⁺ -N 和 NO ₃ ^--N 分别受淤泥颗粒体积分数 (10.3%) 和 AP (15.0%) 的影响。综上所述，春季土壤活性碳、氮成分更容易在PO土壤中积累，表明树种和温度是驱动该地区土壤活性碳、氮周转的关键因素。