| 摘要: |
| 【目的】探究3个龄级油松天然次生林去除凋落物后生长季土壤呼吸速率对环境因素的响应。【方法】采用 LI-8100土壤碳通量仪测定中龄林（HF）、近熟林（NF）、成熟林（MF）3个龄级油松天然次生林生长季总土壤呼吸速率、去除凋落物后土壤呼吸速率，并同步采用自带的土壤温湿度传感器测定5 cm深度处的土壤温度（T）和湿度(W)、近地面大气温度（Ta）和相对湿度(RH)；采用氯仿熏蒸浸提法测定5 cm深处土壤微生物量碳(MBC)。【结果】各林龄油松林土壤呼吸速率及其环境因子均呈明显的季节变化，表现为6-8月较高，5月和9月较低。测量期间，油松HF、NF、MF去除凋落物处理的土壤呼吸速率平均值分别为2.45，2.62和1.85 μmol/（m2·s），分别比未去除凋落物的对照处理的 3.69，3.23，3.48 μmol/（m2·s）下降33.4%，18.8%和47.0%。对照试验条件下，各油松林土壤呼吸速率采用双变量T、W模型拟合时效果较好(R2=0.464～0.821)；去除凋落物试验条件下，各油松林水热因子对土壤呼吸速率的影响较小，MBC对土壤呼吸速率的影响较大，在油松NF、MF林分中均达到显著水平。对照试验条件下，各油松林土壤5 cm深度处的温度敏感性系数QT10值随着林龄的增加而减少；去除凋落物试验条件下，除油松NF的大气温度敏感性系数QTA10升高外，其他林龄油松林温度敏感性系数Q10均降低。【结论】对照试验条件下，水热因子交互作用是土壤呼吸速率变化的主导因子；去除凋落物试验条件下，土壤湿度和MBC是导致各林龄油松林土壤呼吸速率差异的关键因子，较高的土壤水分和MBC更有利于凋落物分解释放CO2。 |
| 关键词: 林龄 土壤呼吸速率 土壤温湿度 土壤微生物量碳 凋落物 |
| DOI： |
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| 基金项目:国家林业局林业公益性行业科研专项“森林生态服务功能分布式定位观测与模型模拟”(201204101) |
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| Effects of litter removal on soil respiration Pinus tabulaeformis natural secondary forests at different ages |
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YU Shu,HAN Hairong,KANG Fengfeng,et al
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| Abstract: |
| 【Objective】The purpose of this study was to explore the response of soil respiration rates to environmental factors after litter removal in Pinus tabulaefomis stands at three different ages during growing season.【Method】Using LI-8100 soil carbon flux instrument,soil respiration rates,soil temperature (T) and moisture (W) at 5 cm depth,atmospheric temperature (Ta) and relative humidity (RH) above ground in half mature P.tabulaefomis forest (HF),near-matureP.tabulaefomis forest (NF),and mature P.tabulaefomis forest (MF) of two treatments (blank control and litter removal test) were measured during growing season.Soil microbial biomass carbon (MBC) at 5 cm depth was extracted using chloroform fumigation extraction method.【Result】Soil respiration rates and their environmental factors in P.tabulaefomis forests showed significantly seasonal patterns,with higher values during June to August and lower values during May and September.Average soil respiration rates in HF,NF and MF P.tabulaefomis forests under the litter removal treatment were 2.45,2.62 and 1.85 μmol/(m2·s),decreased by 33.4%,18.8% and 47.0% compared to those of the control. Under natural conditions,two factor regression models (soil temperature and soil humidity) of soil respiration rate had better fitting results (R2 values ranging from 0.464 to 0.821) than single factor models.Under litter removal treatments,water and heat had smaller influences on soil respiration rates,while MBC had large effects with significant relationship between soil respiration rate and MBC reached in NF and MF P.tabulaefomis forests.Under natural conditions,the soil temperature sensitivity coefficient QT10 decreased with the increase of forest age.Under litter removal conditions,all temperature sensitivity coefficient Q10 values decreased while only atmospheric temperature sensitivity coefficient QTA10 in NF P.tabulaefomis forest increased.【Conclusion】Interaction between water and heat was the major factor affecting soil respiration rates in normal conditions,while soil moisture and MBC were the key factors under removing litter condition.Higher soil moisture and MBC tended to release more CO2 from litters. |
| Key words: forest age soil respiration rate soil temperature and humidity soil microbial biomass carbon litter |
