Abstract:

The increase of atmospheric temperature and litter decomposition affects soil respiration by affecting the activities of soil microorganisms. Open top chamber (OTC) and static chamber gas chromatography were used to observe soil respiration of a Pinus tabulaeformis plantation in Daqing Mountain of Inner Mongolia during the growing season in 2020 (May-October). Four treatments, CK, W, NL and WNL, were set up in the experiment. The temperature and humidity, soil temperature and humidity, and soil physical and chemical properties were measured simultaneously. The results showed that (1) the air temperature and soil temperature at 5 cm and 10 cm increased by 1.21 ℃, 0.50 ℃, 0.43 ℃ and 0.57 ℃, respectively; The soil moisture of 5 cm, 10 cm and 20 cm decreased by 5.4%, 7.1% and 6.4%, respectively. (2) The CO₂ flux ranges between 224.19-601.15 mg∙m^-2∙h^-1 in Daqing Mountain; The CH₄ flux ranges from -28.45 to -90.2 μg∙m^-2∙h^-1;The N₂O flux ranges between 3.94-10.78 μg∙m^-2∙h^-1. During the whole growing season, the soil CO₂ fluxes of the four treatments were the emission sources of CO₂ and N₂O, and the absorption sink of CH₄. (3) Soil CO₂ flux was significantly positively correlated with air temperature and soil temperature (0-5, 5-10, 10-20 cm) (P<0.01), negatively correlated with soil TN (0-10 cm) (P<0.01), and negatively correlated with soil TN (10-20 cm) (P<0.05); Soil CH₄ flux was negatively correlated with atmospheric humidity only under the W treatment (P<0.05); Soil N₂O flux was negatively correlated with soil TN (0-10, 10-20 cm) under the w treatment (P<0.05). Therefore, climate change and surface litter layer are important factors affecting forest soil respiration. Based on a100-yeartime scale, the global warming potential for greenhouse gases was calculated to simulate the soil greenhouse gas emission under warming and litter removal treatments, which showed positive effects on climate warming.

Key words: simulated warming, soil respiration, greenhouse gas flux, litter, Pinus tabulaeformis plantation

摘要：

大气温度的升高及凋落物的分解通过影响土壤微生物的活动,从而影响土壤呼吸。采用开顶箱式增温（Open Top Chamber,OTC）,结合静态箱-气相色谱法,于2020年生长季（5—10月）野外原位观测内蒙古大青山油松（Pinus tabuliformis Carr.）人工林土壤呼吸。试验设置对照（CK）、模拟增温（W）、去除凋落物（NL）、模拟增温+凋落物去除（WNL）4个处理4次重复,同时测定了大气温湿度、土壤温湿度及土壤理化性质。结果表明,（1）增温处理1年后,大气温度、土壤5、10和20 cm处的温度分别较对照增加了1.21、0.50、0.43和0.57 ℃;土壤5、10和20 cm的含水量分别较对照降低了5.4%、7.1%和6.4%。（2）大青山油松人工林土壤CO₂通量变化范围为224.19—601.15 mg∙m^-2∙h^-1;CH₄通量范围为-28.45— -90.2 μg∙m^-2∙h^-1;N₂O通量范围为3.94—10.78 μg∙m^-2∙h^-1。整个生长季4种处理下土壤均表现为CO_2、N₂O的排放源、CH₄的吸收汇。（3）对照和模拟增温处理下土壤CO₂通量与大气温度和土壤温度（0—5、5—10、10—20 cm）呈极显著正相关（P<0.01）,与土壤TN（0—10 cm）呈极显著负相关（P<0.01）,与土壤TN（10—20 cm）呈显著负相关（P<0.05）;土壤CH₄通量仅在W处理下与大气湿度呈显著负相关（P<0.05）;土壤N₂O通量在W处理下与土壤TN（0—10、10—20 cm）呈显著负相关（P<0.05）。由此可见,气候变化及地表凋落物层是影响森林土壤呼吸的重要因素;基于100 a时间尺度计算温室气体全球综合增温潜势,模拟增温和凋落物处理下土壤温室气体的排放对气候变暖具有正反馈作用。

关键词: 模拟增温, 土壤呼吸, 温室气体通量, 凋落物, 油松人工林