海南尖峰岭热带山地雨林林窗对土壤呼吸的影响

李佳灵 许全 杨秋 苏天燕 符群友 杨怀 刘文杰

摘  要：研究林窗對土壤呼吸的影响及其机制，可为热带森林生态系统土壤呼吸的准确估算和森林土壤有机碳管理提供科学依据。以海南岛尖峰岭热带山地雨林林窗（台风干扰形成）样地为研究对象，通过开展林窗内和林窗外（林内）土壤呼吸的原位观测试验，并设置去除/保留凋落物处理来分析凋落物对土壤呼吸的影响;结合林窗内外土壤的理化性质及气象要素，研究土壤呼吸的排放与环境因子的关系。结果表明：林窗的空气相对湿度、土壤温度和土壤含水量与林内均存在极显著差异（P<0.01）;林窗的空气温度与林内的差异不显著（P>0.05）;林窗内外的平均土壤呼吸分别为（3.29±0.54）μmol/（m2·s）和（2.38±0.51）μmol/（m2·s）。在月尺度上，林窗内外的土壤呼吸的排放速率呈现多峰型曲线变化规律，排放趋势大致相同，整体呈现出雨季大于旱季的变化规律。林窗和林内的土壤呼吸速率存在显著差异（P<0.05）。影响林内和林窗土壤呼吸的最主要因素分别是有机碳和地下5 cm温度。

关键词：热带山地雨林;土壤呼吸;林窗

中图分类号：S718.55      文献标识码：A

Abstract： The effect of canopy gaps on soil respiration could provide scientific basis and theoretical reference for accu-rate estimating soil carbon emissions and effective management of soil organic carbon （SOC） accumulation in the trop-ical montane forest ecosystem. In this study， 60 hm2 dynamic observation plots and the natural canopy gaps in the tropical montane rainforest observation sites of the Jianfengling National Natural Reserve in Hainan Island，were se-lected as the research objects. Meteorological factors， soil environmental parameters， soil respiration and other indica-tors were observed and investigated regularly. Based on the observation data， daily and seasonal patterns and differences of soil respiration between the inside and outside of canopy gaps （which was formatted by typhoon interference） were analyzed. Then， the effect of canopy gaps on soil respiration was illustrated. In addition， the effects of litter on soil respiration were analyzed through removing/keeping the litter， and the characters of soil respiration at both inside. The relationship between soil respiration and environmental factors was determined using the best available structural model method， and the characteristics affecting the factors and differences of soil respiration were analyzed inside and outside the canopy gaps. In the result， there was a significant difference between relative air humidity， soil temperature and soil water content （P<0.01）. There was no significant difference between the air temperature of inside and outside the canopy gaps （P>0.05）. The average soil respiration rate was （3.29±0.54） μmol/（m2·s） at the inside canopy gaps， and the average soil respiration rate at the outside canopy gaps was （2.38±0.51） μmol/（m2·s）. At the monthly scales， the discharge rate of soil respiration showed a multi-peak curve at the both inside and outside forest gaps and the variation trend was almost the same. The overall of soil respiration at rain season was greater than that at the dry season. There was a significant difference between relative soil respiration rate of inside and outside the canopy gaps （P<0.05）. Soil respiration was quite different both inside and outside forest gaps. Soil temperature （5 cm） was the most important envi¬r¬onm¬ental factors affecting soil respiration inside the forest gap.

Keywords： tropical montane rainforest; soil respiration; canopy gap

DOI： 10.3969/j.issn.1000-2561.2021.12.040

土壤呼吸是陆地生态系统碳循环的重要组成部分，在全球碳循环中起着至关重要的作用[1]。森林土壤呼吸是大气CO2的主要自然来源，参与陆地生态系统森林碳循环，占生态系统呼吸总量的50%～95%[2-3]，其微小变化，可以显著地改变大气中CO2的浓度，并对气候变化产生潜在的反馈[4]。由温室气体排放导致的全球变暖将给陆地生态系统带来巨大的改变，如植被的生长期、有机碳分解速率、土壤酶活性以及养分循环过程等，进而对生态系统碳平衡造成严重的干扰。……