Abstract:

Moso bamboo (Phyllostachys edulis) forest is a typical forest type in the Yangtze River Delta region and plays a crucial role in mitigating the greenhouse effect and maintaining the carbon balance. The forest litter layer may significantly influence the exchange of carbon dioxide (CO₂) and nitrous oxide (N₂O) between the soil and atmosphere. This study was conducted in a Moso bamboo forest in Anji County, Zhejiang Province, China, where two treatments were implemented: soil without litter (S), and soil with litter (SL). The static chamber gas chromatography method was used to analyze the effects of these treatments on soil CO₂ and N₂O fluxes and the regulating factors involved. The results indicated that the Moso bamboo forest soil was a net source of CO₂ during the observation period, with the highest emissions occurring in summer. Soil without litter turned from a net N₂O source to slight N₂O sinks from summer and fall to winter and spring, whereas soil with litter was consistently a net N₂O source. The litter significantly affected soil CO₂ and N₂O fluxes that the average annual CO₂ flux under the S treatment (779.27 mg·m⁻²·h⁻¹) significantly higher than that the SL treatment (520.07 mg·m⁻²·h⁻¹), indicating a 33.26% inhibitory contribution of litter to soil CO₂ flux. Conversely, the average annual N₂O flux under the S treatment (2.95 μg·m⁻²·h⁻¹) was lower than that under the SL treatment (16.42 μg·m⁻²·h⁻¹). Soil temperature is a key factor in the CO₂ flux in bamboo forest soils, followed by soil organic carbon. Soil temperature was the primary factor influencing the variation in N₂O flux in the S plots, whereas total nitrogen content was the main factor influencingN₂O flux changes in the SL plots. Overall, the litter layer, which is mainly composed of bamboo leaves, inhibits soil CO₂ emissions, but increases N₂O emissions. This study provides important insights into the regulatory mechanisms of soil-atmosphere exchanges in bamboo forests and suggests that the impact of litter must be considered when evaluating the greenhouse gas budget of forests.

Key words: Moso bamboo forest, CO₂, N₂O, flux, litter

摘要：

毛竹（Phyllostachys edulis）林是长江三角洲地区典型的森林类型，在缓解温室效应、维持碳平衡等方面具有重要作用。林地凋落物层可能是影响二氧化碳（CO₂）和氧化亚氮（N₂O）在土壤与大气之间交换的重要因素。以浙江省安吉县毛竹林为对象，采用静态箱-气相色谱法，分析清除凋落物（S）和保留凋落物（SL）处理对土壤CO₂和N₂O通量的影响及调控因素。结果表明，观测期内毛竹林土壤为CO₂的源，夏季排放最强；S处理的毛竹林土壤由夏秋季的N₂O排放源转变为冬春季的N₂O吸收汇；而SL处理的土壤则始终表现为N₂O的排放源。凋落物显著影响毛竹林地土壤CO₂和N₂O通量。S处理下的CO₂年均排放通量（779.27 mg∙m⁻²∙h⁻¹）高于SL处理（520.07 mg∙m⁻²∙h⁻¹），凋落物对土壤CO₂通量的平均抑制贡献率为33.26%；相反，S处理下的N₂O年均排放通量（2.95 μg∙m⁻²∙h⁻¹）则低于SL处理（16.42 μg∙m⁻²∙h⁻¹）。土壤温度是决定竹林土壤CO₂通量的重要因素，其次为土壤有机碳；清除凋落物处理下的土壤温度是影响N₂O通量变化的主要因素，而保留凋落物处理下全氮则是改变N₂O通量的关键因子。总体而言，毛竹林地以竹叶为主的凋落物层会抑制土壤CO₂的排放，促进N₂O的排放。该研究为深入理解竹林土壤地气交换的调控机制提供了重要依据，建议在评估林地温室气体收支时考虑凋落物层的影响。

关键词: 毛竹林, CO₂, N₂O, 通量, 凋落物