三峡库区经济林土壤有机碳特征

Soil Organic Carbon Characteristics of Economic Forest in Three Gorges Reservoir Area

【目的】探究三峡库区退耕还经济林的土壤有机碳储量分布特征,为三峡库区退耕还林工程的生态效益定量评估提供基础数据,也为陆地生态系统碳循环与平衡、碳汇新增长提供参考。【方法】以三峡库区的柑橘园(Citrus reticulata)、茶园(Camellia sinensis)、核桃园(Juglans regia)、花椒园(Zanthoxylum bungeanum)、李子林(Prunus salicina)和板栗林(Castanea mollissima)6种经济林类型为研究对象,以库区内的针叶林、阔叶林、针阔混交林和灌木林4种人工防护林为对照,共416个样地收集0~10 cm、10~20 cm和20~40 cm土壤样本进行理化性质分析和碳储量计算,分析土壤碳储量的空间分布特征及其与理化性质的关系,探讨三峡库区经济林与防护林土壤碳的差异。【结果】三峡库区0~40 cm土层碳储量由高到低为灌木林(107.80 Mg/hm^(2))>阔叶林(98.64 Mg/hm^(2))>针叶林(97.82 Mg/hm^(2))>针阔混交林(96.73 Mg/hm^(2))>茶园(72.32 Mg/hm^(2))>板栗林(67.73 Mg/hm^(2))>核桃园(64.74 Mg/hm^(2))>李子林(54.88 Mg/hm^(2))>柑橘园(53.49 Mg/hm^(2))>花椒园(51.81 Mg/hm^(2))。经济林的碳储量显著低于防护林,0~10 cm、10~20 cm和20~40 cm分别是防护林的68%、61%和51%。土壤碳储量与全氮(TN)、全磷(TP)和有机碳含量(SOC)存在显著正相关。【结论】在现有的经营管理措施下,三峡库区的经济林土壤碳储量是防护林的58%,存在碳损失现象。

【Objective】The research on the distribution characteristics of soil organic carbon stocks in the economic forest converted from farmland in the Three Gorges Reservoir Area not only provides basic data for quantitative evaluation of ecological benefits of the project,but also provides reference for carbon cycle and balance and the new increase of carbon sink of terrestrial ecosystem.【Method】In the Three Gorges Reservoir Area,six kinds of economic forest were set as research objects,including Citrus orchard,Tea garden,Walnut orchard,Prickly ash orchard,Plum forest and Chestnut forest,with coniferous forest,broad-leaved forest,mixed broadleaf-conifer forest and shrub forest as the control.Soil samples of 0~10 cm,10~20 cm and 20~40 cm were collected from 416 sites for physical and chemical properties analysis and carbon stocks calculation.The spatial distribution characteristics of soil carbon storage and its relationship with physical and chemical properties were analyzed,and the difference of soil carbon between economic forest and shelter forest in the Three Gorges Reservoir Area was discussed.【Result】In the Three Gorges Reservoir Area,the carbon storage of 0~40 cm soil layer from high to low is shrub(107.80 Mg/hm^(2))>Broad-leaved forest(98.64 Mg/hm^(2))>Coniferous forest(97.82 Mg/hm^(2))>Mixed broadleaf-conifer forest(96.73 Mg/hm^(2))>Tea garden(72.32 Mg/hm^(2))>Chestnut forest(67.73 Mg/hm^(2))>Walnut Orchard(64.74 Mg/hm^(2))>Plum forest(54.88 Mg/hm^(2))>Citrus orchard(53.49 Mg/hm^(2))>Prickly ash garden(51.81 Mg/hm^(2)).The carbon stocks in economic forest was significantly lower than that in shelter forest,0~10 cm,10~20 cm and 20~40 cm were 68%,61%and 51%of shelter forest,respectively.And there was a significant positive correlation between soil carbon stocks and TN,TP and SOC.【Conclusion】Under the current management measures,the soil carbon stocks of economic forest in the Three Gorges Reservoir Area is 58%of the shelter forest,and there is carbon loss.