川西南常绿阔叶林土壤呼吸及其对氮沉降的响应  

Soil Respiration and Its Response to Simulated Nitrogen Deposition in Evergreen Broad-Leaved Forest,Southwest Sichuan

作　　者：宋学贵[1] 胡庭兴[1] 鲜骏仁[1] 肖春莲[1] 刘文婷[1] 

机构地区：[1]四川农业大学林学园艺学院,四川雅安625014

出　　处：《水土保持学报》2007年第4期168-172,192,共6页Journal of Soil and Water Conservation

基　　金：国家科技部"十五"重大科技攻关项目(2004BA606A-06);四川省科技攻关项目(05SG023-009)

摘　　要：通过原位进行低氮(LN,50 kg N/hm2·a)、中氮(MN,100 kg N/hm2·a)和高氮(HN,150 kg N/hm2·a)处理,研究了川西南天然常绿阔叶林土壤呼吸及其对模拟N沉降的响应.结果表明:(1)该森林土壤呼吸速率最大值612.21±77.82 mg CO2/m2·h出现在7月份,最小值108.95±17.01 mg CO2/m2·h出现在2月,年均土壤呼吸速率为348.00±157.83 mg CO2/m2·h,年均土壤呼吸通量为8.31±3.77 t C/hm2·a.采用双因素关系模型(Rs=aebTWc),土壤温度和土壤湿度共同解释了该常绿阔叶林2005年10月～2006年7月土壤呼吸速率季节变化的68.6%～73.9%,其拟合结果优于以土壤湿度或温度为参数的单因素关系模型.影响土壤呼吸速率的主导因子是温度,其地表温度变化响应的敏感程度Q10值为2.12,以土壤5 cm深处的温度为参数时,Q10值为2.51.(2)N沉降处理3个月后,该森林中HN和MN处理的土壤呼吸速率(309.43±17.24 mg CO2/m2·h,303.82±11.50 mgCO2/m2·h)均显著高于CK(269.28±13.78 mg CO2/m2·h)(P＜0.05);处理4个月后,HN的土壤呼吸速率(272.42±13.25 mg CO2/m2·h)均显著高于MN(239.65±10.33 mg CO2/m2·h)、LN(229.10±9.90 mg CO2/m2·h)和CK(234.51±12.77 mg CO2/m2·h)(P＜0.05);但处理7～10个月时,各处理之间无显著差异.研究表明,N沉降初期明显促进了常绿阔叶林土壤呼吸,后期无明显影响.This study was conducted in native evergreen broadleaf forests aiming at measuring soil respiration and the effects of nitrogen deposition on soil CO2 emission.Nitrogen addition experiments were carried out within the forest selected in 2005.Four N addition treatments(in three replicates) were established in mature forest:control,low N(LN,50 kg N/hm2·a),medium N(MN,100 kg N/hm2·a) and High N(HN,150 kg N/hm2·a).Twelve plots(2 m×2 m) were set up.All plots and treatments were laid out randomly.Ammonium nitrate(NH4NO3) solution was sprayed monthly by hand onto the floor of these plots as 12 equal applications over the whole year and beginning in July 2005.Soil respiration was measured three to five times at mid month from October 2005 to July 2006 through alkali sorption technique.And temperature of top soil and soil at 10 cm depth and water content at 0~10 cm,10~20 cm were menstruated at each measurement occasion.The result showed:(1) Soil respiration rate varied from(612.21±77.82) mg CO2/m2·h to(108.95±17.01) mg CO2/m2·h in the forest reach a minimum in February and maximum in July.The model Rs=aebTWc(Rs soil respiration rate,T soil temperature,W soil water content,and a,b,c the constants) indicated that both soil temperature and soil water content could explain 68.6%~73.9% of seasonal variation in soil respiration rates.Soil temperature and soil water content could explain 67.8%~73.8%,1.2%~4.77% seasonal variation of them.Furthermore,soil temperature would become a mainly limiting factor for soil respiration in the experiment.The Q10 values were 2.12(soil surface) and 2.51(5 cm soil depth).(2) HN(309.43±17.24 mg CO2/m2·h) and MN(303.82±11.50 mg CO2/m2·h) at 0.05 levels were significantly stimulated soil respiration in the forest compared with the control plot(CK,269.28±13.78 mg CO2/m2·h) after 3 months,HN(272.42±13.25 mg CO2/m2·h) was significantly increased compared with those in CK(234.51±12.77 mg CO2/m2·h) after 4 months.However, there was no significant differences between nitrogen addition a

关 键 词：土壤呼吸 Q10值 氮沉降 常绿阔叶林 川西南 

分 类 号：S714.5[农业科学—林学]