施肥对板栗林土壤CO_2通量的影响

Effects of fertilization on soil CO_2 flux in Castanea mollissima stand

2011年6月—2012年6月,在浙江省临安市典型板栗林样地布置施肥试验,研究板栗林土壤CO2通量与环境因子的关系.试验设置不施肥(对照)、施无机肥、有机肥及有机无机混合肥(1/2无机肥+1/2有机肥)4个处理.利用静态箱法测定土壤CO2排放速率,以及土壤温度、含水量和水溶性有机碳(WSOC)含量.结果表明:板栗林中土壤CO2排放呈现显著的季节性变化特征,最小值均出现在2月,最大值均出现在7、8月.施用无机肥、有机肥和有机无机混合肥的土壤年累积CO2通量比对照分别增加29.5%、47.0%和50.7%.施用无机肥的土壤WSOC含量(105.1 mg·kg-1)显著高于对照(76.6 mg·kg-1),但明显低于有机肥(133.0mg·kg-1)和混合肥处理(121.17 mg·kg-1).无机肥、有机肥和混合肥处理的土壤呼吸Q10值(1.75、1.49和1.57)均高于对照(1.47).土壤CO2排放速率与土壤5 cm温度、WSOC含量之间呈极显著正相关,但与土壤含水量没有明显的相关性.施肥导致土壤WSOC含量增加可能是板栗林地土壤CO2排放速率增加的原因之一.

In June 2011-June 2012, a fertilization experiment was conducted in a typical Castanea moUissima stand in Lin＇ an of Zhejiang Province, East China to study the effects of inorganic and organic fertilization on the soil CO2 flux and the relationships between the soil CO2 flux and environ- mental factors. Four treatments were installed, i. e. , no fertilization （ CK）, inorganic fertilization （ IF）, organic fertilization （ OF）, half organic plus half inorganic fertilization （OIF）. The soil CO2 emission rate was determined by the method of static closed ehamber/GC technique, and the soil temperature, soil moisture content, and soil water-soluble organic carbon （WSOC） concentration were determined by routine methods. The soil CO2 emission exhibited a strong seasonal pattern, with the highest rate in July or August and the lowest rate in February. The annual accumulative soil CO2 emission in CK was 27.7 t CO2 · hm-2 · a-1, and that in treatments IF, OF, and OIF was 29.5% , 47.0% , and 50.7% higher than the CK, respectively. The soil W5OC concentration in treatment IF （ 105.1 mg kg-1 ） was significantly higher than that in CK （76.6 mg · kg-1 ）, but was obviously lower than that in treatments OF （ 133.0 mg · kg-1 ） and OIF （ 121.2 mg · kg-1 ）. The temperature sensitivity of respiration （010） in treatments CK, IF, OF, and OIF was 1.47, 1.75, 1.49, and 1.57, respectively. The soil COg emission rate had significant positive correlations with the soil temperature at the depth of 5 em and the soil W5OC concentration, but no significant eorre-lation with soil moisture content. The increase of the soil WSOC concentration caused by fertilization was probably one of the reasons for the increase of soil CO_2 emission from the C. mollissima stand.