With the static opaque chamber and gas chromatography technique, from January 2003 to January 2004 soil respiration was investigated in a tropical seasonal rain forest in Xishuangbanna, SW China. In this study three t...With the static opaque chamber and gas chromatography technique, from January 2003 to January 2004 soil respiration was investigated in a tropical seasonal rain forest in Xishuangbanna, SW China. In this study three treatments were applied, each with three replicates: A (bare soil), B (soil+litter), and C (soil+litter+seedling). The results showed that soil respiration varied seasonally, low from December 2003 to February 2004, and high from June to July 2004. The annual average values of CO2 efflux from soil respiration differed among the treatments at 1 % level, with the rank of C (14642 mgCO2 · m-2 · h-1)>B (12807 mgCO2 · m-2 · h-1)> A (9532 mgCO2·m-2 · h-1). Diurnal variation in soil respiration was not apparent due to little diurnal temperate change in Xishuangbanna. There was a parabola relationship between soil respiration and soil moisture at 1% level. Soil respiration rates were higher when soil moisture ranged from 35% to 45%. There was an exponential relationship between soil respiration and soil temperature (at a depth of 5cm in mineral soil) at 1% level. The calculated Q10 values in this study, ranging from 2.03 to 2.36, were very near to those of tropical soil reported. The CO2 efflux in 2003 was 5.34 kgCO2 · m-2 · a-1 from soil plus litter plus seedling, of them 3.48 kgCO2 · m-2 · a-1 from soil (accounting for 62.5%), 1.19 kgCO2 · m-2 · a-1 from litter (22.3%) and 0.67 kgCO2 · m-2 · a-1 from seedling (12.5%).展开更多
氮沉降可能改变森林土壤CO_2通量,已有研究结果对氮沉降作用的方向和强度上具有很大的不确定性。通过整合已有模拟氮沉降的野外监测数据,评估了氮沉降对中国森林土壤CO_2通量的影响。结果表明,氮沉降平均降低了中国土壤CO_2通量的8.7%,...氮沉降可能改变森林土壤CO_2通量,已有研究结果对氮沉降作用的方向和强度上具有很大的不确定性。通过整合已有模拟氮沉降的野外监测数据,评估了氮沉降对中国森林土壤CO_2通量的影响。结果表明,氮沉降平均降低了中国土壤CO_2通量的8.7%,且这种影响对次生林和人工林影响较大,而对原始林影响较小。同时,氮沉降对土壤CO_2通量的影响对阔叶林、针叶林和针阔混交林均无显著影响,但显著降低了竹林土壤CO_2通量的36%。施加>100 kg N·hm^(-2)·a^(-1)时才会对森林土壤CO_2通量造成显著降低,且施加硝酸铵的降低大于尿素。氮沉降的这种影响主要是由于过多的氮抑制了土壤微生物活性造成的。展开更多
As a result of several decades of peat extraction, the area of cutaway peatlands in Finland totals ca. 50,000 ha. Furthermore, some 2000 - 3000 ha of peatlands are abandoned annually from active peat extraction. Fores...As a result of several decades of peat extraction, the area of cutaway peatlands in Finland totals ca. 50,000 ha. Furthermore, some 2000 - 3000 ha of peatlands are abandoned annually from active peat extraction. Forestry is considered to be their main after-use option. However, since cutaway peat is generally rich in nitrogen, but poor in phosphorus and potassium, soil amelioration measures are needed for successful vegetation and afforestation. Soil preparations bringing mineral soil into peat surface or recycling of ash containing P and K are alternative ways for soil amelioration. We studied the initial effects of soil preparation and ash fertilization on soil CO<sub>2</sub>-effluxes and colonisation of cutaway peat by vegetation. Oppositely to the previous studies, this study shows that carbon released from the residual peat may be so high that the ash-fertilized cutaway peatlands still act as sources of carbon even after afforestation. However, even though the CO<sub>2</sub>-effluxes following ash fertilization or soil preparation may occasionally exceed the carbon sequestration into growing tree stands, afforestation mostly compensates the CO<sub>2</sub>-effluxes if also we take into consideration the below-ground biomass. In conclusion, our study shows that although ash fertilization enhances the CO<sub>2</sub>-effluxes into the atmosphere, it has beneficial effects on the environment by enabling rapid colonisation of vegetation on these sites which would remain vegetationless for decades without soil amelioration.展开更多
The recovering logged-over forest ecosystem increases the CO2 efflux into the atmospheric carbon pool in response to environmental factors to changes in the soil temperature and moisture. These CO2 outbursts can have ...The recovering logged-over forest ecosystem increases the CO2 efflux into the atmospheric carbon pool in response to environmental factors to changes in the soil temperature and moisture. These CO2 outbursts can have a marked influence on the ecosystem carbon balance and thereby affect the atmospheric carbon pool. The study was conducted in the 10-year-old logged-over forest of Sungai Menyala forest, Port Dickson, Negeri Sembilan, Malaysia. The measurements of soil CO2 efflux were conducted using the continuous open flow chamber technique connected to a multi gas-handling unit and infrared CO2/H2O gas analyser. The aim of this study was to determine the soil CO2 efflux and the environmental variables and likewise the impact of environmental factors on soil CO2 efflux. Post-hoc comparisons were made using the Tukey test （p 〈 0.05）, and multiple linear regression to determine the impact of environmental factors on soil CO2 efflux. Soil CO2 efflux ranged from 100.22-553.40 mg m^-2 h^-1 with the highest efflux in the afternoon attributed to an increase in soil temperature and low moisture. A higher soil temperature and low moisture signify an influential factor as the forest is recovering from logging activity. Furthermore, the predictor environmental variables： SOC （soil organic carbon）, TOC （total organic carbon）, SMC （soil moisture content）, Bulk Density, SOCstock （soil organic carbon stock）, TAGB （total above ground carbon biomass）, Below Ground Carbon Biomass, soil pH, Nitrogen to Carbon ratio account for the spatial and temporal variation in soil CO： efflux into the atmosphere. The analysis revealed a strong correlation between soil CO2 efflux, changes soil properties and environmental factors with an R^2 more than 0.80 at p 〈 0.01. This is proven that logging activity accounts for the changes in environmental factors to influence soil CO2 efflux rate within 10-years of logging and forest recovering.展开更多
基金This work was supported by the Knowledge Innovation Program of the Chinese Academy of Sciences(Grant No.KZCX1-SW-01)the Basic Science Development Program of China(Grant No.2002CB412501)the National Natural Science Foundation of China(Grant No.40173039).
文摘With the static opaque chamber and gas chromatography technique, from January 2003 to January 2004 soil respiration was investigated in a tropical seasonal rain forest in Xishuangbanna, SW China. In this study three treatments were applied, each with three replicates: A (bare soil), B (soil+litter), and C (soil+litter+seedling). The results showed that soil respiration varied seasonally, low from December 2003 to February 2004, and high from June to July 2004. The annual average values of CO2 efflux from soil respiration differed among the treatments at 1 % level, with the rank of C (14642 mgCO2 · m-2 · h-1)>B (12807 mgCO2 · m-2 · h-1)> A (9532 mgCO2·m-2 · h-1). Diurnal variation in soil respiration was not apparent due to little diurnal temperate change in Xishuangbanna. There was a parabola relationship between soil respiration and soil moisture at 1% level. Soil respiration rates were higher when soil moisture ranged from 35% to 45%. There was an exponential relationship between soil respiration and soil temperature (at a depth of 5cm in mineral soil) at 1% level. The calculated Q10 values in this study, ranging from 2.03 to 2.36, were very near to those of tropical soil reported. The CO2 efflux in 2003 was 5.34 kgCO2 · m-2 · a-1 from soil plus litter plus seedling, of them 3.48 kgCO2 · m-2 · a-1 from soil (accounting for 62.5%), 1.19 kgCO2 · m-2 · a-1 from litter (22.3%) and 0.67 kgCO2 · m-2 · a-1 from seedling (12.5%).
文摘氮沉降可能改变森林土壤CO_2通量,已有研究结果对氮沉降作用的方向和强度上具有很大的不确定性。通过整合已有模拟氮沉降的野外监测数据,评估了氮沉降对中国森林土壤CO_2通量的影响。结果表明,氮沉降平均降低了中国土壤CO_2通量的8.7%,且这种影响对次生林和人工林影响较大,而对原始林影响较小。同时,氮沉降对土壤CO_2通量的影响对阔叶林、针叶林和针阔混交林均无显著影响,但显著降低了竹林土壤CO_2通量的36%。施加>100 kg N·hm^(-2)·a^(-1)时才会对森林土壤CO_2通量造成显著降低,且施加硝酸铵的降低大于尿素。氮沉降的这种影响主要是由于过多的氮抑制了土壤微生物活性造成的。
文摘As a result of several decades of peat extraction, the area of cutaway peatlands in Finland totals ca. 50,000 ha. Furthermore, some 2000 - 3000 ha of peatlands are abandoned annually from active peat extraction. Forestry is considered to be their main after-use option. However, since cutaway peat is generally rich in nitrogen, but poor in phosphorus and potassium, soil amelioration measures are needed for successful vegetation and afforestation. Soil preparations bringing mineral soil into peat surface or recycling of ash containing P and K are alternative ways for soil amelioration. We studied the initial effects of soil preparation and ash fertilization on soil CO<sub>2</sub>-effluxes and colonisation of cutaway peat by vegetation. Oppositely to the previous studies, this study shows that carbon released from the residual peat may be so high that the ash-fertilized cutaway peatlands still act as sources of carbon even after afforestation. However, even though the CO<sub>2</sub>-effluxes following ash fertilization or soil preparation may occasionally exceed the carbon sequestration into growing tree stands, afforestation mostly compensates the CO<sub>2</sub>-effluxes if also we take into consideration the below-ground biomass. In conclusion, our study shows that although ash fertilization enhances the CO<sub>2</sub>-effluxes into the atmosphere, it has beneficial effects on the environment by enabling rapid colonisation of vegetation on these sites which would remain vegetationless for decades without soil amelioration.
文摘The recovering logged-over forest ecosystem increases the CO2 efflux into the atmospheric carbon pool in response to environmental factors to changes in the soil temperature and moisture. These CO2 outbursts can have a marked influence on the ecosystem carbon balance and thereby affect the atmospheric carbon pool. The study was conducted in the 10-year-old logged-over forest of Sungai Menyala forest, Port Dickson, Negeri Sembilan, Malaysia. The measurements of soil CO2 efflux were conducted using the continuous open flow chamber technique connected to a multi gas-handling unit and infrared CO2/H2O gas analyser. The aim of this study was to determine the soil CO2 efflux and the environmental variables and likewise the impact of environmental factors on soil CO2 efflux. Post-hoc comparisons were made using the Tukey test （p 〈 0.05）, and multiple linear regression to determine the impact of environmental factors on soil CO2 efflux. Soil CO2 efflux ranged from 100.22-553.40 mg m^-2 h^-1 with the highest efflux in the afternoon attributed to an increase in soil temperature and low moisture. A higher soil temperature and low moisture signify an influential factor as the forest is recovering from logging activity. Furthermore, the predictor environmental variables： SOC （soil organic carbon）, TOC （total organic carbon）, SMC （soil moisture content）, Bulk Density, SOCstock （soil organic carbon stock）, TAGB （total above ground carbon biomass）, Below Ground Carbon Biomass, soil pH, Nitrogen to Carbon ratio account for the spatial and temporal variation in soil CO： efflux into the atmosphere. The analysis revealed a strong correlation between soil CO2 efflux, changes soil properties and environmental factors with an R^2 more than 0.80 at p 〈 0.01. This is proven that logging activity accounts for the changes in environmental factors to influence soil CO2 efflux rate within 10-years of logging and forest recovering.
