采伐对大兴安岭落叶松-苔草沼泽土壤有机碳储量的影响

Effects of Harvesting on Soil Organic Carbon Storage of Boreal Larix gmelinii-Carex schmidtii Wetlands in Daxing'anling

对比分析了大兴安岭不同采伐强度(未采伐—对照、轻度择伐—25%、中度择伐—35%、强度择伐—50%)下落叶松-苔草沼泽土壤密度、土壤有机碳含量与土壤有机碳储量的变化,揭示了采伐干扰对森林湿地土壤有机碳储量的影响规律。结果表明:①中度择伐与强度择伐显著提高了其土壤密度,轻度择伐则对土壤密度无显著影响;②轻度择伐显著提高了其表层和深层土壤的有机碳含量,中度择伐与强度择伐显著降低了其各土壤层和中上部土壤层的有机碳含量;③轻度择伐显著提高了其深层土壤有机碳储量,中度择伐和强度择伐则分别显著降低了中下部和中部土壤层的有机碳储量;④轻度择伐样地土壤有机碳储量较对照提高了16.2%(P>0.05),中度择伐和强度择伐样地土壤有机碳储量分别较对照降低了48.5%和30.1%(P<0.05)。

This paper compared the changes of soil bulk density,soil organic carbon concentration and soil organic carbon storage five years after harvesting with different intensities,i.e.unharvesting（the control）,low-intensity selective cutting（25%）,moderate-intensity selective cutting（35%） and heavy-intensity selective cutting（50%） and revealed the influence of harvesting intensity on soil organic carbon storage of Larix gmelinii-Carex schmidtii wetlands in Daxing＇anling.The key results are as follows：（1） the soil bulk density did not differ significantly at the low-intensity selective cutting sites（0.22 ± 0.06 1.17 ± 0.22 g.cm-3）,and increased significantly at the moderate-intensity selective cutting（0.55 ± 0.23 1.58 ± 0.07 g.cm-3） and heavy-intensity selective cutting（0.49 ± 0.24 1.47 ± 0.08 g.cm-3） sites,compared with that at control（0.31 ± 0.09 1.18 ± 0.13 g.cm-3） sites（28.0% 137.0% or 19.7% 98.1%）（P 0.05）;（2） the low-intensity selective cutting（25.55 ± 1.01 253.57 ± 18.89 g.kg-1） led to a significant increase of soil organic carbon concentration（53.8% 126.7%） in the surface and deep layer,however,the moderate-intensity selective cutting（1.52 ± 1.32 62.70 ± 54.33 g.kg-1） and heavy-intensity selective cutting（7.91 ±5.59 102.59 ±67.49 g.kg-1） significantly reduced the soil organic carbon concentration in each layer（62.0% 89.0%） or the middle-upper part layer（37.8% 85.0%）（P 0.05）;（3） the low-intensity selective cutting（2.90 ± 0.51 5.69 ± 1.55 kg.m-2） resulted in a significant increase of soil organic carbon storage（90.7% 128.8%） in the deep layers,while moderate-intensity selective cutting（0.25 ± 0.12 4.65 ± 3.52 kg.m-2） and heavy-intensity selective cutting（1.14 ± 0.79 4.42 ± 1.64 kg.m-2） declined significantly the soil organic carbon storage in the lower-middle part（76.4% 83.0%） or the middle part layer（56.8%）（P 0.05）;（4） harvesting caused a significant increase of soil organic carbon storage by 16.2% at the low-intensity selective cutting sites（20.88 ± 2.62 kg.m-2） or a significant decrease by 48.5% and 30.1% at the moderate-intensity selective cutting（9.01 ± 5.90 kg.m-2） and heavy-intensity selective cutting（12.22 ± 4.25 kg.m-2） sites,respectively,compared with the unharvested stand（17.49 ± 3.71 kg.m-2）（P 0.05）.Therefore,low-intensity selective cutting should be adopted to manage Larix gmelinii – Carex schmidtii wetlands from the carbon sequestration point of view.