火干扰对小兴安岭白桦沼泽和落叶松-苔草沼泽凋落物和土壤碳储量的影响

火干扰在湿地生态系统中起着重要的作用,尽管湿地占全球陆地生态系统很小一部分,却是陆地生态系统一个重要的碳汇。然而关于火干扰对我国小兴安岭森林沼泽生态系统土壤碳库影响的研究鲜有报道。因此选取两种森林沼泽典型地段进行土壤取样,研究火干扰对小兴安岭白桦(Betula platyphylla)沼泽和落叶松(Larix gmelinii)-苔草(Carex schmidtii)沼泽地表凋落物和土壤碳储量(0—50 cm)的影响。研究结果表明:①重度火烧使得白桦沼泽地表凋落物量和碳储量降低了36.36%(0.50 kg/m2)和35.52%(0.23 kg C/m2),而轻度火烧无显著影响;轻度火烧和重度火烧落叶松-苔草沼泽地表凋落物量和碳储量分别减少了45.32%(0.99 kg/m2)和44.66%(0.42 kg C/m2)、50.42%(1.10 kg/m2)和49.71%(0.47 kg C/m2);②白桦沼泽和落叶松-苔草沼泽两者对照样地、轻度火烧样地、重度火烧样地的土壤碳储量(0—50 cm)分别为(23.55±6.34)kg C/m2、(18.50±8.16)kg C/m2、(32.50±7.22)kg C/m2和(20.89±2.59)kg C/m2、(23.52±16.03)kg C/m2、(21.75±6.60)kg C/m2,然而火干扰对两种森林沼泽土壤碳储量(0—50 cm)影响不显著。研究结果可为我国东北开展森林湿地计划火烧和碳管理提供理论依据。

Effects of fire disturbance on litter mass and soil carbon storage of Betula platyphylla and Larix gmelinii-Carex schmidtii swamps in the Xiaoxing'an Mountains of Northeast China

Fire disturbance plays an important role in wetland ecosystems. Although wetlands account for a small percentage of the earth's land surface, they are an important global terrestrial carbon sink. A large amount of carbon stored in wetland soils could be released as carbon dioxide into the atmosphere after fire and this could have a significant impact on global warming. It is for these reasons that soil carbon storage in wetlands after fire disturbance has attracted much research attention in recent years. Previous studies on the influence of fire disturbance on forested swamp ecosystems in the Xiaoxing'an Mountains of Northeast China have lacked adequate reports. Therefore, the objective of this study was to describe both the litter mass and soil carbon storage changes after fire disturbance in two different forested swamp ecosystems to provide a theoretical basis for restoration of forested swamp ecosystems and sustainable wetland management. Soil samples from Betula platyphylla and Larix gmelinii-Carex schmidtii forested swamps in the Xiaoxing'an Mountains of Northeast China were collected from plots disturbed by different intensities of fire and control plots to comprehensively investigate the effects of fire disturbance on litter mass and soil carbon storage (within 0-50 cm depth) of the ecosystems. The results showed the following: 1) The surface litter mass of the control plots, the low intensity fire plots and the high intensity fire plots were 1.37 kg/m² (0.65 kg C/m²), 1.36 kg/m² (0.62 kg C/m²), and 0.87 kg/m² (0.42 kg C/m²), respectively, in the B. platyphylla swamps and 2.19 kg/m² (0.94 kg C/m²), 1.20 kg/m² (0.52 kg C/m²), and 1.09 kg/m² (0.47 kg C/m²), respectively, in the L. gmelinii-C. schmidtii swamps. The surface litter mass and carbon storage in the B. platyphyll swamp decreased by 36.36% (0.50 kg/m²) and 35.52% (0.23 kg C/m²), respectively, after high intensity fire disturbance but no significant changes were detected after low intensity fire disturbance. The surface litter mass and carbon storage of the L. gmelinii-C. schmidtii swamps decreased by 45.32% (0.99 kg/m²) and 44.66% (0.42 kg C/m²), respectively, after low intensity fire disturbance and 50.42% (1.10 kg/m²) and 49.71% (0.47 kg C/m²), respectively, after high intensity fire disturbance. 2) The soil carbon storage of the control plots, low intensity fire plots and high intensity fire plots was (23.55±6.34) kg C/m², (18.50±8.16) kg C/m², and (32.50±7.22) kg C/m², respectively, in the B. platyphylla swamps and (20.89±2.59) kg C/m², (23.52±16.03) kg C/m², and (21.75±6.60) kg C/m², respectively, in the L. gmelinii-C. schmidtii swamps. There was no significant difference between different sampling plots at 0-50 cm depth. However the soil carbon storage of the high intensity fire plots at 0-10 cm in the L. gmelinii-C. schmidtii swamps was decreased by 62.58% (4.61 kg C/m²) and 60.51% (4.22 kg C/m²) compared with the control plots and low intensity fire plots, respectively, at the same depth. There were significant (P<0.01) differences between the high intensity fire plot and the control plot and between the high intensity fire plot and low intensity fire plot (P<0.01). This study aimed to provide useful information for the carbon management and prescribed fire disturbance in the development of the forested wetland ecosystems in Northeast China.