帽儿山干扰系列次生林碳密度恢复

干扰作为森林恢复和生态演替的重要影响因子，通过其改变植被群落的组成和微环境，进而影响森林生态系统碳动态及固碳潜力。针对帽儿山地区阔叶红松原始林不同时期皆伐后形成的次生林干扰系列，包括林木采伐一次(NS,林龄56a)、采伐两次(MS,林龄25a)和采伐两次且扰动表层土壤(YD,林龄15a)的次生林，采用森林清查和异速生长方程结合的方法，旨在量化干扰方式对温带森林恢复进程中生态系统碳密度及分配格局的影响。结果表明：YD、MS和NS的0—50 cm各层次土壤有机碳含量的波动范围依次分别为10.46—29.27 mg/g、6.37—108.40 mg/g、5.21—114.34 mg/g;且随土层的加深土壤有机碳含量显著降低。表层土壤(0—20 cm)有机碳含量在各干扰处理间存在显著差异(P<0.01),而深层土壤有机碳含量差异不显著；土壤有机碳含量与容重呈显著负相关关系。表层土壤有机碳密度占土壤总有机碳密度(0—100 cm)的50%以上，YD的表层土壤有机碳密度(30.91 t/hm²)显著低于MS(54.09 t/hm²)和NS(55.1...

Carbon density recovery of disturbance sequence secondary forests in Maoershan

Disturbance is an important factor affecting forest restoration and ecological succession. It changes plant community composition and microenvironment, and then affects carbon distribution and carbon sequestration potential of forest ecosystem. In this study, we selected disturbance sequence secondary forests, i.e., the near-mature secondary forest (NS, 56 years) formed by natural succession after clear-cutting of the mixed-broadleaved Korean pine forest, the half-mature secondary forest (MS, 25 years) formed by natural succession after clear cutting of NS, and disturbed young secondary forest (YD, 15 years) formed by natural succession after clear cutting of NS and the soil has been disturbed for 15 years. We used the inventory and biometry-based measurement to examine the carbon density and its distribution. Our objectives were to quantify the effect of disturbance types and vegetation restoration on the carbon density and its distribution pattern of the temperate secondary forests in Northeast China. The results showed that the soil organic carbon content ([SOC]) of different soil layers (0-50 cm) varied from 10.46 to 29.27 mg/g, 6.37 to 108.40 mg/g, 5.21 to 114.34 mg/g in YD, MS, and NS, respectively. And the[SOC] decreased significantly with the deepening of soil layer. There were significant differences in the topsoil (0-20 cm)[SOC] among the sequence secondary forests (P<0.01), but no significant difference in subsoil. The[SOC] was negatively correlated with bulk density. The topsoil organic carbon density accounted for more than 50% of the total soil organic carbon density. The topsoil SOC density of YD (30.91 t/hm²) was significantly lower than that of MS (54.09 t/hm²) and NS (55.14 t/hm²). The carbon density of vegetation, soil (0-100 cm), and ecosystem varied from 45.63 to 98.97 t/hm², 62.09 to 91.67 t/hm², and 107.72 to 181.26 t/hm² in the three secondary forests, respectively. The carbon density of vegetation increased with the stand age, but the carbon density change trend of the tree species in different succession periods was not consistent. The carbon density of the pioneer tree species ((37.47±2.64) t/hm²) and shrub species ((0.85±0.48) t/hm²) was not significantly different among the three forest types, while the carbon density of the later species was significantly different among the three secondary forests, and varied from 4.05 t/hm² to 62.48 t/hm². The mean annual increment (MAI) of carbon density decreased from 3.04 t hm^-2 a^-1 in YD to 1.77 t hm^-2 a^-1 in NS. The difference was mainly due to the contributions of pioneer species during succession, while MAI of later species and shrub species did not differ significantly among secondary stands. These findings indicated that the soil disturbance more than ten years changed its microenvironment and bulk density, resulting in the topsoil organic carbon loss of temperate forest in Northeast China. However, the aboveground vegetation cutting disturbance had no significant effect on soil organic carbon. In the process of vegetation restoration, pioneer species promoted short-term carbon fixation, while later species determined vegetation carbon density and carbon sink potential. This provides data support and theoretical basis for the evaluation and estimation of carbon sequestration and its management in temperate forest ecosystems in northeast China.