不同龄级及林分密度天山云杉的碳储量及其分配特征

Carbon storage and distribution characteristics of Picea schrenkiana var.tianschanica natural forest at different age classes and stand densities

为了探究天山北麓不同龄级及林分密度天山云杉天然林生态系统的碳储量及其在各层次(植被层、枯落物层、土壤层)分配格局的变化,分别选择天山北麓中龄林、近熟林和成熟林3种龄级下的低密度(300~500株·hm^(-2))、中密度(500~600株·hm^(-2))、高密度(600~800株·hm^(-2))3种林分密度共9种天山云杉天然林为研究对象,采用野外调查和室内分析相结合的方法,对天山云杉天然林生态系统中不同层次的碳储量进行估算。结果表明:天山云杉天然林乔木层组分地上和地下生物量在中龄林和近熟林中,随林分密度的增大而升高,而在成熟林中则随林分密度的增大呈先升高后降低的变化趋势。在天山云杉天然林草本层与枯落物层中,枯落物层组分生物量为主要分配,占74.46%~99.45%;草本层组分生物量仅占0.55%~25.54%。天山云杉天然林的植被碳储量在中龄林中,随林分密度增大而升高,而在近熟林、成熟林中则随林分密度增大呈先降低后升高的变化趋势;在天山云杉天然林各林分中,土壤碳储量随龄级和林分密度的增大呈先降低后升高的趋势;生态系统碳储量在中龄高密度林最高(570.65 t·hm^(-2)),而在中龄低密度林最低(287.21 t·hm^(-2))。天山云杉天然林生态系统的碳储量空间分布格局为:土壤层碳储量占比最高,为49.74%~72.92%,其次是乔木层碳储量占30.22%~49.54%,草本层和枯落物层的碳储量占比仅为0.32%~2.28%。土壤层是天山云杉天然林生态系统的主要碳库,天山云杉天然林生态系统在生长过程中能显著地积累有机碳,中龄高密度林有助于生物量及碳含量的积累,近熟林、成熟林的高密度林应进行适量的间伐,提高林分的固碳能力。

To explore variations in carbon storage and distribution patterns across various layers(vegetation layer,litter layer,and soil layer)of different age classes and different densities of Picea schrenkiana var.tianschanica natural forest ecosystem in the northern foot of Tianshan Mountains,a total of 9 kinds of P.schrenkiana var.tianschanica natural forest with low(300~500 tree·hm^(-2)),medium(500~600 tree·hm^(-2))and high(600~800 tree·hm^(-2))stand densities under three age classes of the middle⁃aged forest,near⁃mature forest and mature forest were selected as the research objects.Carbon storage at different levels in the natural forest ecosystem of P.schrenkiana var.tianschanica was estimated by field investigation and indoor analysis.The results showed that for the aboveground and belowground biomass of tree layer components in P.schrenkiana var.tianschanica,natural forest increased with an increase in stand density in middle⁃aged and near⁃mature forests.In contrast,in mature forests,it increased first and then decreased with an increase in stand density.In the herb and litter layers of the natural forest of P.schrenkiana var.tianschanica,the biomass of the litter layer was the main component,accounting for 74.46%~99.45%;the herb layer components accounted for only 0.55%~25.54%.The vegetation carbon storage of the P.schrenkiana var.tianschanica natural forest increased with an increase in stand density in the middle⁃aged forest but decreased first and then increased with an increase in stand density in near⁃mature and mature forests.Soil carbon storage in the P.schrenkiana var.tianschanica natural forest first decreased and then increased with an increase in age class and stand density.The ecosystem carbon storage was the highest in the middle⁃aged high⁃density stand(570.65 t·hm^(-2))and the lowest in the middle⁃aged low⁃density stand(287.21 t·hm^(-2)).The spatial distribution pattern of carbon storage in the P.schrenkiana var.tianschanica natural forest ecosystem was as follows:carbon storage in the soil layer accounted for the highest proportion,which was 49.74%~72.92%,followed by carbon storage in the tree layer(30.22%~49.54%),and the proportion of carbon storage in the herb and litter layers was only 0.32%~2.28%.The soil layer serves as the primary carbon reservoir in the natural Schrenkiana spruce forest ecosystem,allowing it to effectively store organic carbon as it grows.Middle⁃to⁃high⁃density forests contribute to the accumulation of biomass and carbon.High⁃density forests in near⁃mature and mature forests should be moderately thinned to increase the carbon sequestration capacity of the stands.