不同林龄杉木人工林碳储量及其分配格局

基于广西北部杉木主产区45块1000 m²样地的调查,研究幼龄林、中龄林、近熟林、成熟林、过熟林5种林龄杉木植被与土壤碳储量的分配格局.结果表明: 杉木人工林生态系统总碳储量表现为过熟林(345.59 t·hm^-2)>成熟林(331.14 t·hm^-2)>近熟林(299.11 t·hm^-2)>幼龄林(187.60 t·hm^-2)>中龄林(182.81 t·hm^-2).不同林龄碳储量分布格局均为土壤层>植被层>凋落物层,地下部分>地上部分.其中,植被层为34.80～134.55 t·hm^-2,占总碳储量的18.6%～38.9%,随林龄的增加而增加;凋落物层为1.26～2.07 t·hm^-2,占总碳储量的0.4%～1.1%;土壤层为149.24～206.02 t·hm^-2,占总碳储量的61.9%～80.0%.植被层碳储量以乔木层(33.51～133.7 t·hm^-2)最大,占92.8%～98.9%.其中,乔木层各器官碳储量以树干(20.98～95.68 t·hm^-2)最大,占乔木层碳储量的62.6%～72.6%,随林龄的增加而增加;枝、叶碳储量分别占4.8%～11.0%和11.1%～14.2%,随林龄的增加而减小,在过熟林阶段有所上升;根的碳储量占11.3%～12.3%,波动较小,比较稳定.

Carbon storage and allocation in Cunninghamia lanceolata plantations with different stand ages.

Based on survey of 45 plots (1000 m² each) of five different stand ages, i.e., young, middle-aged, pre-mature, mature, and over-mature plantations, in the main production area of Cunninghamia lanceolata in the north of Guangxi, China, carbon (C) storage and its allocation in vegetation and soil were studied. The results showed that total carbon storage of C. lanceolata plantations changed in the order of over-mature plantation (345.59 t·hm^-2) > mature plantation (331.14 t·hm^-2) > pre-mature plantation (299.11 t·hm^-2) > young plantation (187.60 t·hm^-2) > middle-aged plantation (182.81 t·hm^-2). For all the stand ages, soil stored the greatest amount of carbon, C pool in vegetation layer was the second, while C storage in the litter layer was lowest. On average, C storage in belowground layer was greater than that in aboveground layer. Carbon storage in aboveground vegetation layer ranged from 34.80 to 134.55 t·hm^-2, which contributed 18.6% to 38.9% to the total ecosystem carbon storage and increased with ages. Carbon storage in the litter layer ranged from 1.26 to 2.07 t·hm^-2, which only contributed 0.4%-1.1% to the total ecosystem carbon storage. Carbon storage in the soil layer ranged from 149.24 to 206.02 t·hm^-2 and represented 61.9%-80.0% of ecosystem carbon storage. Canopy layer stored the highest amount of carbon (33.51-133.7 t·hm^-2) and comprised 92.8%-98.9% of aboveground vegetation carbon storage. Within the canopy layer, carbon storage differed with compartments. Stems stored the highest amount of carbon (20.98-95.68 t·hm^-2) by accounting for 62.6%-72.6% of carbon storage in the canopy layer, which increased with ages. The branches and leaves accounted for 4.8%-11.0% and 11.1%-14.2% of C stored in the canopy layer, respectively, which all decreased with ages, while increased to some extent in the over-mature plantation. Roots occupied 11.3%-12.3% of carbon storage in the canopy layer with small fluctuation with the stand age.