盐湖区生态系统碳密度及其分配格局

Carbon Density and Its Distribution Pattern of Ecosystem in Saline Region

由于对陆地生态系统土壤、植被碳蓄积量了解的缺乏,故在预测气候变化中存在较大分歧,因此很有必要对不同生态系统碳分布情况进行研究。本文以干旱盐湖为研究对象,探究盐湖生态系统碳分布特征。结果表明：土壤有机碳密度分布随土层深度的增加而降低,土壤无机碳呈无规律分布;100 cm土层内有机碳密度介于7.55-15.75 kg·m^-2之间,平均为12.54 kg·m^-2,占植物群落和土壤总有机碳密度的97.84%。黑果枸杞和铃铛刺为盐生群落的优势种,地上平均生物量为261.38 g·m^-2,占总生物量的70.49%,草本植物群落平均生物量仅为109.45g·m^-2;灌木和草本层地上生物量显著高于凋落物层（84.81±9.22）g·m^-2和（79.76±8.61）g·m^-2。盐生植物地下生物量随土层的增加而降低,0-100 cm土层总地下生物量为77.74 g·m^-2。盐生植物总生物量碳密度为276.48 g·m^-2,其中地上、凋落物和地下生物量分别占62.09%、25.75%和12.16%;地上植被和凋落物碳密度显著高于草本植物,根系生物量碳密度在剖面上分布不均,96.55%集中在0-50 cm土层。盐生植物地上地下以及凋落物平均碳含量43.09%,与经验系数（50%）换算得到碳密度相比实际碳密度高出13.80%,这将对植被碳储量的估算产生较大的偏差。

Saline vegetation in arid area is widely distributed,and the plant species are numerous,which plays an important role in the ecosystem carbon balance and regional climate regulation.In this paper,the field investigation in the Dabancheng saline lake area in Xinjiang and the indoor analysis were carried out so as to study the characteristics of carbon density distribution of saline vegetation and soil in this arid area.The results showed that the soil organic carbon density decreased with the increase of soil depth,it varied in a range of 7.55-15.75 kg·m^-2 within0-100 cm soil layer,and its average value was 12.54 kg·m^-2 and accounted for 97.84%of the total organic carbon density of plant community and soil.Lycium ruthenicum and Halimodendron halodendron are the dominant species in the halophyte communities,their average aboveground biomass was 261.38 g·m^-2 and accounted for 70.49%of the total biomass.The biomass of herbaceous plant community was 109.45 g·m^-2.The aboveground biomasses of shrub and herb layers were significantly higher than the biomasses of their litter layers（84.81±9.22）and（79.76±8.61）g·m^-2.The underground biomass of halophytes decreased with the increase of soil depth,and it in 0-100 cm soil layer was 77.74 g·m^-2.The carbon density of total biomass of halophytes was 276.48 g·m^-2,in which the aboveground,litter and underground biomasses accounted for 62.09%,25.75%and 25.75%of the total respectively.The carbon density of aboveground vegetation and litters was significantly higher than that of herbaceous plants,that of root biomass varies and its 96.55%concentrated in 0-50 cm soil layer.The average carbon content of aboveground,underground and litter of halophytes was 43.09%,which was 13.80%higher than the value estimated with empirical coefficient（50%）and produced high deviation in estimating vegetation carbon reserve.