生物结皮-土壤呼吸对冬季低温及模拟增温的响应

Response of biocrust-soil system respiration to winter low temperature and simulated warming

以腾格里沙漠东南缘天然植被区藓类结皮和藻-地衣结皮-土壤为研究对象,利用开顶式生长室(OTC),采用Li-8150系统连续测定了冬季(2015年11月—2016年1月)低温环境下两类结皮-土壤呼吸的变化,分析了低温及模拟增温对两类结皮-土壤呼吸的影响.结果表明:观测期内,藓类结皮、藻-地衣结皮-土壤呼吸速率分别为-0.052~0.418、-0.032~0.493μmol·m^(-2)·s^(-1),且藓类结皮显著高于藻-地衣结皮-土壤系统.不同类型结皮-土壤呼吸速率与5 cm土壤温度和土壤体积含水量均呈显著线性正相关,增温主要是通过加速土壤水分蒸散而抑制生物结皮-土壤呼吸速率.在整个观测期,藓类结皮-土壤系统累计排放9.90 g C·m^(-2),显著高于藻-地衣结皮-土壤系统的7.00 g C·m^(-2).研究区生物结皮-土壤系统冬季累计排放7.40g C·m^(-2),是该荒漠生态系统全年碳收支的重要组成部分.

To study the effects of low temperature and simulated warming on respiration of biocrustsoil systems,intact soil columns covered by two dominant types of biocrusts（moss and algae-lichen crusts）,were collected in a natural vegetation area in the southeast fringe of the Tengger Desert.Automated soil respiration system（Li-8150） was used to measure respiration rates in biocrust-soil systems under warming（by placing them in an open top chamber） and non-warming treatments in winter（from November 2015 to January 2016）.During the whole observation period,soil respiration rates covered by moss crusts were significantly higher than those covered by algae-lichen crusts,which were-0.052 to 0.418 and-0.032 to 0.493 μmol·m-2·s-1,respectively.The respiration rates of the two types of biocrust-soil systems showed significant positive linear correlations with soil temperature and volumetric soil water content at 5 cm depth.Through speeding-up the evaporation rates of soil moisture,imitated warming in winter impeded respiration rates of the two biocrust-soil systems.During the whole observation period,the cumulative carbon（C） release by moss crust-soil system（9.90 g C·m-2） was dramatically higher than that of algae-lichen crust-soil system（7.00 g C·m-2）.The cumulative C release by the biocrust-soil systems in this region in winter was 7.40 g C·m-2,thus comprising an important part of annual C budget in the desert ecosystems.