新疆达坂城盐湖不同植物群落土壤呼吸研究

摘要

新疆盐湖分布地域广泛而不均匀.盐湖生态系统碳循环是干旱区生态系统碳循环的重要组分,其动态变化对干旱区碳平衡有着重要的影响,然而目前对干旱区盐湖土壤呼吸的研究相对薄弱.为探讨盐湖沿岸不同植物群落土壤呼吸及其影响因子,以新疆达坂城盐湖为典型研究区,选取沿岸小獐毛(Aeluropus pungens)、鸢尾(Iris tectorum)、芨芨草(Achnatherum splendens)、黑果枸杞(Lycium ruthenicum Murr)植物群落土壤为主要研究对象,以周边农田撂荒地为对照,利用LI-COR 8100对达坂城盐湖沿岸4种植物群落和撂荒地土壤呼吸进行了监测,结果表明:盐湖沿岸土壤呼吸具有明显的日变化.监测时段内土壤呼吸作用均为单峰曲线,排放通量在13:00左右最高,07:00左右出现最低值.不同群落土壤呼吸速率变化范围在0.89~4.34μmol/(m2·s)之间,撂荒地为1.77~3.48μmol/(m2·s),表现为黑果枸杞>小獐毛>芨芨草>撂荒地>鸢尾.不同植物群落地下生物量影响土壤CO2排放,研究区土壤呼吸日平均累计CO2排放通量为209.28 mg/(m2·d).土壤呼吸速率与土壤5 cm温度呈现显著正相关(P<0.01),可以解释土壤呼吸日变化的69%~78%,是决定达坂城盐湖土壤呼吸变化的主要因子.利用土壤5 cm处温度得到小獐毛、鸢尾、芨芨草、黑果枸杞、撂荒地的Q10值分别为2.30、1.24、1.20、1.57、1.28,小獐毛样地土壤呼吸对温度更敏感.除撂荒地外各群落土壤呼吸与土壤湿度呈显著负相关(R2=0.38~0.51).该研究对进一步明确干旱区盐湖生态系统土壤呼吸变化规律和影响因素,以及对估算区域碳平衡及"碳汇"功能具有重要意义.%The distribution of salt lakes in Xinjiang is broad but uneven. The carbon cycle of the salt lake ecosystem is an important component and has an important impact on carbon equilibrium in the ecosystem of the arid region. However, the research on soil respiration in salt lakes in the arid region is relative weak. A study was conducted in order to explore soil respiration and its influential factors of different plant communities along the Salt Lake in Dabancheng of Xinjiang.Aeluropus pungens,Iris tectorum,Achnatherum splendens,Lycium ruthenicum Murrwere taken as the main plant objects with the abandoned farmland around as the control, soil respiration were measured by LI-COR 8100 (Li-COR, Lincoln, NE, USA). The results showed soil respiration of Salt Lake coastal had obvious diurnal variation and appeared in the pattern of single peak, the highest point occurred at 13:00 while the lowest occurred at around 07:00. The rates of soil respiration ranged from 1.77 to 3.48 μmol/(m2·s) in CK and from 0.89 to 4.34 μmol/(m2·s) under different communities, with an order ofLycium ruthenicum Murr>Aeluropus pungens>Achnatherum splendens>Abandoned Land>Iris tectorum. Underground biomass influenced soil CO2 emissions, the daily average CO2 emission flux of soil respiration in the study region was 209.28 mg/(m2·d). Soil temperature at 5 cm depth had significant correlation with soil respiration rate, which is the dominant factor in determining the diurnal variation of soil respiration and could explain 69%-78% of it. The Q10values calculated based on soil temperature at 5 cm depth were 2.30, 1.24, 1.20, 1.57, and 1.28, soil respiration was most sensitive to soil temperature underAeluropus pungens. Except for abandoned land, there were significantly negative correlation (R2= 0.38-0.51) between soil respiration and soil moisture. The above results disclosed further soil respiration variation and influential factors of Slat Lake ecosystem in the arid region, which is helpful in estimating carbon equilibrium and sequestration.