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土壤呼吸在生态系统碳循环过程中占有重要地位,为探讨纳帕海流域生态系统土壤呼吸过程,于2014年8月中下旬期间,采用LI-8100开路式土壤碳通量测量系统对流域内7种植被类型土壤呼吸速率及其与土壤温度的响应规律进行了研究。结果表明:(1)各植被类型的土壤呼吸速率日变化都呈单峰曲线形式,最高值和最低值分别出现在13:00─16:00和2:00─8:00;(2)各植被类型土壤呼吸速率日均值为自然草地(5.506μmol·m~(-2)·s~(-1))>轻度退化草地(4.322μmol·m~(-2)·s~(-1))>高山灌丛(3.849μmol·m~(-2)·s~(-1))>中度退化草地(3.226μmol·m~(-2)·s~(-1))>重度退化草地(2.959μmol·m~(-2)·s~(-1))>高山松Pinus densata林(2.260μmol·m~(-2)·s~(-1))>青稞Hordeum vulgare Linn.var.nudum Hook.f.地(2.256μmol·m~(-2)·s~(-1));(3)当草地开垦为农田后,其土壤呼吸速率降为最低水平;(4)所有植被类型的土壤呼吸速率与5 cm土壤温度呈指数相关,其中在自然草地上,土壤温度对其土壤呼吸的影响最大,但温度敏感性却较低,重度退化草地的土壤温度对其土壤呼吸的影响最小,但温度敏感性最大。研究可见,区域内人类活动使草地退化、转变为农田等过程,导致其土壤呼吸速率显著下降。重度退化草地对温度变化所表现出的相对较高的敏感性,预示着在环境变化的影响下,生态系统过程及功能将会产生更大的波动。
Soil respiration plays an important role in the carbon cycle of the ecosystem. In order to explore the process of soil respiration in the ecosystem of the Napahai Sea basin, the open soil carbon flux measurement system LI-8100 The respiration rate of soil type under cultivation and its response to soil temperature were studied. The results showed as follows: (1) The diurnal variation of soil respiration rate in all vegetation types presented a unimodal curve with the highest and lowest values occurring at 13:00 to 16:00 and 2:00 to 8:00, respectively The daily mean values of soil respiration rate of vegetation type were 5.506μmol · m -2 · s -1> 4.322μmol · m -2 · s -1 in grassland, )> Alpine shrub (3.849μmol m -2 s -1)> moderately degraded grassland (3.226μmol m -2 s -1)> severe degraded grassland (2.959μmol · m -2 · s -1)> Pinus densata forest (2.260μmol · m -2 · s -1)> Hordeum vulgare Linn. Var. nudum Hook.f. (2.256μmol · m -2 · s -1); (3) When the grassland was reclaimed into farmland, the soil respiration rate was reduced to the lowest level; (4) Of soil respiration rate was exponential correlated with 5 cm soil temperature. Soil temperature had the greatest effect on soil respiration on natural grassland, but its temperature sensitivity was lower. Soil temperature in severely degraded grassland had the least effect on soil respiration , But the temperature sensitivity of the largest. It can be seen from the research that human activities in the region degenerate the grasslands into farmland and other processes, resulting in a significant decrease in soil respiration rate. The relatively high sensitivity of severely degraded grasslands to temperature changes indicates that there will be greater fluctuations in ecosystem processes and functions under the influence of environmental changes.