| 季节非对称升温对喀斯特土壤CO2释放的影响 |
| 摘要点击 1744 全文点击 582 投稿时间：2017-09-04 修订日期：2017-10-10 |
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| 中文关键词 非对称升温 对称升温 温度系数(Q10) 土壤CO2通量 喀斯特 |
| 英文关键词 asymmetric warming symmetric warming temperature coefficient (Q10) soil CO2 efflux Karst |
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| 中文摘要 |
| 全球变暖呈现季节非对称升温特征，若在研究全球变化对生态系统的影响时未充分考虑该特征，很可能导致研究结果失真.基于红外线辐射增温法，野外模拟不同升温情景下喀斯特土壤CO2释放的短期（4 a）特征.升温情景包括不升温（对照）、对称升温（全年同步升温2.0℃）和非对称升温（冬春/夏秋季升温幅度为2.5℃/1.5℃、3.0℃/1.0℃、3.5℃/0.5℃和4.0℃/0℃）.结果表明，与对照相比，升温样地土壤CO2通量显著提高，增加了0.26 μmol·（m2·s）-1，增幅为17.41%，其中冬春季通量增加了0.23 μmol·（m2·s）-1.在平均升温2.0℃情景下，土壤CO2释放的温度系数（Q10）变幅为1.53~3.24之间，平均值为2.23.对称升温处理中夏秋季土壤CO2通量升温贡献率（80%）远高于冬春季（20%）；非对称升温处理夏秋季和冬春季平均升温贡献率相当（46%和54%）.5个升温情景下CO2通量和Q10呈现随升温的非对称性增加而降低的趋势，其中对称升温处理CO2通量显著高于中度、高度和极端非对称升温处理.各处理中，夏秋季Q10均大于冬春季，这可能与土壤含水量、土壤微生物、可溶性无机碳和植被生长等有关.研究揭示，基于对称升温情景可能会高估全球变暖对喀斯特土壤CO2释放的影响. |
| 英文摘要 |
| Seasonal asymmetric warming is one of the distinguishing features of global warming. However, if this feature is not considered in studying the effects of global changes on terrestrial ecosystems, it might probably cause misunderstanding of these studies. The releasing features of soil CO2 in Karst regions under various warming scenarios were simulated following a four-year continuous warming period using infrared radiators. A total of six treatments was arranged:no warming (ambient temp, CK); symmetric warming (ambient plus 2.0℃ full year, SW); and, lowly, moderately, highly, and extremely asymmetric warming (ambient plus 2.5℃/1.5℃, 3.0℃/1.0℃, 3.5℃/0.5℃, and 4.0℃/0℃ in the winter-spring/summer-autumn seasons, respectively, LAW, MAW, HAW, and EAW). The results showed that compared to CK, soil CO2 efflux in all the warming plots significantly increased by 0.26 μmol·(m2·s)-1, or 17.41%. In the winter-spring seasons, soil CO2 efflux in the warming treatments increased by 0.23 μmol·(m2·s)-1. The Q10 values ranged from 1.53 to 3.24 with an average of 2.23 under the scenario of warming up by 2.0℃. The warming-induced contribution of CO2 efflux in the summer-autumn seasons (80%) was obviously higher than that in the winter-spring seasons (20%) in the SW treatment, whereas the mean contribution in the summer-autumn seasons (46%) was closer to that in the winter-spring seasons (54%) in the asymmetric warming treatments. Both soil CO2 efflux and Q10 showed a tendency towards decrease with the increase in the asymmetry of warming under the five warming scenarios. The soil CO2 efflux in the SW treatment was significantly (P<0.05) higher than those in the MAW, HAW, and EAW treatments. The Q10 values in the summer-autumn seasons was larger than those in the winter-spring seasons under each warming treatment or across all warming treatments, which was probably related to soil water content, soil microbe, dissolved inorganic carbon, and vegetation growth. The results revealed that it may potentially overestimate the effects of global warming on soil CO2 releasing subject to symmetric warming. |
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