在室内控制条件下,以腾格里沙漠东南缘1964年人工固沙植被区藻类、混生和藓类结皮为对象,研究了3个温度梯度(15℃、25℃和35℃)和7个水分梯度(3%、5%、10%、15%、20%、25%和30%质量含水量)条件下其碳释放特征。在相同水分条件下,BSCs和流沙呼吸速率随着温度的增加而增加,35℃时BSCs和流沙呼吸速率达到最大值。藓类结皮的呼吸速率显著高于其他土壤类型土壤呼吸。藓类结皮Q10为1.40~3.17,藻类结皮为0.81~3.07,混生结皮为0.55~3.84,流沙为1.19~2.16。BSCs类型、水分和温度显著影响BSCs碳释放量(P < 0.001)。水分含量较高的条件下,藻类和混生结皮的呼吸速率受到了明显抑制,而对藓类结皮的呼吸速率影响不显著。 The carbon release of different types of biological soil crusts (BSC) covered soil was measured under different temperatures condition (15˚C, 25˚C and 35˚C) and different soil water content conditions (3%, 5%, 10%, 15%, 20%, 25% and 30%) in fixed sand dunes at the re-vegetated area in Tengger Desert, Northern China. In the same soil water content condition, the carbon release rate of BSCs and sand were increased with temperature increasing, the highest carbon release rate occurred at 35˚C. The carbon release rate of moss crust was significantly higher than other soil types. Q10 value of moss crust was 1.40 - 3.17, algae crust was 0.81 - 3.07, mixed crust was 0.55 - 3.84 and sand was 1.19 - 2.16. BSCs types, soil water content and temperature were significantly affected on carbon release rate (P < 0.001). The results showed that the respiration rate of the algal crust and mixed crust were significantly restrained by higher soil water content; however, moss crust was not significantly influenced.
生物土壤结皮,碳释放,土壤含水量,温度,腾格里沙漠, Biological Soil Crusts Carbon Release Soil Water Content Temperature Tengger Desert生物土壤结皮碳释放对水热因子的响应
BSCs在荒漠地区碳循环中所起的作用得到了研究者们的广泛的认可 [3] [4] [5] 。Wolfgang等人 [6] 对全球范围内BSC覆盖地区净碳固定量(光合固碳量–呼吸碳释放量)进行了估算,结果表明,BSCs每年能够固定3.9 P g C y−1 (2.1~7.4 P g C y−1),相当于陆生植物净初生产力的7% (56 P g C y−1);BSCs生物体中的碳含量为4.9 P g (3.0~8.2 P g),相当于陆生植物碳含量的1% (470~650 P g)。碳周转率方面,BSCs的周转率约为1.2 年,远远低于陆生植物的10年。Elbert等人 [7] 同样对全球范围内BSCs覆盖地区净碳固定量(光合固碳量–呼吸碳释放量)进行了估算,结果表明,BSCs每年能够固定3.6 P g C y−1,相当于陆生植物净初生产力的6%;BSCs生物体中的碳含量为10 P g,相当于陆生植物碳含量的2%。在Iberian Peninsula (40˚02'N~3˚37'W)干旱、半干旱地区,Castillo-Monroy等 [9] 对不同盖度BSC覆盖条件下,土壤碳释放特征进行了研究,结果表明,BSCs覆盖土壤每年释放240.4~322.6 g C m−2∙y−1;在这一生态系统中,BSCs的碳释放量占到碳释放总量的42% (植被占37%)。因此,BSCs作为干旱、半干旱地区碳循环的重要参与者和主要贡献者已得到广泛共识 [4] [5] [8] [9] 。
图1描述了3个土壤温度和7个水分梯度条件下,不同类型BSC和流沙呼吸速率变化特征。在相同水分条件下,BSCs和流沙呼吸速率随着温度的增加而增加,35℃时BSCs和流沙呼吸速率达到最大值。而在相同温度条件下,不同类型BSCs和流沙呼吸速率随着水分的变化表现出不同的变化趋势。藓类结皮呼吸速率表现为随着水分增加而逐渐增加的趋势,15℃和35℃条件下,最大值均出现在25%含水量条件为1.33和3.38 μmol CO2 m−2∙s−1;25℃条件下,最大值出现在20%含水量条件为1.65 μmol CO2 m−2∙s−1。藻类结皮呼吸速率在15℃和25℃条件下表现为随着水分增加先急剧增加而后逐渐下降的趋势,最大值均
图1. 土壤温度和水分对BSC呼吸速率(Mean ± SE)的影响
出现在8%含水量条件为1.10和1.34 μmol CO2 m−2∙s−1;而在35℃条件下,呼吸速率表现为随着水分增加而逐渐增加的趋势,最大值出现在20%含水量条件下为3.18 μmol CO2 m−2∙s−1。混生结皮呼吸速率在15℃条件下表现出随着水分增加先急剧增加而后逐渐下降的趋势,最大值均出现在6%含水量条件,为1.07 μmol CO2 m−2∙s−1;而在25℃和35℃条件下,呼吸速率表现为随着水分增加而逐渐增加的趋势,最大值出现在15%和20%含水量条件下为1.44和2.80 μmol CO2 m−2∙s−1。流沙呼吸速率表现出随着水分增加而逐渐增加的趋势,15℃条件下,最大值出现在15%含水量条件下,为0.23 μmol CO2 m−2∙s−1;而在25℃和35℃条件下,最大值均出现在17%含水量条件下分别为0.47和0.68 μmol CO2 m−2∙s−1。
吴玉哲,林庆功,张志山,赵洋. 生物土壤结皮碳释放对水热因子的响应Response of Biological Soil Crusts Carbon Release to Hydrothermic Factors[J]. 土壤科学, 2018, 06(01): 1-10. http://dx.doi.org/10.12677/HJSS.2018.61001
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