Biological Soil Crust Microsites Are the Main Contributor to Soil Respiration in a Semiarid Ecosystem
Biological Soil Crust Microsites Are the Main Contributor to Soil Respiration in a Semiarid Ecosystem
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DOI：
10.1007/s10021-011-9449-3
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发表时间：
2011-08-01
期刊：
影响因子：
3.7
通讯作者：
Garcia-Palacios, Pablo
中科院分区：
文献类型：
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作者：
Castillo-Monroy, Andrea P.;Maestre, Fernando T.;Garcia-Palacios, Pablo
生物土壤结皮(BSCs)是全世界旱地生态系统的关键生物组成部分。然而，到目前为止，大多数关于这些生态系统中碳(C)通量的研究，如土壤呼吸，都忽略了它们。为了评价半干旱针茅草原土壤呼吸的时空异质性，以及生物多样性优势区对整个生态系统年土壤呼吸的贡献，我们进行了为期3.5年的田间试验。我们选择了研究区内最常见的6个微型站点：针茅(ST)、球果树灌木(RS)，以及具有非常低(<；5%BSC盖度，BS)、低、中、高盖度的开阔地带。土壤呼吸速率在以BSC为主的微站点之间没有差异，但分别显著高于BS和ST微站点的呼吸速率。土壤温度和土壤水分模型解释了整个研究期间土壤呼吸的时间变化的85%以上。利用该模型估算了研究区土壤呼吸释放的Cm(-2)y(-1)为240.4-322.6 g。植被(ST和RS)和以BSC为主的微站点分别占总数的37%和42%。我们的结果表明，要在生态系统水平上对土壤呼吸通量提供准确的估计，考虑BSCS引起的土壤呼吸的空间异质性是至关重要的。他们还强调，平衡计分卡占主导地位的地区是土壤呼吸释放的总碳的主要贡献者，因此，在估计旱地的碳收支时必须考虑到这一点。
Biological soil crusts (BSCs) are a key biotic component of dryland ecosystems worldwide. However, most studies carried out to date on carbon (C) fluxes in these ecosystems, such as soil respiration, have neglected them. We conducted a 3.5-year field experiment to evaluate the spatio-temporal heterogeneity of soil respiration in a semiarid Stipa tenacissima steppe and to assess the contribution of BSC-dominated areas to the annual soil respiration of the whole ecosystem. We selected the six most frequent microsites in the study area: Stipa tussocks (ST), Retama sphaerocarpa shrubs (RS), and open areas with very low (< 5% BSC cover, BS), low, medium and high cover of well-developed BSCs. Soil respiration rates did not differ among BSC-dominated microsites but were significantly higher and lower than those found in BS and ST microsites, respectively. A model using soil temperature and soil moisture accounted for over 85% of the temporal variation in soil respiration throughout the studied period. Using this model, we estimated a range of 240.4-322.6 g C m(-2) y(-1) released by soil respiration at our study area. Vegetated (ST and RS) and BSC-dominated microsites accounted for 37 and 42% of this amount, respectively. Our results indicate that accounting for the spatial heterogeneity in soil respiration induced by BSCs is crucial to provide accurate estimations of this flux at the ecosystem level. They also highlight that BSC-dominated areas are the main contributor to the total C released by soil respiration and, therefore, must be considered when estimating C budgets in drylands.