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Plant community composition alters moisture and temperature sensitivity of soil respiration in semi-arid shrubland
Oecologia ( IF 2.7 ) Pub Date : 2021-06-18 , DOI: 10.1007/s00442-021-04961-4
M Mauritz 1 , D A Lipson 2
Affiliation  

Soil respiration (Rs) is the second largest carbon (C) flux to the atmosphere and our understanding of how Rs and its components shift with plant-community composition remains an important question. We used high-frequency soil respiration measurements and root exclusion to evaluate how Rs, autotrophic respiration (Ra) and heterotrophic respiration (Rh) vary between a semi-arid perennial shrub community and annual invasive community. Over two growing seasons, total Rs was 40% higher under annual vegetation compared to shrubs. Partitioning revealed consistently higher Ra under annual vegetation which accounted for most of the difference in Rs. Under annual vegetation, Ra increased soon after the first rain events and remained high despite cooling temperatures while shrub Ra increased only when soil temperature began to warm up. The Rh rates were similar between vegetation types when daily soil temperatures were lower than 20 °C. As soil temperatures increased and soil moisture dropped below 10%, Rh was consistently higher under annual vegetation than shrubs. Seasonal dynamics of Rs and Rh were best modeled with an interaction term between soil moisture and temperature with significantly different model parameters for each vegetation type. Differences in the timing and magnitude of Rs and Ra between vegetation types are consistent with phenological differences between shrubs and annuals. Under annuals, larger Rh at high temperatures suggests that expansion of annual vegetation and future hotter and drier conditions could lead to greater C losses from this semi-arid shrub system.



中文翻译:

植物群落组成改变半干旱灌丛土壤呼吸的水分和温度敏感性

土壤呼吸 (Rs) 是进入大气的第二大碳 (C) 通量,我们对 Rs 及其成分如何随植物群落组成变化的理解仍然是一个重要问题。我们使用高频土壤呼吸测量和根排除来评估 Rs、自养呼吸 (Ra) 和异养呼吸 (Rh) 在半干旱多年生灌木群落和年度入侵群落之间的变化。在两个生长季节中,与灌木相比,一年生植被下的总卢比高出 40%。分区显示一年生植被下的 Ra 始终较高,这是 Rs 差异的主要原因。在一年生植被下,Ra 在第一次降雨事件后很快增加,尽管温度降低,但仍保持高位,而灌木 Ra 仅在土壤温度开始升温时才增加。当日土壤温度低于 20 °C 时,不同植被类型的 Rh 率相似。随着土壤温度升高和土壤湿度降至 10% 以下,一年生植被下的 Rh 始终高于灌木。Rs 和 Rh 的季节性动态最好用土壤水分和温度之间的相互作用项建模,每种植被类型的模型参数显着不同。植被类型之间 Rs 和 Ra 的时间和幅度差异与灌木和一年生植物之间的物候差异一致。在一年生植物下,高温下较大的 Rh 表明,一年生植被的扩张和未来更热和更干燥的条件可能会导致这种半干旱灌木系统的碳损失更大。随着土壤温度升高和土壤湿度降至 10% 以下,一年生植被下的 Rh 始终高于灌木。Rs 和 Rh 的季节性动态最好用土壤水分和温度之间的相互作用项建模,每种植被类型的模型参数显着不同。植被类型之间 Rs 和 Ra 的时间和幅度差异与灌木和一年生植物之间的物候差异一致。在一年生植物下,高温下较大的 Rh 表明,一年生植被的扩张和未来更热和更干燥的条件可能会导致这种半干旱灌木系统的碳损失更大。随着土壤温度升高和土壤湿度降至 10% 以下,一年生植被下的 Rh 始终高于灌木。Rs 和 Rh 的季节性动态最好用土壤水分和温度之间的相互作用项建模,每种植被类型的模型参数显着不同。植被类型之间 Rs 和 Ra 的时间和幅度差异与灌木和一年生植物之间的物候差异一致。在一年生植物下,高温下较大的 Rh 表明,一年生植被的扩张和未来更热和更干燥的条件可能会导致这种半干旱灌木系统的碳损失更大。Rs 和 Rh 的季节性动态最好用土壤水分和温度之间的相互作用项建模,每种植被类型的模型参数显着不同。植被类型之间 Rs 和 Ra 的时间和幅度差异与灌木和一年生植物之间的物候差异一致。在一年生植物下,高温下较大的 Rh 表明,一年生植被的扩张和未来更热和更干燥的条件可能会导致这种半干旱灌木系统的碳损失更大。Rs 和 Rh 的季节性动态最好用土壤水分和温度之间的相互作用项建模,每种植被类型的模型参数显着不同。植被类型之间 Rs 和 Ra 的时间和幅度差异与灌木和一年生植物之间的物候差异一致。在一年生植物下,高温下较大的 Rh 表明,一年生植被的扩张和未来更热和更干燥的条件可能会导致这种半干旱灌木系统的碳损失更大。

更新日期:2021-06-18
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