Measurement strategies to account for soil respiration temporal heterogeneity across diverse regions
Measurement strategies to account for soil respiration temporal heterogeneity across diverse regions
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DOI：
10.1016/j.soilbio.2018.07.003
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发表时间：
2018-10-01
影响因子：
9.7
通讯作者：
Hodges, Steven C.
中科院分区：
文献类型：
--
作者：
Jian, Jinshi;Steele, Meredith K.;Hodges, Steven C.
土壤呼吸速率每日和季节性波动;因此，在估算日平均值和按比例放大至年度土壤呼吸速率时，测量的时机至关重要。时间波动也随气候和生物群落而变化，但目前关于何时测量Rs的建议（例如，09：00至12：00）尚未针对不同的气候、生物群落和季节进行评估。为了提供更精确的测量Rs的建议，我们：1）分析了Rs的昼夜和季节波动，并测试了不同气候和生物群落下典型测量实践的准确性，2）确定了不同气候和生物群落所需的测量频率，以达到一定的精度水平，估计年度Rs。在整个生物群落中，Rs的日变化在春季和夏季相当大，秋季中等，冬季最小，并与土壤温度密切相关。基于这些昼夜模式，估计每日平均Rs的最佳测量时间是10：00在所有的气候和生物群落，这是在9：00和12：00以前确定的温带森林的建议范围内。在20：00至23：00之间进行的测量也准确地估计了每日平均Rs。一年中植物覆盖率高的地区季节变化较小，需要的测量频率也较少。对于全球规模的估计，Rs需要每天测量一次，以达到Rs总体平均值+/- 10%的准确度，置信度为95%，每月测量一次，以达到+/- 30%，置信度为80%。这项研究的结果提供了指导方针，减少测量频率，同时保持合理的准确性，更好地Rs估计使用手动室系统。
Soil respiration (Rs) rates fluctuate daily and seasonally; therefore, the timing of measurements is critical when estimating the daily mean and scaling up to annual Rs rates. Temporal fluctuations also vary with climate and biome, yet the current recommendation for when to measure Rs (e.g., 09:00 to 12:00) has not been evaluated for different climates, biomes, and seasons. To provide more refined recommendations for measuring Rs, we: 1) analyzed the diurnal and seasonal fluctuations of Rs and tested the accuracy of typical measurement practices under different climates and biomes, and 2) identified the measurement frequency necessary for different climates and biomes to achieve certain levels of accuracy in estimating annual Rs. Across biomes, diurnal variation in Rs is considerable in spring and summer, moderate in autumn, and minimal in winter, and closely related with soil temperature. Based on these diurnal patterns, the best measurement time for estimating the daily mean Rs was 10:00 in all climates and biomes, which is within the recommended range of 9:00 and 12:00 previously identified for temperate forests. Measurements made between 20:00 and 23:00 also accurately estimated the daily mean Rs. Regions with high plant coverage over the year have lower seasonal variation and require less measurement frequency. For global scale estimates, Rs needs to be measured once per day to attain an accuracy of +/- 10% of the Rs population mean with 95% confidence, and once per month to achieve +/- 30% with a confidence of 80%. Results from this study provide guidelines that reduce measurement frequency while retaining reasonable accuracy for better Rs estimates using manual chamber systems.