Soil temperature, not aboveground plant productivity, best predicts intra-annual variations of soil respiration in central Iowa grasslands
Soil temperature, not aboveground plant productivity, best predicts intra-annual variations of soil respiration in central Iowa grasslands
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DOI：
10.1007/s10021-005-0093-7
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发表时间：
2006-09-01
期刊：
影响因子：
3.7
通讯作者：
Raich, James W.
中科院分区：
文献类型：
--
作者：
Dornbush, Mathew E.;Raich, James W.
土壤呼吸（R-SOIL）是陆地系统与大气之间的第二大碳通量，其量级是人为二氧化碳产生的10倍。因此，了解并预测R-SOIL对气候变化的反应是非常重要的。虽然人们早就认识到温度对R-SOIL有积极的、显著的影响，但最近的研究强调了当前光合作用在控制R-SOIL中的压倒一切的重要性。我们验证了一个假设，即与仅基于土壤温度的预测相比，模型中包含的地上净初级生产力（ANPP）的年内变化显著改善了R-SOIL估计。我们还通过验证R-SOIL的种间差异与根系生物量的相关性比与ANPP的相关性更强的假设，评估了冠层产量与R-SOIL的直接联系较少的可能性。我们通过测量爱荷华州四个不同地上物候和生产力的草地的R-SOIL、ANPP和根系生物量来验证这些假设。在所有站点中，R-SOIL的年内变化与土壤温度（R-2 = 0.89）关系最密切，而与ANPP （R-2 = 0.53）关系最弱。所有样地对土壤温度变化的响应相同（逐点P = 0.53），但对地上动态变化的响应不一致（逐点P < 0.0001）。将冠层动力学纳入基于温度的预测模式，最大可使模式R-2提高0.01。不同地点间R-SOIL差异与根系生物量相关（P < 0.001），与ANPP无关（P = 0.34）。我们发现冠层特征与年内或特定地点的R-SOIL预测之间没有有用的联系，这可能是因为茎和根的动态不一致地随时间或地点而联系。
Soil respiration (R-SOIL) is the second largest carbon flux between terrestrial systems and the atmosphere, with a magnitude 10 times greater than anthropogenic carbon dioxide production. Therefore, it is important that we understand, and be able to predict, how R-SOIL responds to climate change. Although a positive, significant temperature effect on R-SOIL has long been recognized, recent studies emphasize the overriding importance of current photosynthesis in controlling R-SOIL. We tested the hypothesis that model inclusion of intra-annual variations in aboveground net primary productivity (ANPP) significantly improves R-SOIL estimates over predictions based on soil temperature alone. We also evaluated the possibility that canopy production is less directly linked to R-SOIL, by testing the hypothesis that intersite differences in R-SOIL correlate more strongly with root biomass than with ANPP. We tested these hypotheses by measuring R-SOIL, ANPP, and root biomass at four Iowa grasslands that differed in aboveground growth phenology and productivity. Among all sites, intra-annual variations in R-SOIL were most strongly related to soil temperature (R-2 = 0.89), not ANPP (R-2 = 0.53). All sites responded identically to changes in soil temperature (site-by-temperature P = 0.53), but inconsistently to variation in aboveground dynamics (site-by-canopy P < 0.0001). Incorporating canopy dynamics into temperature-based predictive models improved model R-2 by a maximum of 0.01. Among-site differences in R-SOIL were related to root biomass (P < 0.001) but not ANPP (P = 0.34). We found no useful linkage between canopy characteristics and intra-annual or site-specific R-SOIL predictions, perhaps because shoot and root dynamics were not consistently linked through time or among sites.