Changes in photosynthesis and soil moisture drive the seasonal soil respiration-temperature hysteresis relationship
Changes in photosynthesis and soil moisture drive the seasonal soil respiration-temperature hysteresis relationship
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光合作用和土壤湿度的变化驱动季节性土壤呼吸-温度滞后关系
DOI：
10.1016/j.agrformet.2018.05.005
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发表时间：
2018-09
影响因子：
6.2
通讯作者：
Kimberly A. Novick
中科院分区：
文献类型：
--
作者：
Quan Zhang;Richard P. Phillips;Stefano Manzoni;Russell L. Scott;A. Christopher Oishi;Adrien Finzi;Edoardo Daly;Rodrigo Vargas;Kimberly A. Novick
在几乎所有的大尺度陆地生态系统模型中，土壤呼吸都是土壤温度的函数。然而，土壤呼吸和土壤温度之间的关系是高度可变的网站和土壤呼吸温度的关系在整个生长季节的过程中往往有一个明显的滞后。这一现象表明，生物物理因素的重要性，而不仅仅是温度在控制土壤呼吸。为了确定季节性土壤呼吸温度滞后的潜在机制，我们开发了一套数值模型来演示光合作用，土壤水分和土壤温度，单独和组合，影响滞后关系。然后，我们使用了一个变体的模型，该模型通过对多个中干旱和半干旱生态系统的土壤呼吸、土壤温度、光合作用和土壤水分的观测来量化滞后的频率，并确定其潜在的控制因素。我们表明，滞后可能是由于光合作用的季节性循环（为根际呼吸提供碳）和土壤水分（当过低或过高时限制异养呼吸）。通过对土壤呼吸的实地观测，我们发现了8个不同生物群落中15个站点年中有9个存在季节性滞后的证据。具体而言，顺时针滞后发生时，光合作用之前，季节性土壤温度和逆时针滞后发生时，光合作用滞后土壤温度。我们发现，在所有的网站，大部分的呼吸温度滞后解释的光合作用和温度的脱钩，突出了最近同化的碳土壤呼吸的重要性。对129个FLUXNET站点观测结果的分析表明，总初级生产力（冠层光合作用的代表）和土壤温度之间的时间滞后是常见现象，这往往会在低纬度站点造成逆时针滞后，在高纬度站点造成顺时针滞后。总的来说，我们的结果表明，将光合作用和土壤水分纳入标准指数土壤呼吸温度模型（即，Q10模型）提高了模型在局部尺度上的解释能力。
In nearly all large-scale terrestrial ecosystem models, soil respiration is represented as a function of soil temperature. However, the relationship between soil respiration and soil temperature is highly variable across sites and there is often a pronounced hysteresis in the soil respiration-temperature relationship over the course of the growing season. This phenomenon indicates the importance of biophysical factors beyond just temperature in controlling soil respiration. To identify the potential mechanisms of the seasonal soil respiration-temperature hysteresis, we developed a set of numerical models to demonstrate how photosynthesis, soil moisture, and soil temperature, alone and in combination, affect the hysteresis relationship. Then, we used a variant of the model informed by observations of soil respiration, soil temperature, photosynthesis, and soil moisture from multiple mesic and semi-arid ecosystems to quantify the frequency of hysteresis and identify its potential controls. We show that the hysteresis can result from the seasonal cycle of photosynthesis (which supplies carbon to rhizosphere respiration), and soil moisture (which limits heterotrophic respiration when too low or too high). Using field observations of soil respiration, we found evidence of seasonal hysteresis in 9 out of 15 site-years across 8 diverse biomes. Specifically, clockwise hysteresis occurred when photosynthesis preceded seasonal soil temperature and counterclockwise hysteresis occurred when photosynthesis lagged soil temperature. We found that across all sites, much of the respiration-temperature lag was explained by the decoupling of photosynthesis and temperature, highlighting the importance of recently assimilated carbon to soil respiration. An analysis of observations from 129 FLUXNET sites revealed that time lags between gross primary productivity (a proxy for canopy photosynthesis) and soil temperature were common phenomena, which would tend to drive counterclockwise hysteresis at low-latitude sites and clockwise hysteresis at high-latitude sites. Collectively, our results show that incorporating photosynthesis and soil moisture in the standard exponential soil respiration-temperature model (i.e., Q10model) improves the explanatory power of models at local scales.
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影响因子：
2.2
作者：
BOWDEN, RD;NADELHOFFER, KJ;GARRISON, JB
通讯作者：
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影响因子：
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作者：
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He G
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