Temperature Response of Respiration Across the Heterogeneous Landscape of the Alaskan Arctic Tundra
Temperature Response of Respiration Across the Heterogeneous Landscape of the Alaskan Arctic Tundra
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DOI：
10.1029/2017jg004227
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发表时间：
2018-07
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影响因子：
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通讯作者：
E. Wilkman;D. Zona;Yanfei Tang;B. Gioli;D. Lipson;W. Oechel
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作者：
E. Wilkman;D. Zona;Yanfei Tang;B. Gioli;D. Lipson;W. Oechel
预测生态系统呼吸对北极变暖的反应没有受到很好的约束，部分原因是这些永久冻土占主导地位的地区具有相当大的空间异质性。准确计算呼吸作用的原位温度敏感性（Q10）对于预测未来北极排放至关重要。为了了解空间异质性对呼吸速率和Q10的影响，我们将从当地主要景观形式（高中心和低中心，多边形边缘，多边形槽）的自动室测量的呼吸与从相邻涡度协方差塔收集的通量分区净生态系统交换的估计值进行了比较。微地形类型似乎是解释呼吸速率变化的最重要变量，低中心多边形和多边形槽显示出最大的累积呼吸速率，可能与其更深的解冻深度和更高的植物生物量有关。无论绝对呼吸速率的差异，Q10是令人惊讶的所有microtopographic功能相似，可能表明类似的温度限制分解整个景观。Q10较高，在较冷的初夏和较低的温暖的生长高峰期，在较冷的条件下，温度敏感性升高一致。在季节早期和高峰期，由箱测量的呼吸和白天通量分区涡度协方差数据的估计值在不确定性范围内，但在生长季节后期高估了呼吸。总的来说，这项研究表明，它是可能的，以简化估计的温度敏感性的呼吸在异质景观，但季节性变化Q10应纳入模型模拟。
Predictions of the response of ecosystem respiration to warming in the Arctic are not well constrained, partly due to the considerable spatial heterogeneity of these permafrost‐dominated areas. Accurate calculations of in situ temperature sensitivities of respiration (Q10) are vital for the prediction of future Arctic emissions. To understand the impact of spatial heterogeneity on respiration rates and Q10, we compared respiration measured from automated chambers across the main local polygonized landscape forms (high and low centers, polygon rims, polygon troughs) to estimates from the flux‐partitioned net ecosystem exchange collected in an adjacent eddy covariance tower. Microtopographic type appears to be the most important variable explaining the variability in respiration rates, and low‐center polygons and polygon troughs show the greatest cumulative respiration rates, possibly linked to their deeper thaw depth and higher plant biomass. Regardless of the differences in absolute respiration rates, Q10 is surprisingly similar across all microtopographic features, possibly indicating a similar temperature limitation to decomposition across the landscape. Q10 was higher during the colder early summer and lower during the warmer peak growing season, consistent with an elevated temperature sensitivity under colder conditions. The respiration measured by the chambers and the estimates from the daytime flux‐partitioned eddy covariance data were within uncertainties during early and peak seasons but overestimated respiration later in the growing season. Overall, this study suggests that it is possible to simplify estimates of the temperature sensitivity of respiration across heterogeneous landscapes but that seasonal changes in Q10 should be incorporated into model simulations.