Seasonality buffers carbon budget variability across heterogeneous landscapes in Alaskan Arctic tundra
Seasonality buffers carbon budget variability across heterogeneous landscapes in Alaskan Arctic tundra
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DOI：
10.1088/1748-9326/abe2d1
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发表时间：
2021-02
影响因子：
6.7
通讯作者：
Josh Hashemi;D. Zona;K. Arndt;A. Kalhori;W. Oechel
中科院分区：
文献类型：
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作者：
Josh Hashemi;D. Zona;K. Arndt;A. Kalhori;W. Oechel
北极冻原在微地形、水文和活动层深度方面具有很大的景观异质性。虽然许多碳通量的测量和实验都是在中尺度（101 km）或以下进行的，但现代生态系统碳模拟通常是在0.25°-1.0°纬度的尺度上进行的，这导致过程、过程输入数据和验证数据之间不匹配。在这里，我们安排的自然复杂的地形到不同的微地形和水分状况的中尺度景观类型，以评估景观类型的不同CO2和CH 4平衡及其组合的变暖潜力，表示为CO2当量（CO2当量）。利用连续4年的CO2和CH 4通量数据集，从三个涡度相关（EC）塔，我们调查的综合动态景观类型，植被群落，水分状况，和季节的净CO2和CH 4通量。EC塔坐落在一个湿度梯度，包括潮湿的高地苔原，异质多边形苔原，和淹没排水湖盆。我们发现，碳排放的季节性变化缓冲了由场地变异性引起的年度碳预算差异。值得注意的是，高生长季节总初级生产力导致秋季零幕二氧化碳排放量增加，减少了年度预算的变化和更具生产力的地点的碳汇强度。另外，秋季零幕CH 4排放量是平等的景观类型，表明网站的变化有很大的差异，尽管在生长季节的CH 4排放量在秋季影响不大。我们发现多边形地点的平均变暖潜力最大（107 ± 8.63 g C-CO2-eq m-2 yr-1），其次是排水湖盆地地点（82.12 ± 9.85 g C-CO2-eq m-2 yr-1）和高地地点（77.19 ± 21.8 g C-CO2-eq m-2 yr-1），尽管差异并不显着。最高的温度敏感性也是在多边形的网站之间的CO2和CH 4在其他网站的混合结果。结果表明，类似的平均每年净变暖效应，但这些景观类型的差异显着的CO2和CH 4通量的数量和时间。
Arctic tundra exhibits large landscape heterogeneity in microtopography, hydrology, and active layer depth. While many carbon flux measurements and experiments are done at or below the mesoscale (⩽1 km), modern ecosystem carbon modeling is often done at scales of 0.25°–1.0° latitude, creating a mismatch between processes, process input data, and verification data. Here we arrange the naturally complex terrain into mesoscale landscape types of varying microtopography and moisture status to evaluate how landscape types differ in terms of CO2 and CH4 balances and their combined warming potential, expressed as CO2 equivalents (CO2-eq). Using a continuous 4 year dataset of CO2 and CH4 fluxes obtained from three eddy covariance (EC) towers, we investigate the integrated dynamics of landscape type, vegetation community, moisture regime, and season on net CO2 and CH4 fluxes. EC towers were situated across a moisture gradient including a moist upland tundra, a heterogeneous polygon tundra, and an inundated drained lake basin. We show that seasonal shifts in carbon emissions buffer annual carbon budget differences caused by site variability. Of note, high growing season gross primary productivity leads to higher fall zero-curtain CO2 emissions, reducing both variability in annual budgets and carbon sink strength of more productive sites. Alternatively, fall zero-curtain CH4 emissions are equal across landscape types, indicating site variation has little effect on CH4 emissions during the fall despite large differences during the growing season. We find that the polygon site has the largest mean warming potential (107 ± 8.63 g C–CO2-eq m−2 yr−1) followed by the drained lake basin site (82.12 ± 9.85 g C–CO2-eq m−2 yr−1) and the upland site (77.19 ± 21.8 g C–CO2-eq m−2 yr−1), albeit differences were not significant. The highest temperature sensitivities are also at the polygon site with mixed results between CO2 and CH4 at the other sites. Results show a similar mean annual net warming effect across dominant landscape types but that these landscape types vary significantly in the amounts and timing of CO2 and CH4 fluxes.