Ecosystem carbon dynamics differ between tundra shrub types in the western Canadian Arctic
Ecosystem carbon dynamics differ between tundra shrub types in the western Canadian Arctic
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加拿大西部北极地区苔原灌木类型之间的生态系统碳动态存在差异
DOI：
10.1088/1748-9326/aad363
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发表时间：
2018
影响因子：
6.7
通讯作者：
P. Wookey
中科院分区：
文献类型：
--
作者：
L. Street;J. Subke;R. Baxter;K. Dinsmore;C. Knoblauch;P. Wookey
高纬度地区的灌木扩张与推动植被“绿化”趋势有关，并可能部分抵消土壤变暖造成的二氧化碳排放。然而，我们还不知道北极灌木扩张将如何影响生态系统碳(C)循环，这限制了我们预测净碳储量变化和由此产生的气候反馈的能力。本文量化了两种常见的北极落叶灌木在不同生态系统组分之间的光合分配，这两种灌木在研究区域的丰度都在增加；绿桤木（Alnus viridis (Chaix) DC.）和矮桦木（Betula glandulosa micx .）。, b)。利用13C同位素标记，我们发现两种灌木在生长旺季的碳利用效率（即减去呼吸作用后剩余的总光合作用的比例）相似（绿刺为56±12%，腺刺为59±6%），但生物量生产效率（分配给生物量生产的植物C吸收，每单位总光合作用）绿刺为56±14%，腺刺为31±2%。在绿桫椤占主导的群落中，最近光合作用分配给木质生物量的比例（27±5%）显著高于腺桫椤占主导的群落（4±1%）。C在地下池中的分配也存在显著差异；2.5周后，我们在无根土壤中恢复了28±6%的近期光合产物，而在绿芽草下，我们无法检测到土壤中的近期光合产物。我们提供了第一个证据，表明灌木扩张对北极C循环的影响将是物种依赖的。在桦树占主导地位的地方，最近光合作用的约1/3的碳将迅速分配到地下的土壤和微生物池中。在桤木占主导地位的地方，最近固定的碳将分配给木质生物质。我们的结论是，仅由遥感的地上冠层特征（即绿度）驱动的模式将无法准确地反映植被变化对北极碳储量的影响。
Shrub expansion at high latitudes has been implicated in driving vegetation ‘greening’ trends and may partially offset CO2 emissions from warming soils. However, we do not yet know how Arctic shrub expansion will impact ecosystem carbon (C) cycling and this limits our ability to forecast changes in net C storage and resulting climate feedbacks. Here we quantify the allocation of photosynthate between different ecosystem components for two common deciduous Arctic shrubs, both of which are increasing in abundance in the study region; green alder (Alnus viridis (Chaix) DC.) and dwarf birch (Betula glandulosa Michx., B.). Using 13C isotopic labelling, we show that carbon use efficiency (i.e. the fraction of gross photosynthesis remaining after subtracting respiration) in peak growing season is similar between the two shrubs (56 ± 12% for A. viridis, 59 ± 6% for B. glandulosa), but that biomass production efficiency (plant C uptake allocated to biomass production, per unit gross photosynthesis) is 56 ± 14% for A. viridis, versus 31 ± 2% for B. glandulosa. A significantly greater proportion of recent photosynthate is allocated to woody biomass in A. viridis dominated plots (27 ± 5%), compared to plots dominated by B. glandulosa (4 ± 1%). Allocation of C to belowground pools also differs significantly; after 2.5 weeks we recovered 28 ± 6% of recent photosynthate in root-free soil under B. glandulosa, but under A. viridis we were unable to detect recent photosynthate in the soil. We provide the first evidence that the impact of shrub expansion on Arctic C cycling will be species dependant. Where Betula dominates, ~1/3 of recently photosynthesised C will be rapidly allocated belowground to soil and microbial pools. Where Alnus dominates, more recently fixed C will be allocated to woody biomass. We conclude that models driven by remotely-sensed aboveground canopy characteristics alone (i.e. greenness) will be unable to accurately represent the impact of vegetation change on Arctic C storage.
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影响因子：
14.6
作者：
Martijn Gough
通讯作者：
Martijn Gough
影响因子：
30.7
作者：
Hartley, Iain P.;Garnett, Mark H.;Wookey, Philip A.
通讯作者：
Wookey, Philip A.
DOI：
10.1111/nph.12285
发表时间：
2013-07
期刊：
The New phytologist
影响因子：
--
作者：
L. Street;J. Subke;M. Sommerkorn;V. Sloan;Helene Ducrotoy;G. Phoenix;M. Williams
通讯作者：
L. Street;J. Subke;M. Sommerkorn;V. Sloan;Helene Ducrotoy;G. Phoenix;M. Williams
北极源头流域活性层的氧化还原动力学；
影响因子：
4.9
作者：
Street L
通讯作者：
Street L