Energy exchange and water budget partitioning in a boreal minerogenic mire
Energy exchange and water budget partitioning in a boreal minerogenic mire
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DOI：
10.1029/2012jg002073
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发表时间：
2013-03
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通讯作者：
M. Peichl;Jörgen Sagerfors;A. Lindroth;I. Buffam;A. Grelle;L. Klemedtsson;H. Laudon;M. Nilsson
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作者：
M. Peichl;Jörgen Sagerfors;A. Lindroth;I. Buffam;A. Grelle;L. Klemedtsson;H. Laudon;M. Nilsson
这项研究调查了能量通量的季节和年际变化的模式和控制（即，感热，H，和潜热，λE）和水收支的分配（即，降水量P;蒸散;放电，Q;和土壤蓄水量，COMS）在瑞典北部北方的一个北方贫营养沼泽的基础上连续涡度协方差，地下水位（WTL），和堰测量五年（2001-2005）。对于生长季节（5月1日至9月31日），中午（10：00至14：00）Bowen比率（β，即，H/λE）为0.86 ± 0.08。β的季节和年际变化主要由λE驱动，λE本身受到天气（即，蒸汽压不足，D，和净辐射，Rn）和生理参数（即，表面电阻）。在生长季节，表面阻力大大超过空气动力学阻力，这与实际ET与潜在ET比（0.55 ± 0.05）和Priestley-Taylor α（0.89）的低平均值一起表明，在这个水分充足的沼泽中，ET受到显著的生理限制。在水分收支组成部分中，ET的年际变化（199至298 mm）低于Q（225至752 mm），平均分别占生态系统水分损失的34%和65%。P向ET的消耗分数与P呈负相关，与Rn呈正相关。虽然WTL的减少导致了表面电导的减少，但WTL对ET的总体影响是有限的。非生长季节（10月1日至4月30日）H、λE和Q的通量显著，平均分别占其生长季节总和的− 67%、13%和61%（负号表示两个季节之间通量方向相反）。总的来说，我们的研究结果表明，植物功能型组成，P和Rn动态（即，量和时间）的沼泽能量和水收支的分配的主要控制。这对区域气候以及生态系统发展、养分和碳动态都有重要影响。
This study investigated patterns and controls of the seasonal and inter‐annual variations in energy fluxes (i.e., sensible heat, H, and latent heat, λE) and partitioning of the water budget (i.e., precipitation, P; evapotranspiration, ET; discharge, Q; and soil water storage, ∆S) over five years (2001–2005) in a boreal oligotrophic fen in northern Sweden based on continuous eddy covariance, water table level (WTL), and weir measurements. For the growing season (May 1 to September 31), the 5 year averages (± standard deviation) of the midday (10:00 to 14:00 h) Bowen ratio (β, i.e., H/λE) was 0.86 ± 0.08. Seasonal and inter‐annual variability of β was mainly driven by λE which itself was strongly controlled by both weather (i.e., vapor pressure deficit, D, and net radiation, Rn) and physiological parameters (i.e., surface resistance). During the growing season, surface resistance largely exceeded aerodynamic resistance, which together with low mean values of the actual ET to potential ET ratio (0.55 ± 0.05) and Priestley‐Taylor α (0.89) suggests significant physiological constrains on ET in this well‐watered fen. Among the water budget components, the inter‐annual variability of ET was lower (199 to 298 mm) compared to Q (225 to 752 mm), with each accounting on average for 34 and 65% of the ecosystem water loss, respectively. The fraction of P expended into ET was negatively correlated to P and positively to Rn. Although a decrease in WTL caused a reduction of the surface conductance, the overall effect of WTL on ET was limited. Non‐growing season (October 1 to April 30) fluxes of H, λE, and Q were significant representing on average −67%, 13%, and 61%, respectively, of their growing season sums (negative sign indicates opposite flux direction between the two seasons). Overall, our findings suggest that plant functional type composition, P and Rn dynamics (i.e., amount and timing) were the major controls on the partitioning of the mire energy and water budgets. This has important implications for the regional climate as well as for ecosystem development, nutrient, and carbon dynamics.