Importance of recent shifts in soil thermal dynamics on growing season length, productivity, and carbon sequestration in terrestrial high-latitude ecosystems
Importance of recent shifts in soil thermal dynamics on growing season length, productivity, and carbon sequestration in terrestrial high-latitude ecosystems
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DOI：
10.1111/j.1365-2486.2006.01113.x
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发表时间：
2006-04-01
影响因子：
11.6
通讯作者：
Smith, NV
中科院分区：
文献类型：
--
作者：
Euskirchen, ES;McGuire, AD;Smith, NV
在陆地高纬度地区，观测结果表明，最近由于气候变化，积雪、永久冻土和土壤冻融过渡发生了变化。这些变化可能导致生长季节和相关陆地生产力的时间变化。生产力的变化将影响这些生态系统吸收大气二氧化碳的能力。我们使用陆地生态系统模型（TEM）来模拟土壤热状态，以及陆地碳(C)、氮和水的动态，以探讨1960-2100年温带地区（30-90°N）的这些问题。我们的模式模拟显示，从1960年到2100年，积雪和永久冻土的稳定性在减少。积雪减少与美国国家海洋和大气管理局在1972年至2000年间收集的卫星观测结果非常吻合，Pearson秩相关系数在0.58至0.65之间。模式分析还表明，从1988年至2000年，有一种趋势是冻土解冻日期提前，春季生长季节提前约2-4天。在1988年至2000年期间，卫星记录显示解冻和生长期开始的趋势略强，平均提前5至8天。在TEM模拟和卫星记录中，秋季冻结日的趋势都较弱，因此生长期的总体增加主要是由于提前解冻。尽管积雪持续时间最长的地区生长季长度增加幅度最大，但这些地区的生产力和异养呼吸的增加幅度小于积雪持续时间较短和生长季长度增加幅度较小的地区。随着生长季节长度的增加，我们发现土壤C的减少和植被C的增加，在植被较多的地区土壤C的损失最大，但模拟也表明这种趋势在未来可能会逆转。我们的研究结果揭示了积雪、永久冻土、生长季节长度、生产力和净碳吸收的显著变化，表明从一个十年到下一个十年的陆地碳动态预测将需要大尺度模型充分考虑土壤热状态的相应变化。
In terrestrial high-latitude regions, observations indicate recent changes in snow cover, permafrost, and soil freeze-thaw transitions due to climate change. These modifications may result in temporal shifts in the growing season and the associated rates of terrestrial productivity. Changes in productivity will influence the ability of these ecosystems to sequester atmospheric CO2. We use the terrestrial ecosystem model (TEM), which simulates the soil thermal regime, in addition to terrestrial carbon (C), nitrogen and water dynamics, to explore these issues over the years 1960-2100 in extratropical regions (30-90 degrees N). Our model simulations show decreases in snow cover and permafrost stability from 1960 to 2100. Decreases in snow cover agree well with National Oceanic and Atmospheric Administration satellite observations collected between the years 1972 and 2000, with Pearson rank correlation coefficients between 0.58 and 0.65. Model analyses also indicate a trend towards an earlier thaw date of frozen soils and the onset of the growing season in the spring by approximately 2-4 days from 1988 to 2000. Between 1988 and 2000, satellite records yield a slightly stronger trend in thaw and the onset of the growing season, averaging between 5 and 8 days earlier. In both, the TEM simulations and satellite records, trends in day of freeze in the autumn are weaker, such that overall increases in growing season length are due primarily to earlier thaw. Although regions with the longest snow cover duration displayed the greatest increase in growing season length, these regions maintained smaller increases in productivity and heterotrophic respiration than those regions with shorter duration of snow cover and less of an increase in growing season length. Concurrent with increases in growing season length, we found a reduction in soil C and increases in vegetation C, with greatest losses of soil C occurring in those areas with more vegetation, but simulations also suggest that this trend could reverse in the future. Our results reveal noteworthy changes in snow, permafrost, growing season length, productivity, and net C uptake, indicating that prediction of terrestrial C dynamics from one decade to the next will require that large-scale models adequately take into account the corresponding changes in soil thermal regimes.