Decoupling between Plant Productivity and Growing Season Length under a Warming Climate in Canada’s Arctic

Given the short duration of growing season in the Arctic, a strong correlation between plant productivity and growing season length (GSL) is conventionally assumed. Will this assumption hold true under a warming climate? In this study, we addressed the question by investigating the relationship between net primary productivity of leaves (NPPleaf) and GSL for various tundra ecosystems. We quantified NPPleaf and GSL using long-term satellite data and field measurements. Our results indicated that the relationship was not significant (i.e., decoupled) for 44% to 64% of tundra classes in the southern Canadian Arctic, but significant for all classes in the northern Canadian Arctic. To better understand the causes of the decoupling, we further decomposed the relationship into two components: the correspondence of interannual variations and the agreement of long- term trends. We found that the longer the mean GSL for a tundra class, the poorer the correspondence between their interannual variations. Soil moisture limitation further decoupled the relationship by deteriorating the agreement of long-term trends. Consequently, the decoupling between NPPleaf and GSL would be more likely to occur under a warming climate if the tundra class had a mean GSL > 116 (or 123) days with a dry (or moist) soil moisture regime.

全球气候变化对北极海洋生态系统持久性有机污染物和汞途径及暴露的生态影响研究

生物累积性和生物放大污染物，如持久性有机污染物（POPs）和汞（Hg），数十年来一直被公认为在北极海洋生物健康的关注。近年来，全球气候变化（GCC）和北极海冰相关损失已观察到驱动大幅改变北极生态系统。本文综述了研究记录的经验之间的联系GCC诱导的流行和在北极海洋生态系统的汞暴露和通路的生态变化和改变。大多数的研究报道在流行或汞浓度变化与GCC引起的物种营养相互作用的变化组织。这些研究通常集中在阿舞的角色变化，栖息地的范围或接近猎物，尤其是在与海冰变化。然而，生态变化，重新适应污染物的趋势变化往往是不清楚或假定。其他的研究已经成功地使用化学示踪剂，如稳定的氮和碳同位素比值和脂肪酸签名连接这样的生态变化，污染物水平的变化或趋势。较低的海冰与饮食变化/变异与较高的污染水平在一些不同的北极熊，以及相关的环斑海豹，和厚嘴默，但改变营养相互作用影响的流行水平和趋势的大小和方向的变化很大。我们建议在这一新领域的GCC链接ECOTOX -生态学的重点应该放在配套的生态指标与流行和汞的研究常规分析未来的研究，同时考虑了GCC和污染物的相互作用可能发生的多种机制，并有针对性地研究变化的暴露和毒性的物种称为敏感的GCC和污染物[现行生态61（4）：617-628，2015 ]。