Lee Se-Yeun, Ryan Maureen E, Hamlet Alan F, Palen Wendy J, Lawler Joshua J, Halabisky Meghan
Climate Impacts Group, University of Washington, Seattle, Washington, United States of America.
School of Environmental and Forest Sciences, University of Washington, Seattle, Washington, United States of America; Earth to Ocean Research Group, Department of Biology, Simon Fraser University, Burnaby, Canada.
PLoS One. 2015 Sep 2;10(9):e0136385. doi: 10.1371/journal.pone.0136385. eCollection 2015.
Wetlands are globally important ecosystems that provide critical services for natural communities and human society. Montane wetland ecosystems are expected to be among the most sensitive to changing climate, as their persistence depends on factors directly influenced by climate (e.g. precipitation, snowpack, evaporation). Despite their importance and climate sensitivity, wetlands tend to be understudied due to a lack of tools and data relative to what is available for other ecosystem types. Here, we develop and demonstrate a new method for projecting climate-induced hydrologic changes in montane wetlands. Using observed wetland water levels and soil moisture simulated by the physically based Variable Infiltration Capacity (VIC) hydrologic model, we developed site-specific regression models relating soil moisture to observed wetland water levels to simulate the hydrologic behavior of four types of montane wetlands (ephemeral, intermediate, perennial, permanent wetlands) in the U. S. Pacific Northwest. The hybrid models captured observed wetland dynamics in many cases, though were less robust in others. We then used these models to a) hindcast historical wetland behavior in response to observed climate variability (1916-2010 or later) and classify wetland types, and b) project the impacts of climate change on montane wetlands using global climate model scenarios for the 2040s and 2080s (A1B emissions scenario). These future projections show that climate-induced changes to key driving variables (reduced snowpack, higher evapotranspiration, extended summer drought) will result in earlier and faster drawdown in Pacific Northwest montane wetlands, leading to systematic reductions in water levels, shortened wetland hydroperiods, and increased probability of drying. Intermediate hydroperiod wetlands are projected to experience the greatest changes. For the 2080s scenario, widespread conversion of intermediate wetlands to fast-drying ephemeral wetlands will likely reduce wetland habitat availability for many species.
湿地是全球重要的生态系统，为自然群落和人类社会提供关键服务。山地湿地生态系统预计是对气候变化最敏感的生态系统之一，因为它们的存续取决于直接受气候影响的因素（如降水、积雪、蒸发）。尽管湿地具有重要性且对气候敏感，但由于相对于其他生态系统类型而言缺乏工具和数据，湿地往往未得到充分研究。在此，我们开发并展示了一种预测山地湿地气候引起的水文变化的新方法。利用基于物理的可变下渗能力（VIC）水文模型模拟的观测湿地水位和土壤湿度，我们建立了特定地点的回归模型，将土壤湿度与观测到的湿地水位相关联，以模拟美国太平洋西北地区四种类型山地湿地（季节性、间歇性、常年性、永久性湿地）的水文行为。这些混合模型在许多情况下捕捉到了观测到的湿地动态，不过在其他情况下则不太稳健。然后，我们使用这些模型来：a）根据观测到的气候变率（1916 - 2010年或更晚）反推历史湿地行为并对湿地类型进行分类，以及b）利用21世纪40年代和80年代的全球气候模型情景（A1B排放情景）预测气候变化对山地湿地的影响。这些未来预测表明，气候引起的关键驱动变量变化（积雪减少、蒸散增加、夏季干旱延长）将导致太平洋西北地区山地湿地更早且更快地干涸，导致水位系统性下降、湿地水文期缩短以及干涸概率增加。预计间歇性水文期湿地将经历最大变化。对于21世纪80年代的情景，间歇性湿地广泛转变为快速干涸的季节性湿地可能会减少许多物种的湿地栖息地可用性。
