Plant species composition in ITEX subplots in black sand extended growing season experiment, 2018 - ongoing.

As a result of climate change, the Rocky Mountain Front Range is experiencing warmer summers and earlier snowmelt. Due to the importance of snow for regulating soil temperature, growing season length, and available moisture in alpine ecosystems, even small shifts in the snow-free period could have large impacts. The focus of the Black Sand Extended Growing Season Length Experiment is to examine how terrain-related differences in climate exposure influence the way alpine habitats respond to climate change via earlier snowmelt. To simulate how climate exposure may affect plant communities, NWT LTER researchers established 5 experimental sites, each containing a pair 10 x 40m rectangular plots. These sites include north and south facing aspects, subalpine and alpine tundra meadows and a range of hydrological conditions (e.g. dry meadows, moist meadows, wet meadows). We accelerated snowmelt in one plot at each site by adding chemically inert black sand, while keeping the second plot as an unmanipulated control; black sand was added to control plots after snow had naturally melted. We used open top warming chambers (OTCs) to increase summer temperature in three subplots within each of the 10 x 40 m plots. This dataset includes measurements of plant species composition within all snow and warming treatments.

受气候变化影响，落基山脉前缘（Rocky Mountain Front Range）正经历夏季气温升高与融雪期提前的变化。由于积雪对高山生态系统的土壤温度调控、生长季时长及有效水分供给具有关键作用，无雪时段的微小变动均可能引发显著生态影响。黑沙延长生长季长度实验（Black Sand Extended Growing Season Length Experiment）的核心研究目标，是探究气候暴露度的地形差异如何通过融雪期提前的路径，影响高山生境对气候变化的响应模式。为模拟气候暴露度对植物群落的影响，西北领地长期生态研究网络（NWT LTER）的研究人员设置了5个实验样地，每个样地包含一组10×40米的矩形样方对。这些样地涵盖北向与南向坡向、亚高山及高山苔原草甸，同时包含多种水文梯度生境（如旱生草甸、中生草甸、湿生草甸）。研究人员在每个样地的其中一个样方中施加化学惰性黑沙，以加速融雪进程；另一个样方作为未受人工干预的对照样方，且仅在积雪自然融化后，才会向该对照样方施加黑沙。我们在每个10×40米样方内设置3个亚样方，并采用开顶式增温箱（open top warming chambers, OTCs）提升夏季气温。本数据集收录了所有融雪处理与增温处理样地内的植物物种组成调查数据。