Mechanisms and feedback consequences of shrub expansion following long-term increases in winter snow depth in northern Alaska: a legacy for IPY

Welker -0612534基金提供了一个详细的，机械的调查如何灌木成为主导地位，以应对积雪深度的增加-一个过程，已观察到发生在阿拉斯加。 这项研究将定量记录灌木的增加如何改变非生物环境，并导致这些系统在阿拉斯加北极的功能属性的根本变化。 本项目的具体目标是：1.定量地记录了灌木的增加如何影响北极苔原全年的温度和水分状况，以及灌木的增加如何改变系统的能量平衡; 2.描述控制灌木增加的过程，特别是土壤和植物氮循环以及更深的雪对灌木分生组织和树枝的物理保护;和3.定量描述灌木密度的增加如何影响碳[C]循环[C增益，C损失和C分配]的模式和幅度，水资源和生长，地上和地下。观察到的阿拉斯加北极部分地区的灌木扩张可能会产生重大后果，包括气候反馈的变化，改变动物丰度，以及碳和氮循环过程的变化。 由于阿拉斯加的气候变暖速度很快，如果要做出明智的土地利用决策，如果要开发准确的预测模型，就需要对生物反应进行机械性的理解。

Welker - 0612534Funds are provided for a detailed, mechanistic investigation of how shrubs become dominant in response to snow depth increases - a process that has been observed to occur in Alaska. This study will quantitatively document how increases in shrubs have altered the abiotic environment and caused a fundamental change in the functional attributes of these systems in arctic Alaska. The specific goals of this project are to: 1. quantitatively document how shrub increases affect the year-long temperature and water regimes of arctic tundra and how shrub increases change the energy balance of the system; 2. delineate the processes controlling shrub increases, especially soil and plant nitrogen cycling and the physical protection of shrub meristems and branches by deeper snow; and 3. quantitively describe how shrub density increases have affected the patterns and magnitudes of carbon [C] cycling [C gain, C loss and C allocation], water sources and growth, both aboveground and belowground.Observed shrub expansion within portions of arctic Alaska may have significant consequences, including shifts in the albedo-climate feedback, altered animal abundances, and changes in carbon and nitrogen cycling processes. As warming is progressing at a rapid rate in Alaska, a mechanistic understanding of the biotic response is needed, if informed land use decisions are to be made and if accurate forecasting models are to be developed.