Appendix A: Statement of Task
An ad hoc committee will plan and conduct a public workshop that convenes experts to discuss the current state of knowledge regarding shifts in Arctic and subarctic vegetation, as well as knowledge gaps and future research and observational needs to improve understanding. Workshop participants will present on and discuss the broad suite of identified potential drivers of vegetation change, necessary measurements, available tools and satellites for evaluating this change, and the implications of observed patterns.
Specific topics to be addressed include:
Spatial and temporal patterns in Arctic tundra and boreal forest greening versus browning
- What has caused the change from widespread, long-term greening to increased variability in the extent and duration of greening versus browning in tundra and boreal forest?
- What is driving some regions to green while others brown or remain largely unchanged?
- What factors control “flipping” from greening to browning (or vice versa) in tundra ecosystems and at what timescales is this occurring?
- Can we predict future northern latitude vegetation dynamics given what is currently known?
Methods and tools for evaluating northern latitude vegetation change
- Are current observing systems (both satellite and field measurements) adequate for identifying vegetation change and providing information needed to understand the factors influencing vegetation dynamics?
- What are the strengths and weaknesses of the various satellite datasets in evaluating tundra and boreal greening and browning? Are there remote sensing technologies beyond optical remote sensing that can improve understanding of vegetation change?
- Are there new metrics, methods, or measurement tools that could improve understanding of observed vegetation changes?
Implications for Arctic vegetation change
- Can we quantify the effects of shifts in Arctic tundra and boreal forest vegetation on Earth energy balance?
- How does green versus brown vegetation influence soil warming and associated changes in permafrost and carbon cycling?
- Are there hydrological changes that are influencing observed vegetation shifts? Conversely, are shifts in vegetation altering hydrological processes?
- What are the impacts of vegetation change on plant communities and other biota (e.g., birds and mammals)?
- How might variability in greening versus browning on annual or multi-year timescales influence these potential implications?
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