Ponderosa pine forests are declining and their future persistence is uncertain. Most research on forest declines has focused on the effects of disturbances including wildfire, insect outbreaks, and severe drought on mortality of mature trees. Yet, recent research suggests that ponderosa pine declines may be even more severe as these ecosystems fail to regenerate naturally (i.e. grow from seed to adulthood) in a climate that is becoming increasingly less favorable for juvenile tree survival. For land managers to accurately assess and combat the risk of failed regeneration, it is critical to better understand the many factors supporting regeneration across the diverse habitats where these ecosystems are located.
This research will quantify the effects of forest management actions on the conditions supporting juvenile ponderosa pine survival for long-term study locations in the southwestern United States, and will apply this information to anticipate these conditions at additional locations in the region. Building on this insight, researchers will use an ecosystem climate and water balance model to forecast the effects of management activities (such as tree stand and forest understory thinning) of differing intensity on regeneration in scenarios of future climate change for these locations. Outreach activities developed alongside this research will help land managers understand the climate and environmental factors that support or limit regeneration, and the way that management actions will need to adapt to a changing climate to continue to support forest regeneration and resilience. Assessing the impacts of climate change on ecosystem processes that are not well-understood is especially daunting and difficult. This study will develop foundational, quantitative insight on regeneration of ponderosa pine forests, and will help land managers tailor their actions to support forest health and persistence, both now and in the future.
