Program
Biology
College
Arts and Sciences
Student Level
Master's
Start Date
7-11-2018 4:15 PM
End Date
7-11-2018 5:30 PM
Abstract
Ponderosa pine forests are an iconic ecosystem of western North America and provide numerous ecological, economic, and cultural benefits. Historically, these forests experienced regular surface fires that left most large, mature trees surviving. However, suppression of wildfires along with a warming climate have led to catastrophic tree-killing fires that result in vast areas (>200 mi2) dominated by shrubs and grasses. Because of limited survival of tree seedlings in these post-fire habitats, it remains unknown whether ponderosa pines can successfully recolonize severely burned landscapes. Without a mature tree canopy to provide periodic shade, seedlings experience hotter, drier conditions and likely experience increased physiologic stress. To better understand how this absence of tree canopy affects seedling physiology, I conducted a field-based study of twenty ponderosa pine seedlings growing in contrasting conditions in the Jemez Mountains of New Mexico: an unburned portion of forest with mature tree canopy and a nearby burned area of forest that has no surviving trees (i.e. no tree canopy). I used two techniques to measure seedling stress: stable carbon isotope analysis and chlorophyll fluorescence. Together these measurements show that seedlings in the burned area (no tree canopy) experience elevated drought- and light-stress. These results indicate that the absence of mature ponderosa pine trees negatively affects the physiological function of young seedlings. Future research can use these results to model ponderosa pine regeneration across a landscape and aid in reforestation efforts. This research is especially relevant given the increasing threat of large, severe wildfires and the limited success of pine trees following severe fires.
Included in
Ponderosa pine seedling physiology after severe wildfire: Does it take a forest to make a forest?
Ponderosa pine forests are an iconic ecosystem of western North America and provide numerous ecological, economic, and cultural benefits. Historically, these forests experienced regular surface fires that left most large, mature trees surviving. However, suppression of wildfires along with a warming climate have led to catastrophic tree-killing fires that result in vast areas (>200 mi2) dominated by shrubs and grasses. Because of limited survival of tree seedlings in these post-fire habitats, it remains unknown whether ponderosa pines can successfully recolonize severely burned landscapes. Without a mature tree canopy to provide periodic shade, seedlings experience hotter, drier conditions and likely experience increased physiologic stress. To better understand how this absence of tree canopy affects seedling physiology, I conducted a field-based study of twenty ponderosa pine seedlings growing in contrasting conditions in the Jemez Mountains of New Mexico: an unburned portion of forest with mature tree canopy and a nearby burned area of forest that has no surviving trees (i.e. no tree canopy). I used two techniques to measure seedling stress: stable carbon isotope analysis and chlorophyll fluorescence. Together these measurements show that seedlings in the burned area (no tree canopy) experience elevated drought- and light-stress. These results indicate that the absence of mature ponderosa pine trees negatively affects the physiological function of young seedlings. Future research can use these results to model ponderosa pine regeneration across a landscape and aid in reforestation efforts. This research is especially relevant given the increasing threat of large, severe wildfires and the limited success of pine trees following severe fires.
