Effects of Seed Sources and Shelter Log Placements on Survival and Growth of Post-transplant Ponderosa Pine (Pinus Ponderosa) Seedlings PDF Download

Author: Jon Woerheide
Publisher:
ISBN:
Category : Forest management
Languages : en
Pages : 188

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Book Description
In the southwestern U.S., the combination of a changing climate and past forest management practices has resulted in forests that are experiencing larger and more intense wildfires which are expected to continue indefinitely. During recovery from these catastrophic fires, forest managers struggle to reestablish lost stands due to low seedling survival rates. A tool used by nursery managers and foresters to maximize seedling success is the Target Plant Concept (TPC). The TPC is a collaborative framework which utilizes eight elements to ensure seedlings have the best fitness for purpose at a given site. This study examines treatments related to two elements of the TPC, genetics and mitigation via site preparation, and evaluates their effectiveness in terms of seedling survival and growth rates. The study was designed to simultaneously test both factors by utilizing a split-plot design, with the site preparation factor being the whole-plot treatment and the genetic factor being the sub-plot treatment. In 2016, three years post-fire, a ponderosa pine (Pinus ponderosa Douglas ex C. Lawson) site was selected within the severely burned portion of the Thompson Ridge fire scar at Valles Caldera National Preserve near Los Alamos, New Mexico, USA. To implement the site preparation treatment, half of each whole-plot was treated by deliberately placing the felled logs along a west to east orientation, south of, and adjacent to, the seedling planting locations. To test genetic influence, the subplots were then planted with ponderosa pine seedlings from one of six different seed sources, which were selected from three different latitudes. For three consecutive seasons, seedlings were monitored annually for survival, height growth, and radial growth. Additionally, root:shoot biomass ratios and plant moisture stress levels were evaluated to assess physiological plant responses. Results indicate that survival, height, and diameter of seedlings were not consistently affected by either the shelter-log or seed source treatment. The shelter-log treatment improved growth rates initially, but this effect had diminished by season 3. The use of southern seed sources generally improved growth rates throughout the study. Because the more southern seed sources have yet to experience reduced survival on the site, and have experienced sustained improved growth rates, forest managers restoring fire damaged stands in the southwestern U.S. may wish to utilize seed sources from further south in anticipation of climate change.