COS 107-3 - CANCELLED - Effects of salvage logging and tree planting pattern on seedling mortality and growth, fuels, and understory diversity in a mixed-conifer ecosystem

Abstract: Following high-intensity wildfire, planted tree seedling survival and growth are often limited by vigorous shrub growth in many western conifer forests. Post-fire management may include snag removal (salvage), grubbing of shrubs, and herbicide application, but rarely include trials of different tree seedling planting patterns. We compared the effects of four levels of salvage snag removal (none, only small snags ( < 25 cm dbh), large snags ( >40 cm), and all) crossed with four planting arrangements (none, 12’ by 12’ regular spacing, 3-5 seedling clusters, and 12-30 seedling clusters) on seedling survival and growth, surface fuel loads, and herbaceous diversity and cover for seven years after a wildfire in northern California. We found the highest seedling survival and growth rates in larger clusters and very low survival of regularly spaced seedlings as high shrub cover overtopped individual seedlings. Fuel loads decreased with salvage treatment intensity and retained small snags toppled and decomposed rapidly. Generally, herbaceous diversity and cover were low as ceanothus and manzanita shrubs dominated the growing space. However, herb diversity and cover were significantly higher on the outermost edge of clusters, probably due to the larger grubbing radius needed for initial planting of larger clusters. Our findings suggest that current planting practices of regularly spaced individual seedlings is prone to high mortality and slow growth rates without aggressive shrub control. Herbicide use in some areas is very limited and grubbing is costly and labor-intensive. Seedlings planted in clusters have higher survival and faster growth possibly because the cluster holds the growing space and prevents shrub encroachment and overtopping. As the frequency and size of high-severity wildfire effects increase, new practical reforestation methods should be tested given current limited budgets, seedling supplies, changing climate conditions, and labor constraints.