Regeneration of subalpine fir (Abieslasiocarpa) following fire: effects of climate and other factors

Abstract

Subalpine fir (Abieslasiocarpa (Hook.) Nutt.) regeneration following fire was studied at two locations that burned in 1902 northeast of Mount Rainier, Washington. Tree establishment dates were compared with local climatic records using multiple and logistic regression to identify potential relationships between seasonal climate and annual tree establishment. The influence of microsite features on forest regeneration was also explored. Little regeneration occurred in the first 30 years after the fires, and most trees established in the 1950s, 1977, 1983, and 1989. The dominance of trees <50 cm tall at both sites indicates that trees are continuing to establish on these burns. Establishment is positively correlated with warm, dry springs with low snow accumulation, and cool, wet summers with some variation in significant monthly climate between sites. Tree establishment following fire is greater near other trees and woody debris than other microsite features; however, the microsites available and used for tree establisment may change over time as snags fall and trees establish. More than 50% of the recently established trees (<50 cm tall) are located near larger trees and shrubs, and few (<10%) trees are growing in exposed mineral soil. Older trees (≥50 cm tall) are frequently observed near woody debris. The response of subalpine fir regeneration to changes in climate will depend on the magnitude and seasonality of changes in weather, especially during spring. Tree establishment may be enhanced if there is less snow accumulation and a longer growing season. However, warmer, drier summers could result in additional moisture stress to seedlings, especially at sites with high solar radiation (south and west aspects) and well-drained soils.

Fire and weather disturbances in terrestrial ecosystems of the eastern Cascades.

“…These sites are usually steep, south-facing slopes, and colonization lags substantially (30 to 50 years), with most regeneration occurring during wetter than normal summers. Little (1992) found that, on burned sites, extended growing seasons created by early snowmelt in spring and wetterthan-normal summers is associated with tree establishment. In the east Cascades, both of these patterns may exist, and they may be accompanied by yet a third pattern.…”

Regeneration of Abies cephalonica Loudon after a Large Fire in Central Greece

“…However, other studies show that a northern aspect favors fir regeneration [22,26]. Moisture stress can be a critical factor limiting conifer regeneration in dry coniferous forests and is usually higher in sites of high solar radiation [14,17,21,25). Our observations can be partially explained due to the fact that Greek fir is considered one of the best drought-adapted European firs [27].…”

Climate change effects on vegetation in the Pacific Northwest: a review and synthesis of the scientific literature and simulation model projections

“…Highly stress-tolerant conifers in subalpine and alpine meadows can facilitate establishment by less tolerant (but potentially more competitive) tree species by ameliorating stress from deep snowpack, cold temperatures, or high light levels, or by reducing competition from herbaceous vegetation (Bansal et al 2011, Little et al 1994, Stueve et al 2009, Zald et al 2012. For example, subalpine fi r trees are often able to establish under the canopies of large subalpine larch or whitebark pine trees and, being more shade tolerant, may later be able to grow up through the canopy and overtop the pioneer tree Habeck 1972, Tomback et al 2001).…”

“…Wildfi res are infrequent in subalpine forests, as deep snowpacks produce a very short fi re season, fuels are often wet, and spatial discontinuities can inhibit fi re spread (Agee 1993). However, forest vegetation can be dramatically altered by rare wildfi re events, as recovery from stand-replacing wildfi res can be very slow (Little et al 1994). In fact, it can take decades to centuries for tree reestablishment in burned subalpine forests that do not include lodgepole pine (Agee and Smith 1984, Little et al 1994.…”

“…However, forest vegetation can be dramatically altered by rare wildfi re events, as recovery from stand-replacing wildfi res can be very slow (Little et al 1994). In fact, it can take decades to centuries for tree reestablishment in burned subalpine forests that do not include lodgepole pine (Agee and Smith 1984, Little et al 1994. Wildfi re has probably played an important historical role in creating or maintaining subalpine and alpine meadows (Griggs 1938, Kuramoto andBliss 1970).…”