Conifer regeneration in stand-replacement portions of a large mixed-severity wildfire in the Klamath-Siskiyou Mountains.
Authors:
Donato, Daniel C. Fontaine, Joseph B. Campbell, John L. Robinson, W. Douglas Kauffman, J. Boone Law, Beverly E. USDA, FS
Source:
Canadian journal of forest research. 2009 Apr., v. 39, no. 4, p. 823-838.
NALT Subjects:
natural regeneration conifers forest trees temperate forests wildfires tree growth seeds density soil parent materials seed dispersal buried seeds spatial distribution botanical composition environmental factors tree mortality broadleaved evergreens Oregon
Other Subjects:
seed sources pos-fire regeneration
Issue Date:
Apr-2009
Abstract:
Large-scale wildfires (approximately 10(4)-10(6) ha) have the potential to eliminate seed sources over broad areas and thus may lead to qualitatively different regeneration dynamics than in small burns; however, regeneration after such events has received little study in temperate forests. Following a 200 000 ha mixed-severity wildfire in Oregon, USA, we quantified (1) conifer and broadleaf regeneration in stand-replacement patches 2 and 4 years postfire; and (2) the relative importance of isolation from seed sources (live trees) versus local site conditions in controlling regeneration. Patch-scale conifer regeneration density (72%-80% Douglas-fir (Pseudotsuga menziesii (Mirb). Franco)) varied widely, from 127 to 6494 stems·ha-1. Median densities were 1721 and 1603 stems·ha-1 2 and 4 years postfire, respectively, i.e., approximately 12 times prefire overstory densities (134 stems·ha-1). Because of the complex burn mosaic, approximately 58% of stand-replacement area was <or=200 m from a live-tree edge (seed source), and approximately 81% was <or=400 m. Median conifer density exceeded 1000 stems·ha-1 out to a distance of 400 m from an edge before declining farther away. The strongest controls on regeneration were distance to live trees and soil parent material, with skeletal coarse-grained soils supporting lower densities (133 stems·ha-1) than fine-grained soils (729-1492 stems·ha-1). Other site factors (e.g., topography, broadleaf cover) had little association with conifer regeneration. The mixed-severity fire pattern strongly influenced the regeneration process by providing seed sources throughout much of the burned landscape.
