Shrub Seed Banks in Mixed Conifer Forests of Northern California and the Role of Fire in Regulating Abundance
Year: 2012
Type: article
Abstract: Understory shrubs play important ecological roles in forests of the western US, but they can also impede early tree growth and lead to fire hazard concerns when very dense. Some of the more common genera (Ceanothus, Arctostaphylos, andPrunus) persist for long periods in the seed bank, even in areas where plants have been shaded out. To determine shrub seed density and investigate the feasibility of managing shrub abundance by regulating the size of the soil seed bank with fire, we sampled the seed bank in 24 mixed conifer forest stands throughout northern California. Twenty stands were unburned, two had recently burned in wildfires, and two (McCloud and Jennie Springs) were subjected to experimental prescribed fires with unburned controls. Seeds were extracted from duff and soil that was collected in six layers, to a depth of 10 cm in the mineral soil.Ceanothusseeds were the most abundant (mean = 246 seeds m−2), noted at all sites and at 88% of sampling locations within unburned sites.ArctostaphylosandPrunusseeds were less abundant (mean = 29 seeds m−2and 6 seeds m−2, respectively), but still recorded at 64% and 45% of the unburned sites, respectively. The depth of seed burial varied at all unburned sites, but some seed was present even at the deepest (6 cm to 10 cm) soil layer, where seed mortality due to heat from burning is least likely. Seed density was substantially reduced, but not eliminated, by October prescribed burns at both McCloud and Jennie Springs, while seed density following July burns at Jennie Springs did not differ from the control. The abundance of buried seed indicates that restoring shrubs to forest understory should be possible even in areas where they are currently lacking. If preventing shrubs from colonizing a site is the management goal, the effectiveness of a single prescribed fire may be limited.
Source: Fire Ecology
Institutions: US Forest Service, Pacific Southwest Research Station
Language: English
Topic: Fire effects on ecosystems
Subfield: Global and Planetary Change
Field: Environmental Science
Domain: Physical Sciences
SDG: Life on land
Open Access status: gold
Estimated APC paid: $2,590
OpenAlex ID: W2148243114