Research Branch


See below to download Technical Report 037 PDF file.
   

Vegetation Response, Fire Effects, and Tree Growth after Slashburning in the Engelmann Spruce-Subalpine Fir Zone: Goat River Site

Author(s) or contact(s): E.H. Hamilton
Source: Research Branch
Subject: Vegetation Management
Series: Technical Report
Other details:  Published 2006. Hardcopy is available.
 

Abstract

Fire effects, and vegetation and seedling response to burning, were monitored for 10 years after slashburning on the Goat River site. A fire weather station and gravimetric sampling were used to determine weather codes and indices and forest floor moisture content. Fuel loading, fuel consumption, and burn severity were ascertained using fuel assessment triangles and permanent plots. Changes in floristic composition and structure (cover and height) were documented along with survival and growth of planted hybrid white spruce seedlings.

The patchy burn was of fairly low severity, with little mineral soil exposure or large fuel consumption. When measured forest floor moisture content was used as an input, duff and fuel consumption as well as mineral soil exposure were less than predicted by the Prescribed Fire Predictor.

After the site was logged and burned, the vegetation structure at ground level shifted from a community dominated by bryophytes and small herbs to a young conifer forest with mosses, taller herbs, and shrubs. After 10 years, bryophyte cover was 77%, which was comparable to pre-burn levels (82%), herb cover was 14% or approximately one-half of pre-burn levels (24%), and shrub cover was 12% or double the pre-burn levels (6.5%). Shrubs were the tallest life form after the site was logged, but they had not regained pre-burn heights 10 years after burning. Although some of the original forest species were lost, a number of new species established from seed banks and off-plot sources.

Most of the native vascular species diversity was maintained on the plots, but a number of invasive species established. The ericaceous shrubs typical of Engelmann Spruce-Subalpine Fir (ESSF) biogeoclimatic zone sites were not as well adapted to burning as were the species more typical of lower-elevation forests. This would be expected, given the more frequent fires typical of the lower-elevation forests.

The planted spruce seedlings met "free-growing" requirements 10 growing seasons or years after burning. Average tree height after 10 years was 187 cm and average root collar diameter was 5.2 cm. Survival was 77%. More complete burning led to taller shrub and herb vegetation 1 year after burning. This was attributed, in part, to the enhanced invasion of fireweed into burned microsites. Taller vegetation resulted in increased shading of conifer seedlings and increased vegetation press, which reduced tree seedling growth.

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Updated May 11, 2007