Year: 2006
Type: dissertation
Abstract: Fire is considered as the most important disturbance agent in many ecosystems. In northern Europe, fire suppression is today highly effective. This has led to a reduction of species that are dependent on fire for their long-term survival. Above ground positive responses of animal diversity to fire are common, whereas the knowledge of the responses of soil fauna to fire is fairly poor. The main aim of this thesis was to determine effects of wildfire and prescribed burning on survival and recovery of soil mesofauna. Other aims were to determine the effects of fire severity and, of distance to unburnt plots on recovery rates, and to estimate the lethal temperatures of common species. Two wildfires and two prescribed burns were studied for three to five years. In the wildfires, soil fauna was studied in transects from the unburnt forest to the fire centre. The two prescribed burns had different experimental design, one block experiment (burnt clear-cut, unburnt clear-cut and forest) and one experiment in which fire severity was manipulated by addition of different amounts of felling residues. All soil fauna species responded with decreased abundances one week after burning. This decline can partly be explained by high temperatures, because most microarthropod species cannot survive temperatures above 36-40 ºC, which can be reached several centimetres below the charred soil surface. Long-term recovery rates differed between soil fauna groups and between different fire severities. In fires with light severity, total abundance of Collembola and, in one case, Mesostigmata, recovered within one year. In fires with moderate to strong severity, almost all animal groups needed more than five years to recover as regards abundance and species number. Surface-living species were more affected by fire than species living deeper in the soil. Only a few species had significantly higher abundances 3-5 years after moderate/strong burning, whereas most species studied had recovered 5 years after light burning. Consequently, fire severity (burn depth) seems to be a decisive factor explaining survival and recovery rate of soil mesofauna, and this factor should be considered when fire effects on soil organisms are evaluated in forthcoming studies.
Author: Anna Malmström
Institution: Swedish University of Agricultural Sciences
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: green
OpenAlex ID: W92581520