Does forest harvesting emulate fire disturbance? A comparison of effects on selected attributes in coniferous-dominated headwater systems

The emulation of natural disturbances is seen by many as an important management paradigm for achieving sustainable ecosystem management. To successfully emulate natural disturbances, managers must first have an understanding of the complex interactions that occur to the biophysical and chemical attributes of an ecosystem for both the natural and the "emulating" disturbance. The management of riparian ecosystems is an important issue faced by managers since the type of harvesting treatment can have a significant influence on the aquatic component. The removal or retention of riparian forests can have a direct influence on water quality and quantity, particularly on the smaller systems that are found at the headwaters of catchments, but do these treatments invoke a similar response as wildfire? To determine if emulation occurs, the affects of forest harvesting treatments and wildfire on temperature, water chemistry, summer stream flow, and sedimentation in headwater systems were compared using a meta-analysis. A statistically significant difference was found for temperature response between partial/selective harvesting and wildfire, but not after clear-cut harvesting. Water chemistry showed statistically significant differences for I I out of 14 tested attributes, with dissolved organic carbon exhibiting the most marked difference. A significant difference was identified between clear-cut harvesting and wildfire for summer stream flow but not between wildfire and partial/ selective harvest systems. Forest harvesting operations were found to emulate sedimentation through forest roads but not harvest treatment. Partial/selective harvest systems may offer the greatest emulation congruency versus clear-cut harvest systems in terms of overall headwater response and recovery. Partial/selective harvest systems combined with prescribed burning may provide managers with the best solution when attempting to emulate wildfire in headwater systems and reduce the detrimental impact of perturbation on these systems. (c) 2005 Elsevier B.V. All rights reserved.