While a few studies have evaluated the impact of post-beetle salvage logging on tree regeneration and fuel loadings, we know relatively little about how these activities will impact important aspects of forest ecosystem structure and function, including above and belowground carbon and nutrient stocks and fluxes, net primary productivity, soil loss, clean water delivery and biodiversity. The objective of the Environmental Impacts task is to quantify and evaluate the ecological and environmental impacts of different beetle-killed tree harvesting techniques in dominant forest types throughout the study region.  Key questions to be addressed include the fall and decomposition rate of dead trees, and the implications of tree removal for stand regeneration (both total biomass and species distribution over time), soil carbon, system nitrogen retention, and overall ecosystem carbon balance, factors that are key to understanding the overall greenhouse gas balance of any proposed harvest system.  Field research will be conducted in two ways: 1) in a small number of ‘intensive’ sites where sampling is done both before and after stand harvest; and 2) a larger number of ‘extensive’ study sites where a retrospective approach is applied to sites that were harvested 5-10 years in the past following bark beetle impacts.

Intensive pre- and post-harvest field experiments

We will establish experimental study sites that represent the range of forest types across the region. Using paired stands – one harvested and one adjacent, unharvested – selected to capture the variation in traditional and novel salvage approaches, we will establish permanent plots in which to measure a suite of forest structural and functional characteristics. This work will allow us to compare pre- and post-treatment data to provide an understanding of mechanisms behind observed salvage effects. Information collected from these study sites will be useful for developing decision support tools related to harvest site selection and salvage methods.

Extensive post-salvage monitoring studies

In addition to the paired plots for the intensive studies described above, we will also establish study sites where post-disturbance harvesting has already been done. These sites offer the opportunity to monitor treatments implemented in the past to capture longer-term impacts. By varying the time-since-harvest in these plots, we can use a chronosequence approach that may be useful in understanding long-term changes in forest structure and function. Information collected from these study sites will also be useful for developing decision support tools related to harvest site selection and salvage methods.