Making ecological restoration faster and more intense

Background/Question/Methods . Ecological restoration practices usually are slow paced and lag rapidly changing land use policies, decisions, and impacts, outcomes of larger phenomena like anthropogenic climate change and regime shifts, and social-political demands. In my study, the approach is solutions-based because resource producers must conform to licences requiring evidence that full ecosystem compensation (which can be controversial) or restoration goals will likely be met. Producers often must do this within the ca. 50-year lifetime of typical extraction operations. Starkly, previous research has found that efforts fail to restore the ecosystem services of mature natural forests or it can take 150 years to restore 80% of the ecosystem function and diversity of forests. The research question is one that can be understood by stakeholders: can ecologists restore the ecosystem of extraction sites (e.g. tree plantations) better and faster? Using an existing design from the Ontario provincial land management agency, I completed 5 years of research on how to rapidly restore and maintain ecological services, resilience and biological diversity to natural levels through forest management. The goal was to speed up and restore structurally and spatially diverse forests via “variable density thinning” (VDT). This tests which densities of canopy closure and tree density should remain while the rest of the plantation trees are removed versus other methods like transplanting. Retained patches of trees provide habitat, or “lifeboats” for later successional, more shade tolerant plant species already present in the stand; this is very much akin to the nucleation strategies pioneered by colleagues.

Results/Conclusions . I tested whether impacts of thinning are a faster way to restore ecosystem structure and function; here I focused on the soil ecosystem response – nutrients, pH, duff layer, biomass of fungal hyphae (endomycorrhizae), functional groups of Collembola as an indicator of change in soil invertebrates, and soil microbial catabolic activity. Some variables like duff layer, pH, and nutrients did show significant but still modest (as expected) changes according to effect size analyses (mainly using Cohen’s d). The important and startling results were that the most intense VDT treatments (55% thinning) changed soil microbial catabolic activity, fungal hyphae biomass, and functional groups of Collembola to the desired ecological restoration trajectory 9X faster than the control of passive succession and 4X faster than other restoration techniques. That values of Cohen’s d were > 0.8 & probability of superiority were > 0.7 show intense VDT speeds ecological restoration after only 5 years.