An ecological forestry approach, as envisioned by Franklin et al. (2007), is based on three primary axes of understanding of structure/function relationships in forest ecosystems: 1) the role of natural disturbance and biological legacies in ecosystem function; 2) the importance of stand development processes for creating heterogeneity; and 3) the role of recovery time between natural disturbances for development of complexity. These axes translate into management actions that: 1) retain structures and organisms during regeneration harvests; 2) use intermediate treatments in established stands to create heterogeneity; and 3) allow appropriate recovery periods between harvests to allow complexity to develop. While conceptually appealing, the ecological foundations for this management approach are not well explored for many forest types, including the Great Lakes mixed-pine forests of Minnesota, Wisconsin, and Michigan. We have collected a great deal of information from experimental, retrospective, and descriptive studies in an attempt to validate the efficacy of the Franklin model to the Great Lakes mixed-pine forest and to develop ecological approaches to management of this ecosystem based on the Franklin model.
Results/Conclusions
There is convincing evidence from multiple sources that tree-regenerating natural disturbances in the Great Lakes mixed pine forest were often less-than-stand replacing and that substantial structural and compositional legacies of the previous forest were hallmarks of this ecosystem. Moreover, long-term observations of small-scale disturbance events point to the importance of heterogeneous structural conditions for generating complexity and diversity in developing stands. Finally, chronosequence studies and examination of rare old-growth remnants document the role of appropriate recovery in developing structural complexity and carbon storage potential. This deepened understanding of ecosystem structure and function in the Great Lakes mixed-pine forest points to the generality of the Franklin model for ecological management and has direct application for designing management approaches that restore/sustain ecosystems in the face of uncertain climate, market, and social conditions.