Approaches for forest disturbance studies: natural variability and tree regeneration

Sustainable ecosystem management requires an understanding of complex generative ecosystem processes (Jõgiste et al. 2007). These include natural disturbance regimes and the responses of the ecosystems to the affecting disturbances (Parmesan and Yohe 2003). An understanding of these ecosystem functions, which integrate physical and chemical processes with adaptations of individual organisms, requires multidisciplinary and interdisciplinary approaches (Jõgiste et al. 2009). In this context the challenge is to bring together a wide range of experts on the subject matter to develop a shared and well based understanding of the ecosystem and affecting processes to encompass the objectives of improved forest resource utilization and planning.

Forestry is an essential component of ecological, economical, and social structure. Traditional forest management is focused on a few commodities and the resulting forests lead to concerns about to the resilience and sustainability of the ecosystem. These concerns are particularly relevant in the context of changes in global climate and social and economic conditions. Society expects a broader range of forest values to be sustained. Studies on natural disturbances and disturbance regimes provide an opportunity to examine sound management plans for future forests. For this kind of research, specific study design or methodological setup becomes essential.

In order to face the topic, an international workshop of the SNS (Nordic Forest Research Co-operation Committee) network “Natural Disturbance Dynamics Analysis for Forest Ecosystem Management”, organized jointly by the SNS and Estonian University of Life Sciences, was held on 21–25 September 2009 at Vihterpalu, Estonia. The title of the workshop was “Approaches for forest disturbance studies” and it was the 8th international event of the network (Kangur et al. 2009).

The research results presented in this workshop included eleven articles covering various types of forest condition from boreal Fennoscandia and Northern America, hemi-boreal Baltic States to sub-tropical forest in Japan. Presented studies bring forward a variety of study approaches when addressing a broad range of topics related to natural and human-induced forest disturbances. In the beginning of the feature we list two review articles with regard to forest disturbances; Vodde et al. (2011) reviewed the studies of forest regeneration patterns in boreal and hemi-boreal forests depending on the wind-induced microsites, and Seedre et al. (2011) synthesized literature on carbon dynamics of boreal forests in North America after stand replacing wildfire and clear-cut logging. The first three research articles render with issues of disturbance effects on the variability of natural structural elements on a large scale. Liira et al. (2011) quantified the factor complex of forest regeneration in 423 mature and old stands with contrasting environmental conditions. Lõhmus (2011) distinguished between the effects of human-caused disturbances (clear-cutting, planting and thinning) on species richness and fungi composition in even-aged forests in a hemi-boreal landscape. Carlson et al. (2011) discussed the heterogeneous spatial feature of wildfire, with emphasis on burn severity, in a 1200 ha boreal forest landscape.

The subsequent contribution used a stand-scale field experiment—Yoshida et al. (2011) presented a study on stand fragmentation effects on wind disturbance-induced tree mortality. On the other hand, Tilk et al. (2011) studied the nature of forest ecosystems on dunes from the aspects of chemical characteristics of the soil, vascular plant species richness, and the diversity of ground vegetation. Retrospective analysis techniques were also employed—Niukkanen and Kuuluvainen (2011) studied the characteristics and variability of radial growth patterns and occurrence of growth releases in dominant trees in boreal old-growth forests, and Metslaid et al. (2011) developed a growth model for three forest generations by using annual height growth data from Scots pine trees to evaluate a historical growth change. The article presented by Paal et al. (2011) used historical maps to elucidate the effect of long-term land-use history on present day vegetation composition and soil characteristics.

This feature also includes a simulation study—Fujii and Kubota (2011) examined the long-term effects of understory thinning on a subtropical forest based on a spatially explicit individual-based model.

Stand regeneration after disturbance is a critical development phase. The change of conditions is varying and multiple factors combined allow the predicting capacity of the models assembled (Seidl et al. 2011). The authors and the editors of the issue believe this feature will be of interest and enlightening for many audiences, and contribute to the development of forest resource utilization and planning systems in various regions throughout the world.

Acknowledgments

We wish to express our gratitude to all of our colleagues of the SNS network and to all authors of the current issue. The editorial work was supported by The Ministry of Education and Research (project SF0170014s08) and by the Estonian Science Foundation Grant No. 8496. We are grateful to Karit Jäärats for English language correction.