Sustainable Management of Spruce-dominated Ecosystems in Response to Climate Change: Lessons from North America and Europe

C-27: Sustainable Management Of Spruce Dominated Ecosystems in Response to Climate Change

White Spruce (Picea glauca) Credit: SJQuinney Library
White Spruce (Picea glauca)
Credit: SJQuinney Library

Spruce trees are some of the most important trees in many parts of Europe. They form the backbone of the wood processing industries, and provide a variety of materials and services.

The idea behind this session was to discuss some of the emerging evidence regarding how well spruce trees will respond to the projected changes in climate. An important objective for the session was also to share the latest approaches and methodologies being applied to understanding the dynamics of change in spruce-dominated ecosystems. Such information could prove critical to improving silvicultural practices associated the management in spruce ecosystems.

To show the potential effects of climate change on these systems, Harri Mäkinen shared an example from Finland, Germany, and Norway where he and his colleagues subjected Norway spruce to different treatments with one of the main variables being latitude. Dendrochronological analyses showed that there was no correlation between tree growth and latitude. While in warmer regions, the trees benefited from warmer springs, there was a negative correlation with summer months. Artificial snow removal in winter also somewhat delayed the growth of tree cells compared to the control group. The findings from this study are somewhat convoluted, probably reflecting the fact that climate change is not very well understood thus far; however the message is clear: climate change does affect the Norway spruce, although this will partly depend on various environmental factors and site conditions.

Laura Gray of the University of Alberta, Canada, was interested in understanding the geographic patterns of variations in White spruce, with the overall goal of guiding seed transfers for appropriate afforestation programs. Dr. Gray used what she called correlative distribution models that enabled her to predict areas of suitable habitats for White spruce under different climate change scenarios. She was able to identify clusters of trees that could adapt to these change scenarios.

Thinning experiments carried out on Norway spruce in Germany revealed very interesting results. Dr. Julia Sohn found that heavily thinned stands offered less resistance to drought, but in moderately thinned plots, there was higher resistance. However, trees in heavily thinned plots recovered quickly. The hypothesis here is that heavy thinning results in a larger space, more resources and hence trees are bigger and have the capacity (better rooting, larger crowns) to quickly rebound should conditions improve.

Experiments from the Czech Republic on the ecophysiology of Douglas fir, carried out by Josef Urban showed that this species was bigger even in nutrient-poor sites compared to Norway spruce. It also established two weeks earlier, and during drought conditions, it significantly reduced its water intake capacity, thus lowering the rate of transpiration. In other words, D. fir is not a selfish tree; it can share limited water resources when conditions call. The main conclusion here was that D. fir could be a viable alternative to Norway spruce, and possesses just as much value.

Finally, Mr. Bill Mason, a sivilculturalist from Scotland talked about the possibility of establishing continuous cover forest (CCF) plantations of Sitka spruce in Britain. The concept of CCF is to ensure that a location has structurally different forest cover at any given time. This, as Dr. Mason put, reduces the possibility of having a ‘boring’ forest, one that provides only a limited number of services due to uniformity in tree cover. Various treatments showed that Sitka spruce has great potential for establishing CCF in Britain, but there is uncertainty about its distribution by the year 2080.

Overall, this was a very interesting session that highlighted great findings for those who might be interested in management of spruce dominated systems in the Northern Hemisphere. It offers vital information to policy makers as well as commercial timber companies reliant on these species for their operations

Written by: Humphrey Kalibo

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