7.6. Effects of climate change and management on growth of Norway spruce in boreal conditions – an approach based on ecosystem model

Public examination of a doctoral dissertation in the field of forest sciences  

Doctoral candidate: PhD, B.S Zhen-Ming Ge 

Date and venue: 7.6.2011 at 12 noon, BOR100, Joensuu campus

 

ABSTRACT 

The main aim of this work was to study the effects of climate change and management on the growth of Norway spruce (Picea abies L.) in the boreal conditions based on a process-based ecosystem model (FinnFor) simulations. More specifically, it was studied: (i) how the climate change affects the growth of unmanaged Norway spruce stands in relation to the water availability from southern to northern Finland; and (ii) how the climate change and varying management regimes (e.g. thinning intensity and interval) affect the net carbon uptake, total stem wood growth and timber yield in Norway spruce from southern to northern Finland, respectively. 

The permanent sample plots by the Finnish National Forestry Inventory (NFI) and a climate change scenario over Finland (FINADAPT for 2000–2099) by the Finnish Meteorological Institute were used in the simulations. 

In southern Finland, the annual mean temperature increases by 4–6 °C compared to current climate, whereas change expected in the amount of precipitation in summertime is small. The elevated temperature increased evaporation from the canopy and ground surfaces, resulting in a higher ratio of evapotranspiration to precipitation in southern Finland. As a result, less water infiltrated into the soil profile, leading to increasing water deficit and decreasing nitrogen availability for trees. The water deficit occurred earlier and was higher on the site with low soil water availability, resulting in lower carbon uptake and stem wood growth in Norway spruce. 

On average, the total stem wood growth decreased by 5–20% over most of the areas studied in southern Finland due to lower water availability under the changing climate. On the contrary, the total stem wood growth increased by 5–38% in northern Finland under the changing climate. This increase was related to the longer growing season, and higher temperature and precipitation in summertime. 

When thinning was applied in Norway spruce, the soil water deficit was mitigated due to the lower stocking and reduced water depletion, compared to no thinning. The thinning scenarios with frequent thinnings could simultaneously increase the carbon uptake and growth rate of trees on the sites with low soil water availability. On the sites with high soil water availability, the less frequent thinnings or delayed first thinning gave the highest carbon uptake and stem wood growth, but not the highest timber yield. 

In general, the moderate thinning gave the highest carbon uptake, stem wood growth and timber yield in the southern regions under the changing climate, whereas in the north despite of thinning scenarios applied the carbon uptake and total stem wood production decreased compared to no thinning as a result of lower stocking. 

The doctoral dissertation of PhD, B.S. Zhen-Ming Gen entitledEffects of climate change and management on growth of Norway spruce in boreal conditions – an approach based on ecosystem model” The opponent in the public examination is Ari Laurén, Finnish Forest Research Institute and the custos is Professor Seppo Kellomäki of the University of Eastern Finland.will be examined at the Faculty of Science and Forestry.

Photo available for download at http://www.uef.fi/vaitoskuvat

Contact: Zhen-Ming Ge, zhenmg.ge@uef.fi

Publishing year: 2011

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