Multiproduct forest management planning – the case of timber and bilberry production

Jari Miina and Mikko Kurttila

Wild forest berries, including bilberry (Vaccinium myrtillus), are important non-wood forest products in many European countries (Turtiainen and Nuutinen 2012). Berries are harvested for both household use and sale. Recently, wild berries’ use and popularity has increased due to new consumption trends in which their nutritional and health effects have been acknowledged. Their use in health products has increased. Besides environmental conditions, forest management affects the abundance and yields of forest berries. Therefore, many forest owners want to know how incomes from forests are affected if berry yields are taken into account in forest management. Such knowledge on management for producing simultaneously both timber and berries can be obtained by utilizing modern forest management planning systems.

Selecting the optimal treatment schedules for individual stands or finding the best combination of treatment schedules for the whole planning area have been solved by integrating bilberry models (e.g. Miina et al. 2009) into forest management planning systems. Such systems have been used to optimize the joint production of timber and bilberries at the individual stand, forest management unit (FMU) and regional levels (see Kurttila and Tahvanainen 2016).
At the stand level, Miina et al. (2016) included bilberry yield model in a stand growth simulator and multiproduct stand management was optimized by maximizing soil expectation value (SEV) with 3 % discount rate, assuming that 75 % of the bilberry yield is harvested. The current bilberry prices and harvesting costs were included in calculations. The optimal management of average bilberry stands changed very little from the timber-oriented stand management. However, in stands having good bilberry yields, the optimal stand management remarkably changed: about 20 years longer rotation and heavier thinnings were optimal to reduce canopy shading to a level that is favorable for bilberry. The SEV calculated with income from bilberries was more than twice as high as the SEV calculated without bilberries.

At the FMU level, several alternative forest plans for the forthcoming 30-year planning period were created by using a 150 ha forest area in Finland and the forest planning system Monsu (Pukkala 2006). Monsu includes several ecosystem service models, e.g. berry yield models. One of the alternative forest plans was created to maximize bilberry yield during the planning period in the forests of the FMU. The profiles of the FMU-level alternative plans are illustrated as a spider-web diagram, where the axes of the goal variables (e.g. bilberry yield) are scaled between 0 and 1 (Figure 1). In the bilberry plan (Max Bil), the amount of clearfellings is low, but the net present value (NPV) is, however, rather high. In this plan, forest management is based more on uneven-aged management principles, which is more suitable for bilberry (Pukkala et al. 2011). Thematic maps created for the FMU can be used to locate the best places to pick bilberries (Figure 2). The maps could be useful both for private forest owner in her own forest and for public in e.g. state owned forests.

Figure 1. Illustration of profiles of the FMU-level alternative plans created with Monsu as spider-web diagram (3 % interest rate is used in calculations).


Figure 2. Thematic maps for bilberry yields for the FMU in Finland. The maps show the bilberry yields in the beginning (left) and end (right) of the planning period. The darker blue, the higher is the bilberry yield.


The MELA planning system have been used for decades e.g. to analyze the effect of different forest management scenarios on regional and national timber production in Finland (Hirvelä et al. 2017). In calculations for North Karelia region, both biological and harvestable (yield > 10 kg/ha/year) bilberry yields were predicted along the management schedules simulated in EVENFLOW scenario. The scenario aims to even and sustainable flow of timber from forests (through constraints) by maximizing the NPV with 4 % interest rate as the objective variable. In EVENFLOW scenario, the biological bilberry yield decreases due to more intensive cuttings compared to the current ones (5 mill. m3/year) being only 8.6 million kg/year in the end of the planning period (Figure 3). The development of harvestable yields follows that of biological yields.


Figure 3. Timber removals (bars) and biological (solid line) and harvestable (broken line) bilberry yields in the EVENFLOW cutting scenario for five 10-year periods in North Karelia, Finland. The removals were calculated for forests on both mineral soils and peatlands, whereas the berry yields were predicted only for mineral soil forests.


Integrating berry models into the forest management planning systems enabled us to study the effect of forest management on berry yields. The stand-level results provide the forest managers recommendations on how to manage forest stands for the joint-production of timber and berries. The FMU-level results are useful to the forest owner as they illustrate the outcomes of different forest management strategies or alternatives and multi-dimensional production possibilities of her forest holding. The regional level results serve particularly forest policy formulation and e.g. preparation of regional forestry programs. In the above regional example, income from berries did not affect the contents of the regional cutting scenario, i.e. the use of berry models was exogenous. The next step is to analyze the monetary trade-offs between timber and berry at the regional level.

References

Hirvelä, H., Härkönen, K., Lempinen, R. & Salminen, O. 2017. MELA2016 Reference Manual. Natural Resources Institute Finland (Luke). 547 p.

Kurttila, M. & Tahvanainen, V. (eds.) 2016. Description of new decision support tools for optimization of MPT and NWFP management. Deliverable 2.4. FP7 Project no 311919 KBBE.2012.1.2-06, European Commission. 106 p.

Miina, J., Hotanen, J.-P. & Salo, K. 2009. Modelling the abundance and temporal variation in the production of bilberry (Vaccinium myrtillus L.) in Finnish mineral soil forests. Silva Fennica 43: 577-593.

Miina, J., Pukkala, T. & Kurttila, M. 2016. Optimal multi-product management of stands producing timber and wild berries. European Journal of Forest Research 135: 781-794.

Pukkala, T. 2006. Monsu-metsäsuunnitteluohjelmisto. Versio 5. Ohjelmiston toiminta ja käyttö. University of Joensuu. 53 p. (In Finnish)

Pukkala, T., Lähde, E., Laiho, O., Salo, K. & Hotanen, J.-P. 2011. A multifunctional comparison of even-aged and uneven-aged forest management in a boreal region. Canadian Journal of Forest Research 41: 851-862.

Turtiainen, M. & Nuutinen, T. 2012. Evaluation of information on wild berry and mushroom markets in European countries. Small-scale Forestry 11: 131-145.

 

last updated:  Friday, April 7, 2017