Jari Hynynen

Predicting the decomposition of Scots pine, Norway spruce, and birch stems in Finland.

Models were developed for predicting the decomposition of dead wood for the main tree species in Finland, based on data collected from long-term thinning experiments in southern and central Finland. The decomposition rates were strongly related to the number of years after tree death. In contrast to previous studies, which have used the first-order exponential model, we found that the decomposition rate was not constant. Therefore, the Gompertz and Chapman-Richards functions were fitted to the data. The slow initial decomposition period was mainly due to the fact that most dead trees remained standing as snags after their death. The initial period was followed by a period of rapid decomposition and, finally, by a period of moderately slow decomposition. Birch stems decomposed more rapidly than Scots pine and Norway spruce stems. Decomposition rates of Norway spruce stems were somewhat lower than those of Scots pine. Because the carbon concentration of decaying boles was relatively stable (about 50%) the rate of carbon loss follows that of mass loss. Models were also developed for the probability that a dead tree remains standing as a snag. During the first years after death, the probability was high. Thereafter, it decreased rapidly, the decrease being faster for birch stems than for Scots pine and Norway spruce stems. Almost all stems had fallen down within 40 years after their death. In Scots pine and Norway spruce, most snags remained hard and belonged to decay class 1. In birch, a higher proportion of snags belonged to the more advanced decay classes. The models provide a framework for predicting dead wood dynamics in managed as well as dense unthinned stands. The models can be incorporated into forest management planning systems, thereby facilitating estimates of carbon dynamics.

Self-thinning models for even-aged stands of Pinus sylvestris, Picea abies and Betula pendula

Self‐thinning models were developed to describe the relationship between the stem number and mean diameter of even‐aged and monospecific tree stands undergoing self‐thinning. The models were developed separately for Pinus sylvestris L., Picea abies (L.) Karst. and Betula pendula Roth. stands. Data from 41 unthinned permanent sample plots were used. According to Reinekes equation and the —3/2 power rule of self‐thinning, a log‐log plot of average tree size and stem density will give a straight, self‐thinning line of constant slope. According to this study, the slope of the line consistent with Reinekes equation varies for different tree species. Within tree species, the intercept of the self‐thinning line varies according to site index.

Silvicultural management in maintaining biodiversity and resistance of forests in Europe–boreal zone: case Finland

The majority of untouched natural boreal forests have been regenerated through large catastrophes, occurring by intervals between 50 and 100 years. Storm and fire will open the landscape, result in a huge amount of dead or dying trees and let the pioneer tree species germinate. These processes are the guideline for Finnish forest management today. The main focus by maintaining the biodiversity in Finnish boreal forest zone is directed to managed forests. Nature-orientated silviculture on stand level is practised. The site type classification, a reflection of the modern concept of biodiversity and developed by Cajander early in 1900s, on the basis of natural vegetation composition of the site, has the central role by choosing tree species, regeneration methods and thinning procedure, and reflects also on the site productivity. The small size of stands, the abundance of natural seedlings in planted stands and the popularity of mixed stands have a positive impact on biodiversity of forests. The protection of small-sized valuable habitats in commercially managed stands, the leaving of retention trees standing and lying in the forest in all phases of the rotation, are activities made for biodiversity. Many insects and fungi are adapted to catastrophes and so they can survive in single stems left on regeneration areas. Maintaining the biodiversity in multifunctional forests is also supported by the new forest legislation and by the criteria of Finnish Forest Certification System.

Modeling tree growth in fertilized midrotation loblolly pine plantations

Diameter and height growth models for fertilized loblolly pine stands were developed using data from midrotation loblolly pine plantations across the southeastern United States. Tree growth in fertilized stands was predicted with a reference growth model multiplied by an equation predicting the relative growth response following fertilization. The temporal distribution of the growth response was modeled by the Weibull function. These equations for fertilizer growth response were developed to be compatible with individual-tree simulation models. Information about dose, nutrient elements, and time elapsed since fertilization are needed to predict the relative growth response following fertilization.

Global warming potentials of stemwood used for energy and materials in Southern Finland: differentiation of impacts based on type of harvest and product lifetime

Wood harvesting in boreal forests typically consists of sequential harvesting operations within a rotation: a few thinnings and a final felling. The aim of this paper is to model differentiated relative global warming potential (GWP) coefficients for stemwood use from different thinnings and final fellings, and correction factors for long‐lived wood products, potentially applicable in life cycle assessment studies. All thinnings and final fellings influence the development of forest carbon stocks. The climate impact of a single harvesting operation is generated in comparison with no harvesting, thus encountering a methodological problem on how to handle the subsequent operations. The dynamic forest stand simulator MOTTI was applied in the modelling of evolution of forest carbon stocks at landscape level in Southern Finland. The landscape‐level approach for climate impact assessment gave results similar to some stand‐level approaches presented in previous literature that included the same forest C pools and also studied the impacts relative to the no‐harvest situation. The climate impacts of stemwood use decreased over time. For energy use, the impacts were higher or similar in the short term and 0–50% lower in the midterm in comparison with an identical amount of fossil CO2. The impacts were to some extent (approximately 20–40%) lower for wood from intermediate thinnings than for wood from final fellings or first thinnings. However, the study reveals that product lifetime has higher relative influence on the climate impacts of wood‐based value chains than whether the stemwood originates from thinnings or final fellings. Although the evolution of future C stocks in unmanaged boreal forests is uncertain, a sensitivity analysis suggests that landscape‐level model results for climate impacts would not be sensitive to the assumptions made on the future evolution of C stocks in unmanaged forest. Energy use of boreal stemwood seems to be far from climate neutral.

Trade-offs between forest carbon stocks and harvests in a steady state – A multi-criteria analysis

This paper provides a perspective for comparing trade-offs between harvested wood flows and forest carbon stocks with different forest management regimes. A constant management regime applied to a forest area with an even age-class distribution leads to a steady state, in which the annual harvest and carbon stocks remain constant over time. As both are desirable - carbon stocks for mitigating climate change and harvests for the economic use of wood and displacing fossil fuels - an ideal strategy should be chosen from a set of management regimes that are Pareto-optimal in the sense of multi-criteria decision-making. When choosing between Pareto-optimal alternatives, the trade-off between carbon stock and harvests is unavoidable. This trade-off can be described e.g. in terms of carbon payback times or carbon returns. As numerical examples, we present steady-state harvest levels and carbon stocks in a Finnish boreal forest region for different rotation periods, thinning intensities and collection patterns for harvest residues. In the set of simulated management practices, harvest residue collection presents the most favorable trade-off with payback times around 30-40 years; while Pareto-optimal changes in rotation or thinnings exhibited payback times over 100 years, or alternatively carbon returns below 1%. By extending the rotation period and using less-intensive thinnings compared to current practices, the steady-state carbon stocks could be increased by half while maintaining current harvest levels. Additional cases with longer rotation periods should be also considered, but were here excluded due to the lack of reliable data on older forest stands.

Projecting biodiversity and wood production in future forest landscapes: 15 key modeling considerations

A variety of modeling approaches can be used to project the future development of forest systems, and help to assess the implications of different management alternatives for biodiversity and ecosystem services. This diversity of approaches does however present both an opportunity and an obstacle for those trying to decide which modeling technique to apply, and interpreting the management implications of model output. Furthermore, the breadth of issues relevant to addressing key questions related to forest ecology, conservation biology, silviculture, economics, requires insights stemming from a number of distinct scientific disciplines. As forest planners, conservation ecologists, ecological economists and silviculturalists, experienced with modeling trade-offs and synergies between biodiversity and wood biomass production, we identified fifteen key considerations relevant to assessing the pros and cons of alternative modeling approaches. Specifically we identified key considerations linked to study question formulation, modeling forest dynamics, forest processes, study landscapes, spatial and temporal aspects, and the key response metrics - biodiversity and wood biomass production, as well as dealing with trade-offs and uncertainties. We also provide illustrative examples from the modeling literature stemming from the key considerations assessed. We use our findings to reiterate the need for explicitly addressing and conveying the limitations and uncertainties of any modeling approach taken, and the need for interdisciplinary research efforts when addressing the conservation of biodiversity and sustainable use of environmental resources.

Cost-Efficiency of Alternative Forest Conservation Targets, a Case Study from Finland

Temporal contracts to protect biodiversity in forests are a recent approach which has shown to be a promising and cost-efficient procedure. With respect to cost-efficiency of temporal contracts the relevant issue is the goal of conservation: for instance, are we interested in enhancing CWD index (coarse woody debris) or increasing the amount of dead wood in forests? This study focuses on demonstrating the effect of conservation goal (either enhancing CWD index or increasing the amount of dead wood) on costefficiency by optimization. Further, we analyze whether both the length of temporal conservation (10 or 30 years) and discount rate (2% or 4%) would have an effect on optimal solutions. The data consisted of 20 measured forest sites with stand age between 60 and 160 years. Majority of the stands (80%) fulfilled the biological conservation criteria of the Finnish Forest Biodiversity Programme METSO and a few of the stands were managed commercial forests. For temporal conservation (either 10 or 30 years), stand growth and dynamics of decaying wood were forecasted with a stand simulator (Motti) by prolonging the clear-cut with 10 or 30 years. The results for the two alternative conservation periods were compared to business-as-usual, BAU, with respect to income losses. Then, for ecological responses the initial, measured stand characteristics were set for the baseline to which temporal conservation alternatives (10 or 30 years) were compared to. The results of optimization distinctively demonstrated that the conservation goal has a relevant effect on the cost-efficiency. Further, the length of the conservation period has also an important role in cost-efficiency whereas the discount rate plays only a minor role in this study context. In the optimal solutions the forest sites with distinctively above-average initial amount of dead wood and excellent growth predictions which imply lower than average income losses due to conservation shone through with respect to cost-efficiency. As a word of caution, it should be pointed out that if one merely chooses the most cost-efficient sites for conservation, there is a possibility that a desirable level of biodiversity might not be fulfilled. To test this, the study needs to be next extended to landscape level with larger data input.

Genetically improved reforestation stock provides simultaneous benefits for growers and a sawmill, a case study in Finland

ABSTRACT Recent research has demonstrated benefits of genetically improved seed material (from seed orchards) for growers. In this study, we analyzed whether the profits of genetically faster growing material are also realized as simultaneous economic benefits for a sawmill. We compared three types of improved Scots pine (Pinus sylvestris L.) seedlots to unimproved seedlots on three climatically different sites using stand-simulation software MOTTI. Genetic gains in early-rotation growth traits were incorporated in the growth models as genetic multipliers. Bare land values of the simulated stands were maximized using stand-level optimization. Consequently, removals of each thinning and final harvest were used to estimate the total value of sawing yield. This was subsequently maximized by optimizing the sawing procedure of the logs assuming identical timber quality between improved and unimproved seedlots. The results indicate that simultaneous financial incentives from tree breeding are achievable for both agents (growers and a sawmill). In general, the financial potential increases with the growth potential of the regeneration material, although the form of the relationship is not linear in all cases.

Raaka-aineita, hiilensidontaa ja bioenergiaa – Suomen metsien monet mahdollisuudet

Luonnonvarojen kestävän hyödyntämisen kannalta on elintärkeää siirtyä maailmanlaajuisesti hyödyntämään uusiutuvia raaka-aineita uusiutumattomien sijaan. Suomessa metsät ovat tärkein uusiutuvan raaka-aineen lähde eikä puusta ole tällä hetkellä pulaa. Metsät kasvavat paljon enemmän kuin puuta käytetään. Puunkäytön lisäämisen pullonkaulana, niin nyt kuin lähitulevaisuudessakin, on puun riittävyyden sijaan sen saatavuus ja kilpailukyky raaka-aineena. Miten uusiutuva raaka-aine otetaan talteen metsästä ja edelleen valmistetaan tuotteiksi niin kannattavasti, että toiminta on globaalisti kilpailukykyistä, ja voisi siten korvata uusiutumattomien raaka-aineiden käyttöä? Taloudellinen kannattavuus ei pelkästään takaa puun saatavuutta, vaan lisäksi raaka-ainetuotannon on oltava ekologisesti ja sosiaalisesti kestävää sekä yleisesti hyväksyttävää. Metsien käsittelyllä voidaan vaikuttaa siihen, miten puuraaka-aineen saatavuutta edistetään kestävällä ja hyväksyttävällä tavalla. Vuosikymmenien aikana tehty tutkimustyö ja myös käytännön kokemukset ovat selvästi osoittaneet, että intensiivisellä metsänhoidolla voidaan tehostaa raaka-ainetuotantoa 1) lisäämällä puuntuotosta pinta-alayksikköä kohti, 2) ohjaamalla puun raaka-aineominaisuuksia haluttuun suuntaan ja 3) pienentämällä metsänhoidon ja puunkorjuun yksikkökustannuksia. Oikein mitoitettuna ja kohdennettuna tehostetut metsänkäsittelytoimet täyttävät myös kestävyyskriteerit. Suomen metsävarojen tulevaisuuden tuotantopotentiaalia selvitettiin FIBIC Oy:n EffFibre-tutkimusohjelmassa. FIBIC Oy (Finnish Bioeconomy Cluster Oy, entinen Metsäklusteri Oy) on yksi Suomen kuudesta strategisen huippuosaamisen keskittymästä. EffFibre-tutkimusja kehittämisohjelman tavoitteena on kasvattaa kotimaisen puuraaka-aineen saatavuutta ja puuntuotannon kustannustehokkuutta sekä parantaa koko klusterin kilpailukykyä kehittämällä radikaalisti uudenlaisia energiatehokkaita ja resursseja säästäviä tuotantoteknologioita. Skenaarioeli ennustetutkimuksen avulla selvitettiin metsävarojen ja metsien hoidon mahdollisuudet vaikuttaa tulevaisuudessa saatavan raakaaineen määrään ja laatuun. Tutkimuksessa tarkasteltiin puuntuotantomahdollisuuksia monipuolisesti eri näkökulmista. Raaka-aineen määrän ja laadun ohella tarkasteltiin metsänkäsittelyvaihtoehtojen vaikutuksia metsänkasvatuksen kannattavuuteen metsänomistajan näkökulmasta. Näiden lisäksi tarkasteltiin teollisuus-, työllisyysja ilmastovaikutuksia. Tavoitteena oli myös selvittää puuntuotannon alueellisia mahdollisuuksia ja edellytyksiä.