Ingrid Stjernquist

Developing principles and models for sustainable forestry in Sweden

1. Introduction to the SUFOR programme. 2. On Swedish forests. 3. Defining sustainability. 4. Principles of sustainable forest management. 5. Integrated modelling. 6. Models of the risk of windthrow and frost. 7. Biogeochemical processes and mechanisms. 8. Forest vitality and stress implications. 9. Biodiversity in sustainable forestry. 10. Forests, acidification and the socio-economic cost. 11. Assessing effects of wildlife on forestry. 12. Sustainability in spruce and mixed-species stands. 13. Productivity scenarios for the Asa Forest Park. 14. Assessment of sustainability in the Asa Forest Park. 15. Nutrient sustainability for Swedish forests. 16. General conclusions. 17. References.

Chemical and biological effects of artificially increased nitrogen deposition to the ground in a Swedish beech forest

During 1985–90, effects of N deposition to a beech forest floor in south Sweden were studied by supplying 12 and 36 kg N ha‐1, as NH4NO3, on 25 occasions, i.e. 60 and 180 kg ha‐1 yr‐1, corresponding to ca. 3 and 9 times the ambient deposition rate. Treatments raised the output of NO‐ 3 and several base and metal cations from the soil. There was some increase in the total N content of the leaves and a considerable increase in the contents of free amino acids, whereas phenols decreased. Leaf concentrations of Ca, P and K were lower than in controls. Throughfall chemistry was generally little influenced by the treatments. There was no measurable change in the wood production. Fruitbody production of ectomycorrhizal fungi almost ceased, whereas that of major decomposer species increased considerably. The biomass of most field layer species was reduced to some extent in the treated plots and no new vascular plant species appeared during this five‐year period as a result of the treatments.

Micronutrient levels in some temperate European tree species: a comparative field study

Micronutrient concentrations in foliage and stemwood (including bark) of six European tree species (Betula pendula Roth., Quercus robur L., Fraxinus excelsior L., Fagus sylvatica L., Tilia cordata Mill. and Picea abies (L.) Karst.) planted on the same type of soil at six sites in three different countries were studied. Micronutrient concentrations in foliage were considerably higher than in stemwood for all elements and species studied, except for Fe in spruce. Interspecies comparisons revealed significant differences in concentrations both in foliar and stemwood biomass, as well as in stemwood:foliage nutrient ratios. Lime foliage showed a considerably higher concentration of B than all other species, while the stemwood concentration of this element was highest in ash. Mn concentration in both foliar and stemwood biomass of ash was extremely low compared with concentrations in other species. Birch stemwood showed nearly double the level of Zn in other species at all sites. Zn concentrations in the birch foliage were also higher than in other species, with the exception of the Lithuanian sites, which showed lower EDTA-extractable Zn concentrations in the soils. The concentration of Cu was lowest in spruce foliage, while Cu concentrations in stemwood were similar in all species. It was concluded that species-related differences in microelement nutrition must be taken into account when evaluating the nutrient status of common European forest tree species, and when using them as bio-indicators of the effects of environmental pollution.

Seasonal dynamics, especially autumnal retranslocation, of nitrogen and phosphorus in foliage of dominant and suppressed trees of beech, Fagus sylvatica

Seasonal changes in the N and P content of foliage in a young forest of Fagus sylvatica were measured. Leaves from branches of the upper and lower crown of dominant trees and from suppressed trees were compared. Nutrient retranslocation rates during senescence differed considerably between trees. This variation appeared not to be related to any differences in environmental factors or tree vigour, and was probably genetically induced. In dominant trees the most efficient retranslocation of N was recorded in the upper crown and probably resulted from higher leaf temperatures and a longer senescent period in the sun leaves than in the shade leaves. Phosphorus retranslocation efficiency was higher in suppressed trees than in dominant ones, but no such tendency was observed with N. The most obvious difference between leaves at different crown levels concerned the time at which P translocation began; an outflow of P from leaves in the lower crown began in June, while in the upper crown this outflow did not begi...

An integrated environmental analysis of short rotation forests as a biomass resource

Two types of sustainability ought to be discussed in connection with biomass use for energy, the long term sustainability of biomass production as such, and the overall ecosystem sustainability under the existing and future global climatic conditions. This framework will stress the importance of using biomass as an energy resource, for reducing the use of fossil fuels. An integrated view of the environmental effects of short-rotation forest plantations should include an analysis of the effects from production to conversion and an analysis of the range of the specific environmental effect in relation to other alternatives for producing energy or wood products. Many negative effects from the utilization step of short-rotation forest plantations can be minimized depending on the choice of land, cultivation methods and target levels yield. Short-rotation plantations is an environmental sound energy resource if. (1) the biomass production systems are not pressed to maximum production, (2) cultivation measures are taken to minimize nutrient leaching, (3) the short-rotation plantations are designed for visual adaptation to the landscape, and (4) directed silvicultural measures are taken to retain and improve important habitats and protect marginal forest areas.

Assessment of sustainability in the Asa Forest Park

The main objectives of the geochemical investigation in Asa Forest Research Park (referred to henceforth simply as Asa) were as follows: 1. to calculate the release of Ca, Mg, K, and P from mineral weathering using PROFILE, a biogeochemical soil model, 2. to determine the geographical distribution of the results of weathering rate calculations carried out both at the site level and on a regional scale and 3. to propose a mass balance method for calculating the optimal sustainable biomass production of a forested area in southern Sweden

Application of natural, social, and economical sustainability limitations to forest management, based on Swedish experiences

Abstract We suggest a method of analyzing the sustainability conditions for forestry from three major realms: environmental, social, and economic. The tools and methods were tested at sites in Sweden. Assessments were made for the long-term sustainability concerning the impact of present management practices on the balances of nutrients in monocultures and mixed-species stands. In the economic assessments, both traditional terms but also costs and revenues from adaptation to defined biodiversity criteria and public service demands were accounted for. An alternative to traditional discounting was used for transferring monetary value over time, by introducing spruce pulp equivalent units. Several scenarios with unsustainable conditions could be identified as well as appropriate management measures that can be taken to correct the issue. Results showed that the changes in management methods needed are possible and feasible. No significant difference in the net profit from the Norway spruce monocultures and the deciduous-conifer mixed stands were found. An increased use of deep rooting tree species has the potential to increase the total sustainable harvest volume.

Factors toxic to beech (Fagus sylvatica L.) seedlings in acid soils

The effects of highly and moderately acid soils on total biomass, biomass partitioning, fine root characteristics and nutritional status of beech seedlings (Fagus sylvatica L.) were studied in a growth chamber experiment. In Haplic Arenosols seedlings grew slowly but equally well without damage symptoms in a highly acid and a moderately acid soil horizon. The moderately acid Ah+Bw-horizon of a Eutric Cambisol was favourable to seedling growth. The fine root development was reduced in the highly acid A+Bw-horizon of a Dystric Cambisol and in the Ah+E-horizon of a Haplic Podzol, the latter of which also caused increased mortality. Seedling growth in the B2-horizon of the Haplic Podzol was vigorous, in spite of a higher level of extractable Al and lower base saturation as compared with the Ah+E-horizon. These results are interpreted in relation to soil acidity, soil Al and nutritional status of the seedlings. We conclude that neither Al-toxicity nor nutrient deficiency cause the damage symptoms observed in the Ah+E-horizon of a Haplic Podzol and the fine root reduction in the A+Bw-horizon of a Dystric Cambisol. The damage symptoms of the PZhA treatment seems to be more the result of H-toxicity or H-related factors other than nutrient shortage or Al-toxicity. Other pH-related toxic factors are discussed.

Growth and nutrient dynamics of beech (Fagus sylvatica L.) seedlings in acid soils

The relative uptake rates of N, P, K, S, Ca, Mg, Fe, Mn, Zn, Cu, and Al were estimated in beech seedlings pot cultured in the field in six acid soils (treatments). The relative uptake rates were compared with the relative growth rates. The relative uptake rates of N, K and Ca agreed well with the growth rates of the seedlings irrespective of widely differing soil conditions (acid sand-clayey till, pH 4–6). The relative uptake rates of P, Fe, and Al differed from that predicted by the growth rate. The uptake rates of Fe and Al were highest at the lowest growth rates, and the P uptake rate was lower than the growth rate in these treatments. Thus the P availability probably limited growth in an eluvial (E) horizon of a podzol, and possibly in the illuvial (B) horizon of a podzol and in an acid clayey till (Dystric Cambisol). Low P uptake was associated with a tendency towards higher relative root growth rates. In terms of the concept of steady state nutrition the high relative root growth rate in some treatments may be interpreted as an acclimation to low P supply. The P limitation seemed to be related to interactions among Fe, Al and organic compounds of the soil solution.

Forest vitality and stress implications

Changes in forest vitality affect such fundamental tree functions as growth, reproduction and defence against pests (McLaughlin and Percy 1999). Stress factors acting on the forest limit the resource utilisation, effective growth and reproduction (Grime 1991). For sustainable forestry in southern Sweden, the current objective is to balance the goal of achieving high growth per year, high wood quality, of preserving or increasing biodiversity, of maintaining long-term soil productivity and of preventing the leaching into streams of soil nutrients and metals due to natural and anthropogenic stress factors.