A survey was conducted to assess the impact of the choice of definition on reported quantities of dead wood in Swedish forests, which to more than 90% are located in the boreal zone. The data collection was made on a subsample of the permanent plots of the Swedish national forest inventory. The objects included were standing dead trees and snags down to 5-cm diameter at breast height, dead lying stems and branches down to a threshold diameter of 1 cm and stumps down to a threshold diameter of 5-cm at normal stump height. Standing trees, snags and stumps were inventoried on 10-m radius circular plots while the downed objects were inventoried using both circular plots and line intersect sampling; thin objects (diameter 1–5 cm) were assessed only through line intersect sampling. The results showed that the estimated volume of dead wood was as high as 25 m3 ha−1 when all components were included. With the standard Swedish definition, the corresponding estimate was only 10.9 m3 ha−1, or 43% of the total value. Since definitions of dead wood vary greatly between countries we conclude that great caution must be exercised when figures are compared in connection with international reporting. For example, adding stumps to the Swedish definition would increase the amounts of dead wood from 10.9 to 15.7 m3 ha−1, i.e. with 44%.

This study investigated the influence of contrasting parent materials on tree chemical composition and growth rate under field conditions. On the island of Alnö, Sweden, alkaline intrusions are interspersed into non-alkaline gneiss bedrock, which provides a unique opportunity to conduct this study with a minimum of confounding effects.

The dynamic interactions between society and land resources have to be taken into account when planning and managing natural resources. A computer model, using STELLA software, was developed through active participation of purposively selected farm households from different wealth groups, age groups and gender within a rural community and some members of Kebelle council. The aim of the modeling was to study the perceived changes in land-use, population and livelihoods over the next 30 years and to improve our understanding of the interactions among them. The modeling output is characterized by rapid population growth, declining farm size and household incomes, deteriorating woody vegetation cover and worsening land degradation if current conditions remain. However, through integrated intervention strategies (including forest increase, micro-finance, family planning, health and education) the woody vegetation cover is likely to increase in the landscape, population growth is likely to slow down and households' income is likely to improve. A validation assessment of the simulation model based on historical data on land-use and population from 1973 to 2006 showed that the model is relatively robust. We conclude that as a supporting tool, the simulation model can contribute to the decision making process.

Informed decision on the management of natural resources requires an understanding of the complex dynamics of socio-economic and biophysical factors. This study aimed at exploring the land use change in southern Burkina Faso at regional and local levels and the underlying causes of change. The local level study was conducted in two villages, Boala and Yalé, in Sissili Province. Aerial photos from 1984 and 1997 and satellite images from 1986 and 2002 were employed to describe the land use dynamics. The spatial approach was combined with field data collected in 2003 and 2005 for ground-truth checking and gathering other relevant data. Semi-structured questionnaire was used for gathering data on socio-economic factors driving land use changes at local level. At regional scale, the annual rate of change in forest land, grazing land, gallery forest and cropland was −0.4, −0.9, −1.6 and 3.8%, respectively. The size of croplands increased by 14% in some districts with an equivalent annual rate of conversion to cropland estimated at 0.6% during 1986–2002. At the local level, the size of croplands increased from 7 to 14% in Boala and from 21 to 30% in Yalé at the expense of shrinking of forest cover from 78 to 40% in the former and from 41 to 18% in the latter village. Rural migration (3.3% at regional level, and as high as 97% in Yalé and 9% in Boala) coupled with extensive subsistence farming, large-scale commercial farming, intensive fuelwood extraction and other disturbances were the main factors driving land use change. In conclusion, the results show that in a decade and half the southern region of Burkina Faso has moved from a sparsely populated area with subsistence farming to a more complex zone of production characterized by high competition between different land use types. Integrated management of the natural resources in the region should, therefore, be given more attention.

The impact of soil parent material on soil chemical conditions, needle composition and tree growth

In this study, the effect of shelterwood density on radial increment and stem form changes was evaluated after 9 yrs for a trial in a forest in northern Sweden dominated by Norway spruce [Picea abies (L.) Karst.]. Radial increment increased after the shelterwood cut, compared with control stands. The effect was of the same magnitude for sparse and dense shelterwoods. The response started in the third growing season and increased until the seventh season after release. The relative increment response was highest in the lower parts of the tree trunk, which indicates a reallocation of increment during the shelterwood period, causing a slight taper deterioration.

In 1994, a large survey of soil chemistry was undertaken in thecounty of Värmland in central Sweden (Lundström et al. , 1998).The southern part of the county was affected by soilacidification whereas there were no such indications in thenorthern part. To investigate the influence of soil chemistryon the trees at the specific sites, the survey was continued byan analysis of needle chemistry (Norway spruce) which wasundertaken at 150 of the 180 sites, and of tree growth at 65 ofthe 180 sites. Growth was expressed as a ratio between expectedgrowth, estimated with a national, empirical growth model, andthe growth observed in the field. In statistical analyses,using rank correlation, PCA and PLS, there were only weakindications of an influence of soil chemistry on needlechemistry and on tree growth. A moderate correlation betweennitrogen and sulphur in needles was found, which wasinterpreted as an effect of deposition and of processes in thetree canopy. No obvious regional pattern of the growth ratiowas found, in contrast to the clear pattern of soilacidification. The statistical analysis could not with anycertainty point out any of the soil chemistry variables asespecially important for the tree growth ratio.

Forest biodiversity has become a new concern for society. It has introduced new regulations and new ways of thinking in areas of forest use and planning. In Sweden the Forestry Act of 1993 states that timber production and maintenance of biodiversity are objectives of equal dignity. This results in a need for monitoring the maintenance of biodiversity in order to know if the policy intentions are followed. The problem of maintenance of biodiversity can be looked at from different scales, such as species, ecosystem, landscape, regional and national.On the national and regional level it is possible to use forest resource inventory data to get an overview of the forest biodiversity changes. The method used was to analyse the relative changes of variables related to biodiversity over time. The changes are compared to a reference period (1983-1987) and can be calculated as either an annual change or as a moving average of three years data. The variables studied were proportion of the broadleaved species in middle aged forests, amount of dead or windthrown trees, amount of big trees, amount of old unmanaged forest, proportion of wet forests, clear-cut area and habitat diversity. These variables are considered important substrata to produce and maintain a high forest biodiversity.The results show that it is possible to follow the changes of the substrata (prerequisites) which indicate a high forest biodiversity on a broader scale. By introducing new variables more directly related to biodiversity and combining different information sources more effective methods can be developed.