|
Standing volume in Sweden's forests has increased consistently since the 1920's when the National Forest Inventory first started collecting data. In the middle of the 1920's the total stadning volume was 1 719 million m3sk, and has increase to the current level of 3 100 million m3sk. This represents and increase of 84%. This steady increase indicates a long term trend of higher growth than loss (natural loss and fellings) during the period.
The reason for this increase is the production and growth based forest management introduced with the more intensive forest use which started at the beginning of the 20th century.
Sweden's forests are dominated by pine and spruce which is natural considering the majority of the country lies within the boreal region. The increase seen in standing volume was primarily in spruce up until the 1970s, since then the increase in stadning voulme is from spruce, pine and broadleaves. In recent years spruce volume have stabilised and increases are primarily due to pine and broadleaves.
The proportion of broadleaves has increased from 15% at the end of the 1950's to 19% today. This means we are now back to the same proportion of broadleaves as was seen in the 1920's. From the 1990's the proportion of spruce has decreased slightly from 45% to 41%. An important reason behind this decrease is the effects of the severe storms in southern Sweden during the past few years which primarily affected medium aged spruce forests. The volume of dead and wind thrown trees has been reletively constant, with a slght increase due to storms at the end of the 1960's. An increase can be seen however for the last 10-15 years and the proportion dead and windthrown trees is now 3% of the total living standing volume. The proportion for all dead wood, that is to say dead wood in all decomposition classes is 6% of the total living standing volume.
The volume dead wood in Swedish forest is a well established indicator of biodiversity (Samuelsson & Ingelög 1996).  Many species are dependant on dead wood in different stages of decay and the absence of dead wood has been identified as the most important threat to already endagered species in Swedish forests (Swedish speceis information center, 2000). From the map shown here it can be seen that dead wood is distributed over the whole country. The highest volumes are seen below the apline region in northern Sweden. High volumes are also seen in cental northen sweden and on the west coast. Volume dead wood decreases in two general patterns, one southerly and one easterly. The average volume dead wood for the whole country is 8.2 m³/ha. Large differences can be seen for forest land within and outside of protected areas with 22.1m³/ha and 7.7m³/ha respectively.
All the data above are 5 year averages for the period 2006-2010 |