78 FOREST REPORT 2005
4.2 Regeneration
Over 80% of Swiss forests today regenerate nat- urally and natural regeneration is increasing.
Trees that have regenerated naturally are optimally adapted to their surroundings.
Today trees are planted to strengthen protection forests, promote species diversity, or to produce valuable timber with indigenous tree species.
Swiss forests are becoming older and denser , and areas with young trees are becoming smaller.
This is particularly unfortunate for species that need light and warmth.
Natural
regeneration
For forests to regenerate, the young trees need enough light andspace.Suchconditions occur when clearings are ripped open by stormslikeLothar,burnt clean by forest fires orcleared by tree- felling.Clearingsare not only im- portant for new treegrowth,but also for all plants and animals that needlight andwarmth.Ac- cording to theNationalForest In- ventory(NFI),between1985and 1995 Swiss forests became 4%
denser. Areas with new growth fellfrom10 to8%,sincewithless intensive management there is less regeneration felling.
Whenaforest develops nat- urally,shrubsand trees that need light,likewillow,birch,ash,cher- ry and aspenare the first togrow.
These plant communitiesare the so-called pioneer communities that provide the conditions for other animals and plants to es- tablish.These newspeciesgradu- ally replace the pioneersand the forest begins to take on itsdefi- nite shape.
Over 80% of Switzerland’s
young forest has developed
through natural seeding, which isa European record.In moun- tain forests naturalregeneration ismore than90% since, toavoid excessive costs, trees are sel- dom planted.If timber is felled 4.2.1
Undergrowth
Inopen stands like this theforest can naturally regenerate.
79 4BIOLOGICAL DIVERSITY
onlargerareas,usually in forests at loweraltitudes, then so-called young growthandthickets form.
Only 60% of these today consist of naturally grown plants,while the rest areallormostly planted.
Thanks to increasingly near-nat- uralforest management,howev- er, the proportion of naturalre- generation in the young growth rose by 10% between 1985 and 1995.
People’s requirements of the forest changewith time,as sales from tree nurseries show.At the beginning of the 20th centu- ry spruce seedlingswere partic- ularly in demand to strengthen protection forestsand to restock formerbroadleaf forestswith fast- growing conifers. After the Sec- ond World War foresters some- times planted broadleaf trees in the newly created conifer forests to improve themecologically.In the 1960s and 1970s fast-grow- ing,undemandingsprucewas in demand again for construction timber, partly in reaction to the
4.2.3
Area covered by young forest
Young growth/thicket in uniform high forest.Regeneration according toNFI2.
Natural
regeneration Mixed regeneration Artificial regeneration
1985 50% 26% 24%
1995 60% 26% 14%
FURTHERINFORMATION Swiss Federal Research Institute WSL 8903 Birmensdorf
National Forest Inventory Research Dept. LANDSCAPE Section Landscape inventories (0) 44/ 739 23 43
Swiss Agency for the Environment, Forests and Landscape SAEFL 3003 Bern
Forest Agency
Section Forest conservation and bio- diversity
(0) 31 324 77 78
Over 80% of Switzerland’s young forest has developed through natural seeding, which is a European record. In mountain forests natural regeneration is more than 90% since, to avoid excessive costs, trees are seldom planted.
No. of plants [in millions]
25 20 15 10 5 0
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 Conifer
Broadleaf 4.2.2
Seedling use
Turnover of treenurseries in Switzerland from1896 to 2002.
fallin prices for fuel-wood.In the 80sand90s naturalregeneration became widely accepted, main- ly for ecological reasons. While in 1970around20million seed- lingswere supplied by tree nurs- eries,in2001only 2millionwere.
Today planting tends only tobe done to strengthen protection forests, to increase speciesdiver- sity or to produce valuable tim- ber fromindigenous trees instead of spruce plantations.
