30 FOREST REPORT 2005
1.2 Growing stock
Swiss forests contain a total of 420 million m
3of wood: 367 m
3per hectare. This average for the whole country is the European record.
Conifers account for 71% of the standing grow- ing stock, and broadleaf trees for 29%.
Spruce, silver fir and beech together account for 80% of the growing stock.
Growing stock increases by almost 1% annually.
Storms have hardly any impact on this increase.
The increase in timber is more of a disadvantage for species diversity and timber production, but advantageous for the CO
2balance.
Growing stock
The growing stock of a forest is equivalent to the volume ofwood in its stands. This includes the standing stemsand thebark, but not the branches or the brush- wood.In total, the growing stock inSwiss forestsamounts toabout 420million m3.Thisisanaverage of367m3ofwoodfor each hec- tare of forest,whichis more than in any othercountry inEurope.
By way ofillustration: thiswould be enough tocover thewhole of Switzerlandwithalayer ofwood onecentimetre thick.
Growing stocksare not equal- ly largeinallof the forestsinSwit- zerland.On the southern side of the Alps stocksarecomparative- ly small,with an average of219 m3per hectare.By comparison,in the Central Plateau one hectare of forest contains onaverage440 m3of timberandin thePre-Alps 469 m3 per hectare. The forests in the Jura and Alpine regions have365and318m3per hectare, which isclose to the Swiss aver- age.
Differencesarealsoapparent depending on the type of owner- ship.Privately ownedforests have larger stocks,with an average of 420m3ofwoodper hectare, than publicly owned forests, with av- erage stocks of only 341 m3 per hectare.
Conifersaccount for 71% of the standing growing stock, while broadleaf trees only account for 29%. In the Alps and Pre-Alps conifersare even moredominant.
Of all the tree species, Norway spruce(Picea abies) accounts for the largest percentage (47%) of the growing stock.It is followed by Europeanbeech(Fagus sylvati- ca,18%of the growing stock)and silver fir (Abies alba, 15%). Vol- umes of other tree species,such aspine (Pinus(spp)), European larch (Larix decidua), sycamore (Acer(spp)),ash(Fraxinus excel- sior)andoak(Quercus(spp)),are alot lower(merely 2% to 5%).
FURTHERINFORMATION Swiss FederalResearchInstituteWSL 8903 Birmensdorf
ResearchDept. FOREST Section Silvicultural strategies (0)44/ 739 2486
Swiss Agencyfor theEnvironment, Forests andLandscape SAEFL 3003 Bern
Forest Agency
SectionForest utilization and timber industry
(0) 31/ 32477 78
31 1 RESOURCES
Increase in stocks
Around1950forestry experts es- timated the growing stock tobe roughly 250 m3 per hectare of forest.Since then stocks havein- creased considerably –by almost 1%annually.Thisis mainly due to the fact, that for several dec- ades, less wood has been used thanactually grows.Additionally, theincreasednitrogencontent of theairis thought toact asaferti- lizer for the forest andstimulate the growth of the trees.
Between 1985 and 1995 alone, growing stocks increased by 7.6%,equivalent toanannu- al increase of3.2m3ofwoodper hectare.2.5 m3of thiswas from living trees, 0.7 m3 from dead wood. The increasing expan- sion of the forest ontoprevious- ly cultivated areasisaccelerating the growth of these stocks.If the freshly forested areasareinclud- ed, theincreasein growing stock between 1985 and 1995 was as muchas 11.7%.
Growing stocksareincreasing throughout Switzerland,with the most markedincrease ofabout 4 m3ofwoodper hectareand year in thePre-Alps.The total propor- tion of broadleaf treesalso rose slightly between 1985 and 1995.
During this period annual new growth ofbroadleaf treeswas 1.3 m3 per hectare and of conifers 1.2m3per hectare.This trendfor growing stocks to increase has, like the trend for forested areas to spread, remained unbroken.
Even strong storms have barely halted this risein stocks.For ex- ample,one year’s growthafter the 1999storm“Lothar”was equiva- lent toall the treesblown down in the storm.And the forest only neededhalfa year tocompensate for the damage causedby “Vivi- an”in 1990.
1.2.1
Growing stock according to forestry region
Growing stockof broadleaf andconiferous treesin thediffer- ent forestry regions and thewhole of Switzerland.
Effects of the large stocks of timber and wood
Growing stock is a forest own- er’s capital. However, in this case “more” does not necessari- ly mean“better”.Theincreasein the growing stocks has had, on thewhole,anegative effect since a forest with a high volume of growing stock is usually dense and dark. As a result, species needing a lot of light lose their habitat,and the forest cannot re- generate sufficiently.This means
that thereare then more old trees in the forest,whichlose their val- uebecause,withincreasingage, more rotten patches develop in the wood. The damage poten- tialof stormsalso rises the more wood thereisin the forest.These areallarguments for using more woodfromSwiss forests.Howev- er,with thecurrent lowdemand forSwisswood, thisis hardly pos- sible.Moreover most forest own- ersare not inclined to fellmore trees because timber prices are currently solow.
[m3/ha]
■Broadleaf trees
■Conifers
Jura Central Pre-Alps Alps South Switzerland
Plateau of the Alps
1.2.2
Growing stock according to tree species
Distribution according tothedifferent tree species.
Conifers:
■Spruce
■Fir
■Pine
■Larch
■Swiss stone pine
■Other conifers Broadleaf trees:
■Beech
■Sycamore
■Ash
■Oak
■Chestnut
■Other broadleaf trees 500
400 300 200 100 0
