Metsän erirakenteisuutta edistävien hakkuiden kannattavuustarkastelu metsäaluetasolla

Tutkimuksessa vertailtiin metsän erirakenteisuutta edistävien poimintahakkuiden ja pienaukkohakkuiden kannattavuutta metsänhoitosuositusten mukaiseen metsänkasvatukseen Keski-Suomessa. Poimintahakkuut ja pienaukkohakkuut ovat menetelmiä, joilla voidaan lisätä luonnonmetsän häiriödynamiikan mukaista pienipiirteistä elinympäristöjen vaihtelua ja siksi ne sopivat etenkin erityiskohteisiin monimuotoisuuden, maiseman tai metsien monikäytön vuoksi. Ne johtavat yleensä vähitellen eri-ikäisrakenteiseen metsään, jossa puuston läpimittaluokkajakauma muistuttaa käänteistä J-kirjainta. Eri-ikäisrakenteisen metsänkäsittelyn taloudellista kannattavuutta puoltavat uudistumiskustannusten poisjäänti ja tukkipuihin painottuvat säännöllisin väliajoin toteutuvat hakkuut. Menetelmän soveltumista Suomen olosuhteisiin pidetään kuitenkin epävarmana. Tässä tutkimuksessa tarkasteltiin tasaikäisrakenteisen metsän muuttamista eri-ikäisrakenteiseksi 40 vuoden siirtymäaikana Metsähallituksen hallinnoimassa Isojäven ympäristöarvometsässä Kuhmoisissa. Tutkimusaineisto koostui 405 kuusivaltaisesta tasaikäisestä kuviosta, joiden pinta-alasta metsämaata on 636 hehtaaria. Metsän kehitystä simuloitiin puutason kasvumalleja käyttäen ja käsittelytoimenpiteet simuloitiin viisivuotiskausittain SIMO-metsäsuunnitteluohjelmistolla. Simulointien avulla selvitettiin jokaisen käsittelyskenaarion hakkuumäärät puutavaralajeittain, diskontatut kassavirrat ja puustopääoman muutos tarkasteluajanjakson aikana. Puunkorjuun yksikkökustannusten laskennan apuna käytettiin automatisoitua seurantajärjestelmää, jossa metsäkoneisiin asennettuilla matkapuhelimilla kerättiin MobiDoc2-sovelluksella metsäkoneiden käytöstä kiihtyvyystiedot, GPS-paikkatiedot ja syötetiedot. Lopulta jokaiselle käsittelyskenaariolle laskettiin metsän puuntuotannollista arvoa kuvaavalla tuottoarvon yhtälöllä nettonykyarvot, josta vähennettiin diskontatut puunkorjuun kustannukset. Tutkimuksen tulosten mukaan poimintahakkuun NPV oli 3 prosentin korkokannalla noin 91 % (7420 €/ha) ja pienaukkohakkuiden noin 99 % (8076 €/ha) metsänhoitosuositusten mukaisesta käsittelystä (8176 €/ha). Komparatiivinen statiikka osoitti, että korkokannan kasvattaminen 5 prosenttiin ei olennaisesti lisännyt nettonykyarvojen eroja. Poimintahakkuiden puunkorjuun yksikkökustannukset olivat 0,8 €/m3 harvennushakkuita pienemmät ja 7,2 €/m3 uudistushakkuita suuremmat. Pienaukkohakkuiden yksikkökustannukset olivat 0,7 €/m3 uudistushakkuita suuremmat.Tulosten perusteella on väistämätöntä että siirtymävaihe tasaikäisrakenteisesta eri-ikäisrakenteiseksi metsäksi aiheuttaa taloudellisia tappioita siitäkin huolimatta, että hakkuut ovat voimakkaita ja tehdään varttuneeseen kasvatusmetsään. Tappion määrä on metsän peitteisyyden ylläpidosta aiheutuva vaihtoehtoiskustannus.

Biokaasun tuotannon ja lietelannan jakeistamisen taloudelliset vaikutukset nautatilalle

Työn tavoitteena on tutkia nautatilojen lannan käsittelytapojen taloudellista kannattavuutta. Tutkimuksessa verrataan lietelannan vaihtoehtoisia käsittelytapoja, joita ovat (a) lietteen levittäminen peltoon ilman esikäsittelyä, (b) lietelannan jakeistaminen typpipitoiseen nestejakeeseen ja fosforipitoiseen kuivajakeeseen sekä (c) lannan hyödyntäminen biokaasun tuotannossa. Aineistona tutkimuksessa käytetään aiempia tutkimustuloksia sekä Vieremällä sijaitsevien nautatilojen (21 kpl) tietoja. Menetelmänä käytetään lineaarista ohjelmointia ja malli ratkaistaan GAMS -ohjelmaa käyttämällä. Teoriana tutkimuksessa on tuotanto- ja kustannusteoria. Tutkimuksessa tarkastellaan kuinka eläintiheys, peltolohkorakenne sekä kustannusten muutokset vaikuttavat lannankäsittelyyn. Tutkimuksessa havaitaan, että kun kaikkea lietettä ei voida levittää tilan hallinnassa oleville pelloille, on lietteen jakeistaminen kannattavaa, jos jakeistuskustannus ei ylitä 1,2 €/m3. Sijoituslevityksen havaitaan olevan hajalevitystä kannattavampaa, paitsi typen hinnan ollessa hyvin alhainen hajalevitys on kannattavampi vaihtoehto. Korkea typpikustannus ja lietteen jakeistuskustannus tekevät biokaasun tuotannosta kannattavan vaihtoehdon, jos biokaasulaitos sijaitsee hyvin lähellä tilaa. Lietteen jakeistaminen on kannattavaa alueilla, joilla lannanlevityspinta-alasta on niukkuutta. Jakeistettavaa lietettä on kuitenkin oltava vähintään 20 000 m3/a, jotta jakeistuslaitteen hankkiminen on kannattavaa. Biokaasun tuotannon ei katsota olevan tällä hetkellä kannattava lannan käsittelyvaihtoehto, koska laitoksen olisi saatava tarvittava raaka-ainemäärä kaikissa tapauksissa alle kahden kilometrin säteeltä, eikä tämän katsota onnistuvan. Vieremän tiloista ainoastaan yksi tila sijaitsee riittävän lähellä suunniteltua laitoksen sijaintipaikkaa.

Harvesting undelimbed Scots pine (Pinus sylvestris L.) from first thinnings for integrated production of kraft pulp and energy

The present study evaluates the feasibility of undelimbed Scots pine (Pinus sylvestris L.) for integrated production of pulp and energy in a kraft pulp mill from the technical, economic and environmental points of view, focusing on the potential of bundle harvesting. The feasibility of tree sections for pulp production was tested by conducting an industrial wood-handling experiment, laboratory cooking and bleaching trials, using conventional small-diameter Scots pine pulpwood as a reference. These trials showed that undelimbed Scots pine sections can be processed in favourable conditions as a blend with conventional small-diameter pulpwood without reducing the pulp quality. However, fibre losses at various phases of the process may increase when using undelimbed material. In the economic evaluation, both pulp production and wood procurement costs were considered, using the relative wood paying capability of a kraft pulp mill as a determinant. The calculations were made for three Scots pine first-thinning stands with the breast-height diameter of the removal (6 12 cm) as the main distinctive factor. The supply chains included in the comparison were based on cut-to-length harvesting, whole-tree harvesting and bundle harvesting (whole-tree bundling). With the current ratio of pulp and energy prices, the wood paying capability declines with an increase in the proportion of the energy fraction of the raw material. The supply system based on the cut-to-length method was the most efficient option, resulting in the highest residual value at stump in most cases. A decline in the pulp price and an increase in the energy price improved the competitiveness of the whole-tree systems. With short truck transportation distances and low pulp prices, however, the harvesting of loose whole trees can result in higher residual value at stump in small-diameter stands. While savings in transportation costs did not compensate for the high cutting and compaction costs by the second prototype of the bundle harvester, an increase in transportation distances improved its competitiveness. Since harvesting undelimbed assortments increases nutrient export from the site, which can affect soil productivity, the whole-tree alternatives included in the present study cannot be recommended on infertile peatlands and mineral soils. The harvesting of loose whole trees or bundled whole trees implies a reduction in protective logging residues and an increase in site traffic or payloads. These factors increase the risk of soil damage, especially on peat soils with poor bearing capacity. Within the wood procurement parameters which were examined, the CO2 emissions of the supply systems varied from 13 27 kg m3. Compaction of whole trees into bundles reduced emissions from transportation by 30 39%, but these reductions were insufficient to compensate for the increased emissions from cutting and compaction.

Tree mortality, fire scar formation and regeneration 8 years after low-intensity fire in managed Pinus sylvestris stands

Fire is an important driver of the boreal forest ecosystem, and a useful tool for the restoration of degraded forests. However, we lack knowledge on the ecological processes initiated by prescribed fires, and whether they bring about the desired restoration effects. The purpose of this study was to investigate the impacts of low-intensity experimental prescribed fires on four ecological processes in young commercial Scots pine (Pinus sylvestris) stands eight years after the burning. The processes of interest were tree mortality, dead wood creation, regeneration and fire scar formation. These were inventoried in twelve study plots, which were 30 m x 30 m in size. The plots belonged to two different stand age classes: 30-35 years or 45 years old at the time of burning. The study was partly a follow-up of study plots researched by Sidoroff et al. (2007) one year after burning in 2003. Tree mortality increased from 183 stems ha-1 in 2003 to 259 stems ha-1 in 2010, corresponding to 15 % and 21 % of stem number respectively. Most mortality was experienced in the stands of the younger age class, in smaller diameter classes and among species other than Scots pine. By 2010, the average mortality of Scots pine per plot was 18%, but varied greatly ranging from 0% to 63% of stem number. Delayed mortality, i.e. mortality that occurred between 2 and 8 years after fire, seemed to become more important with increasing diameter. The input of dead wood also varied greatly between plots, from none to 72 m3 ha-1, averaging at 12 m3 ha-1. The amount of fire scarred trees per plot ranged from none to 20 %. Four out of twelve plots (43 %) did not have any fire scars. Scars were on average small: 95% of scars were less than 4 cm in width, and 75% less than 40 cm in length. Owing to the light nature of the fire, the remaining overstorey and thick organic layer, regeneration was poor overall. The abundance of pine and other seedlings indicated a viable seed source existed, but the seedlings failed to establish under dense canopy. The number of saplings ranged from 0 to 12 333 stems ha-1. The results of this study indicate that a low intensity fire does not necessarily initiate the ecological processes of tree mortality, dead wood creation and regeneration in the desired scale. Fire scars, which form the basis of fire dating in fire history studies, did not form in all cases.

Integrated climatic impacts of forestry and fibre-based packaging

The purpose of this study was to examine the integrated climatic impacts of forestry and the use fibre-based packaging materials. The responsible use of forest resources plays an integral role in mitigating climate change. Forests offer three generic mitigation strategies; conservation, sequestration and substitution. By conserving carbon reservoirs, increasing the carbon sequestration in the forest or substituting fossil fuel intensive materials and energy, it is possible to lower the amount of carbon in the atmosphere through the use of forest resources. The Finnish forest industry consumed some 78 million m3 of wood in 2009, while total of 2.4 million tons of different packaging materials were consumed that same year in Finland. Nearly half of the domestically consumed packaging materials were wood-based. Globally the world packaging material market is valued worth annually some €400 billion, of which the fibre-based packaging materials account for 40 %. The methodology and the theoretical framework of this study are based on a stand-level, steady-state analysis of forestry and wood yields. The forest stand data used for this study were obtained from Metla, and consisted of 14 forest stands located in Southern and Central Finland. The forest growth and wood yields were first optimized with the help of Stand Management Assistant software, and then simulated in Motti for forest carbon pools. The basic idea was to examine the climatic impacts of fibre-based packaging material production and consumption through different forest management and end-use scenarios. Economically optimal forest management practices were chosen as the baseline (1) for the study. In the alternative scenarios, the amount of fibre-based packaging material on the market decreased from the baseline. The reduced pulpwood demand (RPD) scenario (2) follows economically optimal management practices under reduced pulpwood price conditions, while the sawlog scenario (3) also changed the product mix from packaging to sawnwood products. The energy scenario (4) examines the impacts of pulpwood demand shift from packaging to energy use. The final scenario follows the silvicultural guidelines developed by the Forestry Development Centre Tapio (5). The baseline forest and forest product carbon pools and the avoided emissions from wood use were compared to those under alternative forest management regimes and end-use scenarios. The comparison of the climatic impacts between scenarios gave an insight into the sustainability of fibre-based packaging materials, and the impacts of decreased material supply and substitution. The results show that the use of wood for fibre-based packaging purposes is favorable, when considering climate change mitigation aspects of forestry and wood use. Fibre-based packaging materials efficiently displace fossil carbon emissions by substituting more energy intensive materials, and they delay biogenic carbon re-emissions to the atmosphere for several months up to years. The RPD and the sawlog scenarios both fared well in the scenario comparison. These scenarios produced relatively more sawnwood, which can displace high amounts of emissions and has high carbon storing potential due to the long lifecycle. The results indicate the possibility that win-win scenarios exist by shifting production from pulpwood to sawlogs; on some of the stands in the RPD and sawlog scenarios, both carbon pools and avoided emissions increased from the baseline simultaneously. On the opposite, the shift from packaging material to energy use caused the carbon pools and the avoided emissions to diminish from the baseline. Hence the use of virgin fibres for energy purposes, rather than forest industry feedstock biomass, should be critically judged if optional to each other. Managing the stands according to the silvicultural guidelines developed by the Forestry Development Centre Tapio provided the least climatic benefits, showing considerably lower carbon pools and avoided emissions. This seems interesting and worth noting, as the guidelines are the current basis for the forest management practices in Finland.