Browsing by discipline "Skoglig ekologi och resurshushållning"
Now showing items 41-60 of 82
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(2017)Tutkimus käsittelee kuusikuitupuun tuoretiheyden vaihtelua. Tuoretiheyden yksikkö on kg/m³. Tutkimuksen tavoitteena on selvittää, kuinka suurta vaihtelu on kahden eri vastaanottopisteen välillä. Lisäksi saadaan selville, voidaanko eri tehtailla mitattuja tietoja käyttää toisella maantieteellisellä alueella sijaitsevalla tehtaalla. Tutkimuksessa vertailtiin kahdelta eri tehtaalla mitattuja tuoretiheyksiä sekä metsäntutkimuslaitoksen alueellisia tuoretiheyslukuja. Tutkimusaineisto koostui 254 otantanipusta, jotka mitattiin Rauman paperitehtaalla 22.6.–30.12.2015. Otanta käsitti 3859,8 m³ kuusikuitupuuta, joka jakautui 254 nippuun. Otantanippujen keskimääräinen kiintotilavuus oli 15,5 m³. Pölkyt mitattiin mittasaksilla keskuskiintomittauksella. Pituus mitattiin 5 cm tasaavaa luokitusta käyttäen ja läpimitta 1 mm:n tarkkuudella. Vertailuaineistona käytettiin nipun saapumisajankohtana Jämsänkosken paperitehtaan vastaanotossa käytössä ollutta keskimääräistä tuoretiheyttä. Vertailussa oli mukana myös vuodesta 2012 alkaen kuukausittaisia tuoretiheyksien keskiarvoja. Aineistoista selvitettiin tuoretiheyksien vaihtelun aiheuttamien tilavuuserojen tilastollinen merkitsevyys t-testillä sekä tutkittiin erojen ja hajonnan suuruutta ja suuntaa. Lisäksi selvitettiin vuorokauden keskilämpötilan ja haihdunnan vaikutusta tuoretiheyteen. Tuoretiheyksien erojen todettiin olevan eri maantieteellisillä alueilla niin suuria, että paras keino päästä puunmittauslain asettamien raja-arvojen sisälle on käyttöpaikoittainen mittaus. Syyksi eroihin todettiin sää- ja varastointiolosuhteiden sekä puuvirtojen suuruuden vaihtelu. Eri tehtaille raakapuuta saapuu eri tahdissa, jolloin myös tuoretiheyden päivitystaajuus on erilainen.
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(2015)Trees play an important ecological role also after their death. Earlier studies have introduced various methods of modelling coarse woody debris (CWD). However, CWD models that would consider different types of CWD, and their decay class dynamics are lacking from the Finnish commercial forests. The aim of this study was to predict the development of CWD for UPM-Kymmene owned FSC-certified forests in Finland. For that purpose, models for simulating CWD dynamics in Finnish commercial forests were developed for Pinus sylvestris, Picea abies and hardwoods. Trees were classified to different decay classes based on their visual appearance and softness of the wood. The mean residence time of each decay class was used to develop transition matrix model for predicting the possibilities of transitions between different decay classes. In the generated model a tree can stay in the class m or move to classes m+1 or m+2 in a time frame of five years. In addition snags had a possibility to fall i.e. move to down woody debris pool. The results showed that within all the studied tree species, the half-life of snags was 15–20 years. Hardwood logs decomposed faster than softwoods: the half-life of softwood logs was 35–40 years and the half-life of hardwoods was about 25 years. In a hypothetical equilibrium state reached by a continuous CWD input, most snags were in early decay class, whereas most logs were in the advanced decay class. Volume and quality of future CWD in UPM-Kymmene owned FSC-certified forests was predicted, using their current CWD pool and future tree mortality predicted by the forest simulation system MELA. In these simulations, the volume of CWD increased in the future. At the end of the 50-year simulation period, the predicted volume of CWD was 5,9 m3 ha-1. Pinus sylvesris was the dominant CWD species and advanced decayed wood was dominant decay class. The simulation approach demonstrated here has much potential as a useful decision-making tool for CWD management in commercial forests. Incorporating these models into forest management planning could provide valuable information about the effects of management practices on CWD dynamics in commercial forests.
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(2012)Site index and site type are methods for describing a habitat’s highest annual production of tree (m3/ha/a). Site index is based on the growth of trees’ dominant height, and site type on the existence of plant communities in a habitat. This research examined whether site type can be estimated with site index derived by airborne laser scanning (ALS). ALS is a remote sensing method by which trees’ characteristics are predicted based on the height distribution and density values of laser pulses. Data were gathered from Syöte, Northern Ostrobothnia. Arbonaut Oy provided the ALS-data, and Metsähallitus provided age and habitat data of microstands. Site type, trees’ ages and dominant heights were also measured by field surveying. Experimental data from plots were generalized to microstand data. There were 208 experimental plots that were generalized to 39 microstands. Site indexes for experimental plots and microstands were calculated to index age 100 years with Vuokila and Väliaho’s (1980) growth models for dominant height and with Schumacher’s (1939) guide curve. Site indexes were converted to site types with Vuokila and Väliaho’s (1980) conversion diagram and then compared to site types of the field surveys. The accuracy of the site indexes was evaluated with an error matrix. Accuracy of age and dominant height was evaluated with a paired t-test. Variation of index aged dominant height inside a site type was examined with root mean square error (RMSE). The effect of the proportions of tree species on the site index was analyzed with a correlation coefficient. The percentage of properly classified site types was 57 % at best when using Schumacher’s (1939) guide curve and two site types (rich and poor). With Vuokila and Väliaho’s (1980) growth models for dominant height the best percentage of correctly classified site types was 46 %. The variation (RMSE) of index aged dominant height as an average in all site types was 3,2 m. The maximum variation of index aged dominant height in one site type was 6 m. This indicated that the dependency between site index and site type was poor with this data. The proportions of tree species did not have a significant effect on site index. Based on this study, predicting site types with ALS does not work. One problem is the absence of very rich site types. There are also many sources of error: SutiGIS’ (position knowledge system) age data, prescribed burning, possible fertilization of stands, and the problems of fitting site index and site type. Vuokila and Väliaho’s (1980) growth models for dominant height were made in the 1980s, so they do not acknowledge the increased growth of present-day trees. Site index cannot reliably predict the site type, but site index gives valuable extra information about the trees for example when evaluating the value of forest estates.
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(2017)The large area forest mapping is traditionally based on satellite images and laborious field plots. The newer lidar plot concept is the Airborne Laser Scanning (ALS) and a small amount of field plots based plot-level attribute estimation, which is treated similar to the field plots in satellite based mapping. The target of the study was to evaluate the satellite-based, the ALS-based and their combination based forest mapping in the large area by comparing the accuracy of the forest attribute estimations per different amounts of plots. The study area of 3 128 000 hectares in southern Finland included 3630 field plots from the Metsäkeskus of Finland. The attribute estimates were computed from the Landsat 8 image and from the low-density lidar dataset to the field plot locations. The plot-level attribute estimates were calculated for the volume, height, basal area and biomass using k-NN-method (k=5). The accuracy of the mapping methods was evaluated by relative RMSE (Root Mean Square Error), which measured the differences between the estimated and the measured attributes of the validation plots. From the results it can be seen that the relative RMSEs of the attribute estimates from the Landsat-image based mapping on plot-level were at their best 47.6 % for the volume, similarly 26.2 % for the height, 34.6 % for the basal area and 47.7 % for the biomass. For the ALS-based mapping, they were 23.2 %, 9.8 %, 21.0% and 23.7 % respectively. By using 400 field plots to estimate attributes for 2900 lidar plots, and these lidar plots were used further for Landsat-based attribute estimations, these results were quite close to the accuracy of field plots-based Landsat attribute estimations. In addition a small sample of the lidar cover of the area was needed, in this case having less than 1 % area coverage. The lidar plots in Landsat-based mapping could be used for the biomass and carbon mappings in large area even if there are no roads available in the area and only a small amount of plots can be measured. Also, it is suitable for the areas where forest mapping has not started. It can be used also to follow up the changes in large forest areas, due the frequent updates of the satellite image measurements.
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(2016)Beavers (Castor spp.) are species which change the environment and by doing so maintain and create habitats which are important for many other species. That is why beavers are called as ecosystem engineers, key species and facilitators. Beaver creates a pond which offers shelter and food for example for the waterfowl. Previous studies have shown that especially the teal (Anas crecca) benefits from the beaver. Invertebrates, such as water fleas, are numerous in beaver ponds and the teal uses them as nutrition. Because of their feeding habits teals are also able to colonise new habitats, like beaver ponds, quickly. The aim of the thesis was to study the effect of the beaver to the teal on patch and landscape scale. Two landscapes - Evo and Nuuksio - were used in this study. Evo represents a landscape with beaver and Nuuksio without beaver. The pair and brood densities and brood production were compared on the patch scale before the beaver flood and during the beaver flood in order to find out whether the densities and brood production are higher during the flood. In addition, densities and brood production were compared in beaver occupied lakes and non-beaver lakes in Evo. In the landscape scale the annual pair and brood densities and brood production were compared between Evo and Nuuksio. Furthermore, the general linear mixed effect model was used to examine which variables explain the pair and brood numbers in the landscape scale. The results indicated that the brood density and brood production were higher during the beaver flood than before which means that the effect of the beaver to the teal was positive on the patch scale. Instead there was no positive effect on the pair density. Comparison between the beaver and non-beaver lakes showed that brood density and brood production were also higher on the beaver lakes and again there was no effect on pair density. The results also indicated that the pair and brood densities were higher in Evo than in Nuuksio but the brood production did not differ statistically between the regions. The modelling showed that the model which included location as an explanatory variable explained the pair numbers well and the model with location and spring flood as explanatory variables explained brood numbers well. However, there was some uncertainty considering the selection of the most suitable model due to the relatively small differences between the AIC values. As a conclusion it could be said that the facilitative effect of beaver appears both on patch and landscape scale. The beaver effect was especially important for the teal broods which has been noticed also in previous studies. As the beaver effect seems to be important on both scales one might consider whether the ecosystem engineering by beaver should be used in restoration purposes on those areas where the waterfowl density is low.
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(2013)There develops heartwood in the stems of the Scots pines (Pinus sylvestris L.) that differs by its natural characteristics from the other sections of the wood material in the pine stem. Pine heartwood is natural-ly decay resistant and it can be used in conditions where the normal wood products can’t be used. The aim of this study was to develop a method, which can be used for predicting the diameter and volume of heartwood. There is a need for this kind of method, because it still is not possible to estimate the amount of heartwood in a standing tree without damaging the tree itself. The variables measured from single trees describing the diameter of the heartwood on eight relative heights were analysed by using linear regression. When the best explanatory variables were selected, a mixed linear model was created for each of the relative heights. The mixed linear models could also be used for predicting the diameter of pine heartwood at those relative heights. With the help of the pre-dicted diameters a taper curve could be created for the heartwood. The pine heartwood taper curve describes the tapering of the heartwood as function of the tree height. By integrating the taper curve, it was also possible to predict the total volume of the heartwood in a single tree. The models that used tree diameter at breast height and the length of the tree as explanatory variables were able to explain the variation of heartwood diameter on relative heights between 2,5 % and 70 % with coefficient of determination ranging from 0,84 to 0,95 and also recorded a relative RMSE from 15 % to 35 %. Models for relative heights of 85 % and 95 % were not as good as the others (R2-values 0,65 and 0,06 as well as RMSE-values of 74 % and 444 %). Despite not succeeding on all the relative heights, the most important thing is that the models worked best on that area of the stem where most of the heart-wood is located. The volume predictions for single trees based on the heartwood diameter models rec-orded relative RMSE of 35 % and bias of -5 %. Based on the results of the study it shows that exact prediction of pine heartwood diameter is much easier in the base of the stem than in the top part of it. A great deal of variation could be observed whether there was heartwood or not in the top parts of the stem. The volume of heartwood can already be estimated for single trees, but the amount of heartwood can be predicted also in larger scale, such as forest stands. But to get more accurate results in the future, there is a need for more detailed and com-prehensive research data, which would help to determine the still unknown parts of the behaviour of pine heartwood.
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(2012)Tending of seedling stands and improvement of young stands are important steps in wood produc-tion, but they are often postponed or even neglected primarily due to high expenses and poor availability of labour. Machine tending of young stands requires special equipment and appropri-ately suited devices, restricting the method's feasibility to larger stands. For the present, clea-ring and thinning of young stands is mainly accomplished manually using a clearing saw due to lower cost of manual work compared with machine tending. Mechanized pre-commercial thinning further requires that strip roads must be opened, which will reduce the number of growing trees, resulting in diminished area for wood production. Trunk and root damages are a frequent phenomenon and furthermore the terrain can sustain damage. Dam-ages in standing crop and soil can reduce timber output during forest rotation time. The negative contribution of strip roads on timber output and poor forest health should be countered in devel-oping machine tending. The need for the development of machine tending and its benefits increas-es with receding availability of labour. This study focuses on the influence on timber production and trunk damages by a forestry vehicle equipped with a MenSe clearing head. The emphasis lies on examining strip roads and damages in young stands. In addition to conclusions from forest measurements, literature search was applied in studying the effects of machine tending on timber output. The corollary influence of strip roads on future timber output requires further research. The study observes a 10 % decrease in surface area resulting from laying strip roads for mechanized pre-commercial thinning. Trunk damages were present on average in 5 % of the remaining trees. Growth impeding trees surrounding growing trees amounted to 250 trees per hectare and need-lessly removed trees about 90 per hectare. The consumption of working time averaged 8,4 hours per hectare and hourly output 0,12 hectare on all sites. Nonnegligent divergencies in drivers regard-ing efficiency and procedure were observed. Attending to the education, motivation, advicement and supervision of the driver will be worthwhile in the future. Circumstances surrounding both the driver and the forest machine present a challenge in develop-ing the cost-efficiency and labour resultant of mechanized pre-commercial thinning. In the future more alternatives for wood production chain should be considered for research, for instance the possibility of entirely abandoning pre-commercial thinning after the preliminary cleaning of seed-ling stands with an uprooter, subsequently leading to energy wood thinning or first thinning.
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(2014)Tapion taskukirja on Suomessa vuodesta 1910 ilmestynyt metsäalan käsikirja, johon on koottu keskeisiä metsätalo-utta koskevia aiheita. Tähän mennessä suomenkielisiä taskukirjoja on julkaistu yhteensä 25 kappaletta. Työn tarkoi-tus on tutkia taskukirjojen roolia metsänhoidollisten aihepiirien kautta. Tutkin, toimivatko taskukirjat metsäalaa kuvai-levana yleisteoksena vai poliittisena ohjauskeinona. Tutkimuksen taustalla on ajatus, että taskukirjojen sisältö seurai-lee valtion metsätaloudelle asettamia tavoitteita ja taustalla vaikuttavaa kulloistakin kansallista ja kansainvälistä metsäpolitiikkaa. Sisällönanalyysi on laadullisen tutkimuksen menetelmä, jossa tutkittavasta aineistosta, yleensä painetusta materiaa-lista tuotetaan mielekästä, selkeää ja yhtenäistä tietoa. Olen jakanut taskukirjat sisällönanalyysin perusteella kuuteen ryhmään, jotka olen nimennyt seuraavasti: 1910–1922 Neuvoja metsänkäyttöön ja puukauppaan, 1923–1931 Nope-asti kehittyvä taskukirja, 1932–1947 Järjestelmällisen metsänviljelyn ja ojitustyön pohjustusta, 1948–1959 Eroon harsintahakkuista, 1960–1986 Voimakasta metsänparannusta ja 1987–2008 Ympäristöherääminen. Näitä ryhmiä vertailen metsätaloudesta jo tehtyihin aikajanoihin, sekä suomalaisen metsäpolitiikan ja metsäohjelmien tavoitteisiin eri aikakausina. Metsänhoitoasioita käsitellään varhaisissa taskukirjoissa suhteellisen vähän. Alusta lähtien mukana olevia keskei-simpiä aiheita ovat ojitus ja metsänviljely. Metsänviljelyä käsitellään kaikissa painoksissa. Joitakin keskeisiä metsän-hoitotoimia, kuten kasvatus- ja uudistushakkuita ryhdytään käsittelemään taskukirjoissa verraten myöhään, vaikka hakkuut ovat olleet keskeinen metsänhoitomenetelmä jo ensimmäisten taskukirjojen ilmestyessä. Sen sijaan erilasia metsänparannustoimia kuten ojitusta käsitellään taskukirjoissa jo suhteellisen varhain. Tämän tutkimuksen perus-teella taskukirjojen metsänhoitoon liittyvät sisällöt ja teemat tuntuvat seurailevan melko tarkasti valtion metsäohjelmia ja niiden tavoitteita. Erityisen selkeästi tämä näkyy ns. MERA-kausien (1964–1975) aikana ilmestyneissä taskukir-joissa. Metsätalouden rahoitusohjelmien eli MERA-ohjelmien tavoitteena oli lisätä metsien kasvua erilaisten peruspa-rannustoimien kuten ojituksen ja lannoituksen avulla. Taskukirjoissa käsitellään tuona aikakautena paljon juuri näitä teemoja. 1990-luvulta lähtien kirjoissa on havaittavissa entistä ympäristötietoisempi lähestymistapa asioihin. Suomi sitoutui 1990-luvulla kansainvälisiin ympäristösopimuksiin joiden tarkoituksena oli luonnon monimuotoisuuden säilyt-täminen. 1990-luvun taskukirjoissa on muutamassa mukana luku ympäristöasioista, ja metsien monimuotoisuudesta ryhdytään kirjoittamaan runsaasti. Tutkimusta tehtäessä taskukirjoista pyrittiin poimimaan esiin tämän työn tavoitteiden kannalta oleellisia seikkoja. Tuloksia tarkasteltaessa on kuitenkin huomioitava, että tässä taskukirjoja tarkastellaan vain yhdestä näkökulmasta. Tämän tutkimuksen perusteella taskukirjojen rooli metsäpoliittisena ohjauskeinona korostuu erityisesti ryhmän 1960–1986 Voimakasta metsänparannusta aikana sekä metsäojitusta käsittelevissä aiheissa. Kirjoissa korostetaan ojituk-sen tärkeyttä, annetaan tietoa aiheeseen liittyvästä lainsäädännöstä, Tapion tarjoamista palveluista sekä ojitukseen saatavista tuista. Myös muiden ryhmien aikana esitellään metsälainsäädäntöä, käsitellään samoja aihepiirejä kuin metsäpolitiikassa, sekä annetaan tietoa valtion tuista. Tapion vaikutus taskukirjoissa näkyy siinä, että metsänparan-nusta käsitteleviä aiheita on mukana paljon.
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(2016)Metsänhoitoyhdistykset ovat eläneet murrosvaiheessa. Tilanne muuttui edelleen, kun uusi metsänhoitoyhdistyslaki tuli kokonaisuudessaan voimaan vuoden 2015 alussa. Muuttuneen lain myötä veroluonteisesta metsänhoitomaksusta luovuttiin, mikä aiheutti myös sen, että metsänomistajat eivät enää automaattisesti ole metsänhoitoyhdistyksen jäseniä. Tämä asettaa uudenlaisia vaatimuksia metsänhoitoyhdistyksille. Myös metsänomistajakunnan muutos tuo omat haasteensa metsänhoitoyhdistysten markkinoinnille ja viestinnälle. Tavoitteena oli tutkia, miten metsänhoitoyhdistysten viestinnän keinot vaikuttavat erilaisiin kohderyhmiin metsänomistajien keskuudessa, ja onko nykyinen asiakassegmentointi riittävää. Tavoitteena oli myös selvittää, mitkä ovat ne eri keinot, jotka vaikuttavat erilaisiin kohderyhmiin ja saatujen tietojen avulla miettiä, miten metsänhoitoyhdistysten viestintää tulisi kehittää. Tutkimus toteutettiin haastattelututkimuksena ja työn ensisijainen aineisto oli kerätty haastattelumateriaali. Tutkimusta varten haastateltiin sekä metsänomistajia että metsänhoitoyhdistyksen toimihenkilöitä neljästä metsänhoitoyhdistyksestä. Tutkimuksen neljästä metsänhoitoyhdistyksestä haastateltiin jokaisesta 4–5 metsänomistajaa. Haastateltavat metsänomistajat valittiin sen perusteella, että he edustivat mahdollisimman erilaisia metsänomistajia. Joukossa oli nuoria, vanhoja, miehiä ja naisia, etämetsänmetsänomistajia ja lähellä tilaa asuvia sekä metsänomistajia eri puolilta Suomea. Toimihenkilöistä haasteltiin toiminnanjohtaja ja viestinnästä vastaava työntekijä, jos yhdistyksessä oli sellainen nimetty. Metsänomistajahaastattelut toteutettiin ryhmähaastatteluina ja toimihenkilöt haastateltiin yksittäin. Haastattelut toteutettiin puolistrukturoituina haastatteluina ja menetelmänä oli laadullinen tutkimusmenetelmä focus group -ryhmähaastattelu. Tutkimukseni mukaan paras keino metsänomistajien tavoittamiseen on henkilökohtainen ja kontakti. Metsänomistajan henkilökohtaisella metsäneuvojalla on myös suuri vaikutus siihen, kuinka tyytyväinen metsänomistaja on metsänhoitoyhdistyksen palveluihin. Tärkeää on, että metsänomistajan yhteydenottoon vastataan kohtuullisessa ajassa, parin päivän kuluessa. Viestintäkanavista erityisesti henkilökohtaiset neuvontapalvelut ja yhdistysten lehdet saivat kiitosta. Yhdistysten lehdet metsänomistajat kokevat tärkeäksi viestintäkanavaksi ikäryhmästä, sukupuolesta, asuinpaikasta ja metsätilan sijainnista riippumatta. Pääsääntöisesti metsänomistajat ovat tyytyväisiä metsänhoitoyhdistysten viestintään ja markkinointiin. Uudet metsänomistajat ja etämetsänomistajat tekevät poikkeuksen tähän; heidät tulisi huomioida yhdistysten viestinnässä aikaisempaa paremmin. Myös yhtymien osakkaat tulisi huomioida nykyistä paremmin. Tällä hetkellä vain yhdistyksen yhteyshenkilöön ollaan yhteydessä yhdistyksessä, ja yhtymän muut jäsenet saattavat kokea jäävänsä tiedosta paitsi. Tutkimukseni mukaan nykyiset, olemassa olevat kanavat riittävät metsänomistajien tavoittamiseen. Oleellista on, että metsänomistajalle menee tietoa säännöllisesti, viestintään käytetään useaa kanavaa ja metsänomistajan yhteydenottoihin reagoidaan kohtuullisessa ajassa. On kuitenkin syytä muistaa, että se, mikä nyt toimii hyvin, ei välttämättä viestinnässä ja markkinoinnissa toimi enää ollenkaan niin hyvin esimerkiksi viiden vuoden päästä. Siihen vaikuttavat paitsi muutokset media-alalla myös metsänomistajakunnan rakennemuutos.
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(2014)Metsäpeuran kannanhoidon ja suojelun tukemiseksi suunnitellaan palautusistutuksia. Yksi mahdollinen kohde on Isojoen seutu. Palautusistutuksiin liittyen Isojoella järjestettiin metsäpeurafoorumi palautusistutusten sosiaalisten vaikutusten kartoittamiseksi huhtikuussa 2013. Tässä tutkimuksessa syvennetään foorumista saatua antia ja jatkaa hyväksyttävyyden ja metsäpeuran vaikutusten analysointia. Tutkimuksessa haastateltiin yksitellen 20 satunnaisesti valittua henkilöä, jotka oli kutsuttu metsäpeurafoorumiin, mutta missä he eivät olleet läsnä. Haastattelumalli ja tehtävät kopioitiin metsäpeurafoorumista aineiston vertailukelpoisuuden vuoksi. Kevään ja syksyn aineistoja vertailtiin keskenään ja syksyllä kerättyä uutta aineistoa analysoitiin myös omana kokonaisuutenaan. Vertailulla tarkasteltiin kevään aineiston edustavuutta ja samalla menetelmän käyttökelpoisuutta. Keskeisimpinä tuloksina havaitaan positiivinen suhtautuminen metsäpeuran palautuksia kohtaan, mutta toisaalta myös huoli esimerkiksi mahdollisten suurpetojen ja liikennevahinkojen lisääntymisestä. Tutkimuksen perusteella voidaan päätellä, että metsäpeura on Isojoelle tervetullut, kunhan metsäpeuran mahdollisesti aiheuttamat vahingot pyritään tunnistamaan jo suunnitteluvaiheessa ja huomioimaan toteutusvaiheessa. Asukkaiden keskinäiset ristiriidat esimerkiksi mahdollisesta metsäpeurasaaliin jaosta tulevaisuudessa sekä metsäpeuran kulttuuriset vaikutukset jäivät vähiten merkittäviksi. Itse metsäpeuran palautusistutushanke sai paljon positiivista palautetta ja palautusistutusten positiiviset vaikutukset koettiin usein merkittäviksi. Kevään ja syksyn haastattelujen tulokset poikkesivat vain vähän toisistaan huolimatta siitä, että syksyn haastatteluissa oli mukana enemmän ihmisiä, jotka eivät olleet juurikaan perehtyneet aiheeseen. Tämä tutkimus osoittaa, että keväällä järjestetty metsäpeurafoorumi on toimintamallina tarkoituksenmukainen, ja että foorumissa käytetty sosiaalisten vaikutusten arviointimenetelmä edistää riistahallinnon ja kansalaisten vuorovaikutusta riista-asioissa. Vastaavanlaisia foorumeita suunniteltaessa on kuitenkin hyvä kiinnittää huomiota foorumin ajankohtaan sekä tapoihin, joilla tavoitetaan ihmiset, joiden toivotaan osallistuvan.
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(2013)Accurate and economical remote sensing method with good temporal resolution is required for mapping up-to-date information about the forest resources. Detecting forests by optical satellite images is an inaccurate procedure with the saturation problem. Airborne laser scanning (ALS) is a precise application, but the inventory process is slow and expensive. Recently the new synthetic aperture radar (SAR) satellites with a high spatial resolution have caused a renaissance of radar-based remote sensing. The purpose of the master’s thesis was to investigate the accuracy of forest mapping by radargrammetric processing of TerraSAR-X satellite images. The radargrammetry is based on stereoscopic measurement, which calculates 3D coordinates for corresponding points of the SAR image pair. In the research an area-based approach (ABA) was utilized to estimate forest attributes from the 3D points, and digital terrain model (DTM) produced by ALS was used to calculate height of the corresponding points. In plot-level the relative RMSEs for stem volume, biomass, basal area and mean height were 40.3 %, 39.9 %, 34.0 % and 15.9 %. In stands larger than 2 hectares the corresponding RMSEs were 20.2 %, 20.4 %, 36.1 % and 6.9 %. It’s notable that the estimation of basal area didn’t improve in stand-level at all. According to the research SAR radargrammetry is a precise technology to estimate forest canopy height, but the mapping of forest density is very unclear. Nevertheless the results about the estimation accuracy of forest stem volume and biomass by SAR radargrammetry were clearly better than the comparable estimation accuracy of optical satellite images.
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(2014)The definition of the climate impact of peat products along with the possibilities to reduce greenhouse gas emissions are in a key role in peat industry. The climate impact of energy peat has been assessed by using the life cycle analysis but the results vary greatly. There are only few studies on the climate impact of horticultural peat available. Further, the deviation of the emission factors utilized in formal studies has not been assessed. In this master’s thesis the emission factors and their deviation concerning energy and horticultural peat were calculated. Additionally, the carbon footprints and their reliability concerning different peat production chains were assessed. The carbon footprint is a method to estimate the climate impact of a product. Here the carbon footprint was calculated according to ISO/TS 14067 life cycle analysis publication. The climate impact was calculated by adding the greenhouse gas emissions from “cradle to grave” where the life cycle of peat was divided into five different phases including the pre-phase, extraction (including peat extraction and storage), transport, use and after-use. The data was derived from published greenhouse gas studies with emphasis on the clarification of the coefficients of the pre-production and after-use phases. The focus was on carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). The emission factors were defined from the yearly averages and the fluctuations were observed through standard deviations. The accuracy of the estimated averages as well as the differences of pre-production phases were assessed by statistical tests and the reliability of the carbon footprint of peat by variance. According to this study the biggest carbon dioxide-emissions and the lowest reliability of the total emission factors were from cultivated peatlands and from peatlands where extraction occurred. The standard deviation of methane was the highest in pristine mires, whereas the standard deviation of the carbon dioxide was the highest in forestry-drained and cultivated peatlands. The standard deviation of N2O was the highest in cultivated peatlands. According to this study, the emission factors concerning cultivated peatlands and forestry-drained peatlands had considerable risks of uncertainty. A statistical difference occurred in the methane emissions in pristine mires and nitrous oxide emissions in forestry-drained peatlands between low and high nutrient level. The carbon footprint of peat was the smallest when production was started in cultivated peatlands. No major differences were discovered in production started in pristine mires or forestry- drained peatlands or of low or high nutrient level. The best option for after-use was the afforestation and cultivation of green canary grass, which resulted in carbon footprint lower than that of coal. The rewetting resulted in higher climate impact than coal. The reliability of the climate impact estimate was the highest in pristine mires and the lowest in cultivated peatlands. The variation of carbon dioxide emissions in different habitats was high in forestry-drained peatlands: some habitats were considerable sources of carbon dioxide and some were carbon sinks. The carbon dioxide emissions have been calculated by different methods which may result in different CO2-balance. According to the study, the emissions of the peat industry could be lowered through concentration of production on “hot spot” areas such as forestry-drained soils with high emissions. Due to the limited number of studies, the carbon footprint estimate of horticultural peat in this study is merely indicative. As for the life cycle of peat, further study is required especially on the emissions of production and after-use phases.
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(2009)Pressure to replace fossil fuels in order to reduce CO2 emissions as well as the increased demand for energy have resulted in more intensive harvesting of forests. The current harvesting practice is to heap the logging residues rather than spread them on skid trails. However, little is known about the effects of modern harvesting techniques on soil fertility and site productivity. The decomposition of and nutrient release from logging residues after clear-cutting has recently been investigated in Finland, but the nutrient dynamics of logging residues after thinning and especially in the residue heaps is less known. In this study the mass loss of and nutrient release from logging residues were explored for three successive years after first thinning of a Scots pine stand in western Finland. The main objective was to identify the effects of heap structure on decomposition and nutrient dynamics. More specifically, the objectives were: 1) To examine how the position within the heaps affects the decomposition rate and nutrient dynamics of residue fractions. It was hypothesised that the decomposition and the release of nutrients are greater under the residue heaps than on top of the heaps and on the ground. 2) To identify temporal changes in decomposition and nutrient release over a 3-year period. 3) To determine how much N, P, K, Ca and Mg are released from logging residues during the first three years after first thinning. 4) To assess whether it is more beneficial for nutrient cycling to concentrate the logging residues in heaps or to spread them out from the standpoint of site fertility. 5) To assess the timing of harvest of logging residues in terms of their role in nutrient cycling of a stand. The decomposition of Scots pine needles, twigs and branches was determined by measuring the mass loss with the litterbag method. The experimental design was randomized blocks with nine treatments and six replicates. The treatments included three logging residue fractions and three locations of logging residue. The influence of logging residue type and locations of residue on mass and contents of nutrients remaining in litter bags over the entire 3-year period were tested by repeated measures ANOVA. In total, 25% of N, 53% of P, 87% of K, 42% of Ca and 49% of Mg were released from logging residues in three years. The treatments in this study had no clear effects on the mass loss of logging residues. The hypothesis was confirmed only with needles, for which the mass loss and nutrient release was significantly faster under the heaps than on the ground and on top of the heaps. Treatments did not have a significant effect on the decomposition of twigs and branches. In the short-term, the logging residues were a minor source of N but a significant source of K. The results indicate that in the short-term logging residues are insignificant for site productivity on sites where the availability of N limits productivity. On peatland sites, where the availability of K limits productivity, logging residues may be significant on site productivity. However, in the long-term logging residues may be an important source of organic matter and nutrients. Great proportion of nutrients was released from needles within the first year of decomposition. The rate of nutrient release from needles was slightly faster from the heaps than on the ground over the first year. If residues are collected for energy, heaping and removal after one year would result in more released nutrients than if they were spread on the ground throughout the harvested stand. In order to avoid possible soil nutrient depletion and negative effects on the growth of remaining trees, it can be preferable to leave residues in the stand after harvest and remove branches after the needles have been shed.
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(2014)As most conifers, pine trees produce and store oleoresin in their resin ducts. Oleoresin is a defensive secondary metabolite that protects trees mainly against bark beetles and herbivores. The oleoresin of pine trees consists of different hydrocarbons, such as terpenes and resin acids. Inside the resin ducts, the pressure of oleoresin varies from 3 to 12 bars depending on the tree species, individual tree and environmental conditions. Traditionally, oleoresin has been studied because of its defensive features, since it has an important role in preventing insect-induced damage in coniferous forest .The pressure of oleoresin in pine trees has been a subject for excessive studies especially in 1960s and 1970s due to large epidemics of bark beetles, for example Dendroctonus frontalis, in United States of America. As a result, oleoresin pressure has been linked to the water balance of a tree. Since the changes in the tension of water inside water conducting tracheids affect the diameter of xylem, the diurnal pattern of oleoresin pressure and the diameter of xylem have been recorded to be similar. The connections between oleoresin pressure and other physiological processes of a tree have nevertheless been neglected, although there may be a strong relation between the pressure of oleoresin and the BVOC (biogenic volatile organic compound) -emissions from the trunk of a tree. The constituents of oleoresin, for example monoterpenes, form a part of the BVOC emissions that pine forests emit. Estimating the BVOC emissions from tree trunks and from forests and understanding the mechanisms behind monoterpene emissions would be essential, because BVOCs have been detected to contribute to the cloud formation and thus to the climate. In addition, the studies on oleoresin pressure are relatively old and conducted mostly in Southern USA where the climate is mainly subtropical. In boreal forests of Northern Europe, the pressure of oleoresin has not been extensively studied before the summer of 2012, when the preliminary study for this study was conducted. The results of the preliminary study were contrary to the earlier studies conducted in Southern USA. The maximum pressures of oleoresin pressure were recorded in the afternoon and minimum pressures before sunrise, whereas according to the literature the pressure of oleoresin is highest in the early morning and lowest in the afternoon. Hence, in this study the diurnal variations in oleoresin pressure of Scots pine (Pinus sylvestris) are measured at the SMEAR II station in Southern Finland. A pressure gauge system similar to that of Vité (1961) and Perrakis (2008) is employed. The variations in oleoresin pressure are compared to environmental variables (temperature, VPD and PAR) and physiological variables (the diameter of xylem, transpiration and photosynthesis). Furthermore, the connection between oleoresin pressure and monoterpene emissions from a pine trunk is analysed by the means of EFRA - approach. The results on the diurnal pattern of oleoresin pressure are throughout the summer of 2013 similar to the results of the preliminary study. The pressure of oleoresin is highest during the warmest time of a day and lowest during the coldest time of a day. According to the results, temperature is the single variable that explains the changes in oleoresin pressure the best. However, temperature fails to explain all the changes in oleoresin pressure, so there appears to be other influences that are outshadowed by the effect of temperature. These influences could be generated by water balance and VPD, as explained in literature, since the diameter of xylem is the single variable that explains best the changes in temperature corrected oleoresin pressure. Furthermore, a relation between monoterpene emissions and oleoresin pressure is detected, although temperature appears to affect both the emissions of monoterpenes and the pressure of oleoresin.
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(2013)Experimental warming provides a method to determine how an ecosystem will respond to increased temperatures. Northern peatland ecosystems, sensitive to changing climates, provide an excellent setting for experimental warming. Storing great quantities of carbon, northern peatlands play a critical role in regulating global temperatures. Two of the most common methods of experimental warming include open top chambers (OTCs) and infrared (IR) lamps. These warming systems have been used in many ecosystems throughout the world, yet their efficacy to create a warmer environment is variable and has not been widely studied. To date, there has not been a direct, experimentally controlled comparison of OTCs and IR lamps. As a result, a factorial study was implemented to compare the warming efficacy of OTCs and IR lamps and to examine the resulting carbon dioxide (CO2) and methane (CH4) flux rates in a Lake Superior peatland. IR lamps warmed the ecosystem on average by 1-2 oC, with the majority of warming occurring during nighttime hours. OTC's did not provide any long-term warming above control plots, which is contrary to similar OTC studies at high latitudes. By investigating diurnal heating patterns and micrometeorological variables, we were able to conclude that OTCs were not achieving strong daytime heating peaks and were often cooler than control plots during nighttime hours. Temperate day-length, cloudy and humid conditions, and latent heat loss were factors that inhibited OTC warming. There were no changes in CO2 flux between warming treatments in lawn plots. Gross ecosystem production was significantly greater in IR lamp-hummock plots, while ecosystem respiration was not affected. CH4 flux was not significantly affected by warming treatment. Minimal daytime heating differences, high ambient temperatures, decay resistant substrate, as well as other factors suppressed significant gas flux responses from warming treatments.
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(2015)The creation of forest gaps in disturbance emulation forestry alters local environmental conditions, which causes variability in natural seedling regeneration. Understory vegetation plays an important role in early seedling regeneration success and is sensitive to variations in topography and resource availability. Its analysis can uncover the finer-scale impacts of gap characteristics and competition on the patterns of tree regeneration. The objective of this study was to examine the impact of gap characteristics on patterns of natural vegetation and tree seedling regeneration 5 years post-harvest across 18 gaps in Norway spruce (Picea abies (L.) Karst.) dominated forests of Central Finland. Gap characteristics included distance from edge (into residual forest and gap interior), cardinal position in the gap (N, S, E or W), microsite type and dominant topography. All seedlings (≤5m) were counted and measured on 1m2 plots situated along linear strips (2 for each N-S and E-W orientations). On these same plots, vegetation and microsite types were assessed by percent cover for several key categories. Results show that distance from gap edge was the most influential gap characteristic, especially in the ±10m zone. The 0–15m zone inside the gap supported the greatest abundance of seedlings, as well as the highest diversity of both vegetation types and seedling species. The edge zone inside the forest supported shade-tolerant species (dwarf shrubs, mosses). Gap centers (~15m+) supported shade-intolerant species (grasses, shrubs, herbs), creating a highly competitive growing environment. The position within the gap was also an influential characteristic. The N gap positions showed the most statistically significant difference from the others; they had fewer birch seedlings, a greater percent cover of grasses and dwarf shrubs, and a smaller percent cover of ferns. This effect was generally more pronounced in the gap interior. The results of this study support that natural regeneration of seedlings in gaps is quite variable. The mean number of seedlings per ha inside the gaps were 20 360 for Norway spruce, and 6 820 for birch spp. combined; up to 62% were germinants (≤3cm). In the 15m+ region from the gap edge towards the gap center, the mean number of seedlings per m2 was on average ~58% smaller than for the rest of the strip. The presence and abundance of different vegetation species clearly demonstrate that distance from edge and within-gap position strongly affect resource availability and competition. The most significant gap characteristics affecting these patterns of early regeneration for Norway spruce and birch were revealed with the help of generalized additive models (GAMs). Since these gaps are in their early stages of regeneration, the future dynamics and final outcome are still fairly uncertain. However, the current mean number of seedlings inside the gaps suggests a promising potential for natural regeneration. These models point to management actions which could facilitate long-term natural regeneration in similar forest gaps.
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(2016)The purpose of this study was to find out the effect of different seed tree densities on natural regeneration and height development of pine (Pinus sylvestris) in Finnish Lapland. There was no soil preparation done in the stands. An additional aim was to find out the effects of understory vegetation on pine seedling establishment. The purpose of preparatory cutting is to prepare the stand for natural regeneration by enhancing the conditions for good seedling establishment and improve the seed production of the mature trees before the actual regeneration cutting. It also decreases the costs of regeneration in the low-productive and slow-growing forests in Finnish Lapland. The study was established in year 2004 on four different areas in Lapland. The replications were conducted for every area in the years 2005 and 2006.The period of measurement in every replication was 8 years. The examined seed tree densities were 50, 150, 250 stems per hectare and a non-thinned control that demonstrated the initial state of the stands. The data consisted of four hierarchical levels, which were area, replicate, treatment (seed tree densities) and experimental plot. The density model was a generalized mixed model and the height model a general linear model. The best result in seedling establishment was achieved in seed tree density of 50 and 150 stems per hectare, where the requirements for the density of the forest law (1200 seedlings ha-1) was reached in 4‒5 years after the preparation cutting. The amount of the seedlings at the end of the measurement period, did not on an average reach the recommended seedling densities (4000‒5000 seedlings ha-1). The seed tree density of 250 stems per hectare, did not reach either of these requirements for density. In the control plot, the average seedling density was 1500 seedlings per hectare at the end of the measurement period. The variables affecting seedling establishment were interactions between the see tree densities and time, thickness of the moss- and lichen cover and the coverage of lingonberry. Factors affecting the height development of pine seedlings were age of the seedling, interactions between seed-tree density and seedling age and the average density of the seedlings on the plot. Height increased clearly best when seed-tree density was 50 stems ha-1. There were no difference between densities 150 stems per hectare and control. The height development was slowest in the density of 250 stems per hectare.
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(2017)Pruning of Scots pine is a traditional silvicultural method where branches are removed, usually up to 4–6 meters of height. Objective is to obtain better log and finally sawn timber quality. Pine branches fall off naturally as well but artificial pruning hastens the process of forming branchless sapwood. However, pruning of Scots pine has proven to be poorly profitable and is often described as silvicultural technique for active forest owners who do not set remarkable economical goals for their actions. Economic efficiency of pruning is weakened by the lack of quality-based pricing of timber whereupon forest owners or timber merchants do not get sufficient payment for their efforts. Highly developed x-ray log scanners at sawmills are capable of measuring log-internal quality at appropriate resolution. Measured information of log quality is utilized for log sorting at sawmills but it could also be used as the basis of pricing the timber. The aim of this thesis is to examine how pruning shows in log-internal quality which is measured by x-ray log scanner and what kind of differences arise between pruned and reference logs. The material for the thesis included 557 pruned and 111 reference logs which were harvested from a pine stand located in Ruovesi. The time elapsed from pruning was 33 years. The differences between pruned and reference logs were evaluated by quality attributes which were knottiness index, log top-end knottiness index, average knot cluster length, relative volume of largest knot and knot cluster, annual ring width and sapwood density. Finally, the quality differences between pruned and reference logs were inspected with predictions of sawn timber quality which were derived through knottiness index values. The internal quality of pruned proved to be better in every quality defining attribute. Statistical significance (p-value<0.001) between attribute means was found in average knot cluster length and in relative volume of knot as well as knot cluster. The predicted sawn timber quality distribution among the pruned A-graded logs, had 20% increase in U/S-quality and 2% decrease in VI-quality. The results of this thesis confirm the earlier findings that pruning of Scots pine is unsuitable at mesic pine stands and the selection of stands for pruning should be considered carefully. In case of the experimental stand, the sealing-off of pruned branches and the formation of knotless sapwood was still in progress while trees were harvested. In further studies, the effect of pruning on internal quality of timber should be considered with wider sample which consists of stands from divergent site types.
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(2015)Pinus taeda is an important timber species both economically and ecologically. In past years there have been severe economic losses, as well as ecological disruption, due to epidemic outbreaks of Dendroctonus frontalis. Resin flow is the first line of defense within conifer species acting as both a physical and chemical barrier to invading pests. This study demonstrates the effectiveness of utilizing aggregation pheromones to attract Ips spp. bark beetles to Pinus taeda plantation stands in order to study the resin flow defense response mechanism. Individual trees were selected to be baited with aggregation pheromones. Trees in close proximity to the baited tree were labeled as monitor trees, and a control was established. Results of a general linear model for the aggregation pheromone attracting Ips spp. beetles indicate that there was a significant different (p<0.0001) between the baited and control trees. Using a repeated measures ANOVA, differences of resin flow exudation in Pinus taeda were considered among varying stand conditions (fertilizer, fire, anc control plots) during the induced Ips spp. bark beetle attack. This study illustrates that different stand conditions elicit more or less of a response of Ips spp. to the baited trees, however, site treatment did not significantly affect resin flow. We conclude that utilizing pheromones to attract Ips spp. bark beetles in an effective technique for studying the resin flow defense in conifers. From a management perspective, it is concerning to see differences in bark beetle activity amond different stand conditions while simultaneously seeing no difference in resin flow defense, making this an important aspect of integrated pest management study, and an area in need of further research.
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(2014)The first objective of the study was to determine, what kinds of costs are related to the recycling of construction and demolition wood wastes, and how they are distributed among the supply chain. In addition, the objective was to determine, does the price of wood wastes differ, when they are utilized for new products instead of utilizing them in energy production and what is the most potential way of utilizing wood waste chips from a techno-economic perspective. The study was implemented by visiting recycling centres in the Uusimaa region that received wood waste. During the visits wood waste specialists were interviewed at the recycling centres. For conducting information about the possible utilisation options for the wood waste resources, specialists from the subject matter were interviewed. The main purpose of the interviews for the recycling centre was to gather information about the total amount and quality of wood wastes recycled in the Uusimaa region, and to receive information about the cost inquired in the recycling processes. The main purpose for the specialist interviews was to study the different possibilities and constriction in utilizing the heterogeneous wood waste resources. In 2013, the annual production of wood wastes in the Uusimaa region was approximately 185,000 tons. The wood wastes originated mainly from demolition of buildings. The most significant part of the wood waste come to the recycling centre as sorted wood waste from the construction site, while a small proportion comes as mixed construction and demolition waste. Only 33 % of the total amount of wood wastes came as clean wood waste loads, although the total amount of wood waste represented 51 % of clean wood waste. From the total amount of wood wastes, 97.3 % was utilized in energy production in 2013. The average cost for shredding wood wastes was 15.6 €/ton and the average price of wood waste chips was 38.5 €/ton. The objective whereby 70 % of the construction and demolition waste must be recycled by 2020 in Finland will significantly increase the reuse of wastes. The main barriers in reusing wood wastes rise from utilizing painted wood and wood products. The main challenges come from technical and economical issues related in the reuse of these products. Based on the study, wood waste chips produced from construction and demolition wood waste is a potential raw material resource, for example in replacing wood chips from natural forests.
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