Browsing by discipline "Metsäekologia"

Old hollow trees are an important habitat for many saproxylic species. A number of threatened and rare insects are specialized on tree hollows and live in the walls of cavities or in the loose wood mould accumulating in the bottom of the hollow. In this study, I compared the species richness and composition of Coleoptera in hollow trees caught with three trap types, window, aluminium foil and pitfall traps. Furthermore, I compared the time spent handling each sample of the different trap types, when sorting all insect orders (including Coleoptera) from the material. The material was gathered in parks and mansion areas in the Helsinki metropolitan area. Window, foil and pitfall traps were placed inside cavities of Tilia cordata, Acer platanoides and Quercus robur trees. In each tree two of each trap type was placed, i.e. six traps per tree, making a total of 90 traps. The traps were emptied every third week during May to July 2006. When the samples were sorted for the first time to separate different insect orders, the duration of time spent sorting each sample was documented. A total of 3825 Coleoptera individuals from 212 species were caught, of which 3398 individuals from 121 species were saproxylic. Window traps caught 1639 individuals from 140 species, foil traps caught 1506 individuals from 134 species, and pitfall traps caught 680 individuals from 111 species. The time spent sorting each sample was on the average shortest with pitfall traps and longest with aluminium foil traps. The ?-diversity (species composition and abundance) differed between the three trap types. The ?-diversity between window and foil, window and pitfall, and foil and pitfall traps was 37%, 13% and 14% respectively. In addition for the average number of saproxylic beetle species and individuals, the average time spent sorting each sample differed statistically significantly between window and pitfall traps (p<0,05), and foil and pitfall traps (p<0,05). Window and foil traps caught, on the average, clearly more saproxylic species and individuals as compared with pitfall traps. Pitfall traps also caught, on the average, less saproxylic beetles out of total beetle individuals (59%) than window (69%) and foil traps (71%). Window traps were the most efficient conserning the average number of saproxylic beetle individuals in relation to the average time spent sorting each sample. Efficiency value (individuals/minute) for each trap type was 0,74 for window, 0,43 for aluminum foil and 0,21 for pitfall traps. Window traps have never before been used inside tree hollows, they have only been used to collect insects outside the cavities. However they functioned outstandingly inside the cavities. In this study pitfall traps were clearly outperformed by window and foil traps, still many species, even some threatened ones, would have been lost without them. To achieve as diverse a species composition as possible it is recommended to use either window or foil traps parallel with pitfall traps.

Heterobasidion parviporum is a major pathogenic fungus in Northern hemisphere causing root and but rot to the economically valuable conifers. The spreading of Heterobasidion to new forest sites can be controlled with several methods, but there is a strong need for new methods to control established Heterobasidion in the forest site. In Europe, another pathogenic fungus of chestnut trees, Cryphonecteria parasitica has been succesfully controlled with a fungal virus. At least 15 % of H. annosum sensu lato (Fr.) Bref isolates are infected with dsRNA viruses, however the majority of Heterobasidion viruses do not cause notable phenotypic effects on their host fungus. Viruses are known to accumulate in Heterobasdion individuals over time, but not much is known about the possible effects of multiple virus infections on the host fungus. The primary objective of this study was to investigate whether multiple virus infections of Heterobasidion viruses would cause more debilitating phenotypic effects on the host H. parviporum compared to a single virus infection. In this study, the effect of viruses on the growth rate of H. parviporum was investigated at two different temperature conditions, 6 °C and 20 °C. Secondly, the effect of Heterobasidion viruses on the competitive ability of H. parviporum against saprotrophic fungus Phlebiopsis gigantea and mycorrhizal fungi Paxillus involutus and Meliniomyces bicolor was tested on paired cultures. Additionally, Trichoderma atroviride mycelial extract was spread into the substrate and the effect of the treatment on the growth rate of virus infected H. parviporum was investigated. Thirdly, it was investigated with quantitive real time RT–PCR whether the presence of the other viruses in multiple virus infections would affect the virus (RdRp) RNA quantity of a single virus in the host mycelium. The results of the growth experiments revealed that at 20 °C HetPV13–an1 single virus infection caused radical decrease in the growth rate of H. parviporum 7R242, but multiple virus infections had no effect on the growth rate even though HetPV13–an1 was present in the multiple virus infection. At 6 °C, all the virus infections decreased the growth rate of H. parviporum 7R242 but virus HetPV13–an1 more than the other virus infections. The competitive ability of H. parviporum 7R242 against P. gigantea was reduced by virus HetPV13–an1. P. involutus was able to restrict the growth of H. parviporum 7R242 infected with multiple viruses or HetPV13–an1. M. bicolor showed slight antagonistic activity towards H. parviporum but none of the virus infections decreased the competitive ability of H. parviporum enough in order for M. bicolor to restrict the growth of H. parviporum. T. atroviride cellular exudates decreased the growth rate of all the fungal strains, but the treatment seemed to even out the effects of the viruses. The virus RdRp RNA quantity was higher in the presence of other viruses in multiple virus infections. The main conclusion of the study is that the effect of multiple virus infections on H. parviporum is not additive and multiple virus infections did not cause more debilitating effect on the host fungus compared to a single virus infection.

In consequence of transpiration vast amounts of water moves from tree roots to the atmosphere via stem and leaves. Water does not only move directly from roots towards canopy. It is essential element in the maintenance of cells and fuel to solute transport in phloem. Movement of water inside the tree is caused by differences in water potential between cells and tissues. Water moves towards lower pressure potential in the xylem. Pressure is the main component of water potential in the xylem. Phloem transport is also driven by hydrostatic pressure gradient. Water moves from xylem to the phloem when the water potential is lower in the phloem than xylem. Osmotic potential is the main component of phloem water potential. Osmotic potential, practically the osmotic strength, of a cell is related to the soluble sugar and water content in the phloem. Therefore, the main components of tree water potential are pressure and the osmotic strength of a cell. Phloem is the transport pathway of sugars and other important compounds many which role is yet unknown. The dynamics of water and sugar transport is still an enigma for researchers. Understanding of water and sugar transport is vital because they appear to affect other physiological functions in trees, i.e. the function of stomata and cell growth. The research of phloem is very challenging because phloem content is easily contaminated when collected. Phloem cells have several defend reaction when disturbed. Some methods are in use in phloem research but these methods can only be used in laboratory conditions or with specific tree species. Especially few research is been carried out in situ due to its damaging effect when collecting phloem samples. Promising method to assess phloem transport is to utilize diameter measurements. Modeling of phloem transport with xylem diameter data does not disturb the function of phloem. Essential missing piece of information is quantitative data of osmotic strength in the phloem. The topic of this thesis is to examine the diurnal changes of the main components of tree water potential. Emphasis is on examining the osmotic strength of phloem and the testing of new method for studying osmotic strength of phloem. The measurements are mainly carried out with scots pine (Pinus sylvestris L.) and test evaluations are carried out with pillar black alder (Alnus glutinosa F. pyramidalis). The measurements are made with phloem pieces collected from different heights of the tree examined and with leaves from the canopy. Also the leaf water potential is measured which is related to diameter changes of the xylem. The former are compared to the osmotic strength of phloem pieces and leaves. The method used in this thesis is apparently not used in literature. The difference with methods in the literature is the freezing and thawing of phloem pieces before sampling with sentrifuge. Method brings out similar results of phloem osmotic strength found in the literature. The values might be slighlty underestimated due to the method used. According to these results the water potential of phloem are closely related to the xylem water potential with scots pine. The strongest relation with the xylem is in the phloem beneath the canopy and weakest in the phloem collected in the base of a trunk. The phloem water potential of a branch was most difficult to intepret. The osmotic strength and water content of needles were strongly related to the needle water potential. The results support the idea of a strong interaction between phloem and xylem.

When concerning birdlife, Helsinki has two major wetland areas; the shores of Vanhankaupunginlahti and Östersundom. These areas include both natural wildlife conservation areas, and Natura 2000 -protected areas. In addition to an abundant nesting waterbird population, sightings of rarer birds and other vertebrates also occur regularly. The number of pairs of birds and their population density are on top of Finland’s rates. The eutrophic sea gulfs with their plentiful array of vertebrate species lure in small carnivorous mammals. In the valuable birdlife areas, the main concern is the predation pressure imposed by these mammals onto nesting birds. The fox (Vulpes vulpes), badger (Meles meles), pine marten (Martes martes) and the invasive alien species, raccoon dog (Nyctereutes procyonoides), all prey on birds and their eggs. To ensure the vitality of the bird population and other species, it is justified to hunt for the small preying mammals on the wetlands in question. On the lands of the city of Helsinki, Helsinki City Construction Services’ unit of nature preservation is primarily responsible for the hunting. The traditional hunting method uses traps that catch the targets alive. Since these traps have to be checked in person once a day, this method is extremely time and resource consuming with a large number of traps. Utilising modern trail cameras with remote control option and realtime photo transmission is a way to save the time used for hunting considerably. The first objective of this study was to find out just how much time could be saved in the trap hunting of preying mammals when using trail cameras that send realtime photos and could be remotely controlled. To achieve this objective, I collected data of how long trap visits and moving between them took. Furthermore, I obtained information about the frequency of different occurrences around the traps. Using this data, I compared workdays with varying number of traps and the aforementioned two hunting methods. The study shows that as the number of traps increases, the time save does so also when using trail cameras. The biggest difference is in the time used moving between traps, since the trail cameras eliminate unnecessary visits. This enables resources to be used towards keeping more traps active, which increases the efficiency of the hunt and thus may benefit the wellfare of waterbirds and other animals. The second objective was to utilise the photographic material of small carnivorous mammals and to determine their trap catching rate, and study the possible differences between different predator species. Clear divergences were found between these probabilities: the raccoon dog and the badger had the highest catching rate (55 % ja 57 %, respectively), while a pine marten would be trapped with 38 % probability, and a fox with only 12 %. The divergences were tested with an χ2–test, and exluding the raccoon dog-badger pairing were statistically significant.

Monen ulkoisesti mainiolta vaikuttavan riistakosteikon lintutiheydet voivat olla vaatimattomia. Kosteikkojen suunnittelussa ja kunnostamisessa onkin syytä huomioida mitä veden pinnan alla tapahtuu. Useat vesilinnut ja kalat käyttävät ravinnokseen vesiselkärangattomia ja esiintyessään samassa elinympäristössä ne käyvät ravintokilpailua. Linnuille saatavilla olevan ravinnon riittävyys on yksi toimivan riistakosteikon elinehdoista. Työssäni tutkin kalojen vaikutusta vesiselkärangattomiin. Tutkimukseni avulla tietämys vesiselkärangattomia ravinnokseen käyttävien lintujen ravinnon saatavuuteen lisääntyy. Tavoitteena on tuottaa tietoa, jota voidaan soveltaa uusien riistakosteikkojen suunnitteluun, sekä jo olemassa olevien kosteikkojen hoidossa. Tulosten avulla voidaan pyrkiä muuttamaan kosteikkojen ravintotilannetta suotuisammaksi linnuille ja luoda niille parempia pesimä- ja poikueympäristöjä. Karussa ja rakenteeltaan yksikertaisessa ympäristössä tarkastelen kalojen vaikutusta vesiselkärangattomien biomassaan ja yhteisön kokoluokkajakaumaan. Kokoluokkajakaumista tarkastelen koko yhteisön jakaumien lisäksi erikseen sukeltajien (Dytiscidae) jakaumaa. Rehevien ja kalaisten kohteiden tuloksista tutkin elinympäristön rakenteellisuuden vaikutusta vesiselkärangattomien biomassaan ja kokoluokkajakaumaan. Ravinteisuuden vaikutusta vesiselkärangattomiin tarkastelen vertaamalla kalattoman rehevän kohteen tuloksia ja kalattomien karujen vesien tuloksiin. Kalat rajoittavat vesiselkärangattomien määriä, minkä perusteella oletan, että kalaisilla vesillä vesiselkärangattomien biomassa on pienempi verrattuna kalattomiin vesiin. Kalojen puuttumisen uskon suosivan suurikokoisia vesiselkärangattomia, kuten sukeltajia. Rakenteellisesti monipuolisessa elinympäristössä odotan avoimen ympäristön vesiselkärangattomien biomassan olevan pienempi ja suurten vesiselkärangattomien määrän vähäisempi verrattuna tiheän kasvuston ympäristöön. Vesiselkärangattomien biomassan oletan olevan suurempi rehevillä vesillä verrattuna karuihin kohteisiin. Tutkimuksen tulosten mukaan pysyvä kalakanta vaikuttaa vesialueen vesiselkärangatonyhteisön biomassaan vähentävästi. Kalojen vaikutus on riippumaton vesistön ravinteisuudesta. Kalojen puuttumisesta hyötyvät muut vesiselkärangattomia ravinnokseen käyttävät eläimet, kuten sorsalinnut. Tuloset osoittavat myös, että rakenteeltaan monimuotoisessa elinympäristössä, kasvillisuuspeitteisillä alueilla vesiselkärangattomien biomassa on suurempi kuin avoimen veden alueilla. Kalat vähentävät sorsien käyttämää vesiselkärangattomien määrää. Näin ollen kosteikot on perusteltua pyrkiä pitämään kalattomina. Näin parannetaan sorsalintujen elin- ja poikueympäristön laatua. Mikäli kosteikon pitäminen kalattomana on mahdotonta, voidaan ravintotilannetta luoda sorsille edullisemmaksi kasvillisuuden avulla. Kasvillisuuspeitteisillä alueilla vesiselkärangattomien runsaus on avoimen veden alueita suurempi, johtuen kasvillisuuden vesiselkärangattomille antamasta suojasta ja ravinnosta.

The boreal forest is one of the largest biomes in the world, maintaining natural disturbances such as forest fires and insect outbreaks, still occurring widely at their full scale, frequencies and patterns. However, the knowledge of natural forest dynamics, disturbance factors other than fire and post-disturbance development is still inadequate; this is partly due to the lack of accurate, repetitive measurements with adequate temporal resolution. The aim of this study was to examine the structural change and development of natural, Abies balsamea (L.) Mill. dominated forest stands following an insect outbreak of late-1970s to early 1980s. The focus was on annual tree basal area and species composition change at the stand level during the recent decades. The post-disturbance stand development was studied to see whether the stands were following the development model of steady state and quasi-equilibrium. Additionally, the size and age structure of the stands were studied. The objectives were achieved by using dendrochronological methods with tree-ring analyses, in which the forest characteristics were reconstructed at an annual resolution. The study was carried out in the province of Quebec in Eastern Canada, in the North Shore region (Côte-Nord) of St. Lawrence River. Nine sites of a size of 32 m x 32 m were chosen for data collection. The results showed that the tree species composition of the studied stands had clearly changed from the pre-episode to the current state: the composition of A.balsamea, Picea mariana (Mill.) BSP and Betula papyrifera Marsh. in 1975 had changed towards the abundance of A. balsamea, with notably less of P. mariana and B. papyrifera in 2013. Particularly B. papyrifera seems to disappearing from the studied stands. On average, the shape of the live tree diameter distribution for the whole study area was close to a reverse-J, whereas the dead tree diameter distribution resembled rotated sigmoid, with a plateau in the middle. The trees were of all age, mean age for live A. balsamea, P. mariana and B. papyrifera trees was 91 years (SD ± 32 years), 135 years (SD ± 48 years) and 180 years (SD ± 24 years), respectively. The examination of the development of total basal area showed apparent changes during the four decades from 1975 to 2013. The average stand development of total basal area for the whole study area was modest decline after a dramatic post-outbreak drop: the basal area was 33.8 m2 ha-1 (SD ± 4.5 m2 ha-1) in 1975 and 20.7 m2 ha-1 (SD ± 6.0 m2 ha-1) in 2013. Stands showed different types of development: for some of the stands basal area had dropped throughout the observation period, for some the total basal area had started to recover after a decline, and some stands had fairly stable development throughout the observation period. The development of basal area in the past fifteen years has been negative in over half of the studied stands; it seems that the stands are not following the expected post-disturbance development, where the biomass of the forest recovers to the pre-outbreak level and over it, at these time scales of 30-years of observation. Results suggest that the studied forest stands have reached a state where the basal area is yet to be recovered from the decline following the spruce budworm outbreak in the late-1970s to early 1980s. There is a new, on-going defoliation of spruce budworm – that already has heavily affected particularly A. balsamea – in the study area, and therefore the basal area of the forest stands might be expected to furthermore decline in the future.

Suomessa metsäneuvonnan kenttä on monimuotoinen jakautuen usean eri metsäammattilaistahon välille. Metsäammattilaiset ovat kohdanneet työkentällään monia suuria muutoksia, kuten uudet lait ja metsänomistajien keskuudessa tapahtuneet muutokset. Tämän tutkimuksen tarkoituksena oli selvittää metsäammattilaisten universaaleja arvoja, asenteita eri metsänhoidollisiin menetelmiin ja mitä metsänhoidollisia toimenpiteitä he ovat tarjonneet metsänomistajille. Lisäksi selvitettiin, miten eri tahojen metsäammattilaisten näkemykset erotavat toisistaan. Tutkimuksessa sovellettiin sosiaalipsykologian teorioita: Schwartzin arvoteoriaa, Allportin asenneteoriaa ja Ajzenin suunnitellun käyttäytymisen mallia. Arvoja mitattiin Schwartzin mittarilla, jossa oli 23 arvo-osiota. Asenteita ja käytäntöjä mitattiin tätä tutkimustavarten kehitetyillä mittareilla. Tutkimus toteutettiin kyselytutkimuksena e-lomakkeella. Aineisto koottiin valtakunnan tasolla. Kyselyyn vastasi metsäammattilaisia seuraavilta tahoilta: metsäteollisuus, metsäpalveluyritykset, metsänhoitoyhdistykset ja yksityiset metsäpalveluyrittäjät. Otoksen koko oli noin 1410 ja vastauksia saatiin 418. Täten vastausprosentiksi saatiin noin 30. Aineiston analysoinnissa käytettiin tilastollisia tunnuslukuja, t-testiä, faktorianalyysia, summamuuttujia ja varianssianalyysiä. Faktorianalyysilla saatiin tiivistettyä aineisto sekä asenteiden että käyttäytymisaikomuksen osalta viiteen faktoriin. Tärkeimmiksi arvoiksi nousivat hyväntahtoisuus, universalismi ja itseohjautuvuus – vain järjestys vaihteli joidenkin tahojen osalta. Asennoituminen eri menetelmiin oli pääosin neutraalia tai myönteistä. Myönteisintä asennoituminen oli puuntuotannollisia menetelmiä kohtaan. Puuntuotannollisia menetelmiä oli keskimäärin tarjottu eniten ja luonnonhoidollisia menetelmiä vähiten. Asioimistilanne metsäammattilaisen ja metsänomistajan välillä on hyvin monimutkainen ja -ulotteinen ilmiö. Arvot ja asenteet muuttuvat yhteiskunnan muuttuessa, joten jatkotutkimuksille on tarvetta tulevaisuudessakin.

Increased demand for forest-derived biomass has resulted in changes in harvest intensities in Finland. Conventional stem-only harvest (CH) has to some extent been replaced with whole-tree harvest (WTH). The latter involves a greater removal of nutrients from the forest ecosystem, as all the above ground biomass is exported from the site. This has raised concerns that WTH could result in large changes in the nutrient dynamics of a forest stand and could eventually lower its site productivity. Little empirical data exists to support this assumption as only a limited number of studies have been conducted on the topic. A majority of these discuss the short-term effects, thus the long-term consequences remain unknown. The objective of this study was to compare differences in soil properties after CH and WTH in a fertile Norway spruce (Picea abies (L) Karst.) stand in Southern Finland. The site was clear-felled in August 2000 and spruce seedlings were planted in the following summer. Soil sampling in the form of systematic randomized sampling was carried out in May 2011. Changes in base saturation, cation exchange capacity, elemental pools (total and exchangeable) and acidity were studied in both organic and mineral horizons. The results indicate that WTH lowered effective cation exchange capacity and base saturation particularly in the humus layer. The pools of exchangeable Al and Fe were increased in the humus layer, whereas the amount of exchangeable Ca decreased in both layers. WTH also resulted in lower Ca/Al-ratios across the sampled layers. Treatment did not have a significant effect on pH, total pools of elements or on the C/N-ratio of the soil. The results suggest that although the stand possesses significant pools of nutrients at present, WTH, if continued, could have long-term effects on site productivity.

Filamentous fungi vectored by Trypodendron lineatum were identified. The mycota of flying beetles was distinguished from that of hatching ones. The purpose was also to study to what extent T. lineatum is associated with specific fungal partners and opportunistic fungi. The hypotheses stated that: the proportions of beetles carrying epi- and endomycetes (positioned to outer surface and inner parts of insect, respectively) differ (1); proportions of beetles that get attached to fungal propagules vary between collection methods (pheromone traps and stumps) (2); the frequencies of fungal iso-lates differ between positions (3); the frequencies of isolates are unequal between collection meth-ods (4). The beetles were collected from two clear felled spruce dominated sites in Southern Finland with pheromone traps in spring and sawing pieces of stumps in summer. The experimental design of this study is unique in studying the effect of trapping time and method on the resulting assemblage of fungi. Identification of fungi rests on morphological characteristics and DNA-based methods. The sequences were compared against BLAST. The hypotheses were tested statistically using odds ratio (logistic regression) for proportions and ratio of averages (Poisson regression) for frequencies. Species richness and diversity for positions, trap types, sites and treatment methods were analyzed using Shannon-Wiener Diversity Index/Shannon Entropy Calculator and EstimateS. The proportion of beetles carrying epimycetes was greater than that of endomycetes (1). The proportions of vector beetles were not significantly affected by trap type (2). The frequencies of fungal isolates were higher among the epimycota (3). Trap types had no impact on the frequencies of isolated fungi (4). Species richness and diversity analyses supported the outcome of the tested hypotheses. Additionally, they indicated similarity between the mycota of the sites, whereas conclu-sions concerning the treatment methods could not be made. Seven genera (Penicillium sp., Cadophora sp., Cladosporium sp., Rhizosphaera sp., Sydowia sp., Absidia sp. and Mucor sp.) were discovered associated to the striped ambrosia beetle as new. Swarming beetles and those leaving stumps were observed to carry different assemblages of fungi. Origin of the Zygomycota was only traced to the beetles hatching from stumps in midsummer. 61.84 % of the isolates belonged to the Ascomycota, 10.53 % to the Zygomycota and 27.63 % remained unidentified. Best concentrated genera were Hypocrea, Ophiostoma and Sydowia.

Metsien ekologinen ja entistä kestävämpi käyttö on muuttuvan maailman myötä noussut tärkeään asemaan. Hoitamalla metsiä jatkuvasti peitteisenä, luontaisen häiriödynamiikan keinoin, pystytään ylläpitämään monimuotoisuutta sekä vastaamaan metsien monikäytön mahdollisuuksiin ja puuvarantojen kasvattamisen haasteisiin. Metsälain uudistamisen myötä metsänomistaja pystyy nykyisin hoitamaan metsäänsä entistä monimuotoisemmin keinoin. Yhtenä hakkuutapana jatkuvasti kasvatettavassa eri-ikäisrakenteisessa metsässä ovat pienaukkohakkuut. Metsälaissa määritelty pienaukkojen koko on maksimissaan 0,3 hehtaaria ilman uudistamisvelvoitetta. Metsään tehtävissä käsittelyissä, joissa syntyy reuna-alueita, on aina tuulituhoriski. Tuulituhot aiheuttavat Suomessa sekä Euroopan tasolla mittavia taloudellisia tappioita. Tutkimukseni pyrkii vastaamaan kysymykseen, kuinka paljon tuulenkaatoja on pienaukkojen ympärillä. Tutkimusalueet sijaitsivat Keski-Suomessa Isojärven ja Pohjois-Karjalassa Ruunaan alueilla, DISTDYN - häiriödynamiikkahankkeen tutkimusalueen metsiköissä. Pienaukkohakkuut tehtiin koealueille vuosina 2010, 2011 ja 2012. Hakkuissa säästettiin joko 50 % tai 90 % puuston tilavuudesta. Aukot hakattiin rakenteeltaan pehmeästi vaihettuviksi, niin sanotuiksi ”liehuvareunaisiksi” ja erimuotoisiksi. Puoleen aukoista tehtiin maanmuokkaus, ja osa aukkojen välialueista harvennettiin. Aineisto kerättiin kesällä 2015. Aineistoa varten mitattiin yhteensä 123 pienaukkoa 24 metsikössä. Pienaukkojen keskimääräinen koko oli 0,19 ha. Hakkuiden jälkeisistä tuulituhoista mitattiin joko kokonaan kaatunut tai osittain poikki mennyt runko. Mittaukset tehtiin pienaukkojen sisällä sekä 20 m reunasta sisään metsään. Tuulituhot jäivät koealoilla kaiken kaikkiaan melko vähäisiksi. Puita oli kaatunut 4-5 vuodessa, kuusikoissa yksi tukkipuu per yksi pienaukko ja männiköissä yksi tukkipuu per kolme pienaukkoa. Lisäksi 1-3 pientä puuta vaurioitui per yksi pienaukko. Tutkimuksesta selvisi, että hakattavan aukon koolla oli merkitystä, kuten aikaisemmissa tutkimuksissa on osoitettu. Pienimmissä aukoissa tuhot olivat erittäin vähäisiä. Suurin tuulituhoriski oli aukoissa, joiden ympäristö oli voimakkaasti harvennettu, sekä tiheään metsään tehdyssä aukossa, jonka ympärillä olevat hontelot puut altistuivat tuulelle. Aineiston mallinnus olemassa olevilla tuulituhoennustemalleilla ei yrityksistä huolimatta onnistunut ja tuhojen määrän vertailu tällä aineistolla tasaikäiskasvatukseen osoittautui mahdottomaksi. Tutkimukseni tulos näyttää tukevan tuloksia, joissa pienaukkohakkuiden todetaan olevan sopiva hakkuumenetelmä, mikäli halutaan hillitä metsikössä esiintyviä tuulituhoja. Tutkimus vahvistaa käsitystä siitä, että pienaukkojen hakkaaminen metsän keskelle lisää tuulituhoriskiä vain lievästi.