Browsing by Subject "kirjanpainaja"
Now showing items 1-5 of 5
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(2014)The effect of forest health and structure to the relative surface temperature captured by airborne thermal imagery was investigated in Norway Spruce-dominated stands in Southern Finland. Canopy surface temperature has long been recognized useful in monitoring vegetation water status. Recent studies have shown also its potential in monitoring vegetation health. Airborne thermal imagery, Airborne Light Detection and Ranging (LiDAR) and field measurements were acquired from the area of interest (AOI). The relative surface temperature correlated most negatively with the logarithm of stem volume, Lorey’s height and logarithm of basal area at resolution of 254m2 (9-m radius). In other words, taller and older stands had colder surface temperatures. In addition, LiDAR metrics, such as height percentiles and canopy cover percentage, were compared with surface temperature. Standard deviation of canopy height model, height features (H90, CHM_max) and canopy cover percentage were most strongly negatively correlated with the surface temperature. On average, higher surface temperatures were detected in defoliated canopies indicating that thermal images may provide some additional information for classifying forests health status. However, the surface temperature of defoliated plots varied considerably. It was also found that surface temperature differences between canopy and ground responses were higher in defoliated plots. Based on the results, forest health and structure affect to the surface temperature captured by airborne thermal imagery and these effects should be taken into account when developing forest health mapping applications using thermal imagery.
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(2014)The effect of forest health and structure to the relative surface temperature captured by airborne thermal imagery was investigated in Norway Spruce-dominated stands in Southern Finland. Canopy surface temperature has long been recognized useful in monitoring vegetation water status. Recent studies have shown also its potential in monitoring vegetation health. Airborne thermal imagery, Airborne Light Detection and Ranging (LiDAR) and field measurements were acquired from the area of interest (AOI). The relative surface temperature correlated most negatively with the logarithm of stem volume, Lorey’s height and logarithm of basal area at resolution of 254m2 (9-m radius). In other words, taller and older stands had colder surface temperatures. In addition, LiDAR metrics, such as height percentiles and canopy cover percentage, were compared with surface temperature. Standard deviation of canopy height model, height features (H90, CHM_max) and canopy cover percentage were most strongly negatively correlated with the surface temperature. On average, higher surface temperatures were detected in defoliated canopies indicating that thermal images may provide some additional information for classifying forests health status. However, the surface temperature of defoliated plots varied considerably. It was also found that surface temperature differences between canopy and ground responses were higher in defoliated plots. Based on the results, forest health and structure affect to the surface temperature captured by airborne thermal imagery and these effects should be taken into account when developing forest health mapping applications using thermal imagery.
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(2015)Kaarnakuoriaiset (Coleoptera: Scolytidae), joihin kirjanpainaja (Ips typographus L.) kuuluu, ovat Suomessa merkittäviä metsien tuhohyönteisiä. Kirjanpainajan on helpompi iskeytyä ja lisääntyä onnistuneesti, jos metsäkuusi (Picea abies (L.) Karst) heikentyy iän tai tuhon seurauksena. Tässä tutkimuksessa kartoitetaan kirjanpainajan aiheuttamien kuusikkotuhojen laajuutta Etelä-Suomessa Lahden kaupungin taajamametsissä vuonna 2012. Tutkimuksen tarkoituksena on käyttää kirjanpainajan pyyntiin kehitettyjä menetelmiä, kuten feromoniansa- ja pyyntipuumenetelmiä, seurannassa ja tuhojen alentamisessa. Näiden lisäksi paikallistetaan kirjanpainajakannan esiintymät koealamittauksien, runkoanalyysin ja linja-arvioinnin avulla. Työssä selvitetään kirjanpainajan lisäksi myös aitomonikirjaajan (Polygraphus poligraphus L.) ja kuusentähtikirjaajan (Pityogenes chalcographus L.) kantojen tiheyksiä pyyntipuilla samanaikaisesti kirjanpainajan kanssa. Tutkimus aloitettiin toukokuussa pystyttämällä tutkimusalueelle 180 feromoniansaa 42 eri ryhmään varttuneiden kuusikkokuvioiden reunoille. Samanaikaisesti kaupungin alueelle tehtiin myös 29 pyyntipuukasaa kuoriaisia houkuttelemaan. Pyyntipuukasoissa oli kuusentähtikirjaajia ja aitomonikirjaajia enemmän iskeytyneenä sisäänmeno- ja ulostuloreikien perusteella kuin kirjanpainajia. Tutkimusalueelle perustettiin 33 koealaa. Koealojen tarkoitus oli selvittää kirjanpainajakannan tiheyttä yhdessä muiden menetelmien kanssa. Feromoniansoilla ja pyyntipuukasoilla pyrittiin arvioimaan kvantitatiivisesti kirjanpainajan kannantiheys Lahden kaupungin alueella. Metsiin perustettujen koealojen avulla arvioitiin visuaalisesti kirjanpainajien aiheuttamat tuhot alueella. Tutkimuksen aikana feromoniansoilla saatiin kaikkiaan 1 136 000 kirjanpainajaa. Feromoniansoista saatujen tuloksien perusteella kirjanpainajaa oli alueella runsaasti. Molemmat pyyntimenetelmät, feromoniansat ja pyyntipuukasat, olivat toimivia ja menetelmät tukivat toisiaan. Tuloksista päätellen ne myös estimoivat alueen kirjanpainajatiheyden samansuuntaisiksi toisistaan riippumatta. Koealamittauksien perusteella alueen puissa esiintyi pihkavuotoa, harsuuntumista ja iskeytymiä. Kullakin koealalla kaadettiin kaksi puuta, joiden kaarnakuoriaiset inventoitiin. Yhdestäkään kaadetusta puusta ei löydetty iskeytymiä. Tämä viittaa siihen, että puiden ulkonäön perusteella ei voida varmasti päätellä kirjanpainajapopulaation alueellista tiheyttä.
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(2014)Urban forests of Helsinki city are managed in multiple ways and several forest values are taken into account in forest management. Strong forest management actions that change the forest landscape radically have been done quite seldom, which has increased the proportion of old forests. The risk of spruce bark beetle (Ips typographus) outbreaks is often evident especially in older Norway spruce (Picea abies) forests of low vitality. In the winter of 2011 to 2012 storms caused windfalls in some areas of the urban forests in Helsinki city, which increased the risk of spruce bark beetle outbreaks even more. The objective of this study was to assessment the risk of spruce bark beetle outbreaks in the urban forest of Helsinki city and present future forest management recommendations to control the spruce bark beetle damage. Monitoring with pheromone baited traps was used as the main investigation method. Results were compared with spruce bark beetle risk estimates found in literature. Other factors affecting the risk of spruce bark beetle, for example the amount of living Norway spruces infested with the spruce bark beetle, were observed as well. Monitoring with pheromone traps was carried out with 36 traps in three regions in Helsinki Central Park and in one region in Herttoniemi between 6th of May and 4th of July in 2013. Pheromone trap model, WitaTrap Multi Funnel, and pheromone bait Ipsowit® Standard were manufactured by Witasek company. Altogether 79 210 spruce bark beetles were trapped. According to the monitoring results the risk of spruce bark beetle can be high in one region in Central Park area. Living Norway spruces infested by the spruce bark beetle were found in two regions and also in one area outside the investigation area. Based on the results the areas with greatest risk to spruce bark beetle damage were the neighboring areas of previous damage as well as forests with suitable breeding material for the spruce bark beetle. The risk can also be high in Norway spruce forests of low vitality and in recently formed, sun-exposed forest edges dominated by Norway spruce. Forest management recommendations in short time interval to control the spruce bark beetle risk are as follows 1) forest monitoring and removal of spruce bark beetle infested live Norway spruces before Midsummer, 2) observation of storm damage and removal of large diameter Norway spruce windfalls as a rule, 3) monitoring the weather conditions and 4) following national announcements related to the spruce bark beetle risk status. Forest management recommendations for longer time interval are phased regeneration fellings of risk prone Norway spruce forests and changing the forest structures more resistant to spruce bark beetle damage in the future.
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(2018)Forests are important carbon pools for combating climate change. Forest disturbances, such as insect outbreaks, can temporarily change a forest and forest soil to a source of carbon. Tree mortality reduces forest carbon uptake and increases emissions from the decay of killed trees. Climate change is expected to impact the susceptibility of forests to disturbances. For example, the number of insects in forests is predicted to increase and therefore the impact of pests on forest ecosystems will also increase. This can weaken forests carbon sequestration. The purpose of this master's thesis was to study the effect of the European spruce bark beetle (Ips typographus L.) on the carbon in the surface layers (humus and the mineral layer of depth 0‒5 cm) of the soil. In this study, the aim was to study the effect of tree mortality and tree damage intensity caused by the spruce bark beetle on the forest topsoil carbon stock. In addition, changes in the carbon content and C / N ratio of soil surface layers were studied. The aim was also to study the effect of stand- and tree-wise characteristics on the carbon content of the topsoil. The field work was carried out in urban forest area, in Lahti,Southern Finland. In years 2012–2013 stand- and tree-wise characteristics were measured on 49 plots. The spruce bark beetle-induced symptoms and forest site classification were also estimated. Further, three soil samples were taken from each plot for carbon analysis from the humus layer and 0‒5 cm depth of mineral soil. Proportion of carbon (C %) and C/N ratio were analysed from the samples and the amount of carbon (kg C m-2) was determined. The amount of carbon in the experimental area was on average 0.6 kg C m-2 and varied between plots 0.1 and 1.5 kg C m-2. The amount of carbon varied statistically significantly between forest types. At a more herb-rich forest types (OMT/OMaT-groups= more rich forest types), the soil carbon content was significantly higher than in MT-type. Also, the C / N ratio and C % were both significantly higher in the humus layer than in the mineral soil. In this study, the dead spruce trees (%), dead spruces diameter (d1,3) or basal area of dead spruce trees did not increase the amount of carbon in the surface layers of the soil. Also, the tree damage intensity caused by the spruce bark beetle did not explain the amount of carbon (kg C m-2), proportion (C%) or the C / N ratio of the soil surface layers. However, there was a correlation between the stand- and tree-wise characteristics and the carbon content of the soil in more rich vegetation/forest site (OMT/OMaT): The proportion of spruces showed a relationship with C % and C/N-ratio, and basal area of spruces with carbon content of the soil (kg C m-2). This study did not find a relationship between spruce bark beetle and surface layers of soil carbon. This may be due to the fact, that the time frame of this study was too short to observe any changes. In addition, this study did not compare fully healthy vs. seriously damaged spruce forests, in which case the difference in soil carbon content would have been observed. Furthermore, this study did not quantify potential changes in litter layer carbon caused by the spruce bark beetle. The following studies may need to be done over a longer period of time, adding control plots to the study, and also the carbon contained in the litter layer. On the other hand, many environmental factors affect to natural processes simultaneously. Therefore, studying a single variable may not necessarily give a true picture of causality in nature.
Now showing items 1-5 of 5