Browsing by Subject "Norway spruce"

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  • Amin, Al (Helsingin yliopisto, 2021)
    Wood development is a significant process with both financial as well as natural perspectives. Trees and wood are of highly significance in Finland where a huge part of the gross national income devises from the forestry area. Ecologically and commercially the Norway spruce (Picea abies) is one of the most common tree species in Europe. It covers about 30% of Finland's forest area. Norway spruce is frequently used in research to study many phenomena related specifically to the wood formation and lignification. The principal objective of my thesis work was to reveal an unknown step in the lignification process in developing xylem of Norway spruce, i.e. the initiation site(s) for lignification. To achieve this goal, the aim was to investigate the chemical identity of possible lignification initiation sites in the middle lamellae and cell corners of developing Norway spruce xylem, and to answer the question where in the cell wall soluble monolignols first emerge and lead to the start of lignin formation (polymerization). I was approaching this goal with immunolabeling technique for confocal microscopy and Raman spectroscopy to unravel this initiation site of lignification by using specific monoclonal antibodies for cell wall compounds and comparing the results with the initial lignin deposition sites. To detect the location/distribution of some important polysaccharides and lignin substructure for lignification initiation, monoclonal antibodies i.e. LM10, LM11, LM15, LM24 and antibody Dibenzodioxocin or DBD were applied for confocal microscopy and some monolignol specific spectra were applied for Raman microscopy. The xylan was detected by LM10 in secondary cell wall abundantly and few are in primary cell wall of Norway spruce. The LM11 against arabinoxylan was determined more in primary cell walls but less in secondary cell wall. The location of xyloglucan was identified in the middle lamellae, primary and secondary cell wall of Norway spruce by LM15. The LM24 against glycosylated xyloglucan was found in secondary cell walls, abundantly in cell corners but few in primary cell wall. The primary antibody Dibenzodioxocin or DBD for the lignin substructure revealed that these were present in the mature cells of secondary cell walls (S2 and S3 layers). The lignin substructures DBD were not found in youngest cells where secondary cell walls are absent. The developing xylem of Norway spruce was subjected Raman microscopy and which revealed the locations of cinnamyl alcohol, coniferyl alcohol and coniferyl aldehyde. The cinnamyl alcohol was abundantly found at cell corner and middle lamellae in most developing part of xylem. The coniferyl alcohol was determined only in developing xylem cell corners. The coniferyl aldehyde was observed at cell corners, middle lamella and primary cell walls of developing xylem. The coniferyl aldehyde was located more in mature cells than younger cells. So, the Confocal and Raman microscopy images revealed the possible bindings of monolignols to polysaccharide in young cell corners, cell wall layers and middle lamellae.
  • Karttunen, Toni (Helsingfors universitet, 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.
  • Nirhamo, Aleksi; Pykälä, Juha; Halme, Panu; Komonen, Atte (Wiley, 2021)
    Applied Vegetation Science 24: 2
    Questions: Aspen (Populus tremula) is declining in the old-growth forests of boreal Fennoscandia. This threatens the numerous taxa that are dependent on old aspens, including many epiphytic lichens. Potential methods to aid epiphytic lichens on aspen are centered around treatments which affect the density of Norway spruce (Picea abies). In this study, we investigated how epiphytic lichen communities on aspen are affected by the variation of spruce density in the immediate vicinity of the focal aspen. Location: Southern boreal forests in Finland. Methods: We recorded the occurrence of lichens from 120 aspens in 12 semi-natural forest sites. We used spruce basal area as the measure for spruce density. The selected aspens represented a gradient in spruce basal area in the vicinity of the aspen from 0 to 36 m2/ha. We also measured other tree- and stand-level variables that are known to influence lichen occurrence. Results: Lichen communities on aspen were affected by spruce density, stand age and bark pH. Both lichen species richness and the richness of red-listed species were highest at an intermediate spruce density, and both increased with stand age. Lichen species richness was higher when bark pH was lower. Additionally, community composition was influenced the most by spruce density, followed by bark pH. Conclusions: Our study highlights the detrimental effects of high spruce density on lichen diversity on aspens. This is caused by high spruce density resulting in low light availability. Lichen diversity on aspens was highest when spruce density was intermediate. Spruce thinning in aspen-rich old-growth forests can be helpful in ensuring the long-term persistence of old-growth lichens on aspen in protected forests.
  • Raatevaara, Antti; Korpunen, Heikki; Mäkinen, Harri; Uusitalo, Jori (2020)
    In cut-to-length logging, the harvester operator adjusts the bucking in accordance with visible defects on processed stems. Some of the defects, such as a sweep on the bottom of the stem, decrease the yield and quality of sawn products and are difficult for the operator to notice. Detecting the defects with improved sensors would support the operator in his qualitative decision-making and increase value recovery of logging. Predicting the maximum bow height of the bottom log in Norway spruce (Picea abies (L.) Karst.) with log end face image and stem taper was investigated with two modelling approaches. A total of 101 stems were selected from five clear-cut stands in southern Finland. The stems were crosscut and taper measured, and the butt ends of the bottom logs were photographed. The stem diameter, out-of-roundness, and pith eccentricity were measured from the images while the max. bow height was measured by a 3D log scanner at a sawmill. The bottom logs with an eccentric pith had higher max. bow height. In addition, a highly conical bottom part of the stem was more common on the bottom logs with a large max. bow height. Applying both log end face image and stem taper measurements gave the best model fit and detection accuracy (76%) for bottom logs with a large max. bow height. The results indicate that the log end face image and stem taper measurements can be utilised to aid harvester operator in deciding an optimised length for logs according to the bow height.
  • Kellomäki, Seppo; Pohjapelto, Pirkko (Suomen metsätieteellinen seura, 1976)
  • Matkala, Laura; Kulmala, Liisa; Kolari, Pasi; Aurela, Mika; Bäck, Jaana (2021)
    We studied the occurrence of extreme weather events and their effects on the carbon dioxide and water exchange of two subarctic forest stands. One study site was a Scots pine site in eastern Finnish Lapland (VarriO), and the other was a Norway spruce site in western Finnish Lapland (Kenttarova). We compared short-term meteorological data with long-term data and found that the pine forest had experienced extremely warm, wet and dry years as well as cold spells during the growing season in the studied period of 2012-2018. The spruce forest was studied during the period 2003-2013, during which time it experienced extremely warm and wet summers, and dry periods, although the dry times were not statistically defined as such. The spruce forest was less resilient to warm and dry periods, as its total ecosystem respiration and respiration potential decreased during warm and dry summers, while the same effect was not seen in the pine forest. The decreased respiration values may have occurred due to slowed decomposition of organic matter. The pine forest experienced two cold spells during the studied period. One of these cold periods was more of a continuation of the previous cold spring and late start of the growing season in 2017, while the other one occurred after a warm period in 2014. The ecosystem respiration rates and gross primary production in 2017 remained low for the whole July-August time period likely due to cold-inhibited growth of ground vegetation, while in 2014 no such effect could be seen. We saw no effect of extreme weather events in the water exchange related measurements in either of the forests. Overall, both forests, especially the trees, were resilient to the weather extremes and experienced no long-term damage.
  • Niemi, Suvi (Helsingfors universitet, 2012)
    Root and butt rot is the most harmful fungal disease affecting Norway spruce in southern Finland. In approximately 90 % of cases the causal agent is Heterobasidion parviporum. Root and butt rot infections have not been reported in Finnish peatlands. However, the increase in logging operations in peatlands means there is a risk that the fungus will eventually spread to these areas. The aim of this study was to find out the impact of growing site on the resistance of Norway spruce to Heterobasidion parviporum infections. This was investigated by artificially inoculating H. parviporum to spruce trees in pristine mire, drained peatland and mineral soil and comparing the defence reactions. Additionally, the effect of genotype on resistance was studied by comparing the responses of spruce clones representing different geographic origins. The roots and stems of the trees to be sampled were wounded and inoculated with wood dowels pre-colonised by H. parviporum hyphae. The resulting necrosis around the point of inoculation was observed. It was presumed that increased length of necrosis indicates high susceptibility of the tree to the disease. The relationship between growth rate and host resistance was also studied. The results indicated that growing site does not have a statistically significant effect on host resistance. The average length of necrosis around the point of inoculation was 35 mm in pristine mire, 37 mm in drained peatland and 40 mm in mineral soil. It was observed that growth rate does not affect resistance, but that the genotype of the tree does have an effect. The most resistant spruce clone was the one with Russian origin. The results suggest that the spruce stands in peatlands are not more resistant to root and butt rot infections than those in mineral soil. These findings should be taken into consideration when logging peatland forests.
  • Pelto-Arvo, Mikko (Helsingin yliopisto, 2020)
    The European spruce bark beetle Ips typographus (L.) is a severe pest of the Norway spruce Picea abies (Karst.). The species usually attacks weakened trees, but in a consequence of a strong abiotic disturbance event, population may increase sufficiently to threaten even healthy trees. In addition to available trees for feeding and reproduction, temperature is the most important factor limiting the damage of the pest. Limiting potential of the pest’s enemies is potentially important but poorly known. There are several predator and parasite species limiting the success of I. typographus. These species are commonly known as natural enemies or natural enemy complex. Occurrences of these species are investigated in this study. Regardless of intensive studies about natural enemies, there are still remarkable gaps in knowledge. While natural enemies could theoretically be used to control pest populations, practical applications in forestry are in a very limited use. Mechanical methods, mainly sanitation and salvation loggings, are instead used to prevent outbreaks from escalating. These management practices prevent outbreak from spreading, although damage caused by loggings may also harm trees and expose these to pathogens. Possibility of using natural enemies as a part of pest control in forestry is considered in this study. Field study was conducted in SE Finland. I. typographus and natural enemy complex were sampled in 2018 by means of trapping logs settled with fixed number of I. typographus individuals. This was conducted in three different stand classes representing different gradation phases in forests to find differences between regulating potential of enemies. Stand classes were chosen based on the visible symptoms of bark beetle infestation and disturbance history. Classes were healthy (no attack), early outbreak (first symptoms and increased pest population) and declined outbreak (earlier outbreak, pest already declined near endemic level). Trapping logs with settled I. typographus were allocated to these classes, and insects emerging from trapping logs were later collected for sampling in sealed funnel traps. I. typographus population level was simultaneously monitored using pheromone traps. Differences between insect occurrences in different stand classes were statistically analysed by Kruskal-Wallis test with 0.05-level of significance for each identified enemy species and families. Spearman correlation was also used to detect any possible relations between different enemy species. Predators emerging from the logs were identified to six coleopteran families. Species were Thanasimus formicarius (Cleridae), Plegaderus vulneratus (Histeridae), Epuraea spp. (Nitidulidae), Rhizophagus spp. (Monotomidae) and from Staphylinidae Quedius plagiatus, Nudobius lentus, Phloeonomus spp., Leptusa spp. and Placusa spp. Family Elateridae was inspected as a single tested group. Predatory flies and parasitic wasps also emerged from the logs, although these were excluded from the current study. Three species had significant preference to certain outbreak classes. P. vulneratus proved most promising regulator in this study. It reproduced rapidly already during the first year of infestation. T. formicarius had significant preference for stand class, but failed to occur in sufficient numbers during the first year of infestation to have impact on the I. typographus population. Staphylids Phloeonomus spp. were very common at all stand classes but preferred healthy class. For both P. vulneratus and Phloeonomus spp. preferences for stand classes were significant, but the regulation effectiveness of these species is relatively unknown. Results suggested that limited resources in the healthy class, similar to managed forests forces both bark beetles and predators into same space, potentially increasing mortality. This result was observed by increased total numbers of beetles in the trapping logs of healthy class in comparison to outbreak classes, while simultaneously prey-predator ratio was also lower. This means that in addition to removing resources, sanitation loggings could also have increasing effect on enemy induced mortality. Small amount of deadwood potentially sustains higher endemic population of enemies, potentially increasing stands resistance to further insect induced disturbances. While some enemies were more common at the declined outbreak class, this claim was not supported by this study.
  • Ruuskanen, Miikka (Helsingfors universitet, 2017)
    The aim of this thesis was to study how the origin and treatment histories of spruce (Picea abies) and pine (Pinus radiata, Pinus sylvestris) bark influence on the extraction yield of tannin. The bark is produced in large quantities during the debarking process and is considered as waste in traditional forest industry. Bark is mainly used for energy production. In comparison to wood tissue, bark contains more extractives that could have potential for various applications in pharmaceutical industry or bio-based adhesives. Stilbenes, lignans, flavonoids and tannins are typical extractives in wood bark. In this Master’s thesis, the focus is on the extraction of tannins. Bark raw materials were obtained from pulp mills and sawmills. Bark samples were processed as air-dried (drying < 50 °C) or fresh as it is after debarking. Samples were extracted in rotating air bath reactors at 90 °C and 10 % consistency. Eight batches were hot water extracted and five different time points were studied: 40, 60, 80, 100 and 120 minutes. The extracts were analyzed with three UV-spectrophotometric methods: Folin-Ciocalteu assay, UV-280 nm method and Acid-Butanol assay. UV-280 nm method was used in tannin yield calculations. Tannin yield was the highest from air-dried spruce bark from sawmill (5.63 % from original dry bark). The second highest tannin yield (3.33 %) was from air-dried sawmill pine (Pinus radiata) bark extract. Fresh sawmill spruce and pine bark extraction gave 2.59 % and 2.65 % for tannin yield, respectively. The poorest yields came from the pulp mill bark samples. Yields from fresh and air-dried pulp mill spruce barks were 0.41 % and 0.97 %, respectively. In comparison, the tannin yields from fresh and air-dried pulp mill pine (Scots pine) bark were 1.13 % and 1.20 %. Results showed that the tannin yield increased when the extraction time increased. Statistical analysis confirmed that the origin and the treatment have a significant influence on the extraction yield of tannin. The reason for the differences in the extraction yields between barks with different origins are probably related to the different debarking methods. Sawmill bark samples gave a significantly higher tannin yield than samples from pulp mill. In sawmills, logs are debarked as dry in rotary debarker. Drum debarkers are typically being used in pulp and paper mills where water is used in debarking process. Contact with water may leach water-soluble tannins from bark. This is in accordance with the results that bark from sawmill was found to be an optimal raw material for hot water extraction. Further research should focus on optimizing hot water extraction conditions eg. by applications of chemicals.
  • Kaarakka, Lilli (Helsingfors universitet, 2013)
    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.