Tree vascular tissues connect resource availability to tree physiological processes and growth. The xylem transports water from the soil up to the canopy of even 100-metre tall trees, whereas phloem transport connects the photosynthesis in leaves and the tree metabolic processes, including growth and tree defences against insect and pathogen attacks. Water deficit results in the closing of leaf stomata and decreasing photosynthetic production, as water and carbon dioxide are exchanged through the stomata between the leaf and ambient air. Phloem transport is driven by turgor pressure gradients generated by the interplay of phloem osmotic concentration and xylem water potential. Trees have adapted to local environmental conditions and they adjust to fast environmental changes with physiological responses. This thesis investigates tree physiological responses in vascular tissues, such as osmolality, water potential and stomatal conductance, to environmental conditions in two conifers: Scots pine and Norway spruce. Seasonality in soil temperature and soil water content affect soil-to-leaf hydraulic conductance, and stomatal conductance is connected to these seasonal patterns in water transport. Soil environment is thus mediated to tree functionality through tree water transport. This thesis also supports Münch’s theory that it is plausible to explain phloem transport in conifers in field conditions with osmotic gradients and gravity. Xylem water potential reflects to osmotic potential and turgor pressure of the inner bark by modifying tissue solute and water content. The turgor gradients hence seem to determine daily and seasonal carbon allocation patterns according to water availability. Pathogenic infections may introduce more rapid changes in tree hydraulic conductance through a decrease in xylem sap surface tension and xylem conductivity during massive invasions of bark beetles that vector blue-stain fungi such as Endoconidiophora polonica. These pest attacks weaken tree vitality and may also increase tree vulnerability to hydraulic failure in the xylem.
{"title":"Tree water transport mediating the changing environmental conditions to tree physiological processes","authors":"Teemu Paljakka","doi":"10.14214/df.302","DOIUrl":"https://doi.org/10.14214/df.302","url":null,"abstract":"Tree vascular tissues connect resource availability to tree physiological processes and growth. The xylem transports water from the soil up to the canopy of even 100-metre tall trees, whereas phloem transport connects the photosynthesis in leaves and the tree metabolic processes, including growth and tree defences against insect and pathogen attacks. Water deficit results in the closing of leaf stomata and decreasing photosynthetic production, as water and carbon dioxide are exchanged through the stomata between the leaf and ambient air. Phloem transport is driven by turgor pressure gradients generated by the interplay of phloem osmotic concentration and xylem water potential. Trees have adapted to local environmental conditions and they adjust to fast environmental changes with physiological responses. This thesis investigates tree physiological responses in vascular tissues, such as osmolality, water potential and stomatal conductance, to environmental conditions in two conifers: Scots pine and Norway spruce. Seasonality in soil temperature and soil water content affect soil-to-leaf hydraulic conductance, and stomatal conductance is connected to these seasonal patterns in water transport. Soil environment is thus mediated to tree functionality through tree water transport. This thesis also supports Münch’s theory that it is plausible to explain phloem transport in conifers in field conditions with osmotic gradients and gravity. Xylem water potential reflects to osmotic potential and turgor pressure of the inner bark by modifying tissue solute and water content. The turgor gradients hence seem to determine daily and seasonal carbon allocation patterns according to water availability. Pathogenic infections may introduce more rapid changes in tree hydraulic conductance through a decrease in xylem sap surface tension and xylem conductivity during massive invasions of bark beetles that vector blue-stain fungi such as Endoconidiophora polonica. These pest attacks weaken tree vitality and may also increase tree vulnerability to hydraulic failure in the xylem.","PeriodicalId":375560,"journal":{"name":"Dissertationes Forestales","volume":"69 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126015395","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The importance of forests and soil in carbon (C) sequestration and storage is continually increasing with climate change. Disturbances, such as storms and insect outbreaks, are the drivers of forest functioning, composition and structure, and many of them are predicted to become more common in the future. However, environmental factors that predispose forests to disturbance as well as the diverse effects of disturbances on forest C cycling are not fully known. In this dissertation, stand, site and soil characteristics predisposing forest stands to outbreaks of two common insect species that can cause tree damage and mortality—the common pine sawfly (Diprion pini L.) and the European spruce bark beetle (Ips typographus L.)—were examined, and the impacts of storm and I. typographus disturbance on soil respiration, tree and soil C stocks, and microbial community composition and associated C contents were investigated in forests located in eastern and southern Finland. The level of tree damage by D. pini and I. typographus in managed Scots pine (Pinus sylvestris L.) and urban Norway spruce (Picea abies (L.) Karst.) forests, respectively, were associated with various site and soil characteristics. Defoliation of P. sylvestris by D. pini was more severe on sites with soil properties indicating greater fertility (e.g. lower soil C/N ratio and finer textured). Highest cumulative probabilities for severe I. typographus infestation of P. abies were associated with trees growing on sites having an east-facing aspect and the most fertile site types combined with either moderately steep slopes, shallow till soil or high soil C/N ratio. The effects of storm and I. typographus (5–7 years and circa 1–4 years after tree mortality, respectively) disturbance on forest C were studied in P. abies dominated forests that had been left unmanaged after disturbance. Soil surface total and heterotrophic CO2 effluxes, and topsoil C stocks of storm and I. typographus disturbed and undisturbed sites differed little, despite the shift in tree C stocks from living to dead after both disturbances and greater litter detritus C stocks on the I. typographus disturbed sites. Soil surface autotrophic CO2 effluxes were mostly lower at the disturbed sites than at undisturbed ones. The most distinct differences in the humus layer microbiology were the lower abundances of tree-symbiotic ectomycorrhizal fungi, and consequently slightly lower microbial and fungal biomasses in the storm and I. typographus disturbed sites in comparison to the undisturbed sites. The remaining living trees on or in close proximity to the disturbed sites probably mitigated the belowground response to disturbance to some extent. This dissertation shows that certain site and soil characteristics predispose trees and forest stands to D. pini and I. typographus infestations, which could help in identifying sites that are susceptible to insect disturbance. Furthermore, it provides new information about the short-ter
{"title":"Insect and storm disturbance in boreal forests — predisposing site factors and impacts on ecosystem carbon","authors":"M. Kosunen","doi":"10.14214/df.300","DOIUrl":"https://doi.org/10.14214/df.300","url":null,"abstract":"The importance of forests and soil in carbon (C) sequestration and storage is continually increasing with climate change. Disturbances, such as storms and insect outbreaks, are the drivers of forest functioning, composition and structure, and many of them are predicted to become more common in the future. However, environmental factors that predispose forests to disturbance as well as the diverse effects of disturbances on forest C cycling are not fully known. In this dissertation, stand, site and soil characteristics predisposing forest stands to outbreaks of two common insect species that can cause tree damage and mortality—the common pine sawfly (Diprion pini L.) and the European spruce bark beetle (Ips typographus L.)—were examined, and the impacts of storm and I. typographus disturbance on soil respiration, tree and soil C stocks, and microbial community composition and associated C contents were investigated in forests located in eastern and southern Finland. The level of tree damage by D. pini and I. typographus in managed Scots pine (Pinus sylvestris L.) and urban Norway spruce (Picea abies (L.) Karst.) forests, respectively, were associated with various site and soil characteristics. Defoliation of P. sylvestris by D. pini was more severe on sites with soil properties indicating greater fertility (e.g. lower soil C/N ratio and finer textured). Highest cumulative probabilities for severe I. typographus infestation of P. abies were associated with trees growing on sites having an east-facing aspect and the most fertile site types combined with either moderately steep slopes, shallow till soil or high soil C/N ratio. The effects of storm and I. typographus (5–7 years and circa 1–4 years after tree mortality, respectively) disturbance on forest C were studied in P. abies dominated forests that had been left unmanaged after disturbance. Soil surface total and heterotrophic CO2 effluxes, and topsoil C stocks of storm and I. typographus disturbed and undisturbed sites differed little, despite the shift in tree C stocks from living to dead after both disturbances and greater litter detritus C stocks on the I. typographus disturbed sites. Soil surface autotrophic CO2 effluxes were mostly lower at the disturbed sites than at undisturbed ones. The most distinct differences in the humus layer microbiology were the lower abundances of tree-symbiotic ectomycorrhizal fungi, and consequently slightly lower microbial and fungal biomasses in the storm and I. typographus disturbed sites in comparison to the undisturbed sites. The remaining living trees on or in close proximity to the disturbed sites probably mitigated the belowground response to disturbance to some extent. This dissertation shows that certain site and soil characteristics predispose trees and forest stands to D. pini and I. typographus infestations, which could help in identifying sites that are susceptible to insect disturbance. Furthermore, it provides new information about the short-ter","PeriodicalId":375560,"journal":{"name":"Dissertationes Forestales","volume":"75 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-08-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122356921","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This dissertation develops a framework to examine socially optimal forest management when nutrient and sediment loads from forestry are considered as a negative externality. The Faustmann rotation model is extended to include the runoff function to describe the water quality impacts of nutrient and sediment loads from forestry. This thesis consists of an introductory section and four articles that analyze the different forest management practices and associated water protection. Examined practices include final harvesting in both mineral soils and peatlands, stem-only harvesting and whole-tree harvesting in peatlands, and ditch network maintenance. The water protection measures included are buffer zones in mineral soil forestry and overland flow fields and sedimentation ponds in drained peatlands. The main contribution of this thesis is the developed framework for analyzing socially optimal forest management when water quality is taken into account. The analysis shows that the nutrient and sediment load damages associated with forest management depends highly on management practices. The nitrogen load caused by final harvesting in mineral soils results in relatively low nitrogen load damages. In contrast, the sediment load damages due to ditch network maintenance in the sensitive headwater catchment are very high. Furthermore, the cost-effectiveness of water protection measures differs significantly. From society ́s viewpoint, the buffer zones used in mineral soil forest management are not a costeffective water protection measure but when biodiversity benefits are taken into account, in addition to water quality, they become socially desirable. Overland flow fields are very costeffective water protection measures for peatland forestry. Finally, the water protection costs in forestry and agriculture are compared in a river basin model. A cost-effective solution requires the highest nutrient reductions in agriculture, though it also implements water protection measures, especially in drained peatland forestry.
{"title":"Essays on optimal forest management and water protection","authors":"J. Miettinen","doi":"10.14214/df.296","DOIUrl":"https://doi.org/10.14214/df.296","url":null,"abstract":"This dissertation develops a framework to examine socially optimal forest management when nutrient and sediment loads from forestry are considered as a negative externality. The Faustmann rotation model is extended to include the runoff function to describe the water quality impacts of nutrient and sediment loads from forestry. This thesis consists of an introductory section and four articles that analyze the different forest management practices and associated water protection. Examined practices include final harvesting in both mineral soils and peatlands, stem-only harvesting and whole-tree harvesting in peatlands, and ditch network maintenance. The water protection measures included are buffer zones in mineral soil forestry and overland flow fields and sedimentation ponds in drained peatlands. The main contribution of this thesis is the developed framework for analyzing socially optimal forest management when water quality is taken into account. The analysis shows that the nutrient and sediment load damages associated with forest management depends highly on management practices. The nitrogen load caused by final harvesting in mineral soils results in relatively low nitrogen load damages. In contrast, the sediment load damages due to ditch network maintenance in the sensitive headwater catchment are very high. Furthermore, the cost-effectiveness of water protection measures differs significantly. From society ́s viewpoint, the buffer zones used in mineral soil forest management are not a costeffective water protection measure but when biodiversity benefits are taken into account, in addition to water quality, they become socially desirable. Overland flow fields are very costeffective water protection measures for peatland forestry. Finally, the water protection costs in forestry and agriculture are compared in a river basin model. A cost-effective solution requires the highest nutrient reductions in agriculture, though it also implements water protection measures, especially in drained peatland forestry.","PeriodicalId":375560,"journal":{"name":"Dissertationes Forestales","volume":"34 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132565418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This dissertation examines forest owners’ views of forest-related decision support services and knowledge use in them in private forests in Finland. Decision support services provide information through forest management planning and advice. The decision-making about and implementation of forest management take place in a multi-actor network that produces, distributes, and utilises knowledge in technical and social knowledge systems. The thesis is based on two surveys, extensive focus group data and field notes from workshops. It adopts a mixed methods approach. The results show that forest owners with timber production objectives considered the current decision support services most useful. Those who emphasised nature values or had multiple objectives were less satisfied. Forest management preferences are more versatile than what they appear based on overall ownership objectives. The majority of owners are interested in diversifying their forest management to increase other forest functions alongside timber production. Two knowledge systems, technical and social, influence knowledge use in forest management. Several points of discontinuity were identified in knowledge flows within and between forest-related actors and organisations. The codified, technical knowledge system dominates knowledge production and use. The importance of the social knowledge system has not been fully recognised. Independence from time and place, gratuitousness and ease-of-use make forest-related e-service more inviting. Lack of forest inventory data or its perceived low quality and discordance with forest owner objectives deter owners from using e-service. Forest owners expect decision support services to acknowledge their diverse and multiple forest use objectives. Information services on the management of nature values and integration of various objectives are needed. Knowledge flows are weakened by the domination of codified, forest resource-related knowledge, social structures and practices that inhibit the diffusion of knowledge within an organisation, and emphasis on the economic targets. Organisations on the forest sector are in key positions for changing the prevailing decision support practices, but so far the development of new practices has been slow.
{"title":"Knowledge use in the management of privately owned forests: a focus on decision support services for multi-objective forest use","authors":"Sari Pynnönen","doi":"10.14214/df.289","DOIUrl":"https://doi.org/10.14214/df.289","url":null,"abstract":"This dissertation examines forest owners’ views of forest-related decision support services and knowledge use in them in private forests in Finland. Decision support services provide information through forest management planning and advice. The decision-making about and implementation of forest management take place in a multi-actor network that produces, distributes, and utilises knowledge in technical and social knowledge systems. The thesis is based on two surveys, extensive focus group data and field notes from workshops. It adopts a mixed methods approach. The results show that forest owners with timber production objectives considered the current decision support services most useful. Those who emphasised nature values or had multiple objectives were less satisfied. Forest management preferences are more versatile than what they appear based on overall ownership objectives. The majority of owners are interested in diversifying their forest management to increase other forest functions alongside timber production. Two knowledge systems, technical and social, influence knowledge use in forest management. Several points of discontinuity were identified in knowledge flows within and between forest-related actors and organisations. The codified, technical knowledge system dominates knowledge production and use. The importance of the social knowledge system has not been fully recognised. Independence from time and place, gratuitousness and ease-of-use make forest-related e-service more inviting. Lack of forest inventory data or its perceived low quality and discordance with forest owner objectives deter owners from using e-service. Forest owners expect decision support services to acknowledge their diverse and multiple forest use objectives. Information services on the management of nature values and integration of various objectives are needed. Knowledge flows are weakened by the domination of codified, forest resource-related knowledge, social structures and practices that inhibit the diffusion of knowledge within an organisation, and emphasis on the economic targets. Organisations on the forest sector are in key positions for changing the prevailing decision support practices, but so far the development of new practices has been slow.","PeriodicalId":375560,"journal":{"name":"Dissertationes Forestales","volume":"80 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125140986","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Analyzing spatial variation and change in the structure of boreal old-growth forests","authors":"Niko Kulha","doi":"10.14214/df.286","DOIUrl":"https://doi.org/10.14214/df.286","url":null,"abstract":"","PeriodicalId":375560,"journal":{"name":"Dissertationes Forestales","volume":"311 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121011403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Scots pine resin and BVOC emissions in relation to tree water dynamics","authors":"K. Rissanen","doi":"10.14214/df.283","DOIUrl":"https://doi.org/10.14214/df.283","url":null,"abstract":"","PeriodicalId":375560,"journal":{"name":"Dissertationes Forestales","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130492153","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Non-industrial private forest (NIPF) owners are important forest ecosystem service providers and users. Along with the structural and general lifestyle changes of owners, their forest ownership objectives have become more diverse, strongly emphasizing intangible forest values alongside timber production. Therefore, NIPF owners and their versatile forest ownership objectives are a potential source of information for exploring the untapped future potential that could help the forest sector to retain its future viability on the road towards a bioeconomy. This doctoral thesis aims to understand the drivers of demand for new forestry services and forest-based business opportunities from the perspective of NIPF owner objectives and forest meanings. Objectives and forest meanings are examined from methodological, sociodemographic and NIPF owner sustainable lifestyle perspectives, leading to more general examination of NIPF owner perceptions of future utilization prospects of forests and the forest sector. Thus, the objective of the thesis is to build a more in-depth understanding of NIPF owner objectives and to examine how this information could be used in the development and marketing of forestry services and other forest-related products and services. The findings present a way to systematically analyse the objectives of forest ownership and also illustrate how certain segments of forest owners value aesthetics and biodiversity conservation over a traditional monetary value orientation. The results also indicate that the owners with the highest sustainable consumption orientation place a greater emphasis on multiple benefits of forests than owners who have a lower such orientation. The findings show that the future value creation of forests will be based on multiple aspects, and the widening of perspective beyond raw material dominance in the utilization of forests is important. Thus, recognizing customer pressure towards more diversified forestry services would be essential in meeting the versatile needs of forest owners but also from the perspective of developing new forest-based businesses.
{"title":"Finnish forest owner objectives as indicators for a diversifying use of forests on the road to a bioeconomy","authors":"L. Häyrinen","doi":"10.14214/DF.280","DOIUrl":"https://doi.org/10.14214/DF.280","url":null,"abstract":"Non-industrial private forest (NIPF) owners are important forest ecosystem service providers and users. Along with the structural and general lifestyle changes of owners, their forest ownership objectives have become more diverse, strongly emphasizing intangible forest values alongside timber production. Therefore, NIPF owners and their versatile forest ownership objectives are a potential source of information for exploring the untapped future potential that could help the forest sector to retain its future viability on the road towards a bioeconomy. This doctoral thesis aims to understand the drivers of demand for new forestry services and forest-based business opportunities from the perspective of NIPF owner objectives and forest meanings. Objectives and forest meanings are examined from methodological, sociodemographic and NIPF owner sustainable lifestyle perspectives, leading to more general examination of NIPF owner perceptions of future utilization prospects of forests and the forest sector. Thus, the objective of the thesis is to build a more in-depth understanding of NIPF owner objectives and to examine how this information could be used in the development and marketing of forestry services and other forest-related products and services. The findings present a way to systematically analyse the objectives of forest ownership and also illustrate how certain segments of forest owners value aesthetics and biodiversity conservation over a traditional monetary value orientation. The results also indicate that the owners with the highest sustainable consumption orientation place a greater emphasis on multiple benefits of forests than owners who have a lower such orientation. The findings show that the future value creation of forests will be based on multiple aspects, and the widening of perspective beyond raw material dominance in the utilization of forests is important. Thus, recognizing customer pressure towards more diversified forestry services would be essential in meeting the versatile needs of forest owners but also from the perspective of developing new forest-based businesses.","PeriodicalId":375560,"journal":{"name":"Dissertationes Forestales","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124656567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Climate change is amplifying forest disturbances, especially those by insect pests. In addition to native species, biological invasions by alien insects are threatening forest health, ecosystem sustainability, and economic return. Uncertainties related to insect pest infestations are increasing along the risk of high impacts. There is a high demand of accurate, efficient, and cost-effective methods for forest health monitoring to prevent, control, and mitigate the various negative impacts, as well as to support decision-making. Current needs for information for efficient forest management are complex and extensive. The required quality cannot be met with traditional forest inventory methods. Forest information should be up-to date and available across a range of spatial and temporal scales. Rapid development of methods for general forest inventory also support development of forest health monitoring and management. The continuously developing field of remote sensing and geographical information systems provide new means for various forest monitoring tasks. However, disturbance monitoring, especially by insect pests, gives an extra challenge and increased uncertainties compared to other forest monitoring tasks. With new approaches, however, valuable information on disturbances can be derived for evaluation of insect-induced forest disturbance at reasonable high accuracy and reduced amount of needed fieldwork. This dissertation aims towards improved forest health monitoring, particularly disturbances by defoliating insect pests. Insect-induced disturbances from single tree level to larger areas in Fennoscandia and eastern USA were evaluated in five sub-studies. The sixth and final sub-study comprises continental scale species distribution models in North America and East Asia. In these sub-studies, different remote sensing sensors and approaches, and ecological niche modeling for species potential distributions were employed in disturbance evaluation. Study species include native insect pests and an invasive alien species. In context of recent research and the included sub-studies, issues specific to insect disturbance monitoring are discussed. Pattern, frequency, scale, and intensity of insect infestations vary depending on the insect pest and forested landscapes in question affecting disturbance detection and impact evaluation. Sensors, platform, and/or modeling methods have to be chosen accordingly. Environmental features, such as topography, and level of landscape fragmentation give restrictions to the method selection, as well as to the appropriate spatial resolution. Importance of varying information is also affected by the scale and resolution of investigation. Timing of data acquisition is crucial. Early detection and timely management operations are often the only way to control or mitigate insect outbreaks. Moreover, amount and accuracy of auxiliary information, including forest inventory data, and disturbance history, differ between coun
{"title":"Forest health monitoring in transition: Evaluating insect-induced disturbances in forested landscapes at varying spatial scales","authors":"T. Kantola","doi":"10.14214/DF.278","DOIUrl":"https://doi.org/10.14214/DF.278","url":null,"abstract":"Climate change is amplifying forest disturbances, especially those by insect pests. In addition to native species, biological invasions by alien insects are threatening forest health, ecosystem sustainability, and economic return. Uncertainties related to insect pest infestations are increasing along the risk of high impacts. There is a high demand of accurate, efficient, and cost-effective methods for forest health monitoring to prevent, control, and mitigate the various negative impacts, as well as to support decision-making. Current needs for information for efficient forest management are complex and extensive. The required quality cannot be met with traditional forest inventory methods. Forest information should be up-to date and available across a range of spatial and temporal scales. Rapid development of methods for general forest inventory also support development of forest health monitoring and management. The continuously developing field of remote sensing and geographical information systems provide new means for various forest monitoring tasks. However, disturbance monitoring, especially by insect pests, gives an extra challenge and increased uncertainties compared to other forest monitoring tasks. With new approaches, however, valuable information on disturbances can be derived for evaluation of insect-induced forest disturbance at reasonable high accuracy and reduced amount of needed fieldwork. This dissertation aims towards improved forest health monitoring, particularly disturbances by defoliating insect pests. Insect-induced disturbances from single tree level to larger areas in Fennoscandia and eastern USA were evaluated in five sub-studies. The sixth and final sub-study comprises continental scale species distribution models in North America and East Asia. In these sub-studies, different remote sensing sensors and approaches, and ecological niche modeling for species potential distributions were employed in disturbance evaluation. Study species include native insect pests and an invasive alien species. In context of recent research and the included sub-studies, issues specific to insect disturbance monitoring are discussed. Pattern, frequency, scale, and intensity of insect infestations vary depending on the insect pest and forested landscapes in question affecting disturbance detection and impact evaluation. Sensors, platform, and/or modeling methods have to be chosen accordingly. Environmental features, such as topography, and level of landscape fragmentation give restrictions to the method selection, as well as to the appropriate spatial resolution. Importance of varying information is also affected by the scale and resolution of investigation. Timing of data acquisition is crucial. Early detection and timely management operations are often the only way to control or mitigate insect outbreaks. Moreover, amount and accuracy of auxiliary information, including forest inventory data, and disturbance history, differ between coun","PeriodicalId":375560,"journal":{"name":"Dissertationes Forestales","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123691738","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The World’s forests are facing novel stress due to climate change. Pest insects and pathogens are shifting towards new latitudes and heat stress is resulting in increased tree mortality and more frequent forest fires globally. Uncertainty in estimating the magnitude of climate change induced forest and tree decline requires new methods for unbiased estimation of tree decline. The development of remote sensing methods to detect early tree decline has been a major challenge due to the subtle nature of the early changes caused by different stressors. Multispectral lidar technology has the potential of detecting early tree decline by providing accurate three-dimensional and spectral information of tree structure simultaneously. The main objective of this thesis was to investigate the capabilities of multispectral terrestrial lidar in the detection and assessment of tree decline caused by different stressors. This was done by investigating the estimation of a remotely detectable indicator of tree decline, leaf water content (LWC). Specifically, new methods for measuring LWC using multispectral lidar intensity were developed from the leaf to the canopy scale in various environments and the relationship between LWC and tree decline induced by various stressors was investigated. Furthermore, the developed methods were tested in a forest environment to assess the applicability of multispectral lidar in the detection of bark beetle infestation in the field. Studies I-III focused on investigating the relationship between LWC and lidar intensity at multiple wavelengths. First, a hyperspectral lidar instrument was used to detect significant changes between fresh and drought-treated Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L.) trees (study I). Then, a leaf-scale study (II) with Scots pine, Norway spruce, Small-leaved lime (Tilia cordata L.), Norway maple (Acer platanoides L.) and Silver birch (Betula pendula L.) was conducted and a strong relationship (R2=0.93) between a normalized difference index (NDI) calculated from 1550 nm and 690 nm wavelengths and LWC was found. This was followed by a study (III) where LWC estimation and pathogenand drought-induced variation in LWC was studied with Norway spruce seedlings. Bluestain fungi (Endoconidiophora polonica) inoculated seedlings expressed a rapid decrease in LWC while drought-treated seedlings showed more stable LWC until a very severe drought. LWC of the seedlings was predicted with an R2 of 0.89 using an NDI with 1550 nm and 905 nm wavelengths. In study IV, the developed method and the relationship between LWC and tree decline was investigated in the field with European spruce bark beetle (Ips typographus L.) infested trees. It was found that of the LWC metrics studied, gravimetric water content showed significant differences in the early stages of infestation and was more sensitive to bark beetle induced tree decline than equivalent water thickness (i.e. amount of water per leaf area).
{"title":"Utilizing multispectral lidar in the detection of declined trees","authors":"S. Junttila","doi":"10.14214/DF.277","DOIUrl":"https://doi.org/10.14214/DF.277","url":null,"abstract":"The World’s forests are facing novel stress due to climate change. Pest insects and pathogens are shifting towards new latitudes and heat stress is resulting in increased tree mortality and more frequent forest fires globally. Uncertainty in estimating the magnitude of climate change induced forest and tree decline requires new methods for unbiased estimation of tree decline. The development of remote sensing methods to detect early tree decline has been a major challenge due to the subtle nature of the early changes caused by different stressors. Multispectral lidar technology has the potential of detecting early tree decline by providing accurate three-dimensional and spectral information of tree structure simultaneously. The main objective of this thesis was to investigate the capabilities of multispectral terrestrial lidar in the detection and assessment of tree decline caused by different stressors. This was done by investigating the estimation of a remotely detectable indicator of tree decline, leaf water content (LWC). Specifically, new methods for measuring LWC using multispectral lidar intensity were developed from the leaf to the canopy scale in various environments and the relationship between LWC and tree decline induced by various stressors was investigated. Furthermore, the developed methods were tested in a forest environment to assess the applicability of multispectral lidar in the detection of bark beetle infestation in the field. Studies I-III focused on investigating the relationship between LWC and lidar intensity at multiple wavelengths. First, a hyperspectral lidar instrument was used to detect significant changes between fresh and drought-treated Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L.) trees (study I). Then, a leaf-scale study (II) with Scots pine, Norway spruce, Small-leaved lime (Tilia cordata L.), Norway maple (Acer platanoides L.) and Silver birch (Betula pendula L.) was conducted and a strong relationship (R2=0.93) between a normalized difference index (NDI) calculated from 1550 nm and 690 nm wavelengths and LWC was found. This was followed by a study (III) where LWC estimation and pathogenand drought-induced variation in LWC was studied with Norway spruce seedlings. Bluestain fungi (Endoconidiophora polonica) inoculated seedlings expressed a rapid decrease in LWC while drought-treated seedlings showed more stable LWC until a very severe drought. LWC of the seedlings was predicted with an R2 of 0.89 using an NDI with 1550 nm and 905 nm wavelengths. In study IV, the developed method and the relationship between LWC and tree decline was investigated in the field with European spruce bark beetle (Ips typographus L.) infested trees. It was found that of the LWC metrics studied, gravimetric water content showed significant differences in the early stages of infestation and was more sensitive to bark beetle induced tree decline than equivalent water thickness (i.e. amount of water per leaf area). ","PeriodicalId":375560,"journal":{"name":"Dissertationes Forestales","volume":"15 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122469478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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