Ahto Kangur

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• PhD in Forestry
• Professor (Full) at Estonian University of Life Sciences

In this study, we used a comprehensive tree-ring network from Estonia and investigated Scots pine (Pinus sylvestris L.) radial growth responses to changing climate conditions, considering differences in site conditions and local climates. To assess whether climate influences Scots pine radial growth consistently across the country, we developed thi...

Key message An exceptionally high number of blue rings were formed within and between Scots pine trees from Estonia in 1976: a year that is well known for its outstanding summer heatwave over Western Europe, but its extreme autumnal cooling over Eastern Europe has so far been neglected in scientific literature. Abstract ‘Blue rings’ (BRs) are visu...

In the eastern Baltic region, the abundance of Scots pine (Pinus sylvestris L.) has been predicted to shift due to changes in height growth and competitiveness. Under such conditions, the relationships between tree growth and meteorological/climatic conditions can provide valuable information on the ecological plasticity and adaptability of local p...

The breeding of forest tree species in the Baltic region has notably contributed to wood production for the bioeconomy. Growth modelling is used for long-term estimates of forest development. However, usually based on data from unimproved stands, they may underestimate the growth of improved trees. Accordingly, it is important to identify and integ...

Western Taiga habitat (*9010) plays the key role in the Natura 2000 network in Estonia. Natura 2000 is a European Union nature conservation area network aimed to safeguard the long-term survival of Europe’s unique flora and fauna. This study examines the Western Taiga habitat within mixed oligo-mesotrophic and mesotrophic forests on mineral soils w...

The use of a novel chrono-potentiometry method (abbreviated as “CP”) in the determination of the moisture content in wood (abbreviated as “MC”) above the FSP is a practical application of the electrical charging effect (or ECE). In the specific case of this CP method, the ECE consists of an electrical charging phase for the wood and a discharge pha...

In this study, assortment yields were studied for Scots pine, Norway spruce, birch spp. (silver and downy birch), European aspen, black alder, and grey alder stand elements. Theoretical assortment yields were calculated using the Ozolinš’ stem taper curve, incorporating tree diameters and heights. The modelled results were compared with actual yiel...

Understanding how forest ecosystems respond to environmental factors, particu- larly in the context of global climate change, is essential for devising effective mitigation strat- egies. This study focuses on quantifying the interaction between forest ecosystems and atmo- spheric gases. To achieve our objectives, we are using the eddy covariance (E...

The stand level gross volume increment models are used to estimate the future production of tree stands. Very often, the stand growth and yield in the models used in practice are described by the tree volume increment that includes the diameter growth function with the tree height together with stem taper as the input variables. The currently used...

We present the change in the thermal growing season based on a unique long-term cli- matological data set obtained at the Järvselja Training and Experimental Forestry Centre in southeast Estonia. The data cover the years 1955–2020 and we employed the growing degree-days (GDD) algorithm on them. We defined the days when temperature is persis- tently...

Wood moisture content (MC) has a significant impact on all electrical properties of wood. Regarding the development of the (so-called polarization-type) wood moisture meter with the electrical charging effect for monitoring and controlling the wood drying process, it is of interest to expand the theoretical background of this type of novel wood moi...

The breeding of economically important forest tree species in the Baltic Sea region has contributed notably to the availability of quality wood for bioeconomy. Accordingly, the altered stand dynamics of improved trees should be identified and incorporated in growth models to accurately reflect these gains. Such advanced models can be used for asses...

Estimations of forests’ carbon sequestration capacity relies on proper assessment of the eddy covariance measurement mast’s footprint. Harsh winter temperatures in Estonia lead to ice formation on 3D sonic anemometer sensor heads and thus induce measurement gaps in the data. To maximise data availability, we use a smart heating algorithm to mini- m...

The breeding of Norway spruce in northern Europe has substantially contributed to the production of high-quality wood. The vegetative propagation of robust elite clones could help to sustain the provision of high-quality timber in the face of changing climates. For the adequate evaluation of genetic gains, the altered tree growth dynamics of the cl...

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknow...

One of the most fundamental questions in ecology is how many species inhabit the Earth. However, due to massive logistical and financial challenges and taxonomic difficulties connected to the species concept definition, the global numbers of species, including those of important and well-studied life forms such as trees, still remain largely unknow...

Significance Tree diversity is fundamental for forest ecosystem stability and services. However, because of limited available data, estimates of tree diversity at large geographic domains still rely heavily on published lists of species descriptions that are geographically uneven in coverage. These limitations have precluded efforts to generate a g...

The study area is in the Järvselja Training and Experimental Forest Centre, Estonia. The conservation of Järvselja old-growth forest started in 1924 when the area was excluded from all management activities and left to natural development. The aim of this study is to analyse the methods for calculating single tree height, tree stem lateral surface...

The study material of Scots pine sample trees originated from five different forest site types ( Cladonia, Calluna, Myrtillus, natural raised bog and drained raised bog) in Estonia. Altogether, 60 trees were sampled from 10 stands. From these, test disks and sample blocks (1.2 m in length) were cut at 1.3 m height, 1/2 of tree height and 3/4 of tre...

Artikkel veebis - https://loodus.ohtuleht.ee/1030148/riikliku-avaliku-uuringu-salajasuse-vajalikkuse-paradoks-ehk-miks-on-meil-vaja-just-sellist-statistilist-metsainventuuri

Comprehensive description and quantification of stand structure is needed for managing or maintaining forests as complex systems. The tree position and diameter based structural complexity index SCI was used to quantify the structural heterogeneity of forest stands in Estonia. The aims of the study were to determine if SCI is related to the convent...

In light of the difficulties in stand volume estimation of natural forests, we analyzed height–diameter relationships and derived a set of height estimation equations for volume estimation for naturally developing forest ecosystems, using the Järvselja old-growth and the Laeva commercial forest in Estonia as a case study. This contribution presents...

Three cases of violation of forest management regulations in Estonia in 2004, 2005 and 2007 are presented in the study where the required lower limit of basal area after thinnings was not followed. These stands were revisited in 2017 to assess the impacts of such thinnings. The actual thinnings were well justified from the silvicultural and economi...

Growth of CO2 concentration level has strong interactions with forests. Forests are able to sequester carbon (C) through photosynthesis and can help to mitigate the effects of climate warming, as well as to reduce the CO2 concentration in the atmosphere. Drought and other extreme weather conditions play a key role in ecosystem functioning and the C...

Forest ecosystems are shaped by disturbances and functional features of vegetation recovery after disturbances. There is considerable variation in basic disturbance characteristics, magnitude, severity, and intensity. Disturbance legacies provide possible explanations for ecosystem resilience. The impact (length and strength) of the pool of ecosyst...

The data paper refers to the research article “Assessment of spatial stand structure of hemiboreal conifer dominated forests according to different levels of naturalness” [1]. Forest ecosystem structure was quantified by using structural indices based on the nearest-neighbourhood approach for individual trees. Species mingling, deadwood mingling, d...

Ecosystem legacies, reflecting the management history traits, are visible in structural indicators of a forest stand. We assessed patterns of spatial forest structure by using individual tree indices based on the nearest-neighbourhood approach. Five different indices were quantified – species mingling, deadwood mingling, deadwood distribution, diam...

The properties of biomass-based fuel and combustion tests showed that logging residues are promising renewable energy sources. The data used in this study were collected from four clear-felling areas in Järvselja Training and Experimental Forest Centre, Southeast Estonia in 2013–2014. Logging was carried out by harvesters in Scots pine ( Pinus sylv...

2019. A narrative of virtual and augmented reality in the forest sector.-Forestry Studies | Metsanduslikud Uurimused 70, 88-96, ISSN 1406-9954. Journal homepage: http://mi.emu.ee/forestry.studies Abstract. With the rapid development in data acquisition and presentation, there is a growing interest in virtual forests and computer visualization tools...

Aim of study: Modelling of forest growth and dynamics has focused mainly on pure stands. Mixed-forest management lacks systematic procedures to forecast the impact of silvicultural actions. The main objective of the present work is to review current knowledge and forest model developments that can be applied to mixed forests. Material and methods:...

Diverse structural elements play an important role in sustaining biodiversity in old-growth forests. Therefore, it is important to have thorough knowledge about these habitats and their condition in protected areas. Metsakorralduse Büroo OÜ conducted a large-scale Natura 2000 forest habitat inventory that covered 60% of Lahemaa National Park (LNP)...

Currently, about 70% of the forest land in Europe is covered by stands composed of two or more tree species. The similar situation can be found outside Europe too. While forest management of monocultures is well described, multispecies forests still need a better understanding to develop appropriate forest practice. Managing mixed forests can be mo...

In the Baltic States region, anthropogenic disturbances at different temporal and spatial scales mostly determine dynamics and development phases of forest ecosystems. We reviewed the state and condition of hemiboreal forests of the Baltic States region and analyzed species composition of recently established and permanent forest (PF). Agricultural...

A new paradigm in forest management using a streaming input of public participation needs effective online solutions. The process should be real-time, secure, effective and effi cient. People are expected to share their data and thoughts on forest management with forest owners for improving forest management and planning. The participatory approach...

The condition of forest ecosystems depends on the temporal and spatial pattern of management interventions and natural disturbances. Remnants of previous conditions persisting after disturbances, or ecosystem legacies, collectively comprise ecosystem memory. Ecosystem memory in turn contributes to resilience and possibilities of ecosystem reorganiz...

The poster shows the activities to measure air ions, aerosols and their precursor gases at the SMEAR Estonia station.

Key message The allometric relationship of Scots pine height versus diameter is not constant and does not follow elastic similarity and geometric scaling rules in Eastern Europe. Abstract Scots pine is one of the most widely distributed tree species in Europe. It occurs in the boreal forest but also occupies vast areas on dry sites of the Mediterra...

The Natura 2000 network contains many different habitats in Estonia, including old-growth forests and semi-natural woodlands. Ten years after the establishment of the Natura 2000 network in Estonia, changes have occurred in habitat type and habitat quality. Vegetation composition as well as the structural and functional qualities of a forest habita...

Establishment of the SMEAR Estonia at a hemiboreal mixed deciduous broad-leaved-evergreen needle-leaved forest at Järvselja, SouthEastern Estonia, has strongly enhanced the possibilities for national and international cooperation in the fi elds of forest ecosystem – atmosphere research and impacts of climatic changes on forest ecosystems, atmospher...

Growth assessment of young stands gives the possibility of assessing forest site potential, tree species-dependent competition and developing realistic predictions for the following periods. The study is conducted in naturally regenerated broadleaves dominated stands in 2005 at Järvselja Training and Experimental Forest Center. The current study ma...

Forest research has long traditions in Estonia that can be traced back to the 19th century. Data from long-term forest experiments are available since 1921. The first studies mainly focused on silvicultural treatments and application of such data for understanding and modeling ecological processes was limited. The Department of Forest Management of...

Changes in the society have created a need for a systematic approach in forestry combining forest management, timber harvest analysis, research and de-monstration of new technologies. A research and demonstration area is an option for explaining and visualising frameworks of forest design, modelling and planning in the real nature. A research and d...

Presenting the usage of long term flux and forest measurements to assess biomass production sustainablility.

Post-mining restoration sites often develop novel ecosystems as soil conditions are completely new and ecosystem assemblage can be spontaneous even on afforested sites. This study presents results from long-term monitoring and evaluation of an afforested oil-shale quarry in Estonia. The study is based on chronosequence data of soil and vegetation a...

We analysed tree stem size distributions in tree mapping data from a naturally developing forest ecosystem - a primeval forest in Järvselja, Estonia (19.7 hectares). The primeval forest have been in natural successional development more than 90 years, before that very mild management activities have been carried out (occasional removal of dead tree...

Forest research has long tradition in Estonia that can be followed back to 19th century. Data from long-term forest experiments is available since 1921. These studies were focused mainly on silvicultural treatments and the data has limited application for understanding and modelling ecological processes. Department of Forest Management of the Eston...

Uurime Järvselja tähelepanuväärsete puude näitel, milliseid võimalusi pakub tänane mõõteseadmete areng ja uute mõõt-mismetoodikate rakendamine puu kõrguse mõõtmise kiire-maks ja täpsemaks tegemiseks. Kasvava puu kõrguse mõõtmisel on kasutusel olevatest definitsioonidest võimalik välja tuua kolm erinevat sõnastust: 1) arvestuslik vertikaalne kaugu...

Opencast mining creates disturbance to the ecosystem at all ecological scales: species, ecosystem and landscape level. The novel conditions are overwhelming starting from newly established bedrock and habitat distribution for vegetation dynamics. Usually on post-mining restoration sites develop novel ecosystems as soil conditions are completely new...

Height distribution patterns of young, especially naturally regenerated mixed broadleaves stands, have not been extensively studied in Estonia. Still, the percentage of stands left for natural regeneration is increasing and today, 70% of clear-cut stands left for natural afforestation are regenerating by 76% with broadleaved species. Growth assessm...

Forest Ecosystem models are diagnostic tools to assess and understand ecosystem processes. Conflicting interests such as simplicity, observability and biological realism must be addressed to ensure a well balanced modelling approach. Because field observations are usually only available for short time periods or for a limited number of locations, m...

Metabolism of trees, ground vegetation and microbes generate carbon and nitrogen fluxes in forest ecosystems. Carbon flows through the system, and nitrogen circulates between vegetation and soil. Trees synthesise sugars in photosynthesis and take nitrogen from soil. The biochemical regulation system allocates the annual amounts of synthesised sugar...

The legacy of structural homogenization due to forest management for commercial products is a loss of biodiversity. A common policy in many European countries is to increase forest diversity by converting managed forests to more natural conditions. The aim of this study was to provide an early evaluation of the effectiveness of different restoratio...

Background/Question/Methods Changes in regional or global biological diversity or spatial distribution reflect the reactions of organisms in these ecological systems to modified environment conditions. Changes in the behavior of any single species, taxon or geographic region have a number of possible explanations including not only climate change...

This paper seeks to present the process of developing and deploying blended learning approach on forest fire fighting within European context. Between 2004 and 2007 Romania, Hungary, Estonia, the UK and Spain have reported 21,500 fires that destroyed nearly 100,000 ha of agricultural land and forest, with a total value of about € 25 million. Wildla...

Current paper presents the re-inventory results of woodland key habitats in Järvselja Training and Experimental Forest Centre. The current status of the concept of woodland key habitats in Estonia is described and discussed. The status of 31 re-inventoried key habitats in Järvselja forests indicate that 29 out of the originally listed key habitats...

Opencast mining creates disturbance to the ecosystem at all ecological scales: species, ecosystem and landscape level. The novel conditions establish in bedrock and for vegetation dynamics and habitat distribution. Afforestation for ecological rehabilitation has been used in Aidu oil shale quarry since early 1960s. Scots pine shows the best affores...

There is strong evidence that climate change alters tree growth in boreal forests. In Estonia, the analysis of ring measurements has been a common method to study growth changes. In this study, annual height growth data from dominant or co-dominant Scots pine (Pinus sylvestris L.) trees were used to develop a growth model for three forest generatio...

We examined the forest microhabitat rehabilitation on forest plantations established on the planed abandoned oil-shale mining sites in Northeast Estonia. For the rehabilitation purposes several native and exotic tree species were used in single species and mixed species trials established in 1968. On the test site due to the variation in local topo...

Long-term sample plots have been used to study pathways of succession, and its mechanisms and causes. These observations are relevant not only to communities protected from human interference, but also to managed forests, where the objective is to explain response patterns following specific harvesting operations. The establishment and maintenance...

A classic approach to obtain stand height H Dq in advanced stands in Estonia has to use the regression height at the quadratic mean diameter D q. In juvenile stands, where a considerable number of young trees have not reached breast height, the modelling of the height distribution instead of the breast height diameter dbh distribution is more pract...

• This review summarizes early stand-scale studies of pristine forest structures, disturbance regimes and successional patterns carried out in boreal Eurasia. We attempt to reveal, characterize and classify stand dynamic types that can be used as templates for nature-based forest management. • The studies reviewed demonstrate multiple successional...

In general, forests in Estonia are characterized by great variability, not only in protected areas but in commercial forests as well. The data needed for the derivation and calibration of growth models can be obtained by continuous observation of permanent growth plots (also known as longitudinal studies) or by establishing chronosequences with tem...

Oil shale mining in Estonia was started in 1916. Opencast mining provides large areas for rehabilitation with primary forest succession. Mining area covers now total of 13,043 ha. Planned rehabilitation of calcareous detritus for forestry purposes has been carried out on the area 11,330 ha since 1960. Most of the area has been planted with Scots pi...

Ecosystem management assumes that management practices based on natural disturbance patterns are likely to preserve both natural biodiversity and ecosystem functions. Ecosystem management thus combines traditional natural resource management and forestry practices together with classical notions of protection that are focused on sustaining a natura...

There has been a long discussion among ecologists, foresters and natural resource managers over the need to combine traditional natural re- source management and forestry with classical nature protection methods. Ecosystem management is widely proposed in popular and scientific literature as a new way of managing natural resources and ecosystems. T...