<abstract><title style='display:none'>Abstract</title>Blue carbon pertains to carbon stock that is stored by marine ecosystems including mangrove forest. Density and blue carbon stock assessment was conducted covering mature <italic>Rhizophora stylosa</italic> Griff. plantations in Bohol, Philippines. Three stand types were assessed: thinned mature stand (0.34 tree m−2 at 55 years old; 35 ha); non-thinned mature stand (1.2 tree m−2 at 55 years old; 20 ha) and young stand (2.6 tree m−2 at 20 years old; 150 ha). These plantations were initially established with a plant spacing of 0.5 m × 0.5 m. Non-destructive plot sampling technique was used to account biomass and carbon stocks of trees and sediments. Five (5) sample plots measuring 200 m2 were allocated for each stand type. Results showed that the total carbon stock of plantations amassed to 64.5 ktC or 236.6 ktCO2e. More than half (at least 54%) of this stock is imbedded in sediment. Individual accounts showed that carbon stock was largest in non-thinned stand with 435.2 tC ha−1, followed by thinned stand (408.5 tC ha−1) and young stand (276.8 tC ha−1). There was no significant difference between thinned and non-thinned mature stands carbon stocks. Such finding suggested the potential of having thinning intervention. Following the self-thinning rule of 1.1 to 1.3 tree m−2, the local community can harvest as much as 423 trees ha−1 yr−1 for 35 years starting at the plantation age of 20 years. Further, the additional carbon stock between the ages 20 to 55 years could reach about 580 tCO2e ha−1 with an economic value of USD 2,962 ha−1. With this potential benefits, it is recommended that Banacon Island should pursue a carbon offset project for its plantations.</abstract>

Stand density management and blue carbon stock of monospecific mangrove plantation in Bohol, Philippines

<abstract><title style='display:none'>Abstract</title><italic>Eucalyptus</italic> is a plant frequently present and cultivated in arid regions because of its high adaptation to drought. Furthermore, it is known by its numerous species which represent<italic>s</italic> a great opportunity to choose several tolerant species with variable uses. Therefore, the choice of species, hybrids or genotypes resistant to aridity becomes a necessity before any plantation in regions and countries characterized by semi-arid, arid and Saharan climates. Our review shows an important effect of drought on anatomical, physiological and biochemical parameters of <italic>Eucalyptus</italic> spp. Indeed, water stress acts directly on growth, yield and response to pests. However, the response to drought varies significantly among species, genotypes, hybrids and clones. This result represents a field for the selection of eucalypts tolerant and adapted to water deficit or climate change.</abstract>

An overview of adaptative responses to drought stress in <italic>Eucalyptus</italic> spp.

<abstract><title style='display:none'>Abstract</title> Thirteen Nordic stand growth models have been validated by use of a test data set from long-term research plots in Norway. The evaluated data was from time-series of even-aged, pure stands of Norway spruce, Scots pine and birch (silver birch and downy birch). In selected models from Finland, Norway and Sweden measures of site productivity, mean tree size and various stand characteristics are represented. Different models display both strengths and weaknesses in their predicting ability. Several measures of precision and bias have been calculated and the models are ranked due to their performance. We observed site quality, stand density and average tree size as the three main components in the models. Basal area increment model for spruce from Sweden had the lowest standard deviation with 23%. The mean R2 between residuals and stand characteristics from this model was also low (1.3%), which indicates that independent variables are well included. For Scots pine and birch, Finnish volume increment models showed the best fit to the Norwegian test data, with a R2 between residuals and stand characteristics of 2.8 and 6.7%, respectively. Several of the models from Sweden and Finland predicted the growth as well as stand models frequently in use in Norway. The results indicated that similar forest conditions and traditional even-aged forest management practice in the Nordic countries could be seen as a suitable basis for developing a joint family of growth models. By careful recalibration of existing models, a reasonable accuracy could be achieved and the prediction bias could be reduced.</abstract>

Comparison of selected Nordic stand growth models for Norway spruce, Scots pine and birch

<abstract><title style='display:none'>Abstract</title> 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 the Estonian University of Life Sciences started to develop the Estonian Network of Forest Research Plots (ENFRP) in 1995. Since then, plots have been continuously re-measured with 5-year interval. Approximately 100-150 permanent sample plots were measured annually. In 2014, the long-term research network consisted of 729 permanent sample plots, of which 699 have been re-measured at least once, 667 plots - twice and 367 plots - three times. The total number of trees recorded in the network database amounts to 130,479. The plots are systematically distributed throughout the country. Detailed dendrometric measurements including tree spatial distribution are part of the survey protocol. Initially the network was set up to produce suitable data for development of individual tree growth models for Estonia. The significance of the network for the Estonian forest research is continuously increasing and nowadays ENFRP is recognized as an important national research infrastructure.</abstract>

Monitoring and modeling of forest ecosystems: the Estonian Network of Forest Research Plots / Metsaökosüsteemide seire ja modelleerimine metsa kasvukäigu püsiproovitükkide võrgustiku abil

<abstract><title style='display:none'>Abstract</title>A generic regression model for above-ground biomass of forest stands was constructed based on published data (<italic>R</italic>2 = 0.88, <italic>RSE</italic> = 32.8 t/ha). The model was used 1) to verify two allometric regression models of trees from Scandinavia applied to repeated measurements of 275 sample plots from database of Estonian Network of Forest Research (FGN) in Estonia, 2) to analyse impact of between-tree competition on biomass, and 3) compare biomass estimates made with different European biomass models applied on standardized forest structures. The model was verified with biomass measurements from hemiboreal and tropical forests. The analysis of two Scandinavian models showed that older allometric regression models may give biased estimates due to changed growth conditions. More biomass can be stored in forest stands where competition between trees is stronger. The tree biomass calculation methods used in different countries have also substantial influence on the estimates at stand-level. A common database of forest biomass measurements from Europe in similar to pan-tropical tree measurement data may be helpful to harmonise carbon accounting methods.</abstract>

Tartu Observatory, 61602 Tõravere, Tartumaa,

Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, 51014 Tartu,

Institute of Silviculture, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences, Vienna, Peter-Jordan- Str. 82, A-1190 Wien,

Department of Dendrometry and Forest Productivity, Faculty of Forestry, Warsaw University of Life Sciences, Nowoursynowska 159, 02-787 Warsaw,

Restinga and Atlantic Forest Laboratory, Universidade Federal do Espírito Santo, UFES, 29932-540, São Mateus, ES,

Faculty of Forestry and Wood Sciences, Czech University of Life Sciences, Kamycka 129, 165 21 Prague,

Estimation of above-ground biomass in forest stands from regression on their basal area and height

<abstract><title style='display:none'>Abstract</title>Alternatives to the restoration of cutaway peatlands include afforestation, energy forests, agricultural production, wetland restoration (restoration of peataccumulating function), reed canary grass (energy mower) or wild berries (blueberry, cranberry) cultivation, protected area for birds, and artificial lakes. Investigations made in several countries suggest that one of the most promising ways of regenerating cutaway peatlands is afforestation. The re-vegetation of Estonian cutaway peat production fields is mainly the result of natural processes, which are generally very slow: vegetation covers only 10–20% of a peat field. Carbon dioxide is not bound anymore in cutaway peatlands where vegetation layer has been destroyed and therefore photosynthetical processes no more occur. Using biofuel ashes (wood ash, etc.) for the afforestation of cutaway peatlands helps to balance the content of nutrients in peat substrate, which improves the survival of planted seedlings and significantly increases bioproduction. Drained and mined peatlands have become a significant source of CO2 but stimulated woody biomass production can be helpful to balance CO2 emission from cutaway peatlands. Because of the limited resources of fossil fuels and negative impacts on the environment in recent decades alternative sources of energy have been actively looked for. In Scandinavia a lot of attention has been paid to finding possibilities for using biofuels. The situation in Estonia is that only very few types of ashes (for example certified oil shale fly ash with product name Enefix) have been founded to be suitable for utilization and have been used for recycling in agriculture.</abstract>

Afforestation of cutaway peatlands: effect of wood ash on biomass formation and carbon balance

<abstract>
<title style='display:none'>Abstract</title>
There are no systematic approaches available in current specialist literature when it comes to the optimization of the process of drying out hardwood species of wood, such as birch, aspen, or black alder, all of which find industrial uses in Estonia. In order to investigate the drying of these three hardwood species, this paper has made use of an experimental and theoretical drying optimization methodology which was developed previously for pine sapwood within the framework of the EIC Grant No. 16200 project. The same methodology was used to determine the critical diffusion coefficient and corresponding critical relative humidity levels (RH) in relation to the surrounding air, with those levels being important from the point of view of drying optimization, and calculating those levels separately for each species of hardwood. For alder it was found that the critical diffusion coefficient is Dcr = 36.57 * (10−4 mm2 s−1), while for aspen the figure was Dcr = 30.71 * (10−4 mm2 s−1), and for birch it was Dcr = 16.35 * (10−4 mm2 s−1). It was found that the time dependencies for the total deformation of different tree species tend to differ considerably, although the same drying regime was used for all of those tree species which were incorporated into the experiments.
</abstract>

An experimental determination of the critical diffusion coefficient and critical relative humidity (RH) of drying air when optimizing the drying of three hardwood species (birch, aspen, and black alder)

<abstract>
<title style='display:none'>Abstract</title>
The reduction of greenhouse gas (GHG) emissions demands a significant increase in the use of wood as a renewable energy source. However, environmental restrictions determine limits on the further growth of harvesting volume. Therefore, a viable solution to enhance the share of energy wood in Estonia’s energy balance involves focusing on less exploited assortments of raw material and implementing precise logistics planning. In recent years, mild winters have posed challenges to the extraction of residues and local transport of wood fuels, taking place on soft and unfrozen soils. In such conditions, ensuring a reliable supply of wood fuels becomes rather complicated. When piles of logging residues on unfrozen soils are inaccessible, there is a need to process older piles. The quality of wood chips from such piles is lower compared to the norm. To investigate the impact of extra long-term storage of residues in piles, a study was conducted at the Järvselja Training and Experimental Forest Centre. In 2010, sample piles were created in birch and spruce final felling areas. Over an eight-year period, samples were regularly taken from the piles to analyse the properties of woody biomass during storage. The study results indicate that the quality of fuel from covered piles changes slowly during the first two years of storage. Subsequently, the degradation speed equalizes in both uncovered and covered piles. Despite extensive degradation and loss of dry matter during long-term storage (approximately 29% for Norway spruce and 55% for silver birch after eight years), the quality of dry fuels still meets standard requirements and remains acceptable for boiler houses.
</abstract>

The impact of extra long-term storage of logging residues on fuel quality in Estonian conditions – a case study

<abstract>
<title style='display:none'>Abstract</title>
Understanding how forest ecosystems respond to environmental factors, particularly in the context of global climate change, is essential for devising effective mitigation strategies. This study focuses on quantifying the interaction between forest ecosystems and atmospheric gases. To achieve our objectives, we are using the eddy covariance (EC) flux method to measure air turbulence and gas concentrations above the forest canopy at the Station for Measuring Ecosystem-Atmosphere Relations (SMEAR) in southern Estonia. We apply a flux footprint (FFP) model to describe the spatial extent and position of the surface area contributing to the turbulent flux measurements. The FFP analysis provides valuable insights into the long-term changes in SMEAR Estonia, the FFP and its relationship with forest management and land use changes. Our findings reveal that the FFP area varies from year to year due to changes in wind speed and direction, affecting the contribution of different land cover elements to the overall FFP. The average changes in the FFP area at a height of 30 meters were approximately 4.9%, while those at a height of 70 meters were only 1.6%. Moreover, human activities, such as thinning and clear-cutting, influence the growing stock and increment of forest stands.
</abstract>

Development of a footprint description tool utilizing SMEAR Estonia eddy-covariance data and footprint modelling in combination with remote sensed forest species and land cover data

<abstract>
<title style='display:none'>Abstract</title>
<italic>Phellodendron chinense</italic> is an extraordinary medicinal plant, and its stem bark is a famous traditional Chinese medicine in China, containing a number of phytochemicals with biological and pharmacological functions. Studies have shown that the medicinal ingredients in <italic>P. chinense</italic> from various regions are different, as soil types might be important factors affecting the growth and quality of <italic>P. chinense</italic>. In this study, the effects of acidic purple soil, alkaline purple soil, yellow soil and red soil on the growth, nutrient element accumulation and partitioning in <italic>P. chinense</italic> seedlings were studied. Our results showed that the biomass of leaves and stems in acidic purple soil was significantly higher than in other soils, and the root biomass was significantly lower than that in yellow soil. C, N, P and Ca contents cultured in acidic purple soil were the highest compared to other soils, and K and Mg content were the highest in yellow soil and red soil, respectively. The distribution of carbon between different organs can reflect environmental stress. N has become a limiting factor for the growth and development of <italic>P. chinense</italic> seedlings. C:N and C:P ratios in the leaves were significantly lower than those in the stem and roots. Among four soil types, the highest N:P ratio was 1.65 in <italic>P. chinense</italic> seedlings. These results suggest that four soil types may significantly affect the accumulation and distribution of biomass and nutrient elements in <italic>P. chinense</italic> seedlings. The characteristic patterns in different organs have different responses. Acidic purple soil is more suitable for the growth of <italic>P. chinense</italic>. These findings will help to understand the distribution characteristics and requirements of nutrient elements in <italic>P. chinense</italic> seedlings, and further provide a theoretical basis and reference for site selection and cultivation strategy.
</abstract>

Effects of four soil types on growth responses and nutrient stoichiometry in <italic>Phellodendron chinense</italic> seedlings

<abstract>
<title style='display:none'>Abstract</title>
The aim of this paper was to provide an overview of the productivity of the stump lifting device Pallari KH-160, the distribution of working time, and to assess the dependence of the time and productivity of lifting operations on stump diameter in four different sample areas. Viru and Orguse sample areas were located in the <italic>Hepatica</italic> site type, Elva sample area in the <italic>Oxalis</italic> site type, and Rõuge test area in the <italic>Myrtillus</italic> site type. Viru sample area had smaller stumps compared to the others and had more stumps affected by decay. The highest productivity in terms of dry mass or volume was observed in stump lifting in Rõuge sample area, where 9.8 t of stumps were lifted per hour based on dry mass. The productivity of Viru and Orguse sample areas was lower, but these sample areas are located in the <italic>Hepatica</italic> site type, characterized by limestone substrates and leached soils. In contrast, Elva and Rõuge test areas are in the <italic>Oxalis</italic> and <italic>Myrtillus</italic> site types, respectively, with soils that are predominantly sandy. As the diameter of the stumps increased, the time required per stump increased, but the lifting speed per unit mass also increased. In other words, the productivity of lifting in stands with larger stumps is higher than in stands with smaller stumps. For example, the average productivity of lifting 10 cm diameter stumps is 0.8 t/h, for 20 cm stumps it is 2.2 t/h, and for 60 cm stumps it is 11.8 t/h.
</abstract>

Hariliku kuuse (<italic>Picea abies</italic> (L.) H. Karst.) kändude juurimise tootlikkus juurimisagregaadiga Pallari KH-160 neljal Eesti katsealal

<abstract>
<title style='display:none'>Abstract</title>
In a managed forest landscape, the high degree of human intervention has caused significant shifts in natural processes, and preservation of remaining natural ecosystem features is crucial to safeguard ecosystem functioning and support ecosystem services. While drainage ditches, subject to regular maintenance, are anthropogenically created and maintained infrastructure elements, they may still support diverse environmental conditions and provide habitats for a variety of plant species, including flowering plants important for pollinators. We assessed vegetation composition changes on recently reconstructed and unmanaged forest ditches and ditch edges in a commercial forest in Central Latvia in two surveys (one and five years after the ditch reconstruction). We used generalized linear mixed-effects models to analyze the impact of environmental variables on species richness and detrended correspondence analysis to analyze plant species composition. We found higher total plant species richness and insect-pollinated plant species richness along recently reconstructed ditches. The differences were mainly explained by better light availability beside reconstructed ditches. Anthropogenically created and managed ecosystems may support biodiversity and directly and indirectly contribute to the provision of different ecosystem services, including pollination.
</abstract>

Vegetation response to forest ditch reconstruction: Promoting a potential habitat for insect-pollinated plant species?

<abstract xml:lang="en"><title style='display:none'>Recent invasion of foliage fungi of pines (<italic>Pinus</italic> spp.) to the Northern Baltics</title>In the wake of severe climatic extremes during recent years, several new invasive foliage fungi of pines have been reported in Estonia. In this paper the peculiarities of the fast dissemination process, particularly from south to north of two quarantined species, <italic>Mycosphaerella pini</italic> and <italic>M. dearnessii</italic>, but also of <italic>Diplodia pinea</italic> and <italic>Cyclaneusma minus</italic> on different host species are described. These species were known as destructive pathogens in several countries and continents. By today, the range of <italic>M. pini</italic> has already reached northern Finland. In its dissemination process we could follow, with the half-year steps, colonization of Estonia from south to north. Some micromorphological features of these alien species were investigated. Hypothetical risk for pine forests was shortly introduced.</abstract>

Recent invasion of foliage fungi of pines (<italic>Pinus</italic> spp.) to the Northern Baltics

<abstract><title style='display:none'>Abstract</title>Establishment of the SMEAR Estonia at a hemiboreal mixed deciduous broad-leaved-evergreen needle-leaved forest at Järvselja, South-Eastern Estonia, has strongly enhanced the possibilities for national and international cooperation in the fields of forest ecosystem – atmosphere research and impacts of climatic changes on forest ecosystems, atmospheric trace gases, aerosols and air ions. The station provides a multitude of comprehensive continuously measured data covering key climatic and atmospheric characteristics (state and dynamics of solar radiation, trace gases, aerosols and air ions, meteorological parameters) and forest ecosystem traits (net primary productivity, individual tree growth, gas-exchange characteristics, soil variables). The station follows a multidisciplinary and multiscale approach covering processes in spatial dimensions ranging from nanometres to several hundred square kilometres, being thus able to significantly contribute to worldwide measurement networks and the SMEAR network. Here we present an overview of the station, its data produced and we envision future developments towards sustainable research and development of the large-scale scientific infrastructure SMEAR Estonia.</abstract>

Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 51014 Tartu, Estonia

Estonian Academy of Sciences, Kohtu 6, 10130 Tallinn, Estonia

Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 1, 51014 Tartu, Estonia

Institute of Physics, University of Tartu, 18 Ülikooli Street, 50090 Tartu, Estonia

Department of Forest Sciences, P.O. Box 64, FI-00014 University of Helsinki, Finland

Division of Atmospheric Sciences, Department of Physics, P.O. Box 64, FI-00014 University of Helsinki, Finland

SMEAR Estonia: Perspectives of a large-scale forest ecosystem – atmosphere research infrastructure

<abstract><title style='display:none'>Abstract</title>Wildfire is regarded as important environmental factor determining the vegetation of the Earth. We analyzed 11 plots at different types of forest affected by fire at the southern boundary of the taiga zone. These differ in structure of the forest stand and herb-shrub layer. Investigated factors included edaphic (moisture, pH, nitrogen) and climatic (light, temperature, continentality) characteristics. Also, projective cover of <italic>Epilobium angustifolium</italic> L. and undergrowth of secondary growth trees (including forest stand survived after fire influence) were studied. Multivariate data analysis revealed that the rate and character of the vegetation recovery was depended on the ratio of environmental factors and on the species composition of herb-shrub layer. No significant differences were found in Ellenberg’s indicator values between different years of study. All tested forest habitats were distinguished into three main groups: Group I includes broadleaf forests with the forest stand survived after fire influence, Group II includes spruce and birch forests deprived the forest stand due to fire impact, Group III includes more or less dry pine-dominated forests with the forest stand gradually died after fire influence. Two marshy plots have prerequisites to their allocation to a separate group close to the oligotrophic bog forests.</abstract>

Mordovia State Nature Reserve, 431230, Pushta, Temnikov district, Republic of Mordovia,

Department of Botany, Physiology and Ecology of Plants, Mordovia State University, 430005, Bolshevistskaya Street, 68, Saransk, Republic of Mordovia,

National Park “Smolny”, 431660, Topoley Street, 11, Smolny, Ichalki district, Republic of Mordovia,

Vegetation recovery in fire-damaged forests: a case study at the southern boundary of the taiga zone

<abstract><title style='display:none'>Abstract</title>Field measurements from 450 sample plots, airborne lidar data and spectral images from Aegviidu, Estonia, 15 by 15 km test site were used to analyse options to estimate main forest inventory variables using remote sensing data. Up to 7 m random error in location of 15 m radius sample plots within homogeneous stands causes usually about 0.5 m standard deviation in lidar pulse return height distribution percentiles. Forest mean height can be predicted with linear relationship from 80th percentile of lidar pulse return height distribution. Upper percentiles of pulse return height distribution are not significantly affected by omitting returns from ground and forest understorey vegetation. Total stem volume in forest can be predicted by using 80th percentile, 25th percentile and canopy cover as model arguments with less than 70 m3 ha-1 standard error. Best species specific stem volume models had 10 m3 ha-1 smaller standard error.</abstract>

Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Kreutzwaldi 5, Tartu 51014, Estonia;

Tartu Observatory, 61602, Tõravere, Tartumaa, Estonia;

OÜ Metsabüroo, Kadaka tee 86a, 12618, Tallinn, Estonia

Tartu Observatory, 61602, Tõravere, Tartumaa, Estonia

Lennukilidari ja spektraalse kaugseireandmestiku kasutamine metsa peamiste takseertunnuste hindamiseks Aegviidu katsealal / Estimation of main forest inventory variables from spectral and airborne lidar data in Aegviidu test site, Estonia

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