Estonian University of Life Sciences
Recent publications
Northern forest ecosystems make up an important part of the global carbon cycle. Hence, monitoring local-scale gross primary production (GPP) of Northern forest is essential for understanding climatic change impacts on terrestrial carbon sequestration and for assessing and planning management practices. Here we evaluate and compare four methods for estimating GPP using Sentinel-2 data in order to improve current available GPP estimates: four empirical regression models based on either the 2-band Enhanced Vegetation Index (EVI2) or the plant phenology index (PPI), an asymptotic light response function (LRF) model, and a light-use efficiency (LUE) model using the MOD17 algorithm. These approaches were based on remote sensing vegetation indices, air temperature (Tair), vapor pressure deficit (VPD), and photosynthetically active radiation (PAR). The models were parametrized and evaluated using in-situ data from eleven forest sites in North Europe, covering two common forest types, evergreen needleleaf forest and deciduous broadleaf forest. Most of the models gave good agreement with eddy covariance-derived GPP. The VI-based regression models performed well in evergreen needleleaf forest (R² = 0.69–0.78, RMSE = 1.97–2.28 g C m⁻² d⁻¹, and NRMSE = 9–11.0%, eight sites), whereas the LRF and MOD17 performed slightly worse (R² = 0.65 and 0.57, RMSE = 2.49 and 2.72 g C m⁻² d⁻¹, NRMSE = 12 and 13.0%, respectively). In deciduous broadleaf forest all models, except the LRF, showed close agreements with the observed GPP (R² = 0.75–0.80, RMSE = 2.23–2.46 g C m⁻² d⁻¹, NRMSE = 11–12%, three sites). For the LRF model, R² = 0.57, RMSE = 3.21 g C m⁻² d⁻¹, NRMSE = 16%. The results highlighted the necessity of improved models in evergreen needleleaf forest where the LUE approach gave poorer results., The simplest regression model using only PPI performed well beside more complex models, suggesting PPI to be a process indicator directly linked with GPP. All models were able to capture the seasonal dynamics of GPP well, but underestimation of the growing season peaks were a common issue. The LRF was the only model tending to overestimate GPP. Estimation of interannual variability in cumulative GPP was less accurate than the single-year models and will need further development. In general, all models performed well on local scale and demonstrated their feasibility for upscaling GPP in northern forest ecosystems using Sentinel-2 data.
This study aims to assess the factors influential towards decision made by consumers to purchase hydroponic products. A quantitative research employing factor analysis, 100 samples were established as per accidental random sampling. The observed 11 variables – classified in four groups – were of hydroponic product feature (packing, size, freshness, and crunchiness), hydroponic product value (competitiveness and price), customer’s background (income, education, association, and family size), and place (service). The result shows that those who chose the products were mostly female (98) – 73 of them are housewives – aged between 37 and 42 (42) with at least senior high school educational background (69).
The European mink (Mustela lutreola) is one of the most threatened small carnivores, listed as Critically Endangered on the IUCN Red List. Tallinn Zoo started a conservation breeding operation in 1980, which in 1992 was shaped into the European mink EEP Program to maintain a demographically and genetically healthy population in captivity. Since 2000, mink have been translocated on a yearly basis from the breeding facility in the zoo to Hiiumaa Island (Estonia) until the formation of the wild island population in 2016. Maintaining a healthy genetic structure in a captive population was a priority, so genetically the least valuable animals, according to calculations made by a population management program, were used for translocation. This study aims to assess the amount of genetic diversity passed from an ex situ population on to the island population. Comparisons of the genetic diversity were made by mitochondrial, microsatellite and nuclear markers. In addition, our results were combined with the pedigree data from the European mink EEP Studbook to further evaluate the flow of genetic diversity from the founder population to the established wild population. According to the findings, the island population's allelic richness was comparable to that of the founder population, and no evidence was found that its genetic structure had diverged from that of the founder population. It seems that the formation of the island population has been a gradual process of no more than the last seven yearly translocations.
Eutrophication and lake depth are of key importance in structuring lake ecosystems. To elucidate the effect of contrasting nutrient concentrations and water levels on the microbial community in fully mixed shallow lakes, we manipulated water depth and nutrients in a lake mesocosm experiment in north temperate Estonia and followed the microbial community dynamics over a 6-month period. The experiment was carried out in Lake Võrtsjärv-a large, shallow eutrophic lake. We used two nutrient levels crossed with two water depths, each represented by four replicates. We found treatment effects on the microbial food web structure, with nutrients having a positive and water depth a negative effect on the bio-masses of bacterial and heterotrophic nanoflagellates (HNF) (RM-ANOVA, p < 0.05). Nutrients affected positively and depth negatively the mean size of individual HNF and ciliate cells (RM-ANOVA; p < 0.05). The interactions of depth and nutrients affected positively the biomass of bacterivorous and bacteri-herbivorous ciliates and negatively the biomass of predaceous ciliates (RM-ANOVA; p < 0.05). Bacterivorous ciliates had lowest biomass in shallow and nutrient-rich mesocosms, whilst predaceous ciliates had highest biomass here, influencing trophic interactions in the microbial loop. Overall, increased nutrient concentrations and decreased water level resulted in an enhanced bacterial biomass and a decrease in their main grazers. These differences appeared to reflect distinctive regulation mechanisms inside the protozoan community and in the trophic interactions in the microbial loop community.
Background: The space requirements for accommodating cattle during confinement are based on assessment of both the physical space occupied by the animals and that needed for essential behaviours. The aim of this study was to estimate the area (m2 ) occupied by cattle of different liveweights in the static standing (ST), recumbency (SR) and sleeping (SL) postures. Methods: The study was conducted in Chile. The area (m2 ) occupied by 26 female beef cross cattle with liveweights between 45 and 642 kg was estimated in the ST, SR and SL postures through planimetry using overhead photographs. The allometric coefficient k value was obtained for each posture using linear regression equations from the measured weight (kg0.66 ) and area occupied. Results: Less but more variable space was occupied by each individual in the ST posture compared to SR or SL posture, with clear correlations between weight and occupied area. The k values obtained were 0.014 (ST), 0.023 (SR) and 0.021 (SL), which are all less than international recommendations for the same postures. Limitations: The methodology needs refinement to reduce the distance to the object optical effect in the different postures. Further work is also needed to determine additional space requirements for behavioural needs and movements associated with each posture and change of posture, depending on the type of confinement. Conclusions: We provide a scientific basis on which to objectively establish absolute minimum static space requirements for cattle of different breeds, types, weights and anatomical conformations and calculate k values.
Invasive plant species pose a direct threat to biodiversity and ecosystem services. Among these, Rosa rugosa has had a severe impact on Baltic coastal ecosystems in recent decades. Accurate mapping and monitoring tools are essential to quantify the location and spatial extent of invasive plant species to support eradication programs. In this paper we combined RGB images obtained using an Unoccupied Aerial Vehicle, with multispectral Planet-Scope images to map the extent of R. rugosa at seven locations along the Estonian coastline. We used RGB-based vegetation indices and 3D canopy metrics in combination with a random forest algorithm to map R. rugosa thickets, obtaining high mapping accuracies (Sensitivity = 0.92, specificity = 0.96). We then used the R. rugosa presence/absence maps as a training dataset to predict the fractional cover based on multispectral vegetation indices derived from the PlanetScope constellation and an Extreme Gradient Boosting algorithm (XGBoost). The XGBoost algorithm yielded high fractional cover prediction accuracies (RMSE = 0.11, R 2 = 0.70). An in-depth accuracy assessment based on site-specific validations revealed notable differences in accuracy between study sites (highest R 2 = 0.74, lowest R 2 = 0.03). We attribute these differences to the various stages of R. rugosa invasion and the density of thickets. In conclusion, the combination of RGB UAV images and multispectral PlanetScope images is a cost-effective method to map R. rugosa in highly heterogeneous coastal ecosystems. We propose this approach as a valuable tool to extend the highly local geographical scope of UAV assessments into wider areas and regional evaluations.
Unveiling the processes that shape biodiversity patterns is a cornerstone of ecology. Land-use diversity (i.e., the variety of land-use categories within an area) is often considered an important environmental factor that promotes species richness at landscape and regional scales by increasing beta-diversity. Still, the role of land-use diversity in structuring global taxonomic and functional richness is unknown. Here, we examine the hypothesis that regional species taxonomic and functional richness is explained by global patterns of land-use diversity by analyzing distribution and trait data for all extant birds. We found strong support for our hypothesis. Land-use diversity predicted bird taxonomic and functional richness in almost all biogeographic realms, even after accounting for the effect of net primary productivity (i.e., a proxy of resource availability and habitat heterogeneity). This link was particularly consistent with functional richness compared to taxonomic richness. In the Palearctic and Afrotropic realms, a saturation effect was evident, suggesting a non-linear relationship between land-use diversity and biodiversity. Our results reveal that land-use diversity is a key environmental factor associated with several facets of bird regional diversity, widening our understanding of key large-scale predictors of biodiversity patterns. These results can contribute to policies aimed at minimizing regional biodiversity loss.
The effects of ‘nature’ on mental health and subjective well-being have yet to be consistently integrated into ecosystem service models and frameworks. To address this gap, we used data on subjective mental well-being from an 18-country survey to test a conceptual model integrating mental health with ecosystem services, initially proposed by Bratman et al. We analysed a range of individual and contextual factors in the context of 14,998 recreational visits to blue spaces, outdoor environments which prominently feature water. Consistent with the conceptual model, subjective mental well-being outcomes were dependent upon on a complex interplay of environmental type and quality, visit characteristics, and individual factors. These results have implications for public health and environmental management, as they may help identify the bluespace locations, environmental features, and key activities, that are most likely to impact well-being, but also potentially affect recreational demand on fragile aquatic ecosystems.
Using stable carbon and nitrogen isotope analysis (δ¹³C and δ¹⁵N) to assess trophic interactions in freshwater ecosystems is a well established method, providing insight into ecosystem functioning. However, the spatial and temporal variability of isotope values, driven by environmental fluctuation is poorly understood and can complicate interpretations. We investigated how the temporal variation of stable isotopes in consumers (fish, crayfish and macrozoobenthos) of a canyon-shaped oligotrophic reservoir is associated with environmental factors such as water temperature, transparency, flooded area, and water quality measures. Consumers and their putative food sources were sampled and analyzed for carbon and nitrogen stable isotopes annually, and environmental parameters were measured monthly from 2014 to 2016. Results revealed significant differences in δ¹³C and δ¹⁵N values in each consumer among studied years. Over the years, fish and crayfish expressed differences in δ¹³C between 3 and 5‰, whereas in zoobenthos differences were 12‰. Variability in δ¹⁵N was similar across all consumers (2–4‰). Moreover, results suggest that the flooded area of the reservoir was a major driver of δ¹³C stable isotope values variation in consumers, while variation in δ¹⁵N was not linked to any of the studied environmental factors. Bayesian mixing models further showed significant changes in the origin of detritivorous zoobenthos carbon sources (reversal shift from terrestrial detritus to algae origin) between years with low water level to years with the standard water level. Other species showed only slight differences in food source utilization among years. Our study highlights the importance of environmental factors as sources of variation in consumer’s stable isotope values which should be considered especially when studied ecosystem strongly fluctuate in some environmental factor.
Sex differences are apparent in numerous behavioural characteristics. In order to compare and characterize male and female variability of exploratory behaviour, 365 male and 401 female rats were assessed in a task where a bimodal response distribution had previously been established in males. Female rats had significantly higher exploratory activity, and presented normal distribution of the behaviour, very differently from the bimodal distribution of males. No major effect of litter or estrous cycle was detected. Several differences between male and female rats were found in monoamine metabolism measured ex vivo. Male rats had lower levels of dopamine (DA) in frontal cortex, and higher levels of 3,4-dihydroxyphenylacetic acid (DOPAC) in raphe area; higher levels of serotonin (5-HT) and 5-hydroxyindoleacetic acid (5-HIAA) in dorsal striatum but lower levels of 5-HT and 5-HIAA in locus coeruleus area, 5-HIAA levels were also lower in hippocampus as compared to females. Males had higher noradrenaline (NA) levels in hippocampus and lower normetanephrine (NMN) levels in striatum, in both brain regions male animals had lower NMN/NA ratio. No sex difference was found in accumbens. The only brain region with an interaction between sex and the expression of exploratory activity was raphe: Here 5-HT levels were lower, and DOPAC levels and DOPAC/DA and 5-HIAA/5-HT ratios higher in low exploring male but not female rats. Conclusively, female rats not only display higher levels of exploration but the population distribution of this behaviour is distinct; this may be related to differences in the monoaminergic systems between female and male animals.
Climate change enhances the frequency of heatwaves that negatively affect photosynthesis and can alter constitutive volatile emissions and elicit emissions of stress volatiles, but how pre-exposure to mildly warmer temperatures affects plant physiological responses to subsequent severe heat episodes remains unclear, especially for aromatic plants with high and complex volatile defenses. We studied the impact of heat shock (45 °C/5 min) applied alone and after exposure to moderate heat stress (35 °C/1 h; priming) on foliage photosynthesis and volatile emissions in the aromatic plant Origanum vulgare through 72 h recovery period. Heat stress decreased photosynthesis rates and stomatal conductance, whereas the reductions in photosynthesis were primarily due to non-stomatal factors. In non-primed plants, heat shock-induced reductions in photosynthetic activity were the greatest, but photosynthetic activity completely recovered by the end of the experiment. In primed plants, a certain inhibition of photosynthetic activity remained, suggesting a sustained priming effect. Heat shock enhanced the emissions of volatiles including lipoxygenase pathway volatiles, long-chained fatty acid-derived compounds, mono- and sesquiterpenes, geranylgeranyl diphosphate pathway volatiles, and benzenoids, whereas different heat treatments resulted in unique emission blends. In non-primed plants, stress-elicited emissions recovered at 72 h. In primed plants, volatile emissions were multiphasic, the first phase, between 0.5 and 10 h, reflected the primary stress response, whereas the secondary rise, between 24 and 72 h, indicated activations of different defense metabolic pathways. Our results demonstrate that exposure to mild heat leads to a sustained physiological stress memory that enhances plant resistance to subsequent severe heat stress episodes.
During the past century, semi‐natural grasslands, once widespread throughout Europe, have largely been converted into intensively managed agricultural areas, abandoned or afforested. These large‐scale land‐use changes have already resulted in considerable biodiversity loss but can also lead to decline in ecosystem service provision and ecosystem multifunctionality. We assessed the impact of afforestation and abandonment of semi‐natural grasslands on the supply of ecosystem services in Western Estonia. We compared a wide array of services provided by open grasslands, abandoned grasslands, and afforested grasslands. Additionally, we analysed the impact of land‐use change and species richness on ecosystem multifunctionality. Significant declines in the supply of pollination services, natural pest regulation, forage production, soil quality, wild food and cultural appreciation of landscape were detected as a result of overgrowing or afforestation. There was significant positive relationship between species richness and ecosystem multifunctionality, i.e. more biodiverse grasslands were able to support more services at higher capacity. Results show that both grassland degradation due to abandonment, as well as grassland afforestation, have significant negative impacts on biodiversity, on the supply of multiple important ecosystem services and on the ecosystem multifunctionality. Synthesis and applications. Temperate semi‐natural grasslands have high biodiversity and capacity to deliver multiple important ecosystem services simultaneously. Conservation and restoration of grassland habitats must be considered as an important part of sustainable landscape planning.
Bovine tuberculosis (bTB) is an infectious disease with significant impact on animal health, public health and international trade. Standard bTB screening in live cattle consists in injecting tuberculin and measuring the swelling at the place of injection few days later. This procedure is expensive, time-consuming, logistically challenging, and is not conclusive before performing confirmatory tests and additional analysis. The analysis of the volatile organic compounds (VOCs) emitted by non-invasive biological samples can provide an alternative diagnostic approach suitable for bTB screening. In the present study, we analyzed VOC samples emitted through the breath, feces and skin of 18 cows diagnosed with bTB from three farms from Romania, as well as of 27 negative cows for bTB from the same farms. Analytical studies employing gas chromatography coupled to mass spectrometry revealed 80 VOCs emitted through the breath, 200 VOCs released by feces, and 80 VOCs emitted through the skin. Statistical analysis of these compounds allowed the identification of 3 tentative breath VOC biomarkers (acetone; 4-methyldecane; D-limonene), 9 tentative feces VOC biomarkers (toluene; [(1,1-dimethylethyl)thio]acetic acid; alpha-thujene; camphene; phenol; o-cymene; 3-(1,1-dimethylethyl)-2,2,4,4-tetramethyl-3-pentanol; 2,5-dimethylhexane-2,5-dihydroperoxide; 2,4-di-tert-butylphenol), and 3 tentative skin VOC biomarkers (ammonia; 1-methoxy-2-propanol; toluene). The possible pathway of these volatile biomarkers is discussed.
Estimating effective population size (Ne) is important for theoretical and practical applications in evolutionary biology and conservation. Nevertheless, estimates of Ne in organisms with complex life‐history traits remain scarce because of the challenges associated with estimation methods. Partially clonal plants capable of both vegetative (clonal) growth and sexual reproduction are a common group of organisms for which the discrepancy between the apparent number of individuals (ramets) and the number of genetic individuals (genets) can be striking, and it is unclear how this discrepancy relates to Ne. In this study, we analysed two populations of the orchid Cypripedium calceolus to understand how the rate of clonal versus sexual reproduction affected Ne. We genotyped >1000 ramets at microsatellite and SNP loci, and estimated contemporary Ne with the linkage disequilibrium method, starting from the theoretical expectation that variance in reproductive success among individuals caused by clonal reproduction and by constraints on sexual reproduction would lower Ne. We considered factors potentially affecting our estimates, including different marker types and sampling strategies, and the influence of pseudoreplication in genomic data sets on Ne confidence intervals. The magnitude of Ne/Nramets and Ne/Ngenets ratios we provide may be used as reference points for other species with similar life‐history traits. Our findings demonstrate that Ne in partially clonal plants cannot be predicted based on the number of genets generated by sexual reproduction, because demographic changes over time can strongly influence Ne. This is especially relevant in species of conservation concern in which population declines may not be detected by only ascertaining the number of genets.
Biomagnetic monitoring increasingly is applied to assess particulate matter (PM) concentrations, mainly using plant leaves sampled in small geographical area and from a limited number of species. Here, the potential of magnetic analysis of urban tree trunk bark to discriminate between PM exposure levels was evaluated and bark magnetic variation was investigated at different spatial scales. Trunk bark was sampled from 684 urban trees of 39 genera in 173 urban green areas across six European cities. Samples were analysed magnetically for the Saturation isothermal remanent magnetisation (SIRM). The bark SIRM reflected well the PM exposure level at city and local scale, as the bark SIRM (i) differed between the cities in accordance with the mean atmospheric PM concentrations and (ii) increased with the cover of roads and industrial area around the trees. Furthermore, with increasing tree circumferences, the SIRM values increased, as a reflection of a tree age effect related to PM accumulation over time. Moreover, bark SIRM was higher at the side of the trunk facing the prevailing wind direction. Significant relationships between SIRM of different genera validate the possibility to combine bark SIRM from different genera to improve sampling resolution and coverage in biomagnetic studies. Thus, the SIRM signal of trunk bark from urban trees is a reliable proxy for atmospheric coarse to fine PM exposure in areas dominated by one PM source, as long as variation caused by genus, circumference and trunk side is taken into account.
Growing global production leads to continuing generation of waste, part of which still ends its life cycle in landfills and dumps. Despite the efforts of waste reuse and recycling and waste self-degradation, existing and old landfills and dumps remain a huge challenge for the future. The majority of landfills can be identified as non-sanitary and can be designated as existing or former dumps, meaning hills or fields of abandoned garbage and degraded inert waste masses without any or with little aftercare maintenance. In contrast, the term ‘landfill’ refers to legally organized waste disposal sites created in a controlled manner, according to modern environmentally responsible standards. The paper gives a case study-based integrated assessment of closed and revitalized waste disposal sites that have undergone a functional change from ‘lost territories’ to primarily green space beneficial for society and the urban environment, in terms of ecosystem services estimation based on the criteria evaluation approach and monetary assessment of land assets value recovery potential. The chosen four case studies (in the United States, Australia, Poland and Estonia) serve as successful examples of a sustainable degraded site revitalization gateway indicating opportunities for accelerating land value through the prism of ecosystem services estimations and spatial planning criteria. Beneficial value of land assets after site revitalization is assessed in monetary terms.
Soil life supports the functioning and biodiversity of terrestrial ecosystems. Springtails (Collembola) are among the most abundant soil arthropods regulating soil fertility and flow of energy through above- and belowground food webs. However, the global distribution of springtail diversity and density, and how these relate to energy fluxes remains unknown. Here, using a global dataset representing 2470 sites, we estimate the total soil springtail biomass at 27.5 megatons carbon, which is threefold higher than wild terrestrial vertebrates, and record peak densities up to 2 million individuals per square meter in the tundra. Despite a 20-fold biomass difference between the tundra and the tropics, springtail energy use (community metabolism) remains similar across the latitudinal gradient, owing to the changes in temperature with latitude. Neither springtail density nor community metabolism is predicted by local species richness, which is high in the tropics, but comparably high in some temperate forests and even tundra. Changes in springtail activity may emerge from latitudinal gradients in temperature, predation and resource limitation in soil communities. Contrasting relationships of biomass, diversity and activity of springtail communities with temperature suggest that climate warming will alter fundamental soil biodiversity metrics in different directions, potentially restructuring terrestrial food webs and affecting soil functioning.
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1,567 members
Sabarathinam Shanmugam
  • Chair of Bioeconomy Technologies - Institute of Forestry and Engineering
Anton Shkaruba
  • Department of Landscape Management and Nature Conservation
Andres Annuk
  • Department of Energy Application Engineering
Marko Kass
  • Department of Animal Nutrition
Fr. R. Kreutzwaldi 5, 51014, Tartu, Estonia