Mati Ilomets | Tallinn University (original) (raw)

Papers by Mati Ilomets

Mires and Peat, 2021

Milled peatlands in the Northern Hemisphere are frequently restored in order to mitigate negative... more Milled peatlands in the Northern Hemisphere are frequently restored in order to mitigate negative effects of climate change and to benefit biodiversity. The aims of this study are to analyse the development of vegetation on milled peatlands in Estonia after restoration using the moss layer transfer technique (MLTT), relate the plant functional type cover with peat chemical factors, and study correlations between bryophyte and vascular plant cover on sites with different vegetation composition. Nutrient-poor (NP) Viru and nutrient-rich (NR) Ohtu milled peatlands in Northern Estonia were restored via MLTT between 2006 and 2008. Plant species cover was determined annually or biannually from 2009 to 2018, on permanent plots established during the restoration of both sites. Plant functional type cover was assessed in relation to peat chemical properties and time since restoration. The nutrient status of the restoration site plays a major role in vegetation succession, even if similar res...

Restoration Ecology, 2017

18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (include area code) Sta... more 18. NUMBER OF PAGES 19a. NAME OF RESPONSIBLE PERSON 19b. TELEPHONE NUMBER (include area code) Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std. Z39.18

Restoration Ecology, 2020

The number and the area of former milled peatlands under restoration have increased rapidly in th... more The number and the area of former milled peatlands under restoration have increased rapidly in the Northern Hemisphere in recent decades with the primary aim of promoting peat accumulation. However, the application of similar restoration techniques across different sites does not always lead to desired results, and some site-specific modifications may be needed. This study aimed to evaluate the response of aboveground plant biomass on three experimental sites in Northern Estonia to different restoration techniques in degraded peatlands. The sites were restored using the Moss Layer Transfer Technique, which was modified with different This article is protected by copyright. All rights reserved. plant spreading rates and species composition of spread material, fertilization, and creating variations in microtopography. The strongest effect of manipulations was found for bryophyte biomass responses to treatments. The creation of a microtopographic relief during the site preparation phase favored the development of Sphagnum biomass in depressions rather than in positive microforms. The species composition of the spreading material had some effect on bryophyte biomass: Sphagnum biomass was higher where hummock species had been spread. We did not find any statistical difference in the ratio of Sphagnum reintroduction tested ranging from 1:10 to 1:15.

Ecological Research, 2019

Sphagnum is the major genus in northern peatlands that contributes to peat formation and carbon s... more Sphagnum is the major genus in northern peatlands that contributes to peat formation and carbon sequestration. Sphagnum growth in summer has been fairly well studied but the information about growth in autumn and winter is limited. Therefore, we studied how the growth of Sphagnum is seasonally distributed with a particular interest on possible winter growth. The linear increment and biomass production of three Sphagum species was measured in three Northern European bogs over a year. In all sites, our results indicate the highest annual linear increment in S. angustifolium (28 mm), followed by S. magellanicum (20 mm) and S. fuscum (13 mm), but the biomass production was fairly even among the species (189, 192 and 215 g m-2 , respectively). Both linear increment and biomass production depended mostly on meteorological parameters rather than ecophysiological or microsite properties. The seasonal measurements revealed a significant linear increment and biomass production during the winter that accounted for ca 10 % and ca 5 % from the annual values, respectively. Moreover, the mean daily rates of linear increment in autumn often exceeded the increment in summer. Our results thus indicate the ability for year-around growth of Sphagna if the conditions are favourable, including during boreal winter.

Geoderma, 2019

Peat excavation has altered carbon balance in large areas in the Northern Hemisphere and turned p... more Peat excavation has altered carbon balance in large areas in the Northern Hemisphere and turned peatlands from CO 2 sinks to CO 2 sources. Peatland restoration aims at mitigating that situation by supporting CO 2 uptake in these areas through raising the water table, in this way creating conditions for vegetation development and organic matter accumulation. We analysed the relationships between recovering vegetation and CO 2 fluxes on three abandoned peat excavation sites in northern Estonia, which were rewetted and restored using the mosslayer-transfer technique three to ten years before the first measurements. Using chamber measurements, we determined whether these sites were CO 2 sinks or sources during two growing seasons in 2015 (drier) and 2016 (wetter). In the drier growing season, all sites were CO 2 sources from the peatland to the atmosphere (emissions from 1 to 77 g CO 2 m −2), while in the wetter growing season, two sites were CO 2 sinks (uptake from 13 to 210 g CO 2 m −2). CO 2 uptake was higher with higher plant and Eriophorum vaginatum cover, and biomass and cover of Sphagnum. The remotely sensed Normalized Difference Vegetation Index (NDVI) explained about 25% of variation in Net Ecosystem Exchange; CO 2 uptake was higher in plots with higher NDVI values. This provides a potential avenue of investigation of developing remote sensing methods in assessing spatial pattern of CO 2 fluxes in restored peatlands. In order to increase CO 2 uptake in abandoned milled peatlands, it is essential to raise the water level and thus reduce peat oxidation and create conditions for the development of vegetation similar to pristine peatlands.

Science of The Total Environment, 2019

Learning With Multiple Views

Multi-view classification is a machine learning methodology when patterns or objects of interest ... more Multi-view classification is a machine learning methodology when patterns or objects of interest are represented by a set of different views (sets of features) rather than the union of all views. In this paper, multiple views are employed in ensembles of nearest neighbor classifiers where they demonstrate promising results in classifying a challenging data set of protein folds. In particular, up to 4.68% increase in accuracy can be achieved, compared to the best result in single-view classification, thus rendering ensembles of nearest neighbor classifiers employing multiple views an attractive research direction.

Biogeochemistry, 1999

Nitrogen additions as NH 4 NO 3 corresponding to 0 (N0), 1 (N1), 3 (N3) and 10 (N10) g N m −2 yr ... more Nitrogen additions as NH 4 NO 3 corresponding to 0 (N0), 1 (N1), 3 (N3) and 10 (N10) g N m −2 yr −1 were made to Sphagnum magellanicum cores at two-week intervals in situ at four sites across Europe, i.e. Lakkasuo (Finland), Männikjärve (Estonia), Moidach More (UK) and Côte de Braveix (France). The same treatments were applied in a glasshouse experiment in Neuchâtel (Switzerland) in which the water table depth was artifi ially maintained at 7, 17 and 37 cm below the moss surface. In the f eld, N assimilation in excess of values in wet deposition occurred in the absence of growth, but varied widely between sites, being absent in Lakkasuo (moss N:P ratio 68) and greatest in Moidach More (N:P 21). In the glasshouse, growth was reduced by lowering the water table without any apparent effect on N assimilation. Total N content of the moss in fi ld sites increased as the mean depth of water table increased indicating growth limitation leading to increased N concentrations which could reduce the capacity for N retention. Greater contents of NH 4 + in the underlying peat at 30 cm depth, both in response to NH 4 NO 3 addition and in the unamended cores conf rmed poor retention of inorganic N by the moss at Lakkasuo. Nitrate contents in the prof les at Lakkasuo, Moidach More, and Côte de Braveix were extremely low, even in the N10 treatment, but in Männikjärve, where the mean depth of water table was greatest and retention absent, appreciable amounts of NO 3 − were detected in all cores. It is concluded that peatland drainage would reduce the capture of inorganic N in atmospheric deposition by Sphagnum mosses.

Boreal Environment Research, 2019

INTRODUCTION Molinia caerulea with low coverage is quite frequent in native fen communities in Es... more INTRODUCTION Molinia caerulea with low coverage is quite frequent in native fen communities in Estonia, but it gets problem if fens are drained and unmanaged – Molinia outcompetes herbaceous and moss plants by:  mechanical occupation of fen surface area;  producing huge quantities of litter that supresses seed germination, increasses light competition. Expansion of Molinia sharply increases with only a small drop in groundwater level (e.g. Malson, Backeus & Rydin, 2008), which is connected with soil mineralization and creation of Molinia-tussocks.

This chapter presents the delineation approach and results of status assessment of Estonian wetla... more This chapter presents the delineation approach and results of status assessment of Estonian wetlands for implementation of the objectives of the Water Framework Directive (WFD). Determination of WFD important wetlands based on selection and visualisation of wetlands soils from Estonian electronic soil map (data of Estonian Land Board), and corresponding drainage basin delineation, both for wetlands and water bodies by using the ArcMap10.2.2 software. There are 47 WFD important wetlands associated with the flowing water bodies covering more than 27,800 ha, and 19 wetlands associated with the standing water bodies covering 42,000 ha. The number of WFD important floodplain wetlands is 46 covering 15,000 ha, 24 spring mires on 390 ha and 107 coastal wetlands on 265 ha. Due to the heterogeneous landscape structure of Estonian wetlands inside the “zero” wetland contour line, the variability of both water quantity and quality of wetlands is relatively large. Therefore, without field studie...

Boreal Environment Research, 2017

Decreasing snow cover in winter resulting from climate warming increases the incidence of freeze-... more Decreasing snow cover in winter resulting from climate warming increases the incidence of freeze-thaw cycles (FTCs) in many ecosystems, including peatlands. As peatland ecosystems form a globally significant long-term carbon storage, understanding the effects of changing conditions in winter on carbon dynamics is essential. We studied how FTCs affect peatland carbon cycling by conducting mesocosm experiments with Sphagnum. Our results indicate an overall impeding effect of FTCs on Sphagnum photosynthesis, chlorophyll content, ecosystem respiration and enzymatic processes. A threefold reduction in photosynthesis in the FTC treatment was related to a decrease in chlorophyll content, showing that Sphagnum physiologically suffers from repeated FTCs. In the FTC treatment beta-glucosidase and phosphatase enzymatic activities decreased by 50% and 30%, respectively, whilst alanine remained unaffected, indicating that in peat soils short-term FTCs affect the carbon and phosphorus cycles, but...

Rewetting is the most common restoration approach for milled peatlands in Europe, with the aim of... more Rewetting is the most common restoration approach for milled peatlands in Europe, with the aim of creating suitable conditions for the development of peatland specific plant cover and carbon accumulation. Therefore, it is important to determine if time since rewetting is pivotal for milled peatlands to become functionally and structurally similar to their undisturbed counterparts. We investigate the temporal succession in rewetted peatlands in Estonia by a chronosequence of 4, 15, and 35 years before the measurements. Plant functional type (PFT) cover and biomass, bryophyte production and CO2 fluxes were measured on two milled peatlands, as well as undisturbed bogs adjacent to milled peatlands. Differences in vegetation composition and CO2 fluxes between the sites were greater for rewetted than undisturbed sites. The most recently rewetted site was mainly covered in bare peat and Eriophorum vaginatum and was a CO2 source. On the rewetted site of 15 years, Sphagnum was present in add...

We studied the biomass production of moss species typical of pine-dominated drained peatland fore... more We studied the biomass production of moss species typical of pine-dominated drained peatland forests to evaluate their potential role in the carbon cycle of such sites. The study was carried out at two sites in Lakkasuo, central Finland. Prior to drainage, the sites had been mesotrophic and ombrotrophic. Shoots of Pleurozium schreberi, Sphagnum angustifolium, S. fuscum, S. magellanicum and S. russowii were marked in the autumn of 2004 and 2005, incorporated back in the original patches, recovered one year later, and measured for height growth, biomass, and biomass production. Biomass production varied from 16 to 388 g dry mass m–2 yr–1. Both height growth and biomass production were higher at the mesotrophic site, while biomass estimates did not show distinct difference between sites. Variation in production within each dominant species was considerable. A simulation with our production values and published estimates of decomposition rates showed that these species have the potentia...