The Influence of the Degree of Forest Management on Methylmercury and the Composition of Microbial Communities in the Sediments of Boreal Drainage Ditches

Funding: This work was supported by the Latvian Council of Science project no. lzp-2018/1-0434 “Interaction of microbial diversity with methane turnover and mercury methylation in organic soils”.Peer reviewedPublisher PD

FungalTraits:A user-friendly traits database of fungi and fungus-like stramenopiles

The cryptic lifestyle of most fungi necessitates molecular identification of the guild in environmental studies. Over the past decades, rapid development and affordability of molecular tools have tremendously improved insights of the fungal diversity in all ecosystems and habitats. Yet, in spite of the progress of molecular methods, knowledge about functional properties of the fungal taxa is vague and interpretation of environmental studies in an ecologically meaningful manner remains challenging. In order to facilitate functional assignments and ecological interpretation of environmental studies we introduce a user friendly traits and character database FungalTraits operating at genus and species hypothesis levels. Combining the information from previous efforts such as FUNGuild and Fun(Fun) together with involvement of expert knowledge, we reannotated 10,210 and 151 fungal and Stramenopila genera, respectively. This resulted in a stand-alone spreadsheet dataset covering 17 lifestyle related traits of fungal and Stramenopila genera, designed for rapid functional assignments of environmental studies. In order to assign the trait states to fungal species hypotheses, the scientific community of experts manually categorised and assigned available trait information to 697,413 fungal ITS sequences. On the basis of those sequences we were able to summarise trait and host information into 92,623 fungal species hypotheses at 1% dissimilarity threshold

Identification of microorganisms in silver birch Betula pendula Roth discoloured wood and possible interaction with physiological and biochemical processes in wood

Latvijā āra bērzs Betula pendula Roth ir ekonomiski nozīmīgākais lapu koks, kuram vizuāli defekti ir nevēlami, īpaši finiera ražošanā. Sarkanbrūnais iekrāsojums stumbrā ir visizplatītākais vizuālā defekta veids. Pētījuma mērķi bija turpināt apzināt un pielāgot metodes iekrāsojuma pētīšanai, cenšoties galveno uzsvaru likt uz molekulārajām metodēm, piemēram, mikroorganismu profilēšanu, kas ļāva iekrāsotā koksnē identificēt tādas sugas un ģintis kā Pholiota squarrosa, Pholiota multicingulata, Agrocybe rivulosa, Cadophora fastigiata, Helotiales sp., Phialophora sp., Trametes versicolor. Iekrāsojumu mēdz uzskatīt kā koksnes trupes sākuma stadiju, tomēr pētījuma laikā trupējuši stumbri dažāda vecuma bērziem tika reti novēroti. Pētījuma ietvaros iekrāsojumu dabiskās audzēs novēroja vidēji 65,5 % no visiem apskatītajiem kokiem. Inokulācijas norādīja uz iekrāsojumu veidošanos arī no ievainojumiem, kuri sākotnēji netika inficēti. Nosakot koksnes kopējo fenolu daudzumu spektrofotometriski, secināja, ka iekrāsotā koksne saturēja lielāku kopējo fenolu daudzumu nekā neiekrāsotā. Ievērojams daudzums mikroorganismu, t.i., sēņu un baktēriju spēj gan degradēt koksni, gan dzīvot tajā, neizraisot bojājumus. Mikroorganismu mijiedarbība ar dzīvajiem audiem ir komplekss process, kurā var būt iesaistītas daudzas un dažādas fizioloģiskas un bioķīmiskas norises laika gaitā. Viens no pētījuma mērķiem bija apskatīt būtiskāko un aktuālāko literatūru, lai varētu spriest par šo procesu gaitu un iespējamu pielāgošanu saistībā ar iekrāsojuma efektu. Tāpēc darba beigās ir sniegts neliels apraksts faktoriem, kurus būtu jāņem vērā, plānojot detalizētu pētījumu par iekrāsojumu, piemēram, vai pastāv āra bērzu ķīmisko tipu, genotipu un iekrāsojuma savstarpēja saistība. Darbs tika izstrādāts Latvijas Valsts Mežzinātnes institūtā „Silava” Ģenētisko Resursu centrā laika posmā no 2012. gada jūnija līdz 2015. gada maijam.In Latvia white birch Betula pendula Roth is one of the most important deciduous tree species. Visual wood defects are not desirable especially in plywood manufacturing. One of the most common defects is reddish to brownish discolouration in the pith. The aim of the research was to continue adaptation of the methods for investigation of discolouration, focusing on molecular methods such as denaturing gradient gel electrophoresis, which allowed to identify fungi in discoloured wood in this study. These fungi were: Pholiota squarrosa, Pholiota multicingulata, Agrocybe rivulosa, Cadophora fastigiata, Helotiales sp., Phialophora sp., Trametes versicolor. It is believed that discolouration is related to decay of the wood at the early stages. In this study discolouration was observed in 65,5 % of all trees. Inoculation showed that discolouration can be initiated even from wounds without infection. Total phenols were measured in discoloured wood. Results showed that discoloured wood contained six times more total phenols than nondiscoloured wood. A significant amount of microorganisms can degrade wood as well as live in it without any harm. Interaction between microorganisms and living wood can include many different biochemical and physiological reactions. One of the aim of this research was to study most relevant publications in order to get sufficient insight about processes related to discolouration and possible ways to avoid it. At the end of this study there is discussion about various factors which may be considered if detailed study about discolouration would be established. The study was carried out in Latvian State Forest Research Institute "Silava", Genetic Resources Centre, from June 2012 until May 2014

Variation in the Mercury Concentrations and Greenhouse Gas Emissions of Pristine and Managed Hemiboreal Peatlands

We assessed total mercury (THg) concentrations and greenhouse gas (GHG) emissions in pristine and managed hemiboreal peatlands in Latvia, aiming to identify environmental factors that potentially affect their variation. The THg concentrations in soil ranged from −1 to 194.4 µg kg−1. No significant differences between THg concentrations in disturbed and undisturbed peatlands were found, however, the upper soil layer in the disturbed sites had significantly higher THg concentration. During May–August, the mean CO2 emissions (autotrophic and heterotrophic respiration) from the soil ranged from 20.1 ± 5.0 to 104.6 ± 22.7 mg CO2-C m−2 h−1, N2O emissions ranged from −0.97 to 13.4 ± 11.6 µg N2O-N m−2 h−1, but the highest spatial variation was found for mean CH4 emissions—ranging from 30.8 ± 0.7 to 3448.9 ± 1087.8 µg CH4-C m−2 h−1. No significant differences in CO2 and N2O emissions between disturbed and undisturbed peatlands were observed, but CH4 emissions from undisturbed peatlands were significantly higher. Complex impacts of environmental factors on the variation of THg concentrations and GHG emissions were identified, important for peatland management to minimize the adverse effects of changes in the biogeochemical cycle of the biophilic elements of soil organic matter and contaminants, such as Hg