Reindeer grazing history determines the responses of subarctic soil fungal communities to warming and fertilization

Composition and functioning of arctic soil fungal communities may alter rapidly due to the ongoing trends of warmer temperatures, shifts in nutrient availability and shrub encroachment. In addition, the communities may also be intrinsically shaped by heavy grazing, which may locally induce an ecosystem change that couples with increased soil temperature and nutrients and where shrub encroachment is less likely to occur than in lightly grazed conditions. We tested how four years of experimental warming and fertilization affected organic soil fungal communities in sites with decadal history of either heavy or light reindeer grazing using high-throughput sequencing of ITS2 rDNA region. Grazing history largely overrode the impacts of short-term warming and fertilization in determining the composition of fungal communities. The less diverse fungal communities under light grazing showed more pronounced responses to experimental treatments when compared to the communities under heavy grazing. Yet, ordination approaches revealed distinct treatment responses under both grazing intensities. If grazing shifts the fungal communities in Arctic ecosystems to a different and more diverse state, this shift may dictate ecosystem responses to further abiotic changes. This inclines that the intensity of grazing cannot be left out when predicting future changes in fungi-driven processes in the tundra

Identification of Genomic Regions Associated with Phenotypic Variation between Dog Breeds using Selection Mapping

Peer reviewe

Bacterial and fungal communities in sub-Arctic tundra heaths are shaped by contrasting snow accumulation and nutrient availability

Climate change is affecting winter snow conditions significantly in northern ecosystems but the effects of the changing conditions for soil microbial communities are not well-understood. We utilized naturally occurring differences in snow accumulation to understand how the wintertime subnivean conditions shape bacterial and fungal communities in dwarf shrub-dominated sub-Arctic Fennoscandian tundra sampled in mid-winter, early, and late growing season. Phospholipid fatty acid (PLFA) and quantitative PCR analyses indicated that fungal abundance was higher in windswept tundra heaths with low snow accumulation and lower nutrient availability. This was associated with clear differences in the microbial community structure throughout the season. Members of Clavaria spp. and Sebacinales were especially dominant in the windswept heaths. Bacterial biomass proxies were higher in the snow-accumulating tundra heaths in the late growing season but there were only minor differences in the biomass or community structure in winter. Bacterial communities were dominated by members of Alphaproteobacteria, Actinomycetota, and Acidobacteriota and were less affected by the snow conditions than the fungal communities. The results suggest that small-scale spatial patterns in snow accumulation leading to a mosaic of differing tundra heath vegetation shapes bacterial and fungal communities as well as soil carbon and nutrient availability.peerReviewe

Reindeer grazing history determines the responses of subarctic soil fungal communities to warming and fertilization

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Removal of grazers alters the response of tundra soil carbon to warming and enhanced nitrogen availability

The circumpolar Arctic is currently facing multiple global changes that have the potential to alter the capacity of tundra soils to store carbon. Yet, predicting changes in soil carbon is hindered by the fact that multiple factors simultaneously control processes sustaining carbon storage and we do not understand how they act in concert. Here, we investigated the effects of warmer temperatures, enhanced soil nitrogen availability, and the combination of these on tundra carbon stocks at three different grazing regimes: on areas with over 50-yr history of either light or heavy reindeer grazing and in 5-yr-old exlosures in the heavily grazed area. In line with earlier reports, warming generally decreased soil carbon stocks. However, our results suggest that the mechanisms by which warming decreases carbon storage depend on grazing intensity: under long-term light grazing soil carbon losses were linked to higher shrub abundance and higher enzymatic activities, whereas under long-term heavy grazing, carbon losses were linked to drier soils and higher enzymatic activities. Importantly, under enhanced soil nitrogen availability, warming did not induce soil carbon losses under either of the long-term grazing regimes, whereas inside exclosures in the heavily grazed area, also the combination of warming and enhanced nutrient availability induced soil carbon loss. Grazing on its own did not influence the soil carbon stocks. These results reveal that accounting for the effect of warming or grazing alone is not sufficient to reliably predict future soil carbon storage in the tundra. Instead, the joint effects of multiple global changes need to be accounted for, with a special focus given to abrupt changes in grazing currently taking place in several parts of the Arctic

Streams and riparian forests depend on each other:a review with a special focus on microbes

Abstract In this review, we draw together the research on the two-way connection of streams and their riparian forests of the boreal zone from ecological points of view. Although the knowledge about stream-riparian interactions has increased considerably recently, in practice, riparian zones are still mainly seen as buffers for nutrient and sediment loading. However, recent research has shown that riparian forests disproportionately foster regional biodiversity and maintain stream ecosystem functions and diversity. On the other hand, streams contribute to riparian diversity and ecosystem functions. Microbes are key drivers of global biochemical cycles, and they also interact with plants and animals. The knowledge on microbial communities and understanding of processes they drive has considerably increased due to recent development in microbial profiling methods. However, microbes have been largely neglected in former reviews. Thus, this overview has a special focus on the role of microorganisms in controlling stream-riparian interaction. We also review the land-use pressures that are threatening biodiversity and ecosystem processes of riparian zones in forested landscapes. In addition, we review the possible effects of climate change on stream-riparian interactions. Finally, we outline the research gaps that call for future research

Removal of grazers alters the response of tundra soil carbon to warming and enhanced nitrogen availability

Abstract The circumpolar Arctic is currently facing multiple global changes that have the potential to alter the capacity of tundra soils to store carbon. Yet, predicting changes in soil carbon is hindered by the fact that multiple factors simultaneously control processes sustaining carbon storage and we do not understand how they act in concert. Here, we investigated the effects of warmer temperatures, enhanced soil nitrogen availability, and the combination of these on tundra carbon stocks at three different grazing regimes: on areas with over 50‐yr history of either light or heavy reindeer grazing and in 5‐yr‐old exlosures in the heavily grazed area. In line with earlier reports, warming generally decreased soil carbon stocks. However, our results suggest that the mechanisms by which warming decreases carbon storage depend on grazing intensity: under long‐term light grazing soil carbon losses were linked to higher shrub abundance and higher enzymatic activities, whereas under long‐term heavy grazing, carbon losses were linked to drier soils and higher enzymatic activities. Importantly, under enhanced soil nitrogen availability, warming did not induce soil carbon losses under either of the long‐term grazing regimes, whereas inside exclosures in the heavily grazed area, also the combination of warming and enhanced nutrient availability induced soil carbon loss. Grazing on its own did not influence the soil carbon stocks. These results reveal that accounting for the effect of warming or grazing alone is not sufficient to reliably predict future soil carbon storage in the tundra. Instead, the joint effects of multiple global changes need to be accounted for, with a special focus given to abrupt changes in grazing currently taking place in several parts of the Arctic

Reindeer grazing history determines the responses of subarctic soil fungal communities to warming and fertilization

Summary Composition and functioning of arctic soil fungal communities may alter rapidly due to the ongoing trends of warmer temperatures, shifts in nutrient availability, and shrub encroachment. In addition, the communities may also be intrinsically shaped by heavy grazing, which may locally induce an ecosystem change that couples with increased soil temperature and nutrients and where shrub encroachment is less likely to occur than in lightly grazed conditions. We tested how 4 yr of experimental warming and fertilization affected organic soil fungal communities in sites with decadal history of either heavy or light reindeer grazing using high-throughput sequencing of the internal transcribed spacer 2 ribosomal DNA region. Grazing history largely overrode the impacts of short-term warming and fertilization in determining the composition of fungal communities. The less diverse fungal communities under light grazing showed more pronounced responses to experimental treatments when compared with the communities under heavy grazing. Yet, ordination approaches revealed distinct treatment responses under both grazing intensities. If grazing shifts the fungal communities in Arctic ecosystems to a different and more diverse state, this shift may dictate ecosystem responses to further abiotic changes. This indicates that the intensity of grazing cannot be left out when predicting future changes in fungi-driven processes in the tundra

Arktisten alueiden typpi- ja raskasmetallipitoisten valumavesien puhdistaminen hybridipuhdistusratkaisuilla (TypArkt) -hankkeen loppuraportti

Abstract In Finland, many human-derived processes, including mining, municipal wastewater treatment, urban runoff, agriculture, forestry and peat extraction, lead to nitrogen and/or heavy metal loads to recipient water bodies. It is often not cost-effective to build active water treatment units for many of these operations. This is true e.g., for mining operations (especially after mine closure), municipalities producing small amounts of wastewater (e.g., in holiday resorts), urban runoffs, peat extraction and agriculture. When active treatment options are not economically feasible, passive treatment options (bioreactors, moss pools) in various combinations with active treatment can be used to treat the water in a cost-efficient manner. It is expected that the demand for passive treatment options will increase in the future, because the quality limits required in water purification are being tightened and there is a need for year-round control of contaminant load to recipient water bodies. In the TypArkt-project, the year-round monitoring of the hybrid purification systems built for the Pyhäsalmi mine in 2018 and in 2019 for the Kallo village wastewater treatment plant in Kittilä municipality has been continued to obtain longer-term performance data. In addition, the pilot structure designed for Levi’s stormwater treatment has been monitored, along with the mixed woodchip bioreactor built by the mine in October 2022 at the Kevitsa mine. Based on the results, target metals can be well removed in Pyhäsalmi in the hybrid purification system, when the last part of the hybrid purification unit, wetland is left out from the study. However, the wetland, and especially the root clumps of lake sediment brought there from a metal-contaminated area, cause an increase in the concentration of metals when the water flows through the wetland. In the hybrid purification structure of Kallo village’s wastewater treatment plant, nitrogen can be removed by an average of slightly more than 30%, which is very good compared to the initial situation, where there was practically no removal at all. In Levi’s stormwater treatment, there has been a small purification box with moss and mushroom-woodchip units, and there are clear reductions in the concentration of nitrite+nitrate nitrogen, but there is variation of purification efficiency between the sampling times in terms of the small concentrations of metals. Nitrogen can be removed in the woodchip bioreactor built at the Kevitsa mine. As a conclusion from the research results, it can be said that the retention of iron, in particular, requires a large settling tank volume. Birch-woodchip bioreactors in the purification units have worked well in the removal of both metals and nitrate nitrogen, and the community of sulfate-reducing bacteria in the bioreactor has formed over time. Moss accumulates metals in its biomass, e.g., the content of iron in dry biomass increased approximately 8 times in 14 months, and mushroom shavings accumulate metals especially over the long term. At the wetland, it is important to pay attention to the cleanliness of the materials brought there.Tiivistelmä Suomessa ja erityisesti myös Suomen pohjoisosissa kylmissä olosuhteissa on monenlaista typpi ja/tai raskasmetallipitoista kuormitusta aiheuttavaa ihmistoimintaa, kuten kaivostoiminta ja jätevedenpuhdistamot. Erilaisia aktiivisia ja asianmukaisia vedenpuhdistusmenetelmiä on käytössä erityisesti toiminnassa olevilla kaivoksilla ja isoilla jätevedenpuhdistamoilla. Kustannusten vuoksi ei kaikkialle kuitenkaan ole järkevää rakentaa kokonaan aktiivista menetelmää vaan erilaiset passiivisten menetelmien (esim. bioreaktorit, sammalaltaat) sekä passiivisten ja aktiivisten menetelmien yhdistelmät voivat olla toimivia ratkaisuja esim. kaivosten jälkikäyttövaiheeseen, muutaman talon kyläyhteisön tai lomakylän jätevesienkäsittelyyn tai taajamien hulevesien käsittelyyn. Passiivisten puhdistusratkaisujen tarpeen ja kysynnän, yhdistettynä mahdollisesti aktiivisiin menetelmiin, odotetaan yhä kasvavan tulevaisuudessa, sillä vedenpuhdistukselle asetettavat vaatimukset tiukkenevat ja ympärivuotiselle kuormituksen hallinnalle on tarvetta. TypArkt-hankkeessa on jatkettu vuonna 2018 Pyhäsalmen kaivokselle ja vuonna 2019 Kittilän kunnan, Kallon kylän, jätevedenpuhdistamolle rakennettujen hybridipuhdistusratkaisujen ympärivuotista seurantaa pidempiaikaisen toimivuustiedon saamiseksi. Lisäksi on seurattu Levin hulevesien käsittelyyn suunniteltua pilottirakennetta, ja Kevitsan kaivokselle kaivoksen lokakuussa 2022 rakentamaa sekapuuhakebioreaktoria. Tulosten perusteella Pyhäsalmella saadaan hyvin poistettua tavoitemetalleja hybridipuhdistusrakenteessa, kun ei oteta huomioon hybridipuhdistusrakenteen viimeistä yksikköä, kosteikkoa. Kosteikko, ja erityisesti sinne metalleilla kontaminoituneelta alueelta tuodut järviruon juuripaakut, aiheuttavat kuitenkin metallien pitoisuuden lisääntymistä, kun vesi virtaa kosteikon läpi. Kallon kylän jätevedenpuhdistamon hybridipuhdistusrakenteessa saadaan typpeä poistumaan keskimäärin vähän yli 30 %, mikä on erittäin hyvä verrattuna lähtötilanteeseen, jossa poistumia ei käytännössä ollut juuri ollenkaan. Levin hulevesien käsittelyssä on ollut pieni puhdistuslaatikko sammal- ja sienihakeyksikköineen, ja siellä nitriitti+nitraattitypen pitoisuuden osalta saadaan selvästi vähenemiä, mutta metallien pienien pitoisuuksien vuoksi esiintyy vaihtelua näytteenottokertojen välillä. Kevitsan kaivokselle rakennetussa puuhakebioreaktorissa saadaan typpeä poistumaan. Johtopäätöksenä tutkimustuloksista voidaan sanoa, että erityisesti raudan pidättäminen vaatii isoa laskeutusallastilavuutta. Puhdistusyksiköissä koivupuuhakebioreaktorit ovat toimineet hyvin sekä metallien, että nitraattitypen poistossa ja sulfaatinpelkistäjäbakteeriyhteisö bioreaktoriin muodostuu ajan kanssa. Sammal kerryttää biomassaansa metalleja, esim. raudan pitoisuus kuivabiomassassa noussut noin 8 kertaiseksi 14 kk aikana, ja sienihake kerryttää etenkin pitkäaikaisesti metalleja. Kosteikolla on tärkeä kiinnittää huomiota sinne tuotavien materiaalien puhtauteen

Different endophyte communities colonize buds of sprouts compared with mature trees of mountain birch recovered from moth herbivory

Abstract Plant meristems were previously thought to be sterile. Today, meristem-associated shoot endophytes are mainly reported as contaminants from plant tissue cultures, the number of observed species being very low. However, the few strains characterized have the capacity for infecting host cells and affecting plant growth and development. Here we studied the communities of endophytic bacteria in the buds of mountain birch (Betula pubescens ssp. czerepanovii (N. I. Orlova) Hämet-Ahti) exposed to winter moth (Operophtera brumata L.) herbivory, to identify differences between sprouts and branches of mature birch trees. Mountain birch of the high subarctic is cyclically exposed to winter moth and produces sprouts to generate new trees as a survival mechanism. The majority (54%) of operational taxonomic units belonged to Xanthomonadaceae and Pseudomonales of Proteobacteria. Most of the observed species were classified as Xanthomonas (28%). Sprout buds had the highest diversity, containing approximately three times more species, and significantly more (43%) Pseudomonas species than the mature trees (14%). Our results demonstrate that endophytic communities of buds are richer than previously thought. We suggest that the meristem-associated endophytes should be studied further for a possible role in sprouting and aiding regeneration of trees