Small spatial variability in methane emission measured from a wet patterned boreal bog

We measured methane fluxes of a patterned bog situated in Siikaneva in southern Finland from six different plant community types in three growing seasons (2012-2014) using the static chamber method with chamber exposure of 35 min. A mixed-effects model was applied to quantify the effect of the controlling factors on the methane flux. The plant community types differed from each other in their water level, species composition, total leaf area (LAI(TOT)) and leaf area of aerenchymatous plant species (LAI(AER)). Methane emissions ranged from -309 to 1254 mg m(-2) d(-1). Although methane fluxes increased with increasing peat temperature, LAI(TOT) and LAI(AER), they had no correlation with water table or with plant community type. The only exception was higher fluxes from hummocks and high lawns than from high hummocks and bare peat surfaces in 2013 and from bare peat surfaces than from high hummocks in 2014. Chamber fluxes upscaled to ecosystem level for the peak season were of the same magnitude as the fluxes measured with the eddy covariance (EC) technique. In 2012 and in August 2014 there was a good agreement between the two methods; in 2013 and in July 2014, the chamber fluxes were higher than the EC fluxes. Net fluxes to soil, indicating higher methane oxidation than production, were detected every year and in all community types. Our results underline the importance of both LAI(AER) and LAI(TOT) in controlling methane fluxes and indicate the need for automatized chambers to reliably capture localized events to support the more robust EC method.Peer reviewe

Pohjois-Savon ja Pohjois-Karjalan lehtojen kasvillisuusmuutokset 45 vuoden aikana

Tiivistelmä. Tutkin pro gradu -tutkielmassani lehtokasvillisuuden muutoksia 45 vuoden aikana uudelleenotanta-aineiston avulla. Tarkoitukseni on kartoittaa Pohjois-Savon lehtokeskuksen sekä Pohjois-Karjalan Kolin lähialueiden tutkimusaloilla tapahtuneita muutoksia kasvillisuuden lajikoostumuksessa ja monimuotoisuudessa ajan, metsätalouden vaikutuksen ja havupuiden latvuspeittävyyden suhteen, sekä määrittää tutkimusalojen luontotyypit ja tarkastella alueita luontotyyppien uhanalaisuuden kannalta. Tutkimuskysymykseni ja hypoteesini ovat: 1. Onko lehtokasvillisuudessa tapahtunut muutoksia suhteessa aikaan, metsätalouden vaikutuksiin tai havupuiden latvuspeittävyyteen? Hypoteesi: Muutoksia on tapahtunut ajan, metsätalouden vaikutuksen ja havupuiden latvuspeittävyydessä tapahtuneiden muutosten seurauksena häiriötekijöiden lisääntymisen vaikuttaessa kasviyhteisöihin. 2. Ovatko muutokset suurempia siellä, missä metsätalouden vaikutus on suurempaa? Hypoteesi: Muutokset suurenevat metsätalouden vaikutuksen kasvaessa. 3. Ovatko kasviyhteisöjen muutokset niin suuria, että alkuperäiset luontotyypit olisivat muuttuneet? Hypoteesi: Alkuperäiset luontotyypit ovat saattaneet muuttua voimakkaimmin metsätalousvaikutteisilla paikoilla. Lähes puolet tutkimusaloista olivat voimakkaasti metsätalousvaikutteisia. Tuloksien perusteella tilastollisesti merkitseviä muutoksia on tapahtunut ainoastaan ajan ja havupuiden latvuspeittävyyden suhteen. Ajalla oli tilastollisesti merkitsevä vaikutus kasviyhteisöjen muutoksiin sekä kokonais- että sammalten alfadiversiteetin kasvamiseen. Lisäksi ajalla ja havupuiden latvuspeittävyydellä oli merkitsevä vaikutus putkilokasvien peittävyyteen; ajalla peittävyyttä lisäävästi ja havupuiden latvuspeittävyydellä sitä vähentävästi. Metsätaloudella ei ollut merkitsevää vaikutusta yhteisöjen lajistokoostumukseen, niiden monimuotoisuuteen tai kasviryhmien peittävyyksiin. Viidellä tutkimusalalla oli tapahtunut luontotyypin muutos; kahden alan luontotyyppi oli muuttunut kokonaan ja kolmella alalla vuosien välisiä luontotyyppimäärityksiä verrattaessa joko ravinteisuus tai kosteus oli muuttunut; ravinteisuus oli yhdellä alalla laskenut ja toisella alalla noussut ja kosteus oli yhdellä alalla laskenut. Kolme näistä luontotyypiltään muuttuneesta alasta oli voimakkaasti ja yksi lievästi metsätalousvaikutteisia. Tulosten perusteella ensimmäinen ja viimeinen hypoteesi saivat osittain tukea. Muutoksia on siis tapahtunut, mutta ne eivät ole suoraan johdettavissa metsätalousvaikutuksesta johtuviksi

Fine-resolution mapping of microforms of a boreal bog using aerial images and waveform-recording LiDAR

Boreal bogs are important stores and sinks of atmospheric carbon whose surfaces are characterised by vegetation microforms. Efficient methods for monitoring their vegetation are needed because changes in vegetation composition lead to alteration in their function such as carbon gas exchange with the atmosphere. We investigated how airborne image and waveform-recording LiDAR data can be used for 3D mapping of microforms in an open bog which is a mosaic of pools, hummocks with a few stunted pines, hollows, intermediate surfaces and mud-bottom hollows. The proposed method operates on the bog surface, which is reconstructed using LiDAR. The vegetation was classified at 20 cm resolution. We hypothesised that LiDAR data describe surface topography, moisture and the presence and depth of field-layer vegetation and surface roughness; while multiple images capture the colours and texture of the vegetation, which are influenced by directional reflectance effects. We conclude that geometric LiDAR features are efficient predictors of microforms. LiDAR intensity and echo width were specific to moisture and surface roughness, respectively. Directional reflectance constituted 4-34 % of the variance in images and its form was linked to the presence of the field layer. Microform-specific directional reflectance patterns were deemed to be of marginal value in enhancing the classification, and RGB image features were inferior to LiDAR variables. Sensor fusion is an attractive option for fine-scale mapping of these habitats. We discuss the task and propose options for improving the methodology.Peer reviewe

Plant mediated methane efflux from a boreal peatland complex

Purpose Aerenchymous plants are an important control for methane efflux from peatlands to the atmosphere, providing a bypass from the anoxic peat and avoiding oxidation in the oxic peat. We aimed to quantify the drivers of aerenchymous peatland species methane transport and the importance of this process for ecosystem-scale methane efflux. Methods We measured seasonal and interspecies variation in methane transport rate per gram of plant dry mass at a boreal fen and bog, which were upscaled to ecosystem-scale plant methane transport. Results Methane transport rate was better explained by plant species, leaf greenness and area than by environmental variables. Leaves appeared to transport methane even after senescence. Contrary to our expectations, both methane transport rate and the proportion of plant transport were lower in the fen (with greater sedge cover) than in the bog site. At the fen and bog, average methane transport rate was 0.7 and 1.8 mg g(-1) d(-1), and the proportion of seasonally variable plant transport was 7-41% and 6-90%, respectively. Species-specific differences in methane transport rate were observed at the ecosystem-scale: Scheuchzeria palustris, which accounted for 16% of the aerenchymous leaf area in the fen and displayed the greatest methane transport rate, was responsible for 45% of the ecosystem-scale plant transport. Conclusion Our study showed that plant species influence the magnitude of ecosystem-scale methane emissions through their properties of methane transport. The identification and quantification of these properties could be the pivotal next step in predicting plant methane transport in peatlands.Peer reviewe

First Observation of a Spontaneously Matured Female European Eel (Anguilla anguilla)

This study reports on the first observation of a spontaneously matured female European eel. The 43-year-old eel, together with eleven other females, resided at an aquarium house since their capture in 2002 and stocking as glass eels in 1978. In June 2019, the girth of the belly of the female increased as a sign of oocyte maturation. The specimen had an estimated gonadosomatic index (GSI) of 47, only half of the oocytes were hydrated and matured, indicating that European eels are polycyclic batch spawners. The live eels of the cohort were still in the previtellogenic phase but their eye sizes were close to that of the matured eel. We hypothesize that substances released by other maturing and spawning fishes may have triggered puberty of the eel. This first observation, and the possibility of more eels maturing in the near future, provides a natural reference for the sexual maturation of the European eel.</p

Banking After Regulatory Reforms - Business as Usual?

The 5th joint SUERF/Bank of Finland joint conference was held in Helsinki on 13 June 2013. The general theme of the conference was to focus on the regulatory reforms after the global financial crisis and, in particular, how structural reforms of banking ("Volcker, Vickers and Liikanen") could still complement them. The working hypothesis for the conference was that regulatory changes are likely to affect banks' business models, and regulations on banks' structure would interfere with business models most directly. This volume comprises five chapters which are based on the key policy oriented presentations in the conference

HIMMELI v1.0: HelsinkI Model of MEthane buiLd-up and emIssion for peatlands

Wetlands are one of the most significant natural sources of methane (CH4) to the atmosphere. They emit CH4 because decomposition of soil organic matter in waterlogged anoxic conditions produces CH4, in addition to carbon dioxide (CO2). Production of CH4 and how much of it escapes to the atmosphere depend on a multitude of environmental drivers. Models simulating the processes leading to CH4 emissions are thus needed for upscaling observations to estimate present CH4 emissions and for producing scenarios of future atmospheric CH4 concentrations. Aiming at a CH4 model that can be added to models describing peatland carbon cycling, we developed a model called HIMMELI that describes CH4 build-up in and emissions from peatland soils. It is not a full peatland carbon cycle model but it requires the rate of anoxic soil respiration as input. Driven by soil temperature, leaf area index (LAI) of aerenchymatous peatland vegetation and water table depth (WTD), it simulates the concentrations and transport of CH4, CO2 and oxygen (O2) in a layered one-dimensional peat column. Here, we present the HIMMELI model structure, results of tests on the model sensitivity to the input data and to the description of the peat column (peat depth and layer thickness), and an intercomparison of the modelled and measured CH4 fluxes at Siikaneva, a peatland flux measurement site in Southern Finland. As HIMMELI describes only the CH4-related processes, not the full carbon cycle, our analysis revealed mechanisms and dependencies that may remain hidden when testing CH4 models connected to complete peatland carbon models, which is usually the case. Our results indicated that 1) the model is flexible and robust and thus suitable for different environments; 2) the simulated CH4 emissions largely depend on the prescribed rate of anoxic respiration; 3) the sensitivity of the total CH4 emission to other input variables, LAI and WTD, is mainly mediated via the O2 concentrations that affect the CH4 production and oxidation rates; 4) with given input respiration, the peat column description does not affect significantly the simulated CH4 emissions

How consistent are the transcriptome changes associated with cold acclimation in two species of the Drosophila virilis group?

This work was financially support by a Marie Curie Initial Training Network grant, “Understanding the evolutionary origin of biological diversity” (ITN-2008–213780 SPECIATION), grants from the Academy of Finland to A.H. (project 132619) and M.K. (projects 268214 and 272927), a grant from NERC, UK to M.G.R. (grant NE/J020818/1), and NERC, UK PhD studentship to D.J.P. (NE/I528634/1).For many organisms the ability to cold acclimate with the onset of seasonal cold has major implications for their fitness. In insects, where this ability is widespread, the physiological changes associated with increased cold tolerance have been well studied. Despite this, little work has been done to trace changes in gene expression during cold acclimation that lead to an increase in cold tolerance. We used an RNA-Seq approach to investigate this in two species of the Drosophila virilis group. We found that the majority of genes that are differentially expressed during cold acclimation differ between the two species. Despite this, the biological processes associated with the differentially expressed genes were broadly similar in the two species. These included: metabolism, cell membrane composition, and circadian rhythms, which are largely consistent with previous work on cold acclimation/cold tolerance. In addition, we also found evidence of the involvement of the rhodopsin pathway in cold acclimation, a pathway that has been recently linked to thermotaxis. Interestingly, we found no evidence of differential expression of stress genes implying that long-term cold acclimation and short-term stress response may have a different physiological basis.PostprintPeer reviewe