Effect of the temperature and the exclusion of UVB radiation on the phenolics and iridoids in Menyanthes trifoliata L. leaves in the subarctic

The long-term effects of UVB exclusion and temperature on the methanol extractable (ME) phenolics (flavonoids, phenolic acids) and iridoids of Menyanthes trifoliata L. (Mt) leaves were studied in northern Finland (68°N) using wooden frames covered with filters for UVB exclusion (polyester filter), control (cellulose acetate filter) and ambient (no filter) conditions. Analysis of ambient plots showed no effect of the daily mean temperature (2σ = 1.58 °C) on the leaf ME compound content and composition, but minimum temperatures decreased the flavonol content. UVB exclusion did not affect the total ME compound content but significantly decreased the proportion of flavonols concomitantly with an increase in iridoids. Due to its high iridoid content, Mt appears as an interesting model plant for studying the iridoid biosynthesis and its regulation under stress conditions.     

Dissipation of four forest-use herbicides at high latitudes

Background, aim, and scope  Large-scale deforestation is occurring in subarctic North America following clearing by salvage logging or insect attack. Numerous shrubs, herbs, and deciduous tree species tend to dominate areas on which stands of white spruce have grown. In the absence of economically advantageous mechanical methods, several herbicides have value in efforts to reforest by planting white spruce. Glyphosate, imazapyr, triclopyr, and hexazinone are all capable of selectively removing many competing species, but there is concern about whether they would degrade naturally or persist owing to the frigid climate. Materials and methods  We established test plots with all four herbicides in upland and river bottom sites at 65°N and 58°N latitudes. The northern site has extremely cold winters, with soils that freeze to a depth of 1–2 m, and precipitation of 275 mm/year. The southern site has heavy rain and snowfall, amounting to 2,250 mm/year evenly distributed. Soil seldom freezes deeply. On each test plot, one of the four herbicides was applied at twice the normal operational use rate to facilitate detection. They were applied at the normal timing, with hexazinone, imazapyr, and triclopyr applied in June and glyphosate applied in fall. Soils were sampled immediately after treatment and those samples used as references for dissipation data gathered over the next 11–14 months from soil 0- to 15- and 15- to 45-cm depths. Results  Dissipation rates did not follow first-order rates because freezing conditions slowed most microbial activity. All products dissipated to close to or below detection limits within the time of the study. Dissipation from vegetation was substantially more rapid and depended on the nature of the plants treated as well as the product used. While soil residues dissipated more slowly than in temperate regions, they did display consistent dissipation patterns during above-freezing conditions and also the influence of microbial activity. Mobility was very limited with all products but hexazinone. Discussion  These products dissipate during summer in high latitudes much as they would in temperate climates. Winter changes are small, but are not unlike some changes reported elsewhere under freezing conditions. Unlike many other studies, soil water did not influence dissipation heavily, but the high latitude and semi-arid climate also did not create severely droughty soils. Residues in plants were much higher than those in soils, but denatured the vegetation quickly, leading to unsuitability for forage in any case. Conclusions  Low toxicity of these products and their metabolites combined with consistent dissipation and low mobility suggest that toxic hazard of their use at high latitudes need not be a matter of serious concern to humans, terrestrial wildlife, or aquatic systems. They are safe for use in management and rehabilitation of boreal forests when used properly. Recommendations and perspectives  Dissipation at rates approaching those in warmer climates offer a hypothesis that microflora native to high latitudes may be adapted to destruction of such molecules at lower temperatures than may be indicated by experiments with microflora adapted to warmer climates. Residues pose no observable risk to wildlife or humans in the area of use when products are applied properly. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available for authorized users.     

Relict Crustaceans under Conditions of Long-Term Pollution of Subarctic Lake Imandra: Results of Observations in 1930–1998

Changes in the role of relict crustaceans in the zoobenthic communities of large subarctic Lake Imandra are analyzed over the long period of economic development in its drainage area. To date, Mysis relicta as a species highly sensitive to anthropogenic pollution has apparently disappeared from the lake fauna. The currently recorded maximum values of Pontoporeia affinis abundance and biomass are more than 20 times as great as those between 1968 and 1986. As in other lakes with mass development of P. affinis, the populations of this crustacean inhibit chironomid larvae in the communities of Lake Imandra.     

Influence of solar UV radiation on the nitrogen metabolism in needles of Scots pine (Pinus sylvestris L.)

Needles of 20-year-old Scots pine (Pinus sylvestris L.) saplings were studied in an ultraviolet (UV) exclusion field experiment (from 2000 to 2002) in northern Finland (67 °N). The chambers held filters that excluded both UV-B and UV-A, excluded UV-B only, transmitted all UV (control), or lacked filters (ambient). UV-B/UV-A exclusion decreased nitrate reductase (NR) activity of 1-year-old needles of Scots pines compared to the controls. The proportion of free amino acids varied in the range 1.08-1.94% of total proteins, and was significantly higher in needles of saplings grown under UV-B/UV-A exclusion compared to the controls or UV-B exclusion. NR activity correlated with air temperature, indicating a “chamber effect”. The study showed that both UV irradiance and increasing temperature are significant modulators of nitrogen (N) metabolism in Scots pine needles.     

Observed cold season changes in a Fennoscandian fell area over the past three decades

We studied trends and variability in snow and climate characteristics in 1978–2012 in the Värriötunturit fell area, northern Finland. Cold season changes were examined using long-term observational data on snow depths, meteorological data, large-scale climate indices, and reindeer herders’ experiences with difficult snow conditions. Snow depths declined, and temperatures increased significantly over the study period, with the largest changes observed in October–December and in April. Snow depths decreased particularly in forests at lower altitudes but not in treeless areas at higher altitudes. Interannual variability (but not the trends) in snow depths could be partially linked to large-scale climate indices. A majority of difficult reindeer grazing conditions were related to deep snow in the winter or spring. Our observations suggest that shortened duration of snow cover may facilitate reindeer grazing, whereas potentially more frequent formation of ice layers and mold growth on pastures in the future is disadvantageous for reindeer husbandry.     

Analysis of anaerobic BTX biodegradation in a subarctic aquifer using isotopes and benzylsuccinates

In situ biodegradation of benzene, toluene, and xylenes in a petroleum hydrocarbon contaminated aquifer near Fairbanks, Alaska was assessed using carbon and hydrogen compound specific isotope analysis (CSIA) of benzene and toluene and analysis of signature metabolites for toluene (benzylsuccinate) and xylenes (methylbenzylsuccinates). Carbon and hydrogen isotope ratios of benzene were between -25.9 per thousand and -26.8 per thousand for delta13C and -119 per thousand and -136 per thousand for delta2H, suggesting that biodegradation of benzene is unlikely at this site. However, biodegradation of both xylenes and toluene were documented in this subarctic aquifer. Biodegradation of xylenes was indicated by the presence of methylbenzylsuccinates with concentrations of 17-50 microg/L in three wells. Anaerobic toluene biodegradation was also indicated by benzylsuccinate concentrations of 10-49 microg/L in the three wells with the highest toluene concentrations (1500-5000 microg/L toluene). Since benzylsuccinate typically accounts for a very small fraction of the toluene present in groundwater (generally <1 mol%), the signature metabolite approach works best at higher toluene concentrations when it is not constrained by detection limits. In wells with lower toluene concentrations (410-640 microg/L), carbon and hydrogen isotopic values were enriched by up to approximately 2 per thousand for delta13C and approximately 70 per thousand for delta2H. This evidence of isotopic fractionation verifies the effects of biodegradation in these low concentration wells where metabolites may already be below detection limits. The combined use of signature metabolite and CSIA data is particularly valuable given the challenge of verifying biodegradation in subarctic environments where degradation rates are typically much slower than in temperate environments.     

Lake Temperature and Ice Cover Regimes in the Alaskan Subarctic and Arctic: Integrated Monitoring,Remote Sensing,and Modeling1

Arp, C.D., B.M. Jones, M. Whitman, A. Larsen, and F.E. Urban, 2010. Lake Temperature and Ice Cover Regimes in the Alaskan Subarctic and Arctic: Integrated Monitoring, Remote Sensing, and Modeling. Journal of the American Water Resources Association (JAWRA) 46(4): 777-791. DOI: 10.1111/j.1752-1688.2010.00451.x Abstract: Lake surface regimes are fundamental attributes of lake ecosystems and their interaction with the land and atmosphere. High latitudes may be particularly sensitive to climate change, however, adequate baselines for these lakes are often lacking. In this study, we couple monitoring, remote sensing, and modeling techniques to generate baseline datasets of lake surface temperature and ice cover in the Alaskan Subarctic and Arctic. No detectable trends were observed during this study period, but a number of interesting patterns were noted among lakes and between regions. The largest Arctic lake was relatively unresponsive to air temperature, while the largest Subarctic lake was very responsive likely because it is fed by glacial runoff. Mean late summer water temperatures were higher than air temperatures with differences ranging from 1.7 to 5.4°C in Subarctic lakes and from 2.4 to 3.2°C in Arctic lakes. The warmest mean summer water temperature in both regions was in 2004, with the exception of Subarctic glacially fed lake that was highest in 2005. Ice-out timing had high coherence within regions and years, typically occurring in late May in Subarctic and in early-July in Arctic lakes. Ice-on timing was more dependent on lake size and depth, often varying among lakes within a region. Such analyses provide an important baseline of lake surface regimes at a time when there is increasing interest in high-latitude water ecosystems and resources during an uncertain climate future.     

Evidence for the existence of a high-altitude white wagtail (Motacilla alba) population in the Yamal peninsula and the boundaries of its distribution

It has been shown that the white wagtail at the northern limit of its range forms a population or a group of populations with a high degree of independence from conditions of illumination (photoperiod) in the Subarctic and southern Arctic. The boundary between the tundra and boreal populations in Yamal lies in the forest-tundra: wagtails of the tundra population nest north of the 68th parallel, and wagtails of the boreal population nest south of the 66th parallel. The zone between these latitudes is inhabited by representatives of both populations, and active hybridization apparently takes place there.