scholarly journals Post-fire vegetation succession in the Siberian subarctic tundra over 45 years

2019 ◽  
Author(s):  
Ramona J. Heim ◽  
Anna Bucharova ◽  
Leya Brodt ◽  
Johannes Kamp ◽  
Daniel Rieker ◽  
...  
Keyword(s):  
Soil Temperature ◽  
Vegetation Cover ◽  
The Arctic ◽  
Vegetation Recovery ◽  
Long Term Effects ◽  
Forest Tundra ◽  
Permafrost Thaw ◽  
Legacy Effect ◽  
Thaw Depth

AbstractWildfires are relatively rare in subarctic tundra ecosystems, but they can strongly change ecosystem properties. Short-term fire effects on subarctic tundra vegetation are well documented, but long-term vegetation recovery has been studied less. The frequency of tundra fires will increase with climate warming. Understanding the long-term effects of fire is necessary to predict future ecosystem changes.We used a space-for-time approach to assess vegetation recovery after fire over more than four decades. We studied soil and vegetation patterns on three large fire scars (>44, 28 and 12 years old) in dry, lichen-dominated forest tundra in Western Siberia. On 60 plots, we determined soil temperature and permafrost thaw depth, sampled vegetation and measured plant functional traits. We assessed trends in NDVI to support the field-based results on vegetation recovery.Soil temperature, permafrost thaw depth and total vegetation cover had recovered to pre-fire levels after >44 years, as well as total vegetation cover. In contrast, after >44 years, functional groups had not recovered to the pre-fire state. Burnt areas had lower lichen and higher bryophyte and shrub cover. The dominating shrub species, Betula nana, exhibited a higher vitality (higher specific leaf area and plant height) on burnt compared with control plots, suggesting a fire legacy effect in shrub growth. Our results confirm patterns of shrub encroachment after fire that were detected before in other parts of the Arctic and Subarctic. In the so far poorly studied Western Siberian forest tundra we demonstrate for the first time, long-term fire-legacies on the functional composition of relatively dry shrub- and lichen-dominated vegetation.

scholarly journals Изменение сукцессионных систем палеофитоценозов на границе межледниковья и ледниковья позднего эоплейстоцена в пыльцевой записи оз. Эльгыгытгын (Центральная Чукотка)

2021 ◽  
pp. 63-70
Author(s):  
E. Yu. Nedorubova ◽  
Keyword(s):  
Vegetation Cover ◽  
Sharp Increase ◽  
Abrupt Change ◽  
The Arctic ◽  
Meteorite Impact ◽  
Arctic Circle ◽  
Forest Tundra ◽  
Birch Trees ◽  
Lake El’Gygytgyn ◽  
Succession Processes

Lake El'gygytgyn is located beyond the Arctic Circle in Chukotka at 67°30' N, 172°05' E and formed following a meteorite impact that occurred 3.6 million years ago (core interval 45.79-43.65 m). In its sediments, 5 palinologic zones are distinguished; they reflect changes in paleosuccessional systems and are consistent with MIS 33, 32, and 31 (1.114-1.062 mya). During warmings, thickets of birch trees and alder were widely spread. Cliseries, caused by macroclimate changes in cold substages, are characterized by a significant reduction in tree and shrub vegetation as well as by expansion of the arctic and subarctic tundras. Grass tundras dominated and were replaced by forest tundra communities in the valleys of the Anadyr Plateau surrounding the lake. The most abrupt change of phytocenosis succession systems is observed at the border of 32 and 31 isotopic stages. The succession processes are primarily expressed in a sharp increase of birch-shrub communities in the vegetation cover and in the appearance of late succession edificators (Carpinus, Corylus, Myrica, Quercus) forming forest climax associations.

scholarly journals Long-term effects of snowmelt timing and climate warming on phenology, growth and reproductive effort of arctic tundra plant species

2021 ◽  
Author(s):  
Esther R. Frei ◽  
Greg H.R. Henry
Keyword(s):  
Plant Species ◽  
Reproductive Effort ◽  
High Arctic ◽  
Snow Accumulation ◽  
The Arctic ◽  
Plant Responses ◽  
Long Term Effects ◽  
Passive Warming ◽  
Species Specific

Arctic regions are particularly affected by rapidly rising temperatures and altered snow regimes. Snowmelt timing depends on spring temperatures and winter snow accumulation. Scenarios for the Arctic include both decreases and increases in snow accumulation. Predictions of future snowmelt timing are thus difficult and experimental evidence for ecological consequences is scarce. In 1995, a long-term factorial experiment was set up in a High Arctic evergreen shrub heath community on Ellesmere Island, Canada. We investigated how snow removal, snow addition and passive warming affected phenology, growth and reproductive effort of the four common tundra plant species <i>Cassiope tetragona</i>, <i>Dryas integrifolia</i>, <i>Luzula arctica</i> and <i>Papaver radicatum</i>. Timing of flowering and seed maturation as well as flower production were more strongly influenced by the combined effects of snowmelt timing and warming in the two shrub species than in the two herbaceous species. Warming effects persisted over the course of the growing season and resulted in increased shrub growth. Moreover, the long-term trend of increasing growth in two species suggests that ambient warming promotes tundra plant growth. Our results confirm the importance of complex interactions between temperature and snowmelt timing in driving species-specific plant responses to climate change in the Arctic.

scholarly journals Behavioral Response Study on Seismic Airgun and Vessel Exposures in Narwhals

2021 ◽  
Vol 8 ◽  
Author(s):  
Mads Peter Heide-Jørgensen ◽  
Susanna B. Blackwell ◽  
Outi M. Tervo ◽  
Adeline L. Samson ◽  
Eva Garde ◽  
...  
Keyword(s):  
Noise Exposure ◽  
Anthropogenic Activities ◽  
Travel Speed ◽  
The Arctic ◽  
Line Of Sight ◽  
Long Term Effects ◽  
Sound Exposure ◽  
Ice Coverage ◽  
Exposure Levels

One of the last pristine marine soundscapes, the Arctic, is exposed to increasing anthropogenic activities due to climate-induced decrease in sea ice coverage. In this study, we combined movement and behavioral data from animal-borne tags in a controlled sound exposure study to describe the reactions of narwhals, Monodon monoceros, to airgun pulses and ship noise. Sixteen narwhals were live captured and instrumented with satellite tags and Acousonde acoustic-behavioral recorders, and 11 of them were exposed to airgun pulses and vessel sounds. The sound exposure levels (SELs) of pulses from a small airgun (3.4 L) used in 2017 and a larger one (17.0 L) used in 2018 were measured using drifting recorders. The experiment was divided into trials with airgun and ship-noise exposure, intertrials with only ship-noise, and pre- and postexposure periods. Both trials and intertrials lasted ∼4 h on average per individual. Depending on the location of the whales, the number of separate exposures ranged between one and eight trials or intertrials. Received pulse SELs dropped below 130 dB re 1 μPa2 s by 2.5 km for the small airgun and 4–9 km for the larger airgun, and background noise levels were reached at distances of ∼3 and 8–10.5 km, respectively, for the small and big airguns. Avoidance reactions of the whales could be detected at distances &gt;5 km in 2017 and &gt;11 km in 2018 when in line of sight of the seismic vessel. Meanwhile, a ∼30% increase in horizontal travel speed could be detected up to 2 h before the seismic vessel was in line of sight. Applying line of sight as the criterion for exposure thus excludes some potential pre-response effects, and our estimates of effects must therefore be considered conservative. The whales reacted by changing their swimming speed and direction at distances between 5 and 24 km depending on topographical surroundings where the exposure occurred. The propensity of the whales to move towards the shore increased with increasing exposure (i.e., shorter distance to vessels) and was highest with the large airgun used in 2018, where the whales moved towards the shore at distances of 10–15 km. No long-term effects of the response study could be detected.

Short and long-term effects of fire and vegetation cover on four lizard species in Amazonian savannas

2020 ◽  
Author(s):  
Erika dos Santos Souza ◽  
Albertina P. Lima ◽  
William E. Magnusson ◽  
RICARDO ALEXANDRE KAWASHITA-RIBEIRO ◽  
Rodrigo Ferreira Fadini ◽  
...  
Keyword(s):  
Vegetation Cover ◽  
Long Term Effects ◽  
Short Term ◽  
Lizard Species ◽  
Random Factor ◽  
Positive Effects ◽  
Temporal Sampling ◽  
Short And Long Term ◽  
Main Effects

Ecological succession in tropical savannas is limited by seasonal fire, which affects habitat quality. Although fire may cause negligible or positive effects on animals occupying savannas, most short-term studies (months to a few years) are based on a single temporal sampling snapshot, and long-term studies (decades) are rare. We sampled four lizard species in Amazonian savannas to test the effects of fire and vegetation cover on lizard densities at two temporal scales. In the short-term, we use three sampling snapshots to test the effects of fire and vegetation cover on estimated lizard densities over the subsequent 1–5 years. In the long-term, we test the effects of fire and changes in vegetation cover over 21 years on current lizard density differences. In the short-term, species responses were usually consistent with foraging and thermoregulation modes. However, the results were not consistent among species and years, although the variances in species density explained by year as a random factor were generally low. In the long-term, the main effects of fire and vegetation cover show that lizard densities may change spatially, but not necessarily temporarily. Wildfire is a natural resource of savannas and apparently have little impact on resident lizards of that ecosystem.

scholarly journals Long-term effects of permafrost thaw

Nature ◽  
2016 ◽  
Vol 537 (7622) ◽  
pp. 625-626 ◽  
Author(s):  
Donatella Zona
Keyword(s):  
Long Term Effects ◽  
Permafrost Thaw

scholarly journals Long-term effects of fire and three firefighting chemicals on a soil - plant system

2011 ◽  
Vol 20 (7) ◽  
pp. 856 ◽  
Author(s):  
A. Couto-Vázquez ◽  
S. García-Marco ◽  
S. J. González-Prieto
Keyword(s):  
Soil Properties ◽  
Vegetation Cover ◽  
Ammonium Polyphosphate ◽  
Long Term Effects ◽  
Inorganic N ◽  
Noticeable Effect ◽  
Total N ◽  
Foaming Agent ◽  
Plant System

The effects of fire and firefighting chemicals on soil properties and the soil–plant system were evaluated 5 years after treatment application. Unburnt soils were compared with burnt soils treated with water alone (BS) or with foaming agent (BS+Fo), Firesorb polymer (BS+Fi), or ammonium polyphosphate (BS+Ap). Soils (0–2 cm depth) and foliar material (Ulex micranthus, Pterospartum tridentatum, Erica umbellata and Pinus pinaster) were analysed for total C, total N, δ15N, nutrients (soil-available; plant total), pH and inorganic-N (soils) and vegetation cover and height. No long-term effects of firefighting chemicals on soil properties were found except for pH (BS+Fo > BS+Ap), inorganic-N and P (BS+Ap > other treatments). BS+Ap plants usually showed higher values of δ15N, N, P and Na, but less K. Soil coverage by Pterospartum and Ulex was higher in BS+Ap than in other treatments, whereas the opposite was observed for Erica; shrubs were always taller in BS+Ap. After 3 years of growth, the size of pine seedlings followed the order BS+Ap > unburnt soil > other treatments. Foliar N and P, scrub regeneration and growth of pines showed the long-term fertilising effect of ammonium polyphosphate, although the second highest pine mortality was found in the BS+Ap treatment. The foaming agent did not affect vegetation cover, and Firesorb had no noticeable effect on shrubs but the highest pine mortality.

scholarly journals Constraint of soil moisture on CO<sub>2</sub> efflux from tundra lichen, moss, and tussock in Council, Alaska using a hierarchical Bayesian model

2014 ◽  
Vol 11 (4) ◽  
pp. 5903-5939
Author(s):  
Y. Kim ◽  
K. Nishina ◽  
N. Chae ◽  
S. Park ◽  
Y. Yoon ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Temperature ◽  
Co2 Emission ◽  
Emission Rate ◽  
Environmental Parameters ◽  
The Arctic ◽  
Co2 Efflux ◽  
Growing Seasons ◽  
Tundra Ecosystem ◽  
Thaw Depth

Abstract. The tundra ecosystem is quite vulnerable to drastic climate change in the Arctic, and the quantification of carbon dynamics is of significant importance in response to thawing permafrost, changes in the snow-covered period and snow and shrub community extent, and the decline of sea ice in the Arctic. Here, CO2 efflux measurements using a manual chamber system within a 40 m × 40 m (5 m interval; 81 total points) plot were conducted in dominant tundra vegetation on the Seward Peninsula of Alaska, during the growing seasons of 2011 and 2012, for the assessment of the driving parameters of CO2 efflux. We applied a hierarchical Bayesian (HB) model – which is a function of soil temperature, soil moisture, vegetation type and thaw depth – to quantify the effect of environmental parameters on CO2 efflux, and to estimate growing season CO2 emission. Our results showed that average CO2 efflux in 2011 is 1.4-fold higher than in 2012, resulting from the distinct difference in soil moisture between the two years. Tussock-dominated CO2 efflux is 1.4 to 2.3 times higher than those measured in lichen and moss communities, reflecting tussock as a significant CO2 source in the Arctic, with wide area distribution on a circumpolar scale. CO2 efflux followed soil temperature nearly exponentially from both the observed data and the posterior medians of the HB model. This reveals soil temperature as the most important parameter in regulating CO2 efflux, rather than soil moisture and thaw depth. Obvious changes in soil moisture during the growing seasons of 2011 and 2012 resulted in an explicit difference in CO2 efflux – 742 and 539 g CO2 m−2 period−1 in 2011 and 2012, respectively, suggesting that the 2012 CO2 emission rate was constrained by 27% (95% credible interval: 17–36%) compared to 2011, due to higher soil moisture from severe rain. Estimated growing season CO2 emission rate ranged from 0.86 Mg CO2 period−1 in 2012 to 1.2 Mg CO2 period−1 in 2011 within a 40 m × 40 m plot, corresponding to 86% and 80% of the annual CO2 emission rates within the Alaska western tundra ecosystem. Therefore, the HB model can be readily applied to observed CO2 efflux, as it demands only four environmental parameters and can also be effective for quantitatively assessing the driving parameters of CO2 efflux.

scholarly journals Low Persistence of Genetic Rescue Across Generations in the Arctic Fox (Vulpes lagopus)

2021 ◽  
Author(s):  
Anna Lotsander ◽  
Malin Hasselgren ◽  
Malin Larm ◽  
Johan Wallén ◽  
Anders Angerbjörn ◽  
...  
Keyword(s):  
Time Perspective ◽  
Chromosome Analysis ◽  
Small Population ◽  
The Arctic ◽  
Vulpes Lagopus ◽  
Long Term Effects ◽  
Genetic Rescue ◽  
Isolated Populations ◽  
Individual Fitness

Abstract Genetic rescue can facilitate the recovery of small and isolated populations suffering from inbreeding depression. Long-term effects are however complex, and examples spanning over multiple generations under natural conditions are scarce. The aim of this study was to test for long-term effects of natural genetic rescue in a small population of Scandinavian Arctic foxes (Vulpes lagopus). By combining a genetically verified pedigree covering almost 20 years with a long-term dataset on individual fitness (n = 837 individuals), we found no evidence for elevated fitness in immigrant F2 and F3 compared to native inbred foxes. Population inbreeding levels showed a fluctuating increasing trend and emergence of inbreeding within immigrant lineages shortly after immigration. Between 0–5 and 6–9 years post immigration, the average number of breeding adults decreased by almost 22% and the average proportion of immigrant ancestry rose from 14% to 27%. Y chromosome analysis revealed that 2 out of 3 native male lineages were lost from the gene pool, but all founders represented at the time of immigration were still contributing to the population at the end of the study period through female descendants. The results highlight the complexity of genetic rescue and suggest that beneficial effects can be brief. Continuous gene flow may be needed for small and threatened populations to recover and persist in a longer time perspective.

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