scholarly journals Towards rainy Arctic winters: experimental icing impacts tundra plant productivity and reproduction

2021 ◽  
Author(s):  
Mathilde Le Moullec ◽  
Anna-Lena Hendel ◽  
Matteo Petit Bon ◽  
Ingibjorg Svala Jonsdottir ◽  
Oystein Varpe ◽  
...  
Keyword(s):  
Primary Production ◽  
Plant Root ◽  
Vascular Plant ◽  
Combined Treatment ◽  
Growing Season ◽  
Community Level ◽  
The Arctic ◽  
General Effect ◽  
Trade Offs ◽  
Summer Warming

The Arctic is the most rapidly warming region on Earth, but our understanding of ecosystem impacts is still poor. For instance, warming occurs more than twice as fast in winter than in summer, yet long-term tundra vegetation studies have almost exclusively focused on effects of the latter. In winter, more frequent extreme warm spells and associated rain-on-snow events can dramatically alter snowpack conditions and even encapsulate the vegetation in basal ice for several months. Such icing effects on plant phenology, productivity and reproduction remain largely unexplored. We performed a novel five-year-long field experiment in which we simulated every winter a rain-on-snow event resulting in ice encasement of the vegetation, and assessed vascular plant responses in each subsequent growing season. We also tested whether these responses could be modified by summer warming (open top chambers). Icing delayed the dominant shrub`s phenology, in particular early leaf development and seed maturation, increased community-level primary production in the second half of the growing season, but also reduced flower production. These delays and allocation trade-offs were associated with a delay in sub-surface soil thawing and soil warming in spring/summer, conditions known to influence plant root activity and nutrient availability at high latitudes. Interestingly, summer warming mitigated effects of icing alone and the combined treatment showed advanced phenology, increased primary production across the growing season and reduced the negative effects on reproduction. In general, effect sizes of icing were as large as those observed for experimental summer warming alone. The community-level increase in primary production following icing is in sharp contrast with the recently proposed arctic browning effect of extreme winter warm spells in evergreen shrub-dominated tundra communities. Yet, the negative effect on reproductive traits can become critical for species viability if these events become chronic. As we are heading towards a rain-dominated Arctic, our findings highlight the need for coordinated monitoring of the effects of warmer and rainier winters across tundra plant communities and growth forms across the Arctic.

scholarly journals Habitat determines plant community responses to climate change in the High Arctic

2021 ◽  
Author(s):  
Martin A Mörsdorf ◽  
Elisabeth J Cooper
Keyword(s):  
Environmental Change ◽  
Plant Diversity ◽  
Snow Depth ◽  
Ambient Medium ◽  
Vascular Plant ◽  
Plant Species Richness ◽  
High Arctic ◽  
The Arctic ◽  
Summer Warming ◽  
Abundance And Diversity

Plant climate-responses may depend on site-specific environmental context. Using fences and open top chambers (OTCs), we enhanced snow depth (creating Ambient, Medium and Deep regimes) in Svalbard for 11 years and increased temperatures for two summers. Comparison of plant growth form abundance and diversity responses in two habitats showed that response was more limited in dry Heath than mesic Meadow. Common in both habitats was a decrease of shrub abundance and vascular plant species richness in Deep snow regimes. Bryophyte abundance increased with enhanced snow regimes in both habitats, but only up to a certain extent of snow depth in Meadow. However, for many growth forms the effects of snow enhancement were habitat-specific. In mesic Meadow the abundance of forbs and bryophytes increased with snow enhancement, but stronger so if combined with summer warming. The “bryofication”, i.e. an increased abundance of bryophytes in response to snow enhancement and summer warming, also influenced overall plant diversity in mesic Meadow. Bryophytes are species rich taxa and may respond differently than vascular plants to environmental change. We show that even the inclusion of the most common bryophytes into diversity measures may therefore determine overall plant diversity responses to environmental change in the Arctic.

scholarly journals Improving the knowledge of plant potential biodiversity-ecosystem services links using maps at the regional level in Southern Patagonia

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Yamina Micaela Rosas ◽  
Pablo L. Peri ◽  
María Vanessa Lencinas ◽  
Romina Lasagno ◽  
Guillermo J. Martínez Pastur
Keyword(s):  
Ecosystem Services ◽  
Plant Species ◽  
Vegetation Index ◽  
Vascular Plant ◽  
Conservation Strategies ◽  
Cultural Ecosystem Services ◽  
Important Indicator ◽  
Ecological Requirements ◽  
Trade Offs ◽  
Southern Patagonia

Abstract Background Biodiversity supports multiple ecosystem services, whereas species loss endangers the provision of many services and affects ecosystem resilience and resistance capacity. The increase of remote sensing techniques allows to estimate biodiversity and ecosystem services supply at the landscape level in areas with low available data (e.g. Southern Patagonia). This paper evaluates the potential biodiversity and how it links with ecosystem services, based on vascular plant species across eight ecological areas. We also evaluated the habitat plant requirements and their relation with natural gradients. A total of 977 plots were used to develop habitat suitability maps based on an environmental niche factor analysis of 15 more important indicator species for each ecological area (n = 53 species) using 40 explanatory variables. Finally, these maps were combined into a single potential biodiversity map, which was linked with environmental variables and ecosystem services supply. For comparisons, data were extracted and compared through analyses of variance. Results The plant habitat requirements varied greatly among the different ecological areas, and it was possible to define groups according to its specialization and marginality indexes. The potential biodiversity map allowed us to detect coldspots in the western mountains and hotspots in southern and eastern areas. Higher biodiversity was associated to higher temperatures and normalized difference vegetation index, while lower biodiversity was related to elevation and rainfall. Potential biodiversity was closely associated with supporting and provisioning ecosystem services in shrublands and grasslands in the humid steppe, while the lowest values were related to cultural ecosystem services in Nothofagus forests. Conclusions The present study showed that plant species present remarkable differences in spatial distributions and ecological requirements, being a useful proxy for potential biodiversity modelling. Potential biodiversity values change across ecological areas allowing to identify hotspots and coldspots, a useful tool for landscape management and conservation strategies. In addition, links with ecosystem services detect potential synergies and trade-offs, where areas with the lowest potential biodiversity are related to cultural ecosystem services (e.g. aesthetic values) and areas with the greatest potential biodiversity showed threats related to productive activities (e.g. livestock).

scholarly journals Can vegetation index track the interannual variation in gross primary production of temperate deciduous forests?

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Fan Liu ◽  
Chuankuan Wang ◽  
Xingchang Wang
Keyword(s):  
Primary Production ◽  
Vegetation Index ◽  
Near Infrared ◽  
Deciduous Forest ◽  
Gross Primary Production ◽  
Growing Season ◽  
Temperate Deciduous Forest ◽  
Near Infrared Reflectance ◽  
Modis Ndvi ◽  
Temperate Deciduous

Abstract Background Vegetation indices (VIs) by remote sensing are widely used as simple proxies of the gross primary production (GPP) of vegetation, but their performances in capturing the inter-annual variation (IAV) in GPP remain uncertain. Methods We evaluated the performances of various VIs in tracking the IAV in GPP estimated by eddy covariance in a temperate deciduous forest of Northeast China. The VIs assessed included the normalized difference vegetation index (NDVI), the enhanced vegetation index (EVI), and the near-infrared reflectance of vegetation (NIRv) obtained from tower-radiometers (broadband) and the Moderate Resolution Imaging Spectroradiometer (MODIS), respectively. Results We found that 25%–35% amplitude of the broadband EVI tracked the start of growing season derived by GPP (R2: 0.56–0.60, bias < 4 d), while 45% (or 50%) amplitudes of broadband (or MODIS) NDVI represented the end of growing season estimated by GPP (R2: 0.58–0.67, bias < 3 d). However, all the VIs failed to characterize the summer peaks of GPP. The growing-season integrals but not averaged values of the broadband NDVI, MODIS NIRv and EVI were robust surrogates of the IAV in GPP (R2: 0.40–0.67). Conclusion These findings illustrate that specific VIs are effective only to capture the GPP phenology but not the GPP peak, while the integral VIs have the potential to mirror the IAV in GPP.

scholarly journals Contrasting trends in sea ice and primary production in the Bering Sea and Arctic Ocean

2012 ◽  
Vol 69 (7) ◽  
pp. 1180-1193 ◽  
Author(s):  
Zachary W. Brown ◽  
Kevin R. Arrigo
Keyword(s):  
Sea Ice ◽  
Primary Production ◽  
Arctic Ocean ◽  
Bering Sea ◽  
Net Primary Productivity ◽  
Remote Sensing Data ◽  
Ice Cover ◽  
The Arctic ◽  
Light Limitation ◽  
The Bering Sea

Abstract Brown, Z. W., and Arrigo, K. R. 2012. Contrasting trends in sea ice and primary production in the Bering Sea and Arctic Ocean. – ICES Journal of Marine Science, 69: . Satellite remote sensing data were used to examine recent trends in sea-ice cover and net primary productivity (NPP) in the Bering Sea and Arctic Ocean. In nearly all regions, diminished sea-ice cover significantly enhanced annual NPP, indicating that light-limitation predominates across the seasonally ice-covered waters of the northern hemisphere. However, long-term trends have not been uniform spatially. The seasonal ice pack of the Bering Sea has remained consistent over time, partially because of winter winds that have continued to carry frigid Arctic air southwards over the past six decades. Hence, apart from the “Arctic-like” Chirikov Basin (where sea-ice loss has driven a 30% increase in NPP), no secular trends are evident in Bering Sea NPP, which averaged 288 ± 26 Tg C year−1 over the satellite ocean colour record (1998–2009). Conversely, sea-ice cover in the Arctic Ocean has plummeted, extending the open-water growing season by 45 d in just 12 years, and promoting a 20% increase in NPP (range 441–585 Tg C year−1). Future sea-ice loss will likely stimulate additional NPP over the productive Bering Sea shelves, potentially reducing nutrient flux to the downstream western Arctic Ocean.

Life history of tundra-dwelling wolf spiders (Araneae: Lycosidae) from the Yukon Territory, Canada

2012 ◽  
Vol 90 (6) ◽  
pp. 714-721 ◽  
Author(s):  
J.J. Bowden ◽  
C.M. Buddle
Keyword(s):  
Reproductive Effort ◽  
Abiotic Factors ◽  
Wolf Spider ◽  
Local Variation ◽  
Yukon Territory ◽  
The Arctic ◽  
Wolf Spiders ◽  
Female Body Size ◽  
Trade Offs ◽  
History Of

We studied populations of three tundra-dwelling wolf spider (Lycosidae) species to determine reproductive trait relationships and developmental timing in the Arctic. We collected 451 Pardosa lapponica (Thorell, 1872), 176 Pardosa sodalis Holm, 1970, and 117 Pardosa moesta Banks, 1892 during summer 2008. We used log-likelihood ratio tests and multiple linear regressions to determine the best predictors of fecundity and relative reproductive effort. Female body size best explained the variation in fecundity and body condition was the best predictor for relative reproductive effort. We tested for a trade-off between the allocation of resources to individual eggs and the number of eggs produced (fecundity) within each species using linear regression. There was variation in detectable egg size and number trade-offs among sites and these may be related to local variation in resource allocation linked to density-related biotic or abiotic factors. These findings contribute to knowledge about the fitness of arctic wolf spiders in the region of study and are particularly relevant in light of the effects that climate changes are predicted to have on the arctic fauna.

Size-fractionated surface phytoplankton in the Kara and Laptev Seas: environmental control and spatial variability

2021 ◽  
Vol 664 ◽  
pp. 59-77
Author(s):  
AB Demidov ◽  
IN Sukhanova ◽  
TA Belevich ◽  
MV Flint ◽  
VI Gagarin ◽  
...  
Keyword(s):  
Spatial Variability ◽  
Primary Production ◽  
Water Temperature ◽  
Environmental Control ◽  
Size Structure ◽  
Total Carbon ◽  
The Arctic ◽  
Size Groups ◽  
Phytoplankton Size ◽  
Phytoplankton Size Structure

Climate-induced variability of phytoplankton size structure influences primary productivity, marine food web dynamics, biosedimentation and exchange of CO2 between the atmosphere and ocean. Investigation of phytoplankton size structure in the Arctic Ocean is important due to rapid changes in its ecosystems related to increasing temperature and declining sea ice cover. We estimated the contribution of surface micro-, nano- and picophytoplankton to the total carbon biomass, chlorophyll a concentration and primary production in the Kara and Laptev Seas and investigated the relationships of these phytoplankton size groups with environmental factors which determine their spatial variability. Additionally, we compared chlorophyll specific carbon fixation rate, specific growth rate and carbon to chlorophyll ratios among different phytoplankton size groups. The investigation was carried out from August to September 2018. Generally, picophytoplankton was dominant in terms of chlorophyll a and primary production in the whole study area. The spatial variability of phytoplankton size classes was influenced by river discharge and relied mainly on water temperature, salinity and dissolved silicon concentration. Microphytoplankton prevailed across the river runoff region under conditions of low salinity and relatively high water temperature, while picophytoplankton was predominant under conditions of high salinity and low water temperature. Our study is the first to characterize size-fractionated phytoplankton abundance in the Kara and Laptev Seas, and provides a baseline for future assessment of the response of Kara and Laptev Sea ecosystems to climate-induced processes using phytoplankton size structure.

scholarly journals Regional variability of acidification in the Arctic: a sea of contrasts

2014 ◽  
Vol 11 (2) ◽  
pp. 293-308 ◽  
Author(s):  
E. E. Popova ◽  
A. Yool ◽  
Y. Aksenov ◽  
A. C. Coward ◽  
T. R. Anderson
Keyword(s):  
Climate Change ◽  
Primary Production ◽  
Arctic Ocean ◽  
Canadian Arctic ◽  
Atmospheric Co2 ◽  
The Arctic ◽  
Canadian Arctic Archipelago ◽  
Regional Variability ◽  
The Arctic Ocean ◽  
The Impact

Abstract. The Arctic Ocean is a region that is particularly vulnerable to the impact of ocean acidification driven by rising atmospheric CO2, with potentially negative consequences for calcifying organisms such as coccolithophorids and foraminiferans. In this study, we use an ocean-only general circulation model, with embedded biogeochemistry and a comprehensive description of the ocean carbon cycle, to study the response of pH and saturation states of calcite and aragonite to rising atmospheric pCO2 and changing climate in the Arctic Ocean. Particular attention is paid to the strong regional variability within the Arctic, and, for comparison, simulation results are contrasted with those for the global ocean. Simulations were run to year 2099 using the RCP8.5 (an Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5) scenario with the highest concentrations of atmospheric CO2). The separate impacts of the direct increase in atmospheric CO2 and indirect effects via impact of climate change (changing temperature, stratification, primary production and freshwater fluxes) were examined by undertaking two simulations, one with the full system and the other in which atmospheric CO2 was prevented from increasing beyond its preindustrial level (year 1860). Results indicate that the impact of climate change, and spatial heterogeneity thereof, plays a strong role in the declines in pH and carbonate saturation (Ω) seen in the Arctic. The central Arctic, Canadian Arctic Archipelago and Baffin Bay show greatest rates of acidification and Ω decline as a result of melting sea ice. In contrast, areas affected by Atlantic inflow including the Greenland Sea and outer shelves of the Barents, Kara and Laptev seas, had minimal decreases in pH and Ω because diminishing ice cover led to greater vertical mixing and primary production. As a consequence, the projected onset of undersaturation in respect to aragonite is highly variable regionally within the Arctic, occurring during the decade of 2000–2010 in the Siberian shelves and Canadian Arctic Archipelago, but as late as the 2080s in the Barents and Norwegian seas. We conclude that, for future projections of acidification and carbonate saturation state in the Arctic, regional variability is significant and needs to be adequately resolved, with particular emphasis on reliable projections of the rates of retreat of the sea ice, which are a major source of uncertainty.

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 (19) ◽  
pp. 5567-5579 ◽  
Author(s):  
Y. Kim ◽  
K. Nishina ◽  
N. Chae ◽  
S. J. Park ◽  
Y. J. Yoon ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Environmental Factors ◽  
Soil Temperature ◽  
Co2 Emission ◽  
Emission Rate ◽  
Growing Season ◽  
The Arctic ◽  
Co2 Efflux ◽  
Growing Seasons ◽  
Tundra Ecosystem

Abstract. The tundra ecosystem is quite vulnerable to drastic climate change in the Arctic, and the quantification of carbon dynamics is of significant importance regarding thawing permafrost, changes to 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 within dominant tundra vegetation on the Seward Peninsula of Alaska, during the growing seasons of 2011 and 2012, for the assessment of driving parameters of CO2 efflux. We applied a hierarchical Bayesian (HB) model – a function of soil temperature, soil moisture, vegetation type, and thaw depth – to quantify the effects of environmental factors on CO2 efflux and to estimate growing season CO2 emissions. Our results showed that average CO2 efflux in 2011 was 1.4 times higher than in 2012, resulting from the distinct difference in soil moisture between the 2 years. Tussock-dominated CO2 efflux is 1.4 to 2.3 times higher than those measured in lichen and moss communities, revealing tussock as a significant CO2 source in the Arctic, with a wide area distribution on the circumpolar scale. CO2 efflux followed soil temperature nearly exponentially from both the observed data and the posterior medians of the HB model. This reveals that soil temperature regulates the seasonal variation of CO2 efflux and that soil moisture contributes to the interannual variation of CO2 efflux for the two growing seasons in question. Obvious changes in soil moisture during the growing seasons of 2011 and 2012 resulted in an explicit difference between CO2 effluxes – 742 and 539 g CO2 m−2 period−1 for 2011 and 2012, respectively, suggesting the 2012 CO2 emission rate was reduced to 27% (95% credible interval: 17–36%) of the 2011 emission, due to higher soil moisture from severe rain. The estimated growing season CO2 emission rate ranged from 0.86 Mg CO2 in 2012 to 1.20 Mg CO2 in 2011 within a 40 m × 40 m plot, corresponding to 86 and 80% of annual CO2 emission rates within the western Alaska tundra ecosystem, estimated from the temperature dependence of CO2 efflux. Therefore, this HB model can be readily applied to observed CO2 efflux, as it demands only four environmental factors and can also be effective for quantitatively assessing the driving parameters of CO2 efflux.

scholarly journals Bulk partitioning the growing season net ecosystem exchange of CO<sub>2</sub> in Siberian tundra reveals the seasonality of its carbon sequestration strength

2012 ◽  
Vol 9 (10) ◽  
pp. 13713-13742 ◽  
Author(s):  
B. R. K. Runkle ◽  
T. Sachs ◽  
C. Wille ◽  
E.-M. Pfeiffer ◽  
L. Kutzbach
Keyword(s):  
Carbon Sink ◽  
Ecosystem Respiration ◽  
Growing Season ◽  
New Method ◽  
Apparent Temperature ◽  
The Arctic ◽  
Co2 Uptake ◽  
Night Time ◽  
Tundra Ecosystem ◽  
Co2 Sink

Abstract. This paper evaluates the relative contribution of light and temperature on net ecosystem CO2 uptake during the 2006 growing season in a~polygonal tundra ecosystem in the Lena River Delta in Northern Siberia (72°22´ N, 126°30´ E). We demonstrate that the timing of warm periods may be an important determinant of the magnitude of the ecosystem's carbon sink function, as they drive temperature-induced changes in respiration. Hot spells during the early portion of the growing season are shown to be more influential in creating mid-day surface-to-atmosphere net ecosystem CO2 exchange fluxes than those occurring later in the season. In this work we also develop and present a bulk flux partition model to better account for tundra plant physiology and the specific light conditions of the arctic region that preclude the successful use of traditional partition methods that derive a respiration-temperature relationship from all night-time data. Night-time, growing season measurements are rare during the arctic summer, however, so the new method allows for temporal variation in the parameters describing both ecosystem respiration and gross uptake by fitting both processes at the same time. Much of the apparent temperature sensitivity of respiration seen in the traditional partition method is revealed in the new method to reflect seasonal changes in basal respiration rates. Understanding and quantifying the flux partition is an essential precursor to describing links between assimilation and respiration at different time scales, as it allows a more confident evaluation of measured net exchange over a broader range of environmental conditions. The growing season CO2 sink estimated by this study is similar to those reported previously for this site, and is substantial enough to withstand the long, low-level respiratory CO2 release during the rest of the year to maintain the site's CO2 sink function on an annual basis.

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