Matveyeva, N. Journal of Vegetation Science, 5: McDonald, M. Canadian Journal of Fisheries and Aquatic Sciences, McKane, R. Miller, M. Arctic, 3: Archivs fur Hydrobiologie Supplement, 74 1 : Environmental Pollution, Nadelhoffer, K. Washington, D. Nordhagen, R. Oslo, 1: En Plantensosiologisk monografi. Oberdorfer, E. Stuttgart: Ulmer. O'Brien, W. Oechel, W. Holarctic Ecology, Nature, Ohba, T. Carici rupestris-Kobresietea bellardii. Phytocoenologia, 1: Ostendorf, B. Pegau, R. Peterson, B. Ecology, 74 3 : Canadian Journal of Fisheries and Aquatic Sciences, 43 6 : Limnology and Oceanography, Porter, S.
American Journal of Science , Rastetter, E. Water, Air, and Soil Pollution, In Oechel, W. Razzhivin, V. Reed, J. Reynolds, J. Rieger, S. Soil Conservation Service. Polarinst, Roux, C.
Selmann, P. Shaver, G. Bioscience, III, Production biomass relationships and element cycling in contrasting arctic vegetation types. Ecological Monographs, 61 1 : Ecography, III, and Gartner, B. In Turner, M. Onge, D. Tenhunen, J. In Schulze, E. Tieszen, L. Ugolini, F. Soil Science, Department of the Interior, U. Final Legislative Environmental Impact Statement.
Vaikmae, R. Walker, D. Walker D. Walker, M. Dissertationes Botanicae , Journal of Vegetation Science , 5: Washburn, A. Webber, P. Hanover, NH: U. Whalen, S. Tellus, 42b: Global Biogeochemical Cycles, 6: Wilimovsky, N. Williams, J. Geological Survey Professional Paper , 83 p. Wirth, V. Email or Customer ID. Forgot password? Old Password. New Password. Password Changed Successfully Your password has been changed. Returning user. Request Username Can't sign in?
Forgot your username? Shrub growth chronologies for both species were correlated with the regional climate signal and showed spatial correspondence with interannual variation in NDVI in surrounding alpine and Arctic regions. Our results suggest that early summer warming represents a common driver of vegetation change for contrasting shrub species growing in different habitats in the same alpine environments. A warmer and greener cold world: summer warming increases shrub growth in the alpine and high Arctic tundra.
The Arctic and alpine biome is rapidly warming, which might be causing an encroachment of relatively tall woody shrub vegetation into tundra ecosystems, which will probably result in an overall positive feedback to climate warming. This encroachment is, however, believed to remain limited to the relatively warm parts of the biome, where taller shrubs may displace shorter species. Still, climate sensitivity of shrub growth strongly differs between species and sites and High Arctic dwarf shrub species may respond rapidly to increasing temperatures in absence of taller species.
In addition, it remains largely unknown whether shrubs from different functional groups from the same sites respond similarly to climate drivers. In the present study we examined the climate-growth relationships of six different site-species combinations: one evergreen and one deciduous shrub species at two alpine sites, and one evergreen dwarf shrub species at two High Arctic sites.
We compared linear mixed models for each combination, explaining existing shrub growth data with site-speci c interpolated monthly and seasonal climate data from the gridded meteorological dataset CRU TS4. Shrub growth rates were found to be sensitive to summer climate for all species at all sites. Continued and projected warming is thus likely to stimulate a further encroachment of shrubs in these systems, at least through a densi cation of existing stands. Dwarf shrub growth strongly responded to the recent warming at both High Arctic sites, contrasting with previous work suggesting that shrub expansion might remain limited to warmer tundra regions.
At the alpine sites, growth of evergreen shrubs was found to be more dependent on summer climate than growth of deciduous shrubs, perhaps because these evergreen species are less prone to herbivory. However, biome-wide generalizations at the func- tional group level may be dif cult to interpolate to the species level. Micro-site conditions, such as the determination of growing season length and winter soil temperatures, and in uence on growing season soil moisture by snow depth, may determine the strength of the climate-growth relationships found.
Technical comment on Precipitation drives global variation in natural selection. Siepielski et al. Reports, 3 March , p. Three aspects of this analysis cause concern: i lack of within-year climate variables, ii low and variable estimates of covariance relationships across taxa, and iii a lack of mechanistic explanations for the patterns observed; association is not causation.
Climate warming as a driver of shrubline advance in high-latitude alpine tundra. We compared growth and recruitment to climate variables to test the climate sensitivity of shrub increase using annual radial growth analysis, age distributions and repeat field surveys to estimate the current rate of shrubline advance. Mortality was extremely low across the elevation gradient. Aspect, elevation and species identity did not explain variation in recruitment patterns, suggesting a regional factor, such as climate, as the driver of the observed shrubline advance.
Annual radial growth of willows was best explained by variation in summer temperatures, and recruitment pulses by winter temperatures. Our results suggest that shrubline will continue to advance over the next 50 years, if growing conditions remain suitable. However, if future conditions differ between summer and winter seasons, this could lead to contrasting trajectories for recruitment vs.
Our findings in the context of a review of the existing literature indicate that elevational and latitudinal shrublines, like treelines, are advancing in response to climate warming; however, the trajectories of change will depend on the climate drivers controlling recruitment vs. Duffy, et al. Location, location, location: Considerations when using lightweight drones in challenging environments. Lightweight drones have emerged recently as a remote sensing survey tool of choice for ecologists, conservation practitioners and environmental scientists. In published work, there are plentiful details on the parameters and settings used for successful data capture, but in contrast there is a dearth of information describing the operational complexity of drone deployment.
Herein, we describe the most common challenges encountered, alongside mitigation and remediation actions that increase the chances of safe and successful data capture. We also discuss the importance of scientists undertaking ethical assessment of their drone practices, to identify and mitigate potential conflicts associated with drone use in particular areas. Shrub growth and expansion in the Arctic tundra: an assessment of controlling factors using an evidence-based approach. Environmental Research Letters 12 8 , Woody shrubs have increased in biomass and expanded into new areas throughout the Pan-Arctic tundra biome in recent decades, which has been linked to a biome-wide observed increase in productivity.
Experimental, observational, and socio-ecological research suggests that air temperature-and to a lesser degree precipitation-trends have been the predominant drivers of this change. However, a progressive decoupling of these drivers from Arctic vegetation productivity has been reported, and since , vegetation productivity has also been declining. We created a protocol to a identify the suite of controls that may be operating on shrub growth and expansion, and b characterise the evidence base for controls on Arctic shrub growth and expansion.
We found evidence for a suite of 23 proximal controls that operate directly on shrub growth and expansion; the evidence base focused predominantly on just four controls air temperature, soil moisture, herbivory, and snow dynamics. The findings suggest the current evidence base is not sufficiently robust or comprehensive at present to answer key questions of Pan-Arctic shrub change. We suggest future directions that could strengthen the evidence, and lead to an understanding of the key mechanisms driving changes in Arctic shrub environments.
Barrio I, et al.
Background invertebrate herbivory on dwarf birch Betula glandulosa-nana complex increases with temperature and precipitation across the tundra biome. Chronic, low intensity herbivory by invertebrates, termed background herbivory, has been understudied in tundra, yet its impacts are likely to increase in a warmer Arctic. The magnitude of these changes is however hard to predict as we know little about the drivers of current levels of invertebrate herbivory in tundra. We assessed the intensity of invertebrate herbivory on a common tundra plant, the dwarf birch Betula glandulosa-nana complex , and investigated its relationship to latitude and climate across the tundra biome.
Leaf damage by defoliating, mining and gall-forming invertebrates was measured in samples collected from sites at 56 locations. Our results indicate that invertebrate herbivory is nearly ubiquitous across the tundra biome but occurs at low intensity. On average, invertebrates damaged Foliar damage was consistently positively correlated with mid-summer July temperature and, to a lesser extent, precipitation in the year of data collection, irrespective of latitude.
Our results show that invertebrate herbivory on dwarf birch is small in magnitude but given its prevalence and dependence on climatic variables, background invertebrate herbivory should be included in predictions of climate change impacts on tundra ecosystems. Ropars P, S Angers-Blondin, et al. Different parts, different stories: climate sensitivity of growth is stronger in root collars versus stems in tundra shrubs. Long-term analyses based on dendrochronological techniques applied to shrubs have linked this phenomenon to cli-mate change.
We found that root collars had greater sensitivity to climate thanstems and that these differences were maintained across the three types of environments. Growth at the root collarwas best explained by spring precipitation and summer temperature, whereas stem growth showed weak and incon-sistent responses to climate variables.
Publications – Team Shrub
Moreover, sensitivity to climate was not consistent among plant parts, as indi-viduals having climate-sensitive root collars did not tend to have climate-sensitive stems. These differences insensitivity of shrub parts to climate highlight the complexity of resource allocation in multi-stemmed plants. Whereasstem initiation and growth are driven by microenvironmental variables such as light availability and competition, rootcollars integrate the growth of all plant parts instead, rendering them less affected by mechanisms such as competitionand more responsive to signals of global change.
Greater temperature sensitivity of plant phenology at colder sites: implications for convergence across northern latitudes. Warmer temperatures are accelerating the phenology of organisms around the world. Temperature sensitivity of phenology might be greater in colder, higher latitude sites than in warmer regions, in part because small changes in temperature constitute greater relative changes in thermal balance at colder sites. A similar pattern was seen over time for the flowering phenology of a widespread species, Cassiope tetragona.
These are among the first results highlighting differential phenological responses of plants across a climatic gradient and suggest the possibility of convergence in flowering times and therefore an increase in gene flow across latitudes as the climate warms. Vellend M, et al. Plant biodiversity change across scales during the anthropocene. Plant communities have undergone dramatic changes in recent centuries, although not all such changes fit with the dominant biodiversity-crisis nar- rative used to describe them.
Nonnative species introductions have greatly increased plant species richness in many regions of the world at the same time that they have led to the creation of new hybrid polyploid species by bringing pre- viously isolated congeners into close contact. At the local scale, conversion of primary vegetation to agriculture has decreased plant diversity, whereas other drivers of change-e. These results prompt a reassessment of how conservation goals are defined and justified. Vellend, et al. Estimates of local biodiversity change over time stand up to scrutiny.
Second, the conclusion of negative relationships between temporal biodiversity change and study duration was entirely dependent on unrealistic model assumptions, the use of a subset of data, and inclusion of one outlier data point in one study. Finally, the undebatable point, noted in both original papers, that studies in the ecological literature are geographically biased, was used to cast doubt on the conclusion that, outside of areas converted to croplands or asphalt, the distribution of biodiversity trends is centered approximately on zero.
Wrona F, et al. Journal of Geophysical Research: Biogeosciences Numerous international scientific assessments and related articles have, during the last decade, described the observed and potential impacts of climate change as well as other related environmental stressors on Arctic ecosystems.
There is increasing recognition that observed and projected changes in freshwater sources, fluxes, and storage will have profound implications for the physical, biogeochemical, biological, and ecological processes and properties of Arctic terrestrial and freshwater ecosystems. However, a significant level of uncertainty remains in relation to forecasting the impacts of an intensified hydrological regime and related cryospheric change on ecosystem structure and function. We recommend enhanced use of the catchment scale as an integrated unit of study, thereby more explicitly considering the physical, chemical, and ecological processes and fluxes across a full freshwater continuum in a geographic region and spatial range of hydroecological units e.
Wolter J, et al. Vegetation composition and shrub extent on the Yukon coast, Canada, are strongly linked to ice-wedge polygon degradation. Changing environmental and geomorphological conditions are resulting in vegetation change in ice-wedge polygons in Arctic tundra. However, we do not yet know how microscale vegetation patterns relate to individual environmental and geomorphological parameters.
This work aims at examining these relations in polygonal terrain. We analysed composition and cover of vascular plant taxa and surface height, active layer depth, soil temperature, carbon and nitrogen content, pH and electrical conductivity in four polygon mires located on the Yukon coast. We found that vascular plant species composition and cover correlates best with relative surface height.
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Ridges of low-centred polygons and raised centres of high-centred polygons support the growth of mesic and wetland species e. Wetland and aquatic plant species e. We also found a relationship between vascular plant species composition and substrate characteristics such as pH, electrical conductivity and total organic carbon, although the individual influence of these parameters could not be determined because of their correlation with relative surface height.
Our findings stress the regulatory role of microtopography and substrate in vegetation dynamics of polygonal terrain. Ongoing warming in this region will lead to changes to polygonal terrain through permafrost degradation and subsequent conversion of low-centred into high-centred polygons. Our results indicate that shrubs, particularly Betula glandulosa and heath species, have the potential to expand most.
Jaroslav O, et al. Permafrost landscapes experience different disturbances and store large amounts of organic matter, which may become a source of greenhouse gases upon permafrost degradation.
We analysed the influence of terrain and geomorphic disturbances e. Our results indicate a strong correlation between SOC storage and the topographic wetness index. Sites characterised by mass wasting showed significant SOC depletion and soil compaction, whereas sites characterised by the accumulation of peat and fluvial deposits store SOC and TN along the whole core. We upscaled SOC and TN to estimate total stocks using the ecological units determined from vegetation composition, slope angle and the geomorphic disturbance regime.
The ecological units were delineated with a supervised classification based on RapidEye multispectral satellite imagery and slope angle. Climate sensitivity of shrub expansion across the tundra biome. Nature Climate Change 5. Rapid climate warming in the tundra biome has been linked to increasing shrub dominance [1,2,3,4]. Shrub expansion can modify climate by altering surface albedo, energy and water balance, and permafrost [2,5,6,7,8], yet the drivers of shrub growth remain poorly understood.
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Dendroecological data consisting of multi-decadal time series of annual shrub growth provide an underused resource to explore climate-growth relationships. Our analyses demonstrate that the sensitivity of shrub growth to climate was: 1 heterogeneous, with European sites showing greater summer temperature sensitivity than North American sites, and 2 higher at sites with greater soil moisture and for taller shrubs for example, alders and willows growing at their northern or upper elevational range edges.
Across latitude, climate sensitivity of growth was greatest at the boundary between the Low and High Arctic, where permafrost is thawing4 and most of the global permafrost soil carbon pool is stored . The observed variation in climate-shrub growth relationships should be incorporated into Earth system models to improve future projections of climate change impacts across the tundra biome. Media coverage here.
Temperature-induced recruitment pulses of Arctic dwarf shrub communities. Journal of Ecology The effects of climate change on Arctic ecosystems can range between various spatiotemporalscales and may include shifts in population distribution, community composition, plant phenology,primary productivity and species biodiversity. The growth rates and age structure of tundra vegeta-tion as well as its response to temperature variation, however, remain poorly understood becausehigh-resolution data are limited in space and time. Our results reveal a strong temperature dependency of Arctic dwarf shrub reproduction,a high vulnerability of circumpolar tundra ecosystems to climatic changes, and the abil ity of evaluat-ing historical vegetation dynamics well beyond the northern treeline.
The combined wood anatomi-cal and plant ecological approach, considering insights from micro-sections to communityassemblages, indicates that model predictions of rapid tundra expansion i. Elmendorf, SC, et al. Experiment, monitoring, and gradient methods used to infer climate change effects on plant communities yield consistent patterns. Proceedings of the National Academy of Sciences Methodological constraints can limit our ability to quantify potential impacts of climate warming.
We assessed the consistency of three approaches in estimating warming effects on plant community composition: manipulative warming experiments, repeat sampling under ambient temperature change monitoring , and space-for-time substitution.