Climate change biology

Understanding Biodiversity with Socio-Cultural & Environmental Aspects. 30 April 2011

by M.T. Abdullah, PhD

This paper discusses on some concepts and new ideas related to the high biological diversity in Malaysia. This may be... more This paper discusses on some concepts and new ideas related to the high biological diversity in Malaysia. This may be known as integrative biological diversity.

Climate Change and Biodiversity in Malaysia. 2010

by M.T. Abdullah, PhD

Impact, gaps and future of biodiversity in the face of climate change in Malaysia. Impact, gaps and future of biodiversity in the face of climate change in Malaysia.

Ontogenetic niche shifts in three Vaccinium species on a sub-alpine mountain side

by Alistair Auffret

Water brownification may increase the invasibility of a submerged non-native macrophyte

by Roger Paulo Mormul

Biological Invasions 2012 - online first

Environmental conditions and human activities play a significant role in structuring novel assemblages of native and... more Environmental conditions and human activities play a significant role in structuring novel assemblages of native and non-native species. Ongoing and future climatic change may alter the performance of native and non-native species and their biotic interactions. In the northern hemisphere, expected climate changes include warmer temperatures and higher precipitation, the latter of which may increase dissolved organic carbon (humic) concentrations, resulting in browner water in aquatic ecosystems (brownification). We tested the effects of elevated temperature (3ºC) and brownification on native and non-native aquatic plant production in mesocosms over 56 days. Elodea canadensis, an aquatic invasive plant, had higher relative growth rate in terms of both length and weight, as well as higher weight to length ratio when grown in brown vs. clear water; E. canadensis did not respond to temperature treatments. Different functional groups of native producers (phytoplankton, periphyton, macrophytes) showed different relationships to temperature and brownification treatments, with the macrophyte response being most notable because it was opposite to that of E. canadensis. Native macrophytes decreased in biomass in browner water, where they represented about 40% of total biomass compared to 85% in clear water. In regression analyses, E. canadensis length RGR was best predicted only by water color treatment, but biomass RGR and biomass per length were inversely correlated with native macrophyte biomass, which is consistent with competition. Our results unexpectedly showed water brownification to have more influence on lake invasion than climate warming at this temperature regime. Two pathways emerged for climate to interact with biological invasions in structuring novel communities: directly, if non-native species respond positively to climate change, and indirectly through species interactions, for instance, because water brownification impairs growth of native macrophytes and reduces biotic resistance to invasion.

Pleistocene palaeoecology and environmental change on the Darling Downs, southeastern Queensland, Australia

by Gilbert Price

Price, G.J., Sobbe, I.H., 2005. Pleistocene palaeoecology and environmental change on the Darling Downs, southeastern Queensland, Australia. Memoirs of the Queensland Museum 51, 171-201.

A diverse Pleistocene fossil assemblage was recovered from a site (QML1396) exposed in the southern banks of Kings... more A diverse Pleistocene fossil assemblage was recovered from a site (QML1396) exposed in the southern banks of Kings Creek, Darling Downs, southeastern Queensland. The site includes both high-energy lateral channel deposits and low-energy vertical accretion deposits. The basal fossil-bearing unit is laterally extensive, fines upward and its geometry and sedimentary structures suggest deposition within a main channel. The coarse channel fill passes upward into overbank levee deposits made up of lenticular sandy-shelly strata alternating with muds. Several taphonomic biases relating to preservation of different faunal groups and skeletal elements was discerned. Biases may be related to fluvial sorting of the assemblage, but causes for differences between the preservation and accumulation of mammal versus non-mammal terrestrial vertebrates remain unclear. In general, the vertebrate material was accumulated and transported into the deposit from the surrounding proximal floodplain. The assemblage is composed of 44 species including molluscs, teleosts, anurans, chelids, squamates, and small and large-sized mammals. Palaeoenvironmental analysis suggests that a mosaic of habitats, including vine thickets, scrublands, open sclerophyllous woodlands interspersed with sparse grassy understories, and open grasslands, were present on the floodplain during the late Pleistocene. From sedimentological and ecological data, it is evident that increasing aridity during the late Pleistocene led to woodland and vine thicket habitat contraction, and grassland expansion on the floodplain. At present, there is no evidence to support the suggestion that the retraction of late Pleistocene Darling Downs habitats was due to anthropogenic factors.

Dating megafaunal extinction on the Pleistocene Darling Downs, eastern Australia: the promise and pitfalls of dating as a test of extinction hypotheses

by Gilbert Price

Price, G.J., Webb, G.E., Zhao, J.-x., Feng, Y.-x., Murray, A.S., Cooke, B.N., Hocknull, S.A., Sobbe, I.H., 2011. Dating megafaunal extinction on the Pleistocene Darling Downs, eastern Australia: the promise and pitfalls of dating as a test of extinction hypotheses. Quaternary Science Reviews 30, 899-914.

A key to understanding Late Pleistocene megafaunal extinction dynamics is knowledge of megafaunal ecological... more A key to understanding Late Pleistocene megafaunal extinction dynamics is knowledge of megafaunal ecological response(s) to long-term environmental perturbations. Strategically, that requires targeting fossil deposits that accumulated during glacial and interglacial intervals both before and after human arrival, with subsequent palaeoecological models underpinned by robust and reliable chronologies. Late Pleistocene vertebrate fossil localities from the Darling Downs, eastern Australia, provide stratigraphically-intact, abundant megafaunal sequences, which allows for testing of anthropogenic versus climate change megafauna extinction hypotheses. Each stratigraphic unit at site QML796, Kings Creek Catchment, was previously shown to have had similar sampling potential, and the basal units contain both small-sized taxa (e.g., land snails, frogs, bandicoots, rodents) and megafauna. Importantly, sequential faunal horizons show stepwise decrease in taxonomic diversity with the loss of some, but not all, megafauna in the geographically-small palaeocatchment. The purpose of this paper is to present the results of our intensive, multidisciplinary dating study of the deposits (>40 dates). Dating by means of accelerator mass spectrometry (AMS) 14C (targeting bone, freshwater molluscs, and charcoal) and thermal ionisation mass spectrometry U/Th (targeting teeth and freshwater molluscs) do not agree with each other and, in the case of AMS 14C dating, lack internal consistency. Scanning electron microscopy and rare earth element analyses demonstrate that the dated molluscs are diagenetically altered and contain aragonite cements that incorporated secondary young C, suggesting that such dates should be regarded as minimum ages. AMS 14C dated charcoals provide ages that occur out of stratigraphic order, and cluster in the upper chronological limits of the technique (~40-48 ka). Again, we suggest that such results should be regarded as suspicious and only minimum ages. Subsequent OSL and U/Th (teeth) dating provide complimentary results and demonstrate that the faunal sequences actually span ~120-83 ka, thus occurring beyond the AMS 14C dating window. Importantly, the dates suggest that the local decline in biological diversity was initiated ~75,000 years before the colonisation of humans on the continent. Collectively, the data are most parsimoniously consistent with a pre-human climate change model for local habitat change and megafauna extinction, but not with a nearly simultaneous extinction of megafauna as required by the human-induced blitzkrieg extinction hypothesis. This study demonstrates the problems inherent in dating deposits that lie near the chronological limits of the radiocarbon dating technique, and highlights the need to cross-check previously-dated archaeological and megafauna deposits within the timeframe of earliest human colonisation and latest megafaunal survival.

Elevated night soil temperatures result in earlier incidence and increased extent of foliar ozone injury to common bean (Phaseolus vulgaris L.)

by Jennifer Albertine

Climate Evolution in the Northern North Atlantic - 15 Ma to Present

by Fridgeir Grimsson

2011
Thomas Denk, Fridgeir Grimsson, Reinhard Zetter, Leifur A Simonarson
Springer
Chapter 13

Effects of climate on pollination networks in the West Indies

by Jeff Ollerton

Climate Change and Museum Collections

by The International Institute for Conservation IIC

Climate Change and Museum Collections
London, 17th of September 2008

The changing climate of our... more Climate Change and Museum Collections
London, 17th of September 2008

The changing climate of our earth has implications that go well beyond the dramatic effects of storms and rising sea levels, shifts in migratory patterns and habitats, or the potential for increased health risks from pollutants. Weather patterns and temperature variations also affect the long term preservation of the world’s cultural treasures which we enjoy and which inspire us every day.

The threats that come with climate change do not just exist in the outdoor environment. The delicate and fragile treasures within our museums are also susceptible. Museum and house collections that may not have previously required environmental control may soon require such efforts to meet their preservation responsibilities. Those collections protected by environmental systems may be at greater risk if such systems are not updated and expanded in capacity. To remain effective the maintenance plans for historic buildings, public monuments, and archaeological sites will require adaptation to our changing climate.

Environmental control of open-ocean phytoplankton groups: Now and in the future

by Robert Strzepek

Boyd, Philip W., Robert Strzepek, Feixue Fu, and David A. Hutchins

Climate change will alter concurrently many environmental factors that exert control over oceanic phytoplankton.... more Climate change will alter concurrently many environmental factors that exert control over oceanic phytoplankton. Recent laboratory culture work, shipboard experiments, and field surveys reveal many remaining unknowns about the bottom-up controls for five globally important algal groups. Increasing uncertainties exist, respectively, for picocyanobacteria, diatoms, Phaeocystis spp., N(2)-fixing cyanobacteria, and coccolithophores. This missing information about current environmental controls will hinder progress in modeling how these phytoplankton will be influenced by climate change. A review of conceptual approaches used to elucidate the relationship between environmental controls and phytoplankton dominance, from Margalef's mandala to functional traits, uncovered limitations regarding their application to climate-change scenarios. For example, these previous approaches have insufficient scope or dimensions to take into account the confounding effects of synergistic and antagonistic interactions of multiple environmental change variables. A new approach is needed that considers all of the different environmental properties altered by climate change and their interactions while at the same time permitting a subset of the most significant controls for a specific phytoplankton group to be isolated and evaluated in factorial matrix perturbation experiments. We advocate three new interlinked approaches, including environmental clusters that incorporate all factors (temperature, CO(2), light, nutrients, and trace metals), which both exert control over present-day floristics and will be altered by climate change. By carefully linking a holistic conceptual approach to a reductionist experimental design, the future responses of open-ocean phytoplankton groups to a complex, rapidly changing environment can be better predicted.

Ecometrics: the traits that bind the past and present together

by Jussi Eronen

We outline here an approach for understanding the biology of climate change, one that integrates data at multiple... more We outline here an approach for understanding the biology of climate change, one that integrates data at multiple spatial and temporal scales. Taxon-free trait analysis, or “ecometrics,” is based on the idea that the distribution in a community of ecomorphological traits such as tooth structure, limb proportions, body mass, leaf shape, incubation temperature, claw shape, any aspect of anatomy or physiology can be measured across some subset of the organisms in a community. Regardless of temporal or spatial scale, traits are the means by which organisms interact with their environment, biotic and abiotic. Ecometrics measures these interactions by focusing on traits which are easily measurable, whose structure is closely related to their function, and whose function interacts directly with local environment. Ecometric trait distributions are thus a comparatively universal metric for exploring systems dynamics at all scales. The main challenge now is to move beyond investigating how future climate change will affect the distribution of organisms and how it will impact ecosystem services and to shift the perspective to ask how biotic systems interact with changing climate in general, and how climate change affects the interactions within and between the components of the whole biotic-physical system. We believe that it is possible to provide believable, quantitative answers to these questions. Because of this we have initiated an IUBS program iCCB (integrative Climate Change Biology).

Modeling human-induced climatic change: A summary for environmental managers

by Timothy Kittel

Sulzman, E.W., K.A. Poiani, and T.G.F. Kittel. 1995. Modeling human-induced climatic change: A summary for environmental managers. Environmental Management 19:197-224.

DOI: 10.1007/BF02471991

The rapid increase in atmospheric concentrations of greenhouse gases has caused concern because of their potential to... more The rapid increase in atmospheric concentrations of greenhouse gases has caused concern because of their potential to alter the earth's radiation budget and disrupt current climate patterns While there are many uncertainties associated with use of general circulation models (GCMs), GCMs are currently the best available technology to project changes in climate associated with elevated gas concentrations. Results indicate increases in global temperature and changes in global precipitation patterns are likely as a result of doubled CO2.

GCMs are not reliable for use at the regional scale because local scale processes and geography are not taken into account. Comparison of results from five GCMs in three regions of the United States indicate high variability across regions and among models depending on season and climate variable. Statistical methods of scaling model output and nesting finer resolution models in global models are two techniques that may improve projections.

Despite the many limitations in GCMs, they are useful tools to explore climate-earth system dynamics when used in conjunction with water resource and ecosystem models. A variety of water resource models showed significant alteration of regional hydrology when run with both GCM-generated and hypothetical climate scenarios, regardless of region or model complexity. Similarly, ecological models demonstrate the sensitivity of ecosystem production, nutrient dynamics, and distribution to changes in climate and CO2 levels.

We recommend the use of GCM-based scenarios in conjunction with water resource and ecosystem models to guide environmental management and policy in a “no-regrets” framework or as part of a precautionary approach to natural resource protection.

Key words Climate change - Climate models - Ecosystems - Greenhouse effect - Land surface processes - Uncertainty - Validation - Variability - Water resources

Potential climate change impacts on water resources in the Great Plains

by Timothy Kittel

Ojima, D., L. Garcia, E. Elgaali, K. Miller, T.G.F. Kittel, and J. Lackett. 1999. Potential climate change impacts on water resources in the Great Plains. Journal of the American Water Resources Association 35:1443-1454

This paper reports on the current assessment of climate impacts on water resources, including aquatic ecosystems,... more This paper reports on the current assessment of climate impacts on water resources, including aquatic ecosystems, agricultural demands, and water management, in the U.S. Great Plains. Climate change in the region may have profound effects on agricultural users, aquatic ecosystems, and urban and industrial users alike. In the central Great Plains Region, the potential impacts of climate changes include changes in winter snowfall and snow-melt, growing season rainfall amounts and intensities, minimum winter temperature, and summer time average temperature. Specifically, results from general circulation models indicate that both annual average temperatures and total annual precipitation will increase over the region. However, the seasonal patterns are not uniform. The combined effect of these changes in weather patterns and average seasonal climate will affect numerous sectors critical to the economic, social and ecological welfare of this region. Research is needed to better address the current competition among the water needs of agriculture, urban and industrial uses, and natural ecosystems, and then to look at potential changes. These diverse demands on water needs in this region compound the difficulty in managing water use and projecting the impact of climate changes among the various critical sectors in this region.

Sensitivity of a prairie wetland to increased temperature and seasonal precipitation changes

by Timothy Kittel

Poiani, K.A., W.C. Johnson, and T.G.F. Kittel. 1995. Sensitivity of a prairie wetland to increased temperature and seasonal precipitation changes. Water Resources Bulletin 31:283-294.

DOI: 10.1111/j.1752-1688.1995.tb03380.x

Water Resources Bulletin, now "Journal of the American Water Resources Association"

We assessed the potential effects of increased temperature and changes in amount and seasonal timing of precipitation... more We assessed the potential effects of increased temperature and changes in amount and seasonal timing of precipitation on the hydrology and vegetation of a semi-permanent prairie wetland in North Dakota using a spatially-defined, rule-based simulation model. Simulations were run with increased temperatures of 2°C combined with a 10 percent increase or decrease in total growing season precipitation. Changes in precipitation were applied either evenly across all months or to individual seasons (spring, summer, or fall).

The response of semi-permanent wetland P1 was relatively similar under most of the seasonal scenarios. A 10 percent increase in total growing season precipitation applied to summer months only, to fall months only, and over all months produced lower water levels compared to those resulting from the current climate due to increased evapotranspiration. Wetland hydrology was most affected by changes in spring precipitation and runoff. Vegetation response was relatively consistent across scenarios. Seven of the eight seasonal scenarios produced drier conditions with no open water and greater vegetation cover compared to those resulting from the current climate. Only when spring precipitation increased did the wetland maintain an extensive open water area (49 percent).

Potential changes in climate that affect spring runoff, such as changes to spring precipitation and snow melt, may have the greatest impact on prairie wetland hydrology and vegetation. In addition, relatively small changes in water level during dry years may affect the period of time the wetland contains open water. Emergent vegetation, once it is established, can survive under drier conditions due to its ability to persist in shallow water with fluctuating levels. The model's sensitivity to changes in temperature and seasonal precipitation patterns accentuates the need for accurate regional climate change projections from general circulation models.

Keywords:

prairie wetlands;
hydrology and vegetation dynamics;
simulation model;
climate change;
GIS;
waterfowl habitat;
global warming

Comparing the correlative Holdridge model to mechanistic biogeographical models for assessing vegetation distribution response to climatic change

by Timothy Kittel

Yates, D.N., T.G.F. Kittel, and R.F. Cannon. 2000. Comparing the correlative Holdridge model to mechanistic biogeographical models for assessing vegetation distribution response to climatic change. Climatic Change 44:59-87. DOI: 10.1023/A:1005495908758

A well-established and widely used correlative climate-vegetation model (Holdridge Life Zone model) was compared to... more A well-established and widely used correlative climate-vegetation model (Holdridge Life Zone model) was compared to three mechanistic simulation models (BIOME2, Dynamic Global Phytogeography Model (DOLY), and Mapped Atmosphere-Plant-Soil System (MAPSS)) for the conterminous United States under contemporary climate and a set of future climates prescribed by three Global Circulation Model experiments. Output from the mechanistic models were from the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP) intercomparison. Holdridge modeling approaches, using a lsquoSimplersquo implementation (vegetation distribution based on biotemperature and precipitation alone) or a lsquoFullrsquo implementation (vegetation distribution based on biotemperature, precipitation, altitudinal region, latitudinal belt, and transitional vegetation zones), represented current potential natural U.S. vegetation poor to fair, respectively. The more sophisticated mechanistic models were superior at reproducing potential vegetation under current climate compared to Holdridge, although there was significant variability among these models. The Holdridge implementations generally showed similar or greater climate sensitivity with respect to spatial redistribution of vegetation compared to the mechanistic models run both with and without doubled CO2 levels; however, the sensitivity of the Holdridge model depended on the implementation. Reduced sensitivity of the mechanistic models arises from direct (physiological) CO2 effects and other compensating feedbacks not captured by the Holdridge model. The greater degree of physical realism in the mechanistic models makes them the model class of choice for climate impact assessment. However, under circumstances of limited data availability, computation resources, and access to mechanistic models and model expertise, simple correlational models such as Holdridge may be the only method that can be applied. The paper makes some recommendations on the use of the Holdridge model for impact assessment if it is the only available model.

Potential impacts on Colorado Rocky Mountain weather due to land use changes on the adjacent Great Plains

by Timothy Kittel

Chase, T.N., R. Pielke, Sr., T.G.F. Kittel, J.S. Baron, and T.J. Stohlgren. 1999. Potential impacts on Colorado Rocky Mountain weather due to land use changes on the adjacent Great Plains. Journal of Geophysical Research-Atmospheres 104:16673-16690. doi:10.1029/1999JD900118

Evidence from both meteorological stations and vegetational successional studies suggests that summer temperatures are... more Evidence from both meteorological stations and vegetational successional studies suggests that summer temperatures are decreasing in the mountain-plain system in northeast Colorado, particularly since the early 1980s. These trends are coincident with large changes in regional land cover. Trends in global, Northern Hemisphere and continental surface temperatures over the same period are insignificant. These observations suggest that changes in the climate of this mountain-plain system may be, in some part, a result of localized forcing mechanisms. In this study the effects of land use change on the northern Colorado plains, where large regions of grasslands have been transformed into both dry and irrigated agricultural lands, on regional weather is examined in an effort to understand this local deviation from larger-scale trends. We find with high-resolution numerical simulations of a 3-day summer period using a regional atmospheric-land surface model that replacing grasslands with irrigated and dry farmland can have impacts on regional weather and therefore climate which are not limited to regions of direct forcing. Higher elevations remote from regions of land use change are affected as well. Specifically, cases with altered landcover had cooler, moister boundary layers, and diminished low-level upslope winds over portions of the plains. At higher elevations, temperatures also were lower as was low-level convergence. Precipitation and cloud cover were substantially affected in mountain regions. We advance the hypothesis that observed land use changes may have already had a role in explaining part of the observed climate record in the northern Colorado mountain-plain system.

Land-atmosphere energy exchange in Arctic tundra and boreal forest: available data and feedbacks to climate

by Timothy Kittel

Full citation--
Eugster, W., W.R. Rouse, R.A. Pielke, Sr., J. P. McFadden, D.D. Baldocchi, T.G.F. Kittel, F.S. Chapin, III, G.E. Liston, P.L. Vidale, E. Vaganov, and S. Chambers. 2000. Land-atmosphere energy exchange in arctic tundra and boreal forest: available data and feedbacks to climate. Global Change Biology 6 (Suppl. 1): 84-115.
DOI: 10.1046/j.1365-2486.2000.06015.x

Abstract:

This paper summarizes and analyses available data on the surface energy balance of Arctic tundra... more Abstract:

This paper summarizes and analyses available data on the surface energy balance of Arctic tundra and boreal forest. The complex interactions between ecosystems and their surface energy balance are also examined, including climatically induced shifts in ecosystem type that might amplify or reduce the effects of potential climatic change.

High latitudes are characterized by large annual changes in solar input. Albedo decreases strongly from winter, when the surface is snow-covered, to summer, especially in nonforested regions such as Arctic tundra and boreal wetlands. Evapotranspiration (QE) of high-latitude ecosystems is less than from a freely evaporating surface and decreases late in the season, when soil moisture declines, indicating stomatal control over QE, particularly in evergreen forests. Evergreen conifer forests have a canopy conductance half that of deciduous forests and consequently lower QE and higher sensible heat flux (QH). There is a broad overlap in energy partitioning between Arctic and boreal ecosystems, although Arctic ecosystems and light taiga generally have higher ground heat flux because there is less leaf and stem area to shade the ground surface, and the thermal gradient from the surface to permafrost is steeper.

Permafrost creates a strong heat sink in summer that reduces surface temperature and therefore heat flux to the atmosphere. Loss of permafrost would therefore amplify climatic warming. If warming caused an increase in productivity and leaf area, or fire caused a shift from evergreen to deciduous forest, this would increase QE and reduce QH. Potential future shifts in vegetation would have varying climate feedbacks, with largest effects caused by shifts from boreal conifer to shrubland or deciduous forest (or vice versa) and from Arctic coastal to wet tundra. An increase of logging activity in the boreal forests appears to reduce QE by roughly 50% with little change in QH, while the ground heat flux is strongly enhanced.

The VEMAP integrated database for modelling United States ecosystem/vegetation sensitivity to climate change

by Timothy Kittel

Full citation--
Kittel, T.G.F., N.A. Rosenbloom, T.H. Painter, D.S. Schimel, and VEMAP Modeling Participants. 1995. The VEMAP integrated database for modeling United States ecosystem/vegetation sensitivity to climate change. Journal of Biogeography 22: 857-862. Special issue: Terrestrial Ecosystem Interactions with Global Change, Volume 2. http://www.jstor.org/stable/2845986

Dataset access:
http://www.cgd.ucar.edu/vemap/datasets.html

For the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP), we developed a model database of climate, soils,... more For the Vegetation/Ecosystem Modeling and Analysis Project (VEMAP), we developed a model database of climate, soils, and vegetation that was compatible with the requirements of 3 ecosystem physiology models and 3 vegetation lifeform distribution models. A key constraint was temporal, spatial, and physical consistency among data layers to provide these daily or monthly timestep models with suitable common inputs for the purpose of model intercomparison. The database is on a 0.5deg. latitude/longitude grid for the conterminous United States. The set has both daily and monthly representations of the same long-term climate. Daily temperature and precipitation were stochastically simulated with WGEN and daily solar radiation and humidity empirically estimated with CLIMSIM. We used orographically-adjusted precipitation, surface temperature and surface wind speed monthly means to maintain consistency among these fields and with vegetation distribution. Vegetation classes were based on physiognomic and physiological properties that influence biogeochemical dynamics. Soils data include characteristics of the 1-4 dominant soils per cell to account for subgrid variability.

Global and regional modelling of Arctic-boreal vegetation distribution and its sensitivity to altered forcing

by Timothy Kittel

Full citation--
Kittel, T.G.F., W.L. Steffen, and F.S. Chapin, III. 2000. Global and regional modeling of Arctic-boreal vegetation distribution and its sensitivity to altered forcing. Global Change Biology 6 (Suppl. 1): 1-18. DOI: 10.1046/j.1365-2486.2000.06011.x

Understanding the distribution and function of Arctic and boreal ecosystems under current conditions and their... more Understanding the distribution and function of Arctic and boreal ecosystems under current conditions and their vulnerability to altered forcing is crucial to our assessment of future global environmental change. Such efforts can be facilitated by the development and application of ecological models that simulate realistic patterns of vegetation change at high latitudes. This paper reviews three classes of ecological models that have been implemented to extrapolate vegetation information in space (e.g. across the Arctic and adjacent domains) and over historical and future periods (e.g. under altered climate and other forcings). These are: (i) equilibrium biogeographical models; (ii) frame-based transient ecosystem models, and (iii) dynamic global vegetation models (DGVMs). The equilibrium response of high-latitude vegetation to scenarios of increased surface air temperatures projected by equilibrium biogeographical models is for tundra to be replaced by a northward shift of boreal woodland and forests. A frame-based model (ALFRESCO) indicates the same directional changes, but illustrates how response time depends on rate of temperature increase and concomitant changes in moisture regime and fire disturbance return period. Key disadvantages of the equilibrium models are that they do not simulate time-dependent responses of vegetation and the role of disturbance is omitted or highly generalized. Disadvantages of the frame-based models are that vegetation type is modelled as a set unit as opposed to an association of individually simulated plant functional types and that the role of ecosystem biogeochemistry in succession is not explicitly considered. DGVMs explicitly model disturbance (e.g. fire), operate on plant functional types, and incorporate constraints of nutrient availability on biomass production in the simulation of vegetation dynamics. Under changing climate, DGVMs detail conversion of tundra to tree-dominated boreal landscapes along with time-dependent responses of biomass, net primary production, and soil organic matter turnover–-which all increase with warming. Key improvements to DGVMs that are needed to portray behaviour of arctic and boreal ecosystems adequately are the inclusion of anaerobic soil processes for inundated landscapes, permafrost dynamics, and moss-lichen layer biogeochemistry, as well as broader explicit accounting of disturbance regimes (including insect outbreaks and land management). Transient simulation of these landscapes can be further tailored to high-latitude processes and issues by spatially interactive, gridded application of arctic/boreal frame-based models and development of dynamic regional vegetation models (DRVMs) utilizing plant functional type schemes that capture the variety of high-latitude environments.

Keywords:

arctic vegetation;
boreal vegetation;
climate impacts;
DGVM;
global change;
vegetation modelling