Pre-adaptation of Arctic Plants to Climate Change*

Re-appraisal of high latitude ice cover during the Weichselian and the recent discovery of pre-Holocene plant communities in Novaya Zemlya and Northern Norway suggests that the contemporary Arctic flora may have had a longer time span in its occupation of high latitude sites than has hitherto been recognised. The present-day Arctic flora in some regions may therefore have derived at least some of its genetic inheritance from populations that survived in ice-free refugia in the high Arctic polar deserts during the latter stages of the Weichselian glaciation. Increasing evidence for sudden changes in climate at high latitudes in the past, suggests that Arctic vegetation would have been subjected to rapid climatic warming if it had maintained a presence in these regions during the late Weichselian. A review of what is known about plant survival in the high Arctic since pre-Holocene times, coupled with an examination of some of the physiological properties of modern populations in these regions is presented in an attempt to ascertain if high Arctic plants possess mechanisms which facilitate their capacity to respond either phenotypically or physiologically to climatic change.     

Global Climate Change Adaptation Priorities for Biodiversity and Food Security

International policy is placing increasing emphasis on adaptation to climate change, including the allocation of new funds to assist adaptation efforts. Climate change adaptation funding may be most effective where it meets integrated goals, but global geographic priorities based on multiple development and ecological criteria are not well characterized. Here we show that human and natural adaptation needs related to maintaining agricultural productivity and ecosystem integrity intersect in ten major areas globally, providing a coherent set of international priorities for adaptation funding. An additional seven regional areas are identified as worthy of additional study. The priority areas are locations where changes in crop suitability affecting impoverished farmers intersect with changes in ranges of restricted-range species. Agreement among multiple climate models and emissions scenarios suggests that these priorities are robust. Adaptation funding directed to these areas could simultaneously address multiple international policy goals, including poverty reduction, protecting agricultural production and safeguarding ecosystem services.     

Projecting the Hydrologic Impacts of Climate Change on Montane Wetlands

Wetlands are globally important ecosystems that provide critical services for natural communities and human society. Montane wetland ecosystems are expected to be among the most sensitive to changing climate, as their persistence depends on factors directly influenced by climate (e.g. precipitation, snowpack, evaporation). Despite their importance and climate sensitivity, wetlands tend to be understudied due to a lack of tools and data relative to what is available for other ecosystem types. Here, we develop and demonstrate a new method for projecting climate-induced hydrologic changes in montane wetlands. Using observed wetland water levels and soil moisture simulated by the physically based Variable Infiltration Capacity (VIC) hydrologic model, we developed site-specific regression models relating soil moisture to observed wetland water levels to simulate the hydrologic behavior of four types of montane wetlands (ephemeral, intermediate, perennial, permanent wetlands) in the U. S. Pacific Northwest. The hybrid models captured observed wetland dynamics in many cases, though were less robust in others. We then used these models to a) hindcast historical wetland behavior in response to observed climate variability (1916–2010 or later) and classify wetland types, and b) project the impacts of climate change on montane wetlands using global climate model scenarios for the 2040s and 2080s (A1B emissions scenario). These future projections show that climate-induced changes to key driving variables (reduced snowpack, higher evapotranspiration, extended summer drought) will result in earlier and faster drawdown in Pacific Northwest montane wetlands, leading to systematic reductions in water levels, shortened wetland hydroperiods, and increased probability of drying. Intermediate hydroperiod wetlands are projected to experience the greatest changes. For the 2080s scenario, widespread conversion of intermediate wetlands to fast-drying ephemeral wetlands will likely reduce wetland habitat availability for many species.     

Impacts of warming and fertilization on nitrogen-fixing microbial communities in the Canadian High Arctic

The impacts of simulated climate change (warming and fertilization treatments) on diazotroph community structure and activity were investigated at Alexandra Fiord, Ellesmere Island, Canada. Open Top Chambers, which increased growing season temperatures by 1-3 degrees C, were randomly placed in a dwarf-shrub and cushion-plant dominated mesic tundra site in 1995. In 2000 and 2001 20N:20P2O5:20K2O fertilizer was applied at a rate of 5 gm(-2) year(-1). Estimates of nitrogen fixation rates were made in the field by acetylene reduction assays (ARA). Higher rates of N fixation were observed 19-35 days post-fertilization but were otherwise unaffected by treatments. However, moss cover was significantly positively associated with ARA rate. NifH gene variants were amplified from bulk soil DNA and analyzed by terminal restriction fragment length polymorphism analysis. Non-metric multidimensional scaling was used to ordinate treatment plots in nifH genotype space. NifH gene communities were more strongly structured by the warming treatment late in the growing season, suggesting that an annual succession in diazotroph community composition occurs.     

Sentient Beings and Wildlife Resources: Inuit,Beluga Whales and Management Regimes in the Canadian Arctic

Beluga whale hunting is one of the most social subsistence hunting activities to take place in the Canadian Arctic. Through the harvest, distribution and consumption of beluga whales, Inuit identity and social relationships are affirmed. The whale-hunting complex is influenced by beliefs that beluga whales are sentient beings who inhabit a shared social space with humans. Yet, across the region beluga whales are perceived by wildlife managers as scarce resources and as such require protection through the imposition of management plans. There is currently no management of whales on the west coast of Hudson Bay, in Nunavut. In 2002, Inuit there were requested to sell part of their whale harvest to Inuit in Nunavik, northern Quebec, where hunting quotas exist. The outcome of this event was concern in Nunavut for the future of the whale hunt, and a deepening sense of powerlessness in Nunavik due to the management of the whale harvest.

Warming-Induced Shrub Expansion and Lichen Decline in the Western Canadian Arctic

Strong evidence for a pan-Arctic expansion of upright shrubs comes from analysis of satellite imagery, historical photographs, vegetation plots, and growth rings. However, there are still uncertainties related to local-scale patterns of shrub growth, resulting interactions among vegetation functional groups, and the relative roles of disturbance and climate as drivers of observed change. Here, we present evidence that widespread and rapid shrub expansion and lichen declines over a 15,000 km² area of the western Canadian Arctic have been driven by regional increases in temperature. Using 30 m resolution Landsat satellite imagery and high resolution repeat color-infrared aerial photographs, we show that 85% of the land surface has a positive 1985–2011 trend (P < 0.05) in NDVI, making this one of the most intensely greening regions in the Arctic. Strong positive trends (>0.03 NDVI/decade) occurred consistently across all landscape positions and most vegetation types. Comparison of 208, 1:2,000 scale vertical air photo pairs from 1980 and 2013 clearly shows that this greening was driven by increased canopy cover of erect dwarf and tall shrubs, with declines in terricolous lichen cover. Disturbances caused by wildfires, exploratory gas wells, and drained lakes all produced strong, yet localized increases in NDVI due to shrub growth. Our analysis also shows that a 4°C winter temperature increase over the past 30 years, leading to warmer soils and enhanced nutrient mineralization provides the best explanation for observed vegetation change. These observations thus provide early corroboration for modeling studies predicting large-scale vegetation shifts in low-Arctic ecosystems from climate change.     

Diet comparison among demersal marine fish from the Canadian Arctic

Summary The diets of 12 species of demersal marine fish from various locations in the Canadian Arctic comprised a grand total of 267 prey species, mainly invertebrates. The total number of prey species taken by a single fish species ranged from 9 to 91, and the mean number per stomach from 2.0 to 9.4. The most important prey were Crustacea, most frequently epibenthic or planktonic species; Polychaeta, mainly the larger species; and Mollusca, notably the cropped siphons of Macoma calcarea. Generally, only a few species comprised the bulk of the food. Most of the fish had a predominantly benthic or epibenthic diet, a notable exception being Triglops pingeli which ate zoo plankton almost exclusively at the three sites from which it was collected. To a lesser extent, Triglops murrayi, Icelus spatula and Liparis gibbus also fed planktonically. No significant correlations in diet were found among sympatric fish populations, implying a division of resources and reduced interspecific competition.     

Impacts of Grazing and Climate Warming on C Pools and Decomposition Rates in Arctic Environments

Arctic ecosystems are important habitats for Arctic breeding geese which in their turn have a profound impact on the vegetation in these areas. The herbivore pressure is currently on the rise in the region and may interact with climate change to drive changes in both productivity and decomposition rates. In this study, we aim to determine the combined impact of warming and geese on C pools and decomposition in two high Arctic habitats, mesic heath and wet meadow. We employed field-experimental warming and grazing treatments in a fully factorial design and quantified their impact on ecosystems C pools and turnover. High grazing levels reduced vascular biomass and litter C pools at both sites, whereas warming reduced moss biomass at the mesic site only. Grazing increased decomposition rates and reduced the amount of labile C in the soil at the mesic site, whereas warming substantially reduced C concentrations by approximately 25%. Intermediate level of grazing had an opposite effect and resulted in increased soil C storage at the mesic site. In contrast, no effects of the treatment on belowground C cycling were found at the wet site. In conclusion, the two levels of grazing and warming impacted on different aspects of the C cycle investigated in this study. The high grazing and warming treatment promoted reduced carbon storage/decomposition both above- and belowground with the strongest effects seen at the mesic site.     

The influence of water transparency on the distribution and abundance of macrophytes among lakes of the Mackenzie Delta, Western Canadian Arctic

SUMMARY 1. Macrophyte abundance and distribution was assessed in a chain of six interconnected lakes (all with the same flooding frequency) in the Arctic, where increasing distance from the Mackenzie River channel resulted in a gradient of water transparency (‘chain‐set’ lakes), and in a group of 26 spatially discrete lakes where increasing frequency and duration of lake flooding with river water (controlled by sill height) also resulted in a transparency gradient (‘sill‐set’ lakes). 2. Among the chain‐set lakes, above‐ground macrophyte biomass increased from 0 to 1000 g m^?2 with increasing water transparency. Among the sill‐set lakes, the transparency gradient among the lakes was less well defined and the relations with biomass were more varied. A decrease in flooding was associated with increasing water transparency and an increasing biomass of macrophytes from about 0 to over 2000 g m^?2. For a specific flood frequency, however, the effect of flooding was much greater when lakes were directly connected to a river channel than when floodwaters flowed first through an intervening lake. Among infrequently flooded lakes the effect of flooding on water transparency and biomass was negligible. 3. Among relatively clear lakes in both sets of lakes, biomass increased with increasing water transparency and decreasing lake depth. Among relatively turbid lakes, however, biomass increased with the combined effect of increasing water colour (decreasing water transparency) and increasing lake water depth. The increases in biomass with increasing water colour (coloured dissolved organic matter) and increasing depth, which together result in reduced light at the bed, may be explained by reduced exposure to ultra violet light. 4. An average light attenuation of 1.3 m^?1 (Secchi depth about 1 m) over the growing season appears to represent a threshold water transparency which, in combination with water depths early in the growing season, is consistent with a light supply on the bed required for growth of the common macrophytes in lakes of the Mackenzie Delta. However, a comparison with other systems indicates that macrophytes among lakes of the Mackenzie Delta grow deeper, for a given level of transparency, than is reported in lakes at lower latitude, despite the lower sun angles and increased reflectivity of water surfaces in the arctic. 5. A complete accounting of water transparency (at PAR and UV wavelengths), lake depth, summer sun angle and duration of sunlight may be necessary to explain patterns of macrophyte growth among lakes across a full range of latitudes.     

全球气候变化对沈阳地区春玉米生长的可能影响

Physiological ecology simulation modelling of maize growth (MPESM) was used to simulate the variation of soil moisture, maize development and maize growth under twelve prescribed climate scenarios, which include doubling CO2, raising mean temperature by 1.5 ℃, 3.0 ℃ and 4.5 ℃, and changing precipitation by 0, +20%, -20%, and -40%. The simulated results were compared with that of the present climate, to assess the sensitivity of maize to climatic change. The analysis indicated that soil moisture is sensitive to reduced precipitation, maize development is sensitive to the rise of temperature, and maize growth is affected greatly by temperature elevation and precipitation variation, which cancel out the positive effects of CO2 elevation. It was found that with the severe change of climate, the leaf biomass, the female fringe biomass, and the leaf area index would decline greatly, and the biomass of stem and root would increase greatly. The average yield of maize will decline between 5% and 30%.     

全球气候变化对沈阳地区春玉米生长的可能影响

利用玉米（Ｚｅａ ｍａｙｓ Ｌ．）生长生理生态学模拟模型（ＭＰＥＳＭ）,分别模拟了未来气候变化的１２种气候条件下（ＣＯ２浓度倍增,平均气温上升１．５℃、３．０℃和４．５℃,降水量增加２０％、减少２０％、减少４０％和降水量不变）,沈阳地区土壤湿度、玉米发育和玉米生长的变化,并与当前条件下进行了比较,以评价玉米生长对各气候因子变化的敏感性和全球气候变化下沈阳地区春玉米的生长趋势。研究表明：土壤湿度对降     

Assessing Climate Change Impacts on Vernal Pool Ecosystems and Endemic Branchiopods

This study evaluated the hydrologic sensitivity of vernal pool ecosystems in the Central Valley of California to climatic changes projected for 2100. A vernal pool water-balance model was used to evaluate rain-fed vernal pools at four locations under future conditions projected by two contrasting global climate models. The potential for change in the duration of continuous inundation, frequency of reproductively suitable inundation events, and the seasonal distribution of inundation was quantified. The potential impact of hydrologic changes varied by species and by location. Three scales of response were identified: (a) At the regional scale, pools in the middle of the Central Valley near Merced were the most responsive to climatic changes. (b) At the local scale, smaller, shallower pools had the greatest potential to change the distribution of reproductively suitable habitat available to branchiopods. (c) At the individual pool scale, changes in precipitation will dominate changes in temperature, resulting in relatively linear responses in the duration of inundation. The ecological impact of these changes will be determined by a balance between the increasing suitability of vernal pools for branchiopod predators and the hydrologic improvement of currently marginal habitats.     

Climate Change Impacts on Streamflow and Subbasin-Scale Hydrology in the Upper Colorado River Basin

In the Upper Colorado River Basin (UCRB), the principal source of water in the southwestern U.S., demand exceeds supply in most years, and will likely continue to rise. While General Circulation Models (GCMs) project surface temperature warming by 3.5 to 5.6°C for the area, precipitation projections are variable, with no wetter or drier consensus. We assess the impacts of projected 21^st century climatic changes on subbasins in the UCRB using the Soil and Water Assessment Tool, for all hydrologic components (snowmelt, evapotranspiration, surface runoff, subsurface runoff, and streamflow), and for 16 GCMs under the A2 emission scenario. Over the GCM ensemble, our simulations project median Spring streamflow declines of 36% by the end of the 21^st century, with increases more likely at higher elevations, and an overall range of −100 to +68%. Additionally, our results indicated Summer streamflow declines with median decreases of 46%, and an overall range of −100 to +22%. Analysis of hydrologic components indicates large spatial and temporal changes throughout the UCRB, with large snowmelt declines and temporal shifts in most hydrologic components. Warmer temperatures increase average annual evapotranspiration by ∼23%, with shifting seasonal soil moisture availability driving these increases in late Winter and early Spring. For the high-elevation water-generating regions, modest precipitation decreases result in an even greater water yield decrease with less available snowmelt. Precipitation increases with modest warming do not translate into the same magnitude of water-yield increases due to slight decreases in snowmelt and increases in evapotranspiration. For these basins, whether modest warming is associated with precipitation decreases or increases, continued rising temperatures may make drier futures. Subsequently, many subbasins are projected to turn from semi-arid to arid conditions by the 2080 s. In conclusion, water availability in the UCRB could significantly decline with adverse consequences for water supplies, agriculture, and ecosystem health.