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1.
The global climate is changing rapidly and Arctic regions are showing responses to recent warming. Responses of tundra ecosystems to climate change have been examined primarily through short‐term experimental manipulations, with few studies of long‐term ambient change. We investigated changes in above‐ and belowground biomass of wet sedge tundra to the warming climate of the Canadian High Arctic over the past 25 years. Aboveground standing crop was harvested from five sedge meadow sites and belowground biomass was sampled from one of the sites in the early 1980s and in 2005 using the same methods. Aboveground biomass was on average 158% greater in 2005 than in the early 1980s. The belowground biomass was also much greater in 2005: root biomass increased by 67% and rhizome biomass by 139% since the early 1980s. Dominant species from each functional group (graminoids, shrubs and forbs) showed significant increases in aboveground biomass. Responsive species included the dominant sedge species Carex aquatilis stans, C. membranacea, and Eriophorum angustifolium, as well as the dwarf shrub Salix arctica and the forb Polygonum viviparum. However, diversity measures were not different between the sample years. The greater biomass correlated strongly with increased annual and summer temperatures over the same time period, and was significantly greater than the annual variation in biomass measured in 1980–1983. Increased decomposition and mineralization rates, stimulated by warmer soils, were likely a major cause of the elevated productivity, as no differences in the mass of litter were found between sample periods. Our results are corroborated by published short‐term experimental studies, conducted in other wet sedge tundra communities which link warming and fertilization with elevated decomposition, mineralization and tundra productivity. We believe that this is the first study to show responses in High Arctic wet sedge tundra to recent climate change. 相似文献
2.
Gilles Gauthier Jo?l Bêty Marie-Christine Cadieux Pierre Legagneux Madeleine Doiron Clément Chevallier Sandra Lai Arnaud Tarroux Dominique Berteaux 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2013,368(1624)
Arctic wildlife is often presented as being highly at risk in the face of current climate warming. We use the long-term (up to 24 years) monitoring records available on Bylot Island in the Canadian Arctic to examine temporal trends in population attributes of several terrestrial vertebrates and in primary production. Despite a warming trend (e.g. cumulative annual thawing degree-days increased by 37% and snow-melt date advanced by 4–7 days over a 23-year period), we found little evidence for changes in the phenology, abundance or productivity of several vertebrate species (snow goose, foxes, lemmings, avian predators and one passerine). Only primary production showed a response to warming (annual above-ground biomass of wetland graminoids increased by 123% during this period). We nonetheless found evidence for potential mismatches between herbivores and their food plants in response to warming as snow geese adjusted their laying date by only 3.8 days on average for a change in snow-melt of 10 days, half of the corresponding adjustment shown by the timing of plant growth (7.1 days). We discuss several reasons (duration of time series, large annual variability, amplitude of observed climate change, nonlinear dynamic or constraints imposed by various rate of warming with latitude in migrants) to explain the lack of response by herbivores and predators to climate warming at our study site. We also show how length and intensity of monitoring could affect our ability to detect temporal trends and provide recommendations for future monitoring. 相似文献
3.
Footprints of climate change in the Arctic marine ecosystem 总被引:3,自引:0,他引:3
PAUL WASSMANN CARLOS M. DUARTE SUSANA AGUSTÍ MIKAEL K. SEJR 《Global Change Biology》2011,17(2):1235-1249
In this article, we review evidence of how climate change has already resulted in clearly discernable changes in marine Arctic ecosystems. After defining the term ‘footprint’ and evaluating the availability of reliable baseline information we review the published literature to synthesize the footprints of climate change impacts in marine Arctic ecosystems reported as of mid‐2009. We found a total of 51 reports of documented changes in Arctic marine biota in response to climate change. Among the responses evaluated were range shifts and changes in abundance, growth/condition, behaviour/phenology and community/regime shifts. Most reports concerned marine mammals, particularly polar bears, and fish. The number of well‐documented changes in planktonic and benthic systems was surprisingly low. Evident losses of endemic species in the Arctic Ocean, and in ice algae production and associated community remained difficult to evaluate due to the lack of quantitative reports of its abundance and distribution. Very few footprints of climate change were reported in the literature from regions such as the wide Siberian shelf and the central Arctic Ocean due to the limited research effort made in these ecosystems. Despite the alarming nature of warming and its strong potential effects in the Arctic Ocean the research effort evaluating the impacts of climate change in this region is rather limited. 相似文献
4.
Autogenic succession, land-use change, and climatic influences on the Holocene development of a kettle-hole mire in Northern Poland 总被引:5,自引:0,他引:5
Mariusz Lamentowicz Milena Obremska Edward A.D. Mitchell 《Review of Palaeobotany and Palynology》2008,151(1-2):21-40
We reconstructed the Holocene developmental history of a kettle-hole peatland in the Tuchola Forest of Northern Poland, using pollen, testat amoebae and plant macrofossil indicators. Our aims were to determine the timing and pattern of autogenic succession and natural and anthropogenic influences on the peatland. Northern Poland is under mixed oceanic and continental climatic influences but has so far been less studied in a palaeoecological context than more oceanic regions of Europe. In the first terrestrial developmental phase of the mire, the testate amoebae-inferred depth to water table revealed two major dry shifts at ca. 9400 (end of lake phase) and ca. 7100 cal BP (a period of global cooling and dry shift in Western Europe). Conditions became wetter again in two steps at ca. 6700 and ca. 5800 BP after a dry event at ca. 6100 BP. The timing of the wet shift at 5800 BP corresponds to wet periods in Western Europe. Peat accumulation rates were low (0.1 mm yr− 1) between ca. 5600 and ca. 3000 BP when sedges dominated the peatland. In the last 2500 yrs surface moisture fluctuated with wet events at ca. 2750–2400, and 2000 BP, and dry events at ca. 2250–2100 and 1450 BP. After 1450 BP a trend towards wetter conditions culminated at ca. 500 cal BP, possibly caused by local deforestation. Over the mire history, pH (inferred from testate amoebae) was mostly low (around 5) with two short-lived shifts to alkaline conditions (7.5) at ca. 6100 and 1450 BP indicating a minerotrophic influence from surface run-off into the mire. Up to about 1000 BP the ecological shifts inferred from the three proxies agree with palaeoclimatic records from Poland and Western Europe. After this date, however correlation is less clear suggesting an increasing local anthropogenic impact on the mire. This study confirms that kettle-hole peatlands can yield useful palaeoenvironmental data as well as recording land-use change and calls for more comparable studies in regions are the interface between major climate influences. 相似文献
5.
CO2 exchange in three Canadian High Arctic ecosystems: response to long-term experimental warming 总被引:1,自引:0,他引:1
Jeffrey M. Welker Jace T. Fahnestock† Greg H. R. Henry‡ Kevin W. O'Dea Rodney A. Chimner§ 《Global Change Biology》2004,10(12):1981-1995
Carbon dioxide exchange, soil C and N, leaf mineral nutrition and leaf carbon isotope discrimination (LCID‐Δ) were measured in three High Arctic tundra ecosystems over 2 years under ambient and long‐term (9 years) warmed (~2°C) conditions. These ecosystems are located at Alexandra Fiord (79°N) on Ellesmere Island, Nunavut, and span a soil water gradient; dry, mesic, and wet tundra. Growing season CO2 fluxes (i.e., net ecosystem exchange (NEE), gross ecosystem photosynthesis (GEP), and ecosystem respiration (Re)) were measured using an infrared gas analyzer and winter C losses were estimated by chemical absorption. All three tundra ecosystems lost CO2 to the atmosphere during the winter, ranging from 7 to 12 g CO2‐C m?2 season?1 being highest in the wet tundra. The period during the growing season when mesic tundra switch from being a CO2 source to a CO2 sink was increased by 2 weeks because of warming and increases in GEP. Warming during the summer stimulated dry tundra GEP more than Re and thus, NEE was consistently greater under warmed as opposed to ambient temperatures. In mesic tundra, warming stimulated GEP with no effect on Re increasing NEE by ~10%, especially in the first half of the summer. During the ~70 days growing season (mid‐June–mid‐August), the dry and wet tundra ecosystems were net CO2‐C sinks (30 and 67 g C m?2 season?1, respectively) and the mesic ecosystem was a net C source (58 g C m?2 season?1) to the atmosphere under ambient temperature conditions, due in part to unusual glacier melt water flooding that occurred in the mesic tundra. Experimental warming during the growing season increased net C uptake by ~12% in dry tundra, but reduced net C uptake by ~20% in wet tundra primarily because of greater rates of Re as opposed to lower rates of GEP. Mesic tundra responded to long‐term warming with ~30% increase in GEP with almost no change in Re reducing this tundra type to a slight C source (17 g C m?2 season?1). Warming caused LCID of Dryas integrafolia plants to be higher in dry tundra and lower in Salix arctic plants in mesic and wet tundra. Our findings indicate that: (1) High Arctic ecosystems, which occur in similar mesoclimates, have different net CO2 exchange rates with the atmosphere; (2) long‐term warming can increase the net CO2 exchange of High Arctic tundra by stimulating GEP, but it can also reduce net CO2 exchange in some tundra types during the summer by stimulating Re to a greater degree than stimulating GEP; (3) after 9 years of experimental warming, increases in soil carbon and nitrogen are detectable, in part, because of increases in deciduous shrub cover, biomass, and leaf litter inputs; (4) dry tundra increases in GEP, in response to long‐term warming, is reflected in D. integrifolia LCID; and (5) the differential carbon exchange responses of dry, mesic, and wet tundra to similar warming magnitudes appear to depend, in part, on the hydrologic (soil water) conditions. Annual net ecosystem CO2‐C exchange rates ranged from losses of 64 g C m?2 yr?1 to gains of 55 g C m?2 yr?1. These magnitudes of positive NEE are close to the estimates of NPP for these tundra types in Alexandra Fiord and in other High Arctic locations based on destructive harvests. 相似文献
6.
Eric Post Toke T. H?ye 《Philosophical transactions of the Royal Society of London. Series B, Biological sciences》2013,368(1624)
Despite uncertainties related to sustained funding, ideological rivalries and the turnover of research personnel, long-term studies and studies espousing a long-term perspective in ecology have a history of contributing landmark insights into fundamental topics, such as population- and community dynamics, species interactions and ecosystem function. They also have the potential to reveal surprises related to unforeseen events and non-stationary dynamics that unfold over the course of ongoing observation and experimentation. The unprecedented rate and magnitude of current and expected abiotic changes in tundra environments calls for a synthetic overview of the scope of ecological responses these changes have elicited. In this special issue, we present a series of contributions that advance the long view of ecological change in tundra systems, either through sustained long-term research, or through retrospective or prospective modelling. Beyond highlighting the value of long-term research in tundra systems, the insights derived herein should also find application to the study of ecological responses to environmental change in other biomes as well. 相似文献
7.
Climate warming is leading to shrub expansion in Arctic tundra. Shrubs form ectomycorrhizal (ECM) associations with soil fungi that are central to ecosystem carbon balance as determinants of plant community structure and as decomposers of soil organic matter. To assess potential climate change impacts on ECM communities, we analysed fungal internal transcribed spacer sequences from ECM root tips of the dominant tundra shrub Betula nana growing in treatments plots that had received long‐term warming by greenhouses and/or fertilization as part of the Arctic Long‐Term Ecological Research experiment at Toolik Lake Alaska, USA. We demonstrate opposing effects of long‐term warming and fertilization treatments on ECM fungal diversity; with warming increasing and fertilization reducing the diversity of ECM communities. We show that warming leads to a significant increase in high biomass fungi with proteolytic capacity, especially Cortinarius spp., and a reduction of fungi with high affinities for labile N, especially Russula spp. In contrast, fertilization treatments led to relatively small changes in the composition of the ECM community, but increased the abundance of saprotrophs. Our data suggest that warming profoundly alters nutrient cycling in tundra, and may facilitate the expansion of B. nana through the formation of mycorrhizal networks of larger size. 相似文献
8.
Wetlands and global climate change: the role of wetland restoration in a changing world 总被引:11,自引:0,他引:11
Kevin L. Erwin 《Wetlands Ecology and Management》2009,17(1):71-84
Global climate change is recognized as a threat to species survival and the health of natural systems. Scientists worldwide are looking at the ecological and hydrological impacts resulting from climate change. Climate change will make future efforts to restore and manage wetlands more complex. Wetland systems are vulnerable to changes in quantity and quality of their water supply, and it is expected that climate change will have a pronounced effect on wetlands through alterations in hydrological regimes with great global variability. Wetland habitat responses to climate change and the implications for restoration will be realized differently on a regional and mega-watershed level, making it important to recognize that specific restoration and management plans will require examination by habitat. Floodplains, mangroves, seagrasses, saltmarshes, arctic wetlands, peatlands, freshwater marshes and forests are very diverse habitats, with different stressors and hence different management and restoration techniques are needed. The Sundarban (Bangladesh and India), Mekong river delta (Vietnam), and southern Ontario (Canada) are examples of major wetland complexes where the effects of climate change are evolving in different ways. Thus, successful long term restoration and management of these systems will hinge on how we choose to respond to the effects of climate change. How will we choose priorities for restoration and research? Will enough water be available to rehabilitate currently damaged, water-starved wetland ecosystems? This is a policy paper originally produced at the request of the Ramsar Convention on Wetlands and incorporates opinion, interpretation and scientific-based arguments. 相似文献
9.
W. H. Zagwijn 《Vegetation History and Archaeobotany》1994,3(2):65-88
On the basis of distribution maps showing the first pollen occurrences in the Holocene of the well-known climate indicators Hedera, Ilex and Viscum as well as data for Corylus, a series of maps have been prepared that show summer and winter isotherms at various time intervals during the Holocene. From these maps climate curves for Amsterdam, the Netherlands have been set out. These were compared with curves for the Eemian at the same site. In both of these warm periods there is evidence for increased seasonality in the early phases which were relatively continental. Changes in insolation could account for such differences. Summer optima occurred earlier than winter optima. Changes in land-sea distribution are important, especially with regard to the patterns in winter climate. During the latter half of the Eemian, the climate was distinctly more oceanic than in the Holocene. Early in the Holocene, an influx of warm ocean water resulted in higher winter temperatures in the Gulf of Biscay, the Irish Sea, and areas east of Skagerrak-Kattegat. Temperature decline after the climatic optimum was greatest in the north, i.e. at 60°N, where a depression in the order of 2°C in summer and 2–3°C in winter occurred. Temperature decline was less farther south, i.e. at ca. 50°N, where a distinct west-east gradient in temperature change can be observed. 相似文献
10.
11.
General circulation models predict increases in temperature and precipitation in the Arctic as the result of increases in atmospheric carbon dioxide concentrations. Arctic ecosystems are strongly constrained by temperature, and may be expected to be markedly influenced by climate change. Perturbation experiments have been used to predict how Arctic ecosystems will respond to global climatic change, but these have often simulated individual perturbations (e.g. temperature alone) and have largely been confined to the short Arctic summer. The importance of interactions between global change variables (e.g. CO2, temperature, precipitation) has rarely been examined, and much experimentation has been short-term. Similarly, very little experimentation has occurred in the winter when General circulation models predict the largest changes in climate will take place. Recent studies have clearly demonstrated that Arctic ecosystems are not dormant during the winter and thus much greater emphasis on experimentation during this period is essential to improve our understanding of how these ecosystems will respond to global change. This, combined with more long-term experimentation, direct observation of natural vegetation change (e.g. at the tundra/taiga boundary) and improvements in model predictions is necessary if we are to understand the future nature and extent of Arctic ecosystems in a changing climate. 相似文献
12.
1 Five treeline species had low seed germination rates and low survivorship and growth of seedlings when transplanted into Alaskan tundra. Seed germination of all species increased with experimental warming, suggesting that the present treeline may in part result from unsuccessful recruitment under cold conditions.
2 Growth, biomass and survivorship of seedlings of treeline species transplanted into tundra were largely unaffected by experimental warming. However, transplanted seedlings of three species ( Betula papyrifera , Picea glauca and Populus tremuloides ) grew more when below‐ground competition with the extant community was reduced. All three measures of transplant performance were greater in shrub tundra than in the less productive tussock or heath tundra. Establishment of trees in tundra may thus be prevented by low resource availability and competition.
3 Two species ( Alnus crispa and Populus balsamifera ) had low seed germination and survivorship of germinated seeds; transplants of these species did not respond to the manipulations and lost biomass following transplanting into tundra. Isolated populations of these two species north of the present treeline in arctic Alaska probably became established during mid‐Holocene warming rather than in recent times.
4 Of all the species studied here, Picea glauca was the most likely to invade intact upland tundra. Its seeds had the highest germination rates and it was the only species whose seedlings survived subsequently. Furthermore, transplanted seedlings of Picea glauca had relatively high survivorship and positive growth in tundra, especially in treatments that increased air temperature or nutrient availability, two factors likely to increase with climate warming. 相似文献
2 Growth, biomass and survivorship of seedlings of treeline species transplanted into tundra were largely unaffected by experimental warming. However, transplanted seedlings of three species ( Betula papyrifera , Picea glauca and Populus tremuloides ) grew more when below‐ground competition with the extant community was reduced. All three measures of transplant performance were greater in shrub tundra than in the less productive tussock or heath tundra. Establishment of trees in tundra may thus be prevented by low resource availability and competition.
3 Two species ( Alnus crispa and Populus balsamifera ) had low seed germination and survivorship of germinated seeds; transplants of these species did not respond to the manipulations and lost biomass following transplanting into tundra. Isolated populations of these two species north of the present treeline in arctic Alaska probably became established during mid‐Holocene warming rather than in recent times.
4 Of all the species studied here, Picea glauca was the most likely to invade intact upland tundra. Its seeds had the highest germination rates and it was the only species whose seedlings survived subsequently. Furthermore, transplanted seedlings of Picea glauca had relatively high survivorship and positive growth in tundra, especially in treatments that increased air temperature or nutrient availability, two factors likely to increase with climate warming. 相似文献
13.
Ingibjörg S. Jónsdóttir Borgthór Magnússon† Jón Gudmundsson‡ Ásrún Elmarsdóttir† Hreinn Hjartarson§ 《Global Change Biology》2005,11(4):553-563
Facing an increased threat of rapid climate change in cold‐climate regions, it is important to understand the sensitivity of plant communities both in terms of degree and direction of community change. We studied responses to 3–5 years of moderate experimental warming by open‐top chambers in two widespread but contrasting tundra communities in Iceland. In a species‐poor and nutrient‐deficient moss heath, dominated by Racomitrium lanuginosum, mean daily air temperatures at surface were 1–2°C higher in the warmed plots than the controls whereas soil temperatures tended to be lower in the warmed plots throughout the season. In a species‐rich dwarf shrub heath on relatively rich soils at a cooler site, dominated by Betula nana and R. lanuginosum, temperature changes were in the same direction although more moderate. In the moss heath, there were no detectable community changes while significant changes were detected in the dwarf shrub heath: the abundance of deciduous and evergreen dwarf shrubs significantly increased (>50%), bryophytes decreased (18%) and canopy height increased (100%). Contrary to some other studies of tundra communities, we detected no changes in species richness or other diversity measures in either community and the abundance of lichens did not change. It is concluded that the sensitivity of Icelandic tundra communities to climate warming varies greatly depending on initial conditions in terms of species diversity, dominant species, soil and climatic conditions as well as land‐use history. 相似文献
14.
Sønstebø JH Gielly L Brysting AK Elven R Edwards M Haile J Willerslev E Coissac E Rioux D Sannier J Taberlet P Brochmann C 《Molecular ecology resources》2010,10(6):1009-1018
Palaeoenvironments and former climates are typically inferred from pollen and macrofossil records. This approach is time-consuming and suffers from low taxonomic resolution and biased taxon sampling. Here, we test an alternative DNA-based approach utilizing the P6 loop in the chloroplast trnL (UAA) intron; a short (13–158 bp) and variable region with highly conserved flanking sequences. For taxonomic reference, a whole trnL intron sequence database was constructed from recently collected material of 842 species, representing all widespread and/or ecologically important taxa of the species-poor arctic flora. The P6 loop alone allowed identification of all families, most genera (>75%) and one-third of the species, thus providing much higher taxonomic resolution than pollen records. The suitability of the P6 loop for analysis of samples containing degraded ancient DNA from a mixture of species is demonstrated by high-throughput parallel pyrosequencing of permafrost-preserved DNA and reconstruction of two plant communities from the last glacial period. Our approach opens new possibilities for DNA-based assessment of ancient as well as modern biodiversity of many groups of organisms using environmental samples. 相似文献
15.
黑河中游湿地景观破碎化与气候变化的关系 总被引:1,自引:0,他引:1
在遥感和GIS技术支持下,基于1975-2010年长时间序列遥感影像和气象数据资料,结合小波分析、趋势面模拟与空间插值法,选取斑块密度(PD)、斑块平均面积(MPS)、斑块形状破碎化指数(FS)等景观指数,分析了黑河中游的气候空间分布和变化特征,以及该区域湿地的景观破碎化;通过相关分析和多元逐步回归分析,探讨了黑河中游湿地景观破碎化与气候变化的关系.结果表明:1975-2010年,研究区降水量和气温的整体分布格局为高气温区低降水量、低气温区高降水量,且干转湿和冷转暖为其主要变化特征;内陆干旱地区气温对湿地动态变化的影响大于降水,降水对湿地的生态作用甚微;研究区湿地景观破碎化主要表现为MPS减小、PD上升以及FS增大,研究期间,湿地MPS减少48.95 hm2,PD上升0.006个·hm-2. 相似文献
16.
WILFRIED THUILLER † GUY F. MIDGLEY ‡ GREG O. HUGHES § BASTIAN BOMHARD GILL DREW MICHAEL C. RUTHERFORD F. IAN WOODWARD¶ 《Global Change Biology》2006,12(5):759-776
We present a first assessment of the potential impacts of anthropogenic climate change on the endemic flora of Namibia, and on its vegetation structure and function, for a projected climate in ~2050 and ~2080. We used both niche‐based models (NBM) to evaluate the sensitivity of 159 endemic species to climate change (of an original 1020 plant species modeled) and a dynamic global vegetation model (DGVM) to assess the impacts of climate change on vegetation structure and ecosystem functioning. Endemic species modeled by NBM are moderately sensitive to projected climate change. Fewer than 5% are predicted to experience complete range loss by 2080, although more than 47% of the species are expected to be vulnerable (range reduction >30%) by 2080 if they are assumed unable to migrate. Disaggregation of results by life‐form showed distinct patterns. Endemic species of perennial herb, geophyte and tree life‐formsare predicted to be negatively impacted in Namibia, whereas annual herb and succulent endemic species remain relatively stable by 2050 and 2080. Endemic annual herb species are even predicted to extend their range north‐eastward into the tree and shrub savanna with migration, and tolerance of novel substrates. The current protected area network is predicted to meet its mandate by protecting most of the current endemicity in Namibia into the future. Vegetation simulated by DGVM is projected to experience a reduction in cover, net primary productivity and leaf area index throughout much of the country by 2050, with important implications for the faunal component of Namibia's ecosystems, and the agricultural sector. The plant functional type (PFT) composition of the major biomes may be substantially affected by climate change and rising atmospheric CO2– currently widespread deciduous broad leaved trees and C4 PFTs decline, with the C4 PFT particularly negatively affected by rising atmospheric CO2 impacts by ~2080 and deciduous broad leaved trees more likely directly impacted by drying and warming. The C3 PFT may increase in prominence in the northwestern quadrant of the country by ~2080 as CO2 concentrations increase. These results suggest that substantial changes in species diversity, vegetation structure and ecosystem functioning can be expected in Namibia with anticipated climate change, although endemic plant richness may persist in the topographically diverse central escarpment region. 相似文献
17.
Methane emissions from wetland soils are generally a positive function ofplant size and primary productivity, and may be expected to increase dueto enhanced rates of plant growth in a future atmosphere of elevatedCO2. We performed two experiments with Orontium aquaticum, acommon emergent aquatic macrophyte in temperate and sub-tropical wetlands, todetermine if enhanced rates of photosynthesis in elevated CO2atmospheres would increase CH4 emissions from wetland soils.O. aquaticum was grown from seed in soil cores under ambient and elevated(ca. 2-times ambient) concentrations of CO2 in an initialglasshouse study lasting 3 months and then a growth chamber study lasting 6months. Photosynthetic rates were 54 to 71% higher underelevated CO2 than ambient CO2, but plantbiomass was not significantly different at the end of the experiment. Ineach case, CH4 emissions were higher under elevated thanambient CO2 levels after 2 to 4 months of treatment, suggestinga close coupling between photosynthesis and methanogenesis in our plant-soilsystem. Methane emissions in the growth chamber study increased by 136%. We observed a significant decrease in transpirationrates under elevated CO2 in the growth chamber study, andspeculate that elevated CO2 may also stimulate CH4 emissions by increasing the extent and duration offlooding in some wetland ecosystems. Elevated CO2 maydramatically increase CH4 emissions from wetlands, a sourcethat currently accounts for 40% of global emissions. 相似文献
18.
A.T. STRATHDEE J.S. BALE F.C. STRATHDEE W.C. BLOCK † S.J. COULSON ‡ N.R. WEBB§ I. D. HODKINSON‡ 《Global Change Biology》1995,1(1):23-28
- 1 Theory suggests that any given rise in temperature resulting from climate change will have its greatest effect on high Arctic ecosystems where growing seasons are short and temperatures low.
- 2 A small temperature rise, similar to that predicted for the middle of the next century, has profound effects on a population of the high Arctic, Dryas-feeding aphid Acyrthosiphon svalbardicum on Spitsbergen (Strathdee et al. 1993a).
- 3 Here comparative experiments on a closely related Dryas-feeding species, A. brevicorne, at two contrasting sub-Arctic sites are described. Together with the results from Spitsbergen these sites represent two colder sites (high Arctic and upland sub-Arctic) and one warmer site (lowland sub-Arctic).
- 4 Differential responses in aphid population density and overwintering egg production to temperature elevation support the hypothesis that the ecological effects are greatest at sites with the most severe climates; however, there is no similar gradient in advancement of host plant phenology with warming.
19.
Timothy C. Bonebrake Carol L. Boggs Jeannie A. Stamberger Curtis A. Deutsch Paul R. Ehrlich 《Proceedings. Biological sciences / The Royal Society》2014,281(1793)
Difficulty in characterizing the relationship between climatic variability and climate change vulnerability arises when we consider the multiple scales at which this variation occurs, be it temporal (from minute to annual) or spatial (from centimetres to kilometres). We studied populations of a single widely distributed butterfly species, Chlosyne lacinia, to examine the physiological, morphological, thermoregulatory and biophysical underpinnings of adaptation to tropical and temperate climates. Microclimatic and morphological data along with a biophysical model documented the importance of solar radiation in predicting butterfly body temperature. We also integrated the biophysics with a physiologically based insect fitness model to quantify the influence of solar radiation, morphology and behaviour on warming impact projections. While warming is projected to have some detrimental impacts on tropical ectotherms, fitness impacts in this study are not as negative as models that assume body and air temperature equivalence would suggest. We additionally show that behavioural thermoregulation can diminish direct warming impacts, though indirect thermoregulatory consequences could further complicate predictions. With these results, at multiple spatial and temporal scales, we show the importance of biophysics and behaviour for studying biodiversity consequences of global climate change, and stress that tropical climate change impacts are likely to be context-dependent. 相似文献