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1.
Sci Total Environ ; 742: 140637, 2020 Nov 10.
Artigo em Inglês | MEDLINE | ID: mdl-32721746

RESUMO

Soil temperature remains isothermal at 0 °C and water shifts to a liquid phase during soil thawing. Vegetation may receive this process as a signal and a key to restore physiological activity. We aimed to show the relationship between the timing of soil thawing and the spring growth onset. We estimated the delay between the soil thawing and the spring growth onset in 78 sites of the FLUXNET network. We built a soil thawing map derived from modeling for the northern hemisphere and related it to the greenness onset estimated with satellite imagery. Spring onset estimated with GPP time series occurred shortly after soil surface thawing in tundra (1.1 ± 3.5 days) and alpine grasslands (16.6 ± 5.8 days). The association was weaker for deciduous forests (40.3 ± 4.2 days), especially where soils freeze infrequently. Needleleaved forests tended to start the growing season before the end of thawing (-17.4 ± 3.6 days), although observations from remote sensing (MODIS Land Cover Dynamics) indicated that the onset of greenness started after the thawing period (26.8 ± 3.2 days). This study highlights the role of soil temperature at the spring growth onset at high latitudes. Soil thawing becomes less relevant in temperate forests, where soil is occasionally frozen and other climate factors become more important.


Assuntos
Solo , Tundra , Mudança Climática , Ecossistema , Florestas , Estações do Ano , Temperatura
2.
Environ Sci Process Impacts ; 22(7): 1475-1490, 2020 Jul 22.
Artigo em Inglês | MEDLINE | ID: mdl-32475995

RESUMO

Phosphorus (P) is a limiting or co-limiting nutrient to plants and microorganisms in diverse ecosystems that include the arctic tundra. Certain soil minerals can adsorb or co-precipitate with phosphate, and this mineral-bound P provides a potentially large P reservoir in soils. Iron (Fe) oxyhydroxides have a high capacity to adsorb phosphate; however, the ability of Fe oxyhydroxides to adsorb phosphate and limit P bioavailability in organic tundra soils is not known. Here, we examined the depth distribution of soil Fe and P species in the active layer (<30 cm) of low-centered and high-centered ice-wedge polygons at the Barrow Environmental Observatory on the Alaska North Slope. Soil reservoirs of Fe and P in bulk horizons and in narrower depth increments were characterized using sequential chemical extractions and synchrotron-based X-ray absorption spectroscopy (XAS). Organic horizons across all polygon features (e.g., trough, ridge, and center) were enriched in extractable Fe and P relative to mineral horizons. Soil Fe was dominated by organic-bound Fe and short-range ordered Fe oxyhydroxides, while soil P was primarily associated with oxides and organic matter in organic horizons but apatite and/or calcareous minerals in mineral horizons. Iron oxyhydroxides and Fe-bound inorganic P (Pi) were most enriched at the soil surface and decreased gradually with depth, and Fe-bound Pi was >4× greater than water-soluble Pi. These results demonstrate that Fe-bound Pi is a large and ecologically important reservoir of phosphate. We contend that Fe oxyhydroxides and other minerals may regulate Pi solubility under fluctuating redox conditions in organic surface soils on the arctic tundra.


Assuntos
Ferro , Fosfatos , Solo , Alaska , Ecossistema , Gelo , Solo/química , Tundra
3.
J Environ Manage ; 267: 110636, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32421670

RESUMO

Rapid climate change is threatening the stability and functioning of Arctic ecosystems. As the Arctic warms, shrubs have been widely observed to expand, which has potentially serious consequences for global climate regulation and for the ecological processes characterising these ecosystems. However, it is currently unclear why this shrubification has been spatially uneven across the Arctic, with herbivory being suggested as a key regulating factor. By taking advantage of freely available satellite imagery spanning three decades, we mapped changes in shrub cover in the Yamal Peninsula and related these to changes in summer temperature and reindeer population size. We found no evidence that shrubs had expanded in the study site, despite increasing summer temperatures. At the same time, herbivore pressure increased significantly, with the local reindeer population size growing by about 75%. Altogether, our results thus point towards increases in large herbivore pressure having compensated for the warming of the Peninsula, halting the shrubification of the area. This suggests that strategic semi-domesticated reindeer husbandry, which is a common practice across the Eurasian Arctic, could represent an efficient environmental management strategy for maintaining open tundra landscapes in the face of rapid climate change.


Assuntos
Rena , Animais , Regiões Árticas , Mudança Climática , Ecossistema , Tundra
4.
Int J Syst Evol Microbiol ; 70(5): 3455-3461, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32375945

RESUMO

A Gram-stain-negative, rod-shaped, green-pigmented, aerobic and motile bacterium, strain R3-44T, was isolated from Arctic tundra soil. Stain R3-44T clustered closely with members of the genus Chitinimonas, which belongs to the family Burkholderiaceae, and showed the highest 16S rRNA sequence similarity to Chitinimonas naiadis AR2T (96.10%). Strain R3-44T grew optimally at pH 7.0, 28 °C and in the presence of 0-0.5 % (w/v) NaCl. The predominant respiratory isoprenoid quinone of strain R3-44T was identified as ubiquinone Q-8. The polar lipids consisted of phosphatidylglycerol, phosphatidylethanolamine, unidentified aminolipid and unidentified phospholipid. The main fatty acids were summed feature 3 (comprising C16 : 1 ω7c and/or C16 : 1 ω6c, 40.6 %) and C16 : 0 (29.3 %). The DNA G+C content of strain R3-44T was 60.8 mol%. On the basis of the evidence presented in this study, strain R3-44T represents a novel species of the genus Chitinimonas, for which the name Chitinimonas arctica sp. nov. is proposed, with the type strain R3-44T (=CCTCC AB 2010422T=KCTC 72602T).


Assuntos
Burkholderiaceae/classificação , Filogenia , Microbiologia do Solo , Tundra , Regiões Árticas , Técnicas de Tipagem Bacteriana , Composição de Bases , Burkholderiaceae/isolamento & purificação , DNA Bacteriano/genética , Ácidos Graxos/química , Fosfatidiletanolaminas , Fosfolipídeos/química , Pigmentação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Svalbard , Ubiquinona/química
5.
Sci Total Environ ; 724: 138304, 2020 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-32408462

RESUMO

AIMS: Litter decomposition is an important driver of soil carbon and nutrient cycling in nutrient-limited Arctic ecosystems. However, climate change is expected to induce changes that directly or indirectly affect decomposition. We examined the direct effects of long-term warming relative to differences in soil abiotic properties associated with vegetation type on litter decomposition across six subarctic vegetation types. METHODS: In six vegetation types, rooibos and green tea bags were buried for 70-75 days at 8 cm depth inside warmed (by open-top chambers) and control plots that had been in place for 20-25 years. Standardized initial decomposition rate and stabilization of the labile material fraction of tea (into less decomposable material) were calculated from tea mass losses. Soil moisture and temperature were measured bi-weekly during summer and plant-available nutrients were measured with resin probes. RESULTS: Initial decomposition rate was decreased by the warming treatment. Stabilization was less affected by warming and determined by vegetation type and soil moisture. Soil metal concentrations impeded both initial decomposition rate and stabilization. CONCLUSIONS: While a warmer Arctic climate will likely have direct effects on initial litter decomposition rates in tundra, stabilization of organic matter was more affected by vegetation type and soil parameters and less prone to be affected by direct effects of warming.


Assuntos
Ecossistema , Tundra , Regiões Árticas , Mudança Climática , Solo
6.
PLoS One ; 15(3): e0230157, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32182280

RESUMO

The Acidobacteria is one of the major bacterial phyla in soils and peatlands. The currently explored diversity within this phylum is assigned to 15 class-level units, five of which contain described members. The ecologically relevant traits of acidobacteria from different classes remain poorly understood. Here, we compared the patterns of acidobacterial diversity in sandy soils of tundra, along a gradient of increasing vegetation-unfixed aeolian sand, semi-fixed surfaces with mosses and lichens, and mature soil under fully developed plant cover. The Acidobacteria-affiliated 16S rRNA gene sequences retrieved from these soils comprised 11 to 33% of total bacterial reads and belonged mostly to members of the classes Acidobacteriia and Blastocatellia, which displayed opposite habitat preferences. The relative abundance of the Blastocatellia was maximal in unfixed sands and declined in soils of vegetated plots, showing positive correlation with soil pH and negative correlation with carbon and nitrogen availability. An opposite tendency was characteristic for the Acidobacteriia. Most Blastocatellia-affiliated reads belonged to as-yet-undescribed members of the family Arenimicrobiaceae, which appears to be characteristic for dry, depleted in organic matter soil habitats. The pool of Acidobacteriia-affiliated sequences, apart from Acidobacteriaceae- and Bryobacteraceae-related reads, had a large proportion of sequences from as-yet-undescribed families, which seem to specialize in degrading plant-derived organic matter. This analysis reveals sandy soils of tundra as a source of novel acidobacterial diversity and provides an insight into the ecological preferences of different taxonomic groups within this phylum.


Assuntos
Acidobacteria , Bactérias , Microbiologia do Solo , Tundra , Acidobacteria/classificação , Acidobacteria/genética , Acidobacteria/isolamento & purificação , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Biodiversidade , Carbono/análise , Classificação , DNA Bacteriano , Ecossistema , Metagenômica , Nitrogênio/análise , Filogenia , RNA Ribossômico 16S/genética , Solo/química
7.
Nat Commun ; 11(1): 1351, 2020 03 12.
Artigo em Inglês | MEDLINE | ID: mdl-32165619

RESUMO

The majority of variation in six traits critical to the growth, survival and reproduction of plant species is thought to be organised along just two dimensions, corresponding to strategies of plant size and resource acquisition. However, it is unknown whether global plant trait relationships extend to climatic extremes, and if these interspecific relationships are confounded by trait variation within species. We test whether trait relationships extend to the cold extremes of life on Earth using the largest database of tundra plant traits yet compiled. We show that tundra plants demonstrate remarkably similar resource economic traits, but not size traits, compared to global distributions, and exhibit the same two dimensions of trait variation. Three quarters of trait variation occurs among species, mirroring global estimates of interspecific trait variation. Plant trait relationships are thus generalizable to the edge of global trait-space, informing prediction of plant community change in a warming world.


Assuntos
Desenvolvimento Vegetal , Tundra , Clima , Ecossistema , Plantas/classificação , Plantas/genética
9.
Oecologia ; 192(3): 671-685, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32052180

RESUMO

Warming-induced nutrient enrichment in the Arctic may lead to shifts in leaf-level physiological properties and processes with potential consequences for plant community dynamics and ecosystem function. To explore the physiological responses of Arctic tundra vegetation to increasing nutrient availability, we examined how a set of leaf nutrient and physiological characteristics of eight plant species (representing four plant functional groups) respond to a gradient of experimental nitrogen (N) and phosphorus (P) enrichment. Specifically, we examined a set of chlorophyll fluorescence measures related to photosynthetic efficiency, performance and stress, and two leaf nutrient traits (leaf %C and %N), across an experimental nutrient gradient at the Arctic Long Term Ecological Research site, located in the northern foothills of the Brooks Range, Alaska. In addition, we explicitly assessed the direct relationships between chlorophyll fluorescence and leaf %N. We found significant differences in physiological and nutrient traits between species and plant functional groups, and we found that species within one functional group (deciduous shrubs) have significantly greater leaf %N at high levels of nutrient addition. In addition, we found positive, saturating relationships between leaf %N and chlorophyll fluorescence measures across all species. Our results highlight species-specific differences in leaf nutrient traits and physiology in this ecosystem. In particular, the effects of a gradient of nutrient enrichment were most prominent in deciduous plant species, the plant functional group known to be increasing in relative abundance with warming in this ecosystem.


Assuntos
Ecossistema , Tundra , Alaska , Regiões Árticas , Nutrientes
10.
Nat Commun ; 11(1): 1001, 2020 02 21.
Artigo em Inglês | MEDLINE | ID: mdl-32081890

RESUMO

Human activity has caused dramatic population declines in many wild species. The resulting bottlenecks have a profound impact on the genetic makeup of a species with unknown consequences for health. A key genetic factor for species survival is the evolution of deleterious mutation load, but how bottleneck strength and mutation load interact lacks empirical evidence. We analyze 60 complete genomes of six ibex species and the domestic goat. We show that historic bottlenecks rather than the current conservation status predict levels of genome-wide variation. By analyzing the exceptionally well-characterized population bottlenecks of the once nearly extinct Alpine ibex, we find genomic evidence of concurrent purging of highly deleterious mutations but accumulation of mildly deleterious mutations. This suggests that recolonization bottlenecks induced both relaxed selection and purging, thus reshaping the landscape of deleterious mutation load. Our findings highlight that even populations of ~1000 individuals can accumulate mildly deleterious mutations. Conservation efforts should focus on preventing population declines below such levels to ensure long-term survival of species.


Assuntos
Cabras/genética , Mutação , Animais , Animais Selvagens/classificação , Animais Selvagens/genética , Simulação por Computador , Conservação dos Recursos Naturais , Evolução Molecular , Variação Genética , Genética Populacional , Genoma , Cabras/classificação , Modelos Genéticos , Especificidade da Espécie , Tundra
11.
Proc Natl Acad Sci U S A ; 117(6): 3026-3033, 2020 02 11.
Artigo em Inglês | MEDLINE | ID: mdl-31988125

RESUMO

The Arctic climate was warmer than today at the last interglacial and the Holocene thermal optimum. To reveal the impact of past climate-warming events on the demographic history of an Arctic specialist, we examined both mitochondrial and nuclear genomic variation in the collared lemming (Dicrostonyx torquatus, Pallas), a keystone species in tundra communities, across its entire distribution in northern Eurasia. The ancestral phylogenetic position of the West Beringian group and divergence time estimates support the hypothesis of continental range contraction to a single refugial area located in West Beringia during high-magnitude warming of the last interglacial, followed by westward recolonization of northern Eurasia in the last glacial period. The West Beringian group harbors the highest mitogenome diversity and its inferred demography indicates a constantly large effective population size over the Late Pleistocene to Holocene. This suggests that northward forest expansion during recent warming of the Holocene thermal optimum did not affect the gene pool of the collared lemming in West Beringia but reduced genomic diversity and effective population size in all other regions of the Eurasian Arctic. Demographic inference from genomic diversity was corroborated by species distribution modeling showing reduction in species distribution during past climate warming. These conclusions are supported by recent paleoecological evidence suggesting smaller temperature increases and moderate northward forest advances in the extreme northeast of Eurasia during the Late Pleistocene-to-Holocene warming events. This study emphasizes the importance of West Beringia as a potential refugium for cold-adapted Arctic species under ongoing climate warming.


Assuntos
Arvicolinae/genética , Variação Genética/genética , Aquecimento Global/história , Animais , Regiões Árticas , Ásia , Europa (Continente) , Genoma/genética , Genoma Mitocondrial/genética , Genômica , História Antiga , Refúgio de Vida Selvagem , Tundra
12.
Ambio ; 49(3): 666-677, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31955396

RESUMO

Vegetation change has consequences for terrestrial ecosystem structure and functioning and may involve climate feedbacks. Hence, when monitoring ecosystem states and changes thereof, the vegetation is often a primary monitoring target. Here, we summarize current understanding of vegetation change in the High Arctic-the World's most rapidly warming region-in the context of ecosystem monitoring. To foster development of deployable monitoring strategies, we categorize different kinds of drivers (disturbances or stresses) of vegetation change either as pulse (i.e. drivers that occur as sudden and short events, though their effects may be long lasting) or press (i.e. drivers where change in conditions remains in place for a prolonged period, or slowly increases in pressure). To account for the great heterogeneity in vegetation responses to climate change and other drivers, we stress the need for increased use of ecosystem-specific conceptual models to guide monitoring and ecological studies in the Arctic. We discuss a conceptual model with three hypothesized alternative vegetation states characterized by mosses, herbaceous plants, and bare ground patches, respectively. We use moss-graminoid tundra of Svalbard as a case study to discuss the documented and potential impacts of different drivers on the possible transitions between those states. Our current understanding points to likely additive effects of herbivores and a warming climate, driving this ecosystem from a moss-dominated state with cool soils, shallow active layer and slow nutrient cycling to an ecosystem with warmer soil, deeper permafrost thaw, and faster nutrient cycling. Herbaceous-dominated vegetation and (patchy) bare ground would present two states in response to those drivers. Conceptual models are an operational tool to focus monitoring efforts towards management needs and identify the most pressing scientific questions. We promote greater use of conceptual models in conjunction with a state-and-transition framework in monitoring to ensure fit for purpose approaches. Defined expectations of the focal systems' responses to different drivers also facilitate linking local and regional monitoring efforts to international initiatives, such as the Circumpolar Biodiversity Monitoring Program.


Assuntos
Ecossistema , Tundra , Regiões Árticas , Mudança Climática , Solo , Svalbard
13.
Ambio ; 49(3): 732-748, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31955397

RESUMO

Tundra-breeding birds face diverse conservation challenges, from accelerated rates of Arctic climate change to threats associated with highly migratory life histories. Here we summarise the status and trends of Arctic terrestrial birds (88 species, 228 subspecies or distinct flyway populations) across guilds/regions, derived from published sources, raw data or, in rare cases, expert opinion. We report long-term trends in vital rates (survival, reproduction) for the handful of species and regions for which these are available. Over half of all circumpolar Arctic wader taxa are declining (51% of 91 taxa with known trends) and almost half of all waterfowl are increasing (49% of 61 taxa); these opposing trends have fostered a shift in community composition in some locations. Declines were least prevalent in the African-Eurasian Flyway (29%), but similarly prevalent in the remaining three global flyways (44-54%). Widespread, and in some cases accelerating, declines underscore the urgent conservation needs faced by many Arctic terrestrial bird species.


Assuntos
Aves , Tundra , Animais , Regiões Árticas , Mudança Climática , Reprodução
14.
Glob Chang Biol ; 26(3): 1908-1925, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31957145

RESUMO

Warming occurs in the Arctic twice as fast as the global average, which in turn leads to a large enhancement in terpenoid emissions from vegetation. Volatile terpenoids are the main class of biogenic volatile organic compounds (VOCs) that play crucial roles in atmospheric chemistry and climate. However, the biochemical mechanisms behind the temperature-dependent increase in VOC emissions from subarctic ecosystems are largely unexplored. Using 13 CO2 -labeling, we studied the origin of VOCs and the carbon (C) allocation under global warming in the soil-plant-atmosphere system of contrasting subarctic heath tundra vegetation communities characterized by dwarf shrubs of the genera Salix or Betula. The projected temperature rise of the subarctic summer by 5°C was realistically simulated in sophisticated climate chambers. VOC emissions strongly depended on the plant species composition of the heath tundra. Warming caused increased VOC emissions and significant changes in the pattern of volatiles toward more reactive hydrocarbons. The 13 C was incorporated to varying degrees in different monoterpene and sesquiterpene isomers. We found that de novo monoterpene biosynthesis contributed to 40%-44% (Salix) and 60%-68% (Betula) of total monoterpene emissions under the current climate, and that warming increased the contribution to 50%-58% (Salix) and 87%-95% (Betula). Analyses of above- and belowground 12/13 C showed shifts of C allocation in the plant-soil systems and negative effects of warming on C sequestration by lowering net ecosystem exchange of CO2 and increasing C loss as VOCs. This comprehensive analysis provides the scientific basis for mechanistically understanding the processes controlling terpenoid emissions, required for modeling VOC emissions from terrestrial ecosystems and predicting the future chemistry of the arctic atmosphere. By changing the chemical composition and loads of VOCs into the atmosphere, the current data indicate that global warming in the Arctic may have implications for regional and global climate and for the delicate tundra ecosystems.


Assuntos
Aquecimento Global , Compostos Orgânicos Voláteis , Regiões Árticas , Ecossistema , Tundra
15.
J Environ Radioact ; 212: 106125, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-31818733

RESUMO

The paper presents results of the radioecological investigation carried out in south-western Greenland shoreline. There were examined over 50 samples of lichens and mosses collected from 7 locations during two scientific expeditions conducted in the summer of 2012-2013. The levels, trends and the most likely origin were determined for following natural and artificial radionuclides: 90Sr, 137Cs, 230, 232Th, 234, 238U, 238, 239+240Pu and 241Am. The radioactive pollution was found as relatively low, reaching the maximum values at: 25.3 ± 2.04 Bq/kg for 90Sr, 293 ± 27 Bq/kg for 137Cs, 4.01 ± 0.13 Bq/kg for 239+240Pu, 0.1381 ± 0.0070 Bq/kg for 238Pu and 1.90 ± 0.21 Bq/kg of 241Am, 9.15 ± 0.48 Bq/kg for 230Th, 25.1 ± 1.2 Bq/kg for 232Th, 7.5 ± 1.5 Bq/kg for 234U and 7.26 ± 0.80 Bq/kg for 238U. Both activity and mass isotopic ratio assays revealed dominant contribution of the global fallout + SNAP 9A on the presence of plutonium isotopes and 241Am in Greenland tundra. However, noticeable deviations of 241Am/239+240Pu and to a lesser extend of 240Pu/239Pu ratios from the GF level have been observed. The origin of 137Cs was evidently connected with the coexistence of global and Chernobyl fallout, while the presence of 90Sr was caused by nuclear weapon tests and affected by leaching process. The seaborne signature of uranium isotopes was manifested in research material as well.


Assuntos
Monitoramento de Radiação , Tundra , Groenlândia , Plutônio , Cinza Radioativa , Poluentes Radioativos do Solo
16.
Glob Chang Biol ; 26(2): 931-943, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31554024

RESUMO

Nitrous oxide (N2 O) emissions from soil contribute to global warming and are in turn substantially affected by climate change. However, climate change impacts on N2 O production across terrestrial ecosystems remain poorly understood. Here, we synthesized 46 published studies of N2 O fluxes and relevant soil functional genes (SFGs, that is, archaeal amoA, bacterial amoA, nosZ, narG, nirK and nirS) to assess their responses to increased temperature, increased or decreased precipitation amounts, and prolonged drought (no change in total precipitation but increase in precipitation intervals) in terrestrial ecosystem (i.e. grasslands, forests, shrublands, tundra and croplands). Across the data set, temperature increased N2 O emissions by 33%. However, the effects were highly variable across biomes, with strongest temperature responses in shrublands, variable responses in forests and negative responses in tundra. The warming methods employed also influenced the effects of temperature on N2 O emissions (most effectively induced by open-top chambers). Whole-day or whole-year warming treatment significantly enhanced N2 O emissions, but daytime, nighttime or short-season warming did not have significant effects. Regardless of biome, treatment method and season, increased precipitation promoted N2 O emission by an average of 55%, while decreased precipitation suppressed N2 O emission by 31%, predominantly driven by changes in soil moisture. The effect size of precipitation changes on nirS and nosZ showed a U-shape relationship with soil moisture; further insight into biotic mechanisms underlying N2 O emission response to climate change remain limited by data availability, underlying a need for studies that report SFG. Our findings indicate that climate change substantially affects N2 O emission and highlights the urgent need to incorporate this strong feedback into most climate models for convincing projection of future climate change.


Assuntos
Mudança Climática , Ecossistema , Óxido Nitroso , Solo , Tundra
17.
Ambio ; 49(3): 678-692, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30929249

RESUMO

Changes in Arctic vegetation can have important implications for trophic interactions and ecosystem functioning leading to climate feedbacks. Plot-based vegetation surveys provide detailed insight into vegetation changes at sites around the Arctic and improve our ability to predict the impacts of environmental change on tundra ecosystems. Here, we review studies of changes in plant community composition and phenology from both long-term monitoring and warming experiments in Arctic environments. We find that Arctic plant communities and species are generally sensitive to warming, but trends over a period of time are heterogeneous and complex and do not always mirror expectations based on responses to experimental manipulations. Our findings highlight the need for more geographically widespread, integrated, and comprehensive monitoring efforts that can better resolve the interacting effects of warming and other local and regional ecological factors.


Assuntos
Ecossistema , Tundra , Regiões Árticas , Mudança Climática , Plantas , Estações do Ano
18.
BMC Genet ; 20(1): 92, 2019 12 04.
Artigo em Inglês | MEDLINE | ID: mdl-31801460

RESUMO

BACKGROUND: Grasslands in the Arctic tundra undergo irreversible degradation due to climatic changes and also over-exploitation and depletion of scarce resources. Comprehensive investigations of cytogenomic structures of valuable Arctic and sub-Arctic grassland species is essential for clarifying their genetic peculiarities and phylogenetic relationships, and also successful developing new forage grass cultivars with high levels of adaptation, stable productivity and longevity. We performed molecular cytogenetic characterization of insufficiently studied pasture grass species (Poaceae) from related genera representing two neighboring clades: 1) Deschampsia and Holcus; 2) Alopecurus, Arctagrostis and Beckmannia, which are the primary fodder resources in the Arctic tundra. RESULTS: We constructed the integrated schematic maps of distribution of these species in the northern, central and eastern parts of Eurasia based on the currently available data as only scattered data on their occurrence is currently available. The species karyotypes were examined with the use of DAPI-banding, multicolour FISH with 35S rDNA, 5S rDNA and the (GTT)9 microsatellite motif and also sequential rapid multocolour GISH with genomic DNAs of Deschampsia sukatschewii, Deschampsia flexuosa and Holcus lanatus belonging to one of the studied clades. Cytogenomic structures of the species were specified; peculiarities and common features of their genomes were revealed. Different chromosomal rearrangements were detected in Beckmannia syzigachne, Deschampsia cespitosa and D. flexuosa; B chromosomes with distinct DAPI-bands were observed in karyotypes of D. cespitosa and H. lanatus. CONCLUSIONS: The peculiarities of distribution patterns of the examined chromosomal markers and also presence of common homologous DNA repeats in karyotypes of the studies species allowed us to verify their relationships. The obtained unique data on distribution areas and cytogenomic structures of the valuable Arctic and sub-Arctic pasture species are important for further genetic and biotechnological studies and also plant breeding progress.


Assuntos
Avena/genética , Análise Citogenética/métodos , Poa/genética , Aberrações Cromossômicas , Cromossomos de Plantas/genética , Demografia , Cariótipo , Tundra
19.
PLoS One ; 14(11): e0224741, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31747407

RESUMO

In interior Eurasia, high mountain zones are crucial to pastoral subsistence, providing seasonally productive pastures and abundant wild resources. In some areas of northern Mongolia, mountainous tundra zones also support a low-latitude population of domestic reindeer herders-a lifestyle whose origins are poorly characterized in the archaeological record of early Mongolia. Traditionally, reindeer pastoralists make significant seasonal use of munkh mus (eternal ice) for their domestic herds, using these features to cool heat-stressed animals and provide respite from insect harassment. In recent years, many of these features have begun to melt entirely for the first time, producing urgent threats to traditional management techniques, the viability of summer pastures, and reindeer health. The melting ice is also exposing fragile organic archaeological materials that had previously been contained in the patch. We present the results of horseback survey of ice patches in Baruun Taiga special protected area, providing the first archaeological insights from the region. Results reveal new evidence of historic tool production and wild resource use for fishing or other activities, and indicate that ice patches are likely to contain one of the few material records of premodern domestic reindeer use in Mongolia and lower Central Asia. The area's ancient ice appears to be rapidly melting due to changing climate and warming summer temperatures, putting both cultural heritage and traditional reindeer herding at extreme risk in the years to come.


Assuntos
Criação de Animais Domésticos/métodos , Animais Domésticos , Gelo , Rena , Animais , Arqueologia , Mudança Climática , Conservação dos Recursos Naturais , Mongólia , Estações do Ano , Tundra
20.
PLoS One ; 14(11): e0224218, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31693675

RESUMO

Tropical plant species are expected to have high heat tolerance reflecting phenotypic adjustments to warm regions or their evolutionary adaptation history. However, tropical highland specialists adapted to the colder temperatures found in the highlands, where short and prostrated vegetation decouples plants from ambient conditions, could exhibit different upper thermal limits than those of their lowland counterparts. Here we evaluated leaf heat tolerance of 21 tropical alpine paramo species to determine: 1) whether species with restricted distribution (i.e., highland specialists) have lower heat tolerance and are more vulnerable to warming than species with widespread distribution; 2) whether different growth forms have different heat tolerance; and 3) whether species height (i.e., microhabitat) influences its heat tolerance. We quantified heat tolerance by evaluating T50, which is the temperature that causes a reduction in 50% of initial Fv/Fm values and reflects an irreversible damage to the photosynthetic apparatus. Additionally, we estimated the thermal safety margins as the difference between T50 and the maximum leaf temperature registered for the species. All species presented high T50 values ranging between 45.4°C and 53.9°C, similar to those found for tropical lowland species. Heat tolerance was not correlated with species distributions or plant height, but showed a strong relationship with growth form, with rosettes having the highest heat tolerance. Thermal safety margins ranged from 12.1 to 31.0°C. High heat tolerance and broad thermal safety margins suggest low vulnerability of paramo species to warming as long as plants are capable of regulating the leaf temperature within this threshold. Whether paramo plants would be able to regulate leaf temperature if drought episodes become more frequent and transpirational cooling is compromised is the next question that needs to be answered.


Assuntos
Mudança Climática , Folhas de Planta/fisiologia , Termotolerância/fisiologia , Clima Tropical/efeitos adversos , Tundra , Colômbia , Temperatura Alta/efeitos adversos , Dispersão Vegetal/fisiologia
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