Low Competitive Ability Research Articles

Forage Potential of Cereal/Legume Intercrops: Agronomic Performances, Yield, Quality Forage and LER in Two Harvesting Times in a Mediterranean Environment

The crop yield and quality of seven annual forages (four grasses and three legumes) in sole crop and in mixtures (ratio 50:50) for oat (Avena sativa L.), Italian ryegrass (Lolium multiflorum Lam.), triticale (x Triticosecale Wittmack), barley (Hordeum vulgare L.), pea (Pisum sativum L.), berseem (Trifolium alexandrinum L.) and common vetch (Vicia sativa L.) were evaluated in a two-year field experiment adopting two harvesting times, green fodder and silage. The main bio-agronomic traits, dry matter forage yield (DMY) and quantity of crude protein (CP) were determined in both sole crop and intercrop. The land equivalent ratio (LER) was used for evaluating biological efficiency and competitive ability of the intercrops. Our results showed that the total calculated LER for fodder and protein yields was always greater than one and corresponded to crop yield advantages of 16.0% and 11.5%, respectively. Our data also highlighted the low competitive ability of the ryegrass in intercrop, which achieved the lowest yield among all the mixtures. Conversely, the same grass showed the best green fodder quality, due to the high incidence of the legume, equal (on average) to 46%. Triticale and barley, harvested for silage (hard dough stage), provided the best quantitative and qualitative results both in sole crop and intercropped with common vetch and pea, determined mainly by the cereal grain.

Along with intraspecific functional trait variation, individual performance is key to resolving community assembly processes

Abstract Species contributing high proportions to community biomass strongly influence ecosystem processes within the community. Studies have shown that dominant species may serve as nurse plants, helping to ensure biomass stability of the subordinate species under stress conditions. The question is widely debated as to whether either niche differentiation or neutral processes drive the net outcome of plant interactions within a subordinate plant community. To answer this question, requires precise estimates of individual variation in functional traits and performance. In a 5‐year mesocosm experiment, the functional responses of a subordinate plant community to the removal of the dominant species were evaluated across two drought‐stress scenarios. Small‐scale (i.e. large pots) wetland communities were constructed comprising one dominant species Carex elata and three subordinate species. Removal of the dominant species allowed evaluation of the net effects of drought and interspecific interactions. We estimated the functional divergences for three traits (SLA, leaf dry matter content and allocation to height growth) and compared these with performance differences quantified individually. This enabled distinctions to be made between deterministic (i.e. niche differentiation) and neutral processes driving the drought response of the subordinate community. We showed that the dominant species decreased relative performance differences within the subordinate plant community under conditions of permanent drought stress. These changes were associated with the convergence of traits related to resource acquisition and growth. The dominant species equalized species performance differences by supressing relatively drought‐tolerant species with low competitive ability and by supporting the less drought‐tolerant species with relatively high competitive ability. Meanwhile, under conditions of inter‐annual drought, the subordinate species likely coexisted due to differentiation in resource‐use strategies and the interaction with the dominant species. Inclusion of individual variation in performance with a functional trait approach provides valuable insights into the processes structuring plant communities. Ours is the first study to provide evidence that subordinate species exposed to drought may coexist via neutral processes arising from their interactions with the dominant species, leading to functional convergence of traits associated with the trade‐off between stress tolerance and competitive ability. A free Plain Language Summary can be found within the Supporting Information of this article.

Intercropping Winter Lupin and Triticale Increases Weed Suppression and Total Yield

Lupin (Lupinus sp.) produces protein-rich grains, but its adoption in cropping systems suffers from both its low competitive ability against weeds and its high yield variability. Compared with legume sole cropping, grain legume–cereal intercropping benefits include better weed suppression and higher yield and yield stability. However, the potential of enhancing crop competitive ability against weeds in additive winter grain legume–cereal intercrops is not well-known, and this potential in long crop cycles is even less studied. We studied how intercropping with a triticale (×Triticosecale) alters weed biomass and productivity of winter white lupin (Lupinus albus L.). The experimental setup consisted of eleven sites during a two-year period in western France. In each site-year, winter white lupin sole cropping was compared to winter white lupin-triticale intercropping in an additive sowing design. We found that intercropping reduced weed biomass at lupin flowering by an average of 63%. The rapid growth and high soil N acquisition of triticale compensated for the low competitive ability of lupin against weeds until lupin flowering. Competition from triticale in the intercrop reduced lupin grain yield (−34%), but intercropping produced a higher total grain yield (+37%) than did lupin sole cropping while maintaining the total protein grain yield.

A re-evaluation of the Chaetothyriales using criteria of comparative biology

Chaetothyriales is an ascomycetous order within Eurotiomycetes. The order is particularly known through the black yeasts and filamentous relatives that cause opportunistic infections in humans. All species in the order are consistently melanized. Ecology and habitats of species are highly diverse, and often rather extreme in terms of exposition and toxicity. Families are defined on the basis of evolutionary history, which is reconstructed by time of divergence and concepts of comparative biology using stochastical character mapping and a multi-rate Brownian motion model to reconstruct ecological ancestral character states. Ancestry is hypothesized to be with a rock-inhabiting life style. Ecological disparity increased significantly in late Jurassic, probably due to expansion of cytochromes followed by colonization of vacant ecospaces. Dramatic diversification took place subsequently, but at a low level of innovation resulting in strong niche conservatism for extant taxa. Families are ecologically different in degrees of specialization. One of the clades has adapted ant domatia, which are rich in hydrocarbons. In derived families, similar processes have enabled survival in domesticated environments rich in creosote and toxic hydrocarbons, and this ability might also explain the pronounced infectious ability of vertebrate hosts observed in these families. Conventional systems of morphological classification poorly correspond with recent phylogenetic data. Species are hypothesized to have low competitive ability against neighboring microbes, which interferes with their laboratory isolation on routine media. The dataset is unbalanced in that a large part of the extant biodiversity has not been analyzed by molecular methods, novel taxonomic entities being introduced at a regular pace. Our study comprises all available species sequenced to date for LSU and ITS, and a nomenclatural overview is provided. A limited number of species could not be assigned to any extant family.

RELATIONSHIP OF TOTAL QUALITY MANAGEMENT TO QUALITY PRODUCT AND CORPORATE PERFORMANCE

Background: Small and medium businesses (SMEs) have major problems with regard to product quality so that it affects the low competitive ability. Some indications include high product variability, low process capability and low customer satisfaction. The purpose of this study is to prove whether the implementation of Total Quality Management (TQM) in SMEs influences product quality and company performance? The research method is descriptive qualitative with a survey approach, samples taken using the simple random sampling method of 60 SMEs in two districts namely Cianjur and Bandung. The questionnaire was used as a data collection tool. Based on the results of the study showed that the quality of products perceived by consumers is influenced by the implementation of TQM, the better SMEs implement TQM, the better the product quality. The data further proves that organizational performance as assessed by ROA (Return of Investment) is influenced by product quality, so that if the company wants to increase profits then improve product quality. This research is limited to processing industry SMEs not to the service sector. Some of the limitations of SMEs that have an impact on low quality are low access to technology, access to raw material sources which results in high product variability.

Typology of contractors for forestry services: Insights from Slovakia

The forestry services market in Slovakia has begun to form in the early 1990s under unstable and changing conditions due to the restitution of forest property rights and the restructuring of state-owned enterprises. The transition of State Enterprise Forests towards outsourcing of forestry activities was completed in a relatively short time period, which was insufficient for an adequate formation of this sector. Therefore, it is weakly developed, undercapitalised and has a low competitive ability. On the other hand, at present, there is a high dependence on contractor firms, which carry out the most part of logging, silviculture and transport activities within the forestry. Nowadays, the forest business community consists of more than 10,600 contractors, 88% are self-employed persons and 12% represent business companies. According to the structure of revenues and cost items, the aim of the study was to identify and characterize the firm types of contractors in the forest service sector in Slovakia, with an emphasis on Limited Liability Companies. Methodologically, it is based on the analysis of basic economic data from a representative sample of 152 contractors and a vertical analysis of their income statements. A detailed analysis of revenue and cost items showed that the most significant part of total income of the selected companies comes from the sale of own products and services (58%). On the other hand, the highest value within the total expenses were found for production consumption (57.2%) and cost of merchandise sold (31.8%). Subsequently, five types of business strategies were identified and characterised. Business strategies of contractors are influenced by the current situation within the sector. Low prices for provided services and a lack of qualified workers in the labour market cause mean that it is not possible to apply the classic business strategies. Contractors try to apply their own strategies such as orientation to business or management of subcontractors. They mostly prefer the so-called „Classic strategy”, which focuses on providing services as well as trading activities to complement their business activities. We therefore expect an increased number of contractors who provide forestry services through their own employees. Another possible way is to allow contractors to implement new business strategies and innovations through a higher degree of the standing timber sale.

Latitudinal directionality in ectotherm invasion success.

A striking pattern, seen in both fossil and extant taxa, is that tropical ectotherms are better at invading temperate habitats than vice versa. This is puzzling because tropical ectotherms, being thermal specialists, face a harsher abiotic environment and competition from temperate residents that are thermal generalists. We develop a mathematical framework to address this puzzle. We find that (i) tropical ectotherms can invade temperate habitats if they have higher consumption rates and lower mortality during warmer summers, (ii) stronger seasonal fluctuations at higher latitudes create more temporal niches, allowing coexistence of tropical invaders and temperate residents, and (iii) temperate ectotherms' failure to invade tropical habitats is due to greater mortality rather than lower competitive ability. Our framework yields predictions about population-level outcomes of invasion success based solely on species' trait responses to temperature. It provides a potential ecological explanation for why the tropics constitute both a cradle and a museum of biodiversity.

A novel approach to estimating the competitive ability of Cirsium arvense in cereals using unmanned aerial vehicle imagery

SummaryEight experiments were carried out in Denmark to determine the yield loss of spring barley due to Cirsium arvense in farmers' fields and to suggest and evaluate a novel approach for quantifying C. arvense infestation in large plots. Literature about the competitive ability of C. arvense is old, scattered and inconclusive, and existing models for estimating crop yield loss are based on data from North America. This study showed that C. arvense coverage could be quantified from unmanned aerial vehicle imagery using a manual image analysis procedure. This gave similar results as scoring the coverage. Yield loss of spring barley due to C. arvense infestation assessed at harvest was given by Y = 100·(1−exp(−0.00170·X)) where Y is the percentage of crop yield loss and X is the percentage of C. arvense coverage. The yield loss was much lower than estimates from models that have been developed in North America. It is speculated that the main reason for this is the later emergence of C. arvense than the crop due to lower soil temperatures in spring. Grain moisture increased linearly with C. arvense coverage: M = 0.0310·X where M is the proportional (%) increase in grain moisture and X is the proportion (%) of C. arvense coverage. Automated image analysis procedures are needed to estimate C. arvense coverage on field scales, and further experiments are needed to reveal whether the low competitive ability of C. arvense found in this study is representative for Northern Europe.

First Record of True Albinism in a Natural Population of Collared Flycatchers Ficedula albicollis

Albinism is a remarkably rare colour deficiency among natural populations of bird species. Here we document the first record of true albinism in a wild population of Collared Flycatchers Ficedula albicollis. We found a nest of two albino and three melanised nestlings, and the former became progressively underdeveloped and perished by the end of the nestling feeding period. It is possible that parents differentiated between chick types when provisioning the brood or that the albinos were of lower competitive ability; these could be additional reasons for the rare occurrence of this phenotype in the wild.

Male responses to conspecific and heterospecific songs in two field cricket species

Many animals produce acoustic signals for displaying their territoriality to other males and attracting mating partners. However, the acoustic signals are often eavesdropped on by other species. If a species with higher competitive ability eavesdrops on the acoustic signals of a species with lower competitive ability, the former can deprive the latter of their suitable calling sites. Therefore, the species with higher competitive ability exhibits a positive response to the acoustic signals of those with lower competitive abilities, whereas the species with lower competitive ability exhibits a negative response to the calling songs of those with higher competitive abilities. In the present study, male responses to conspecific and heterospecific song in two field cricket species Teleogryllus occipitalis (Audinet-Serville 1839) (Gryllidae) and Loxoblemmus equestris Saussure 1877 (Gryllidae) were investigated by playback experiments. T. occipitalis has larger body size than L. equestris. Both species did not exhibit precise negative or positive responses to conspecific and heterospecific songs. The results suggest that the cricket species do not utilize heterospecific song to acquire their calling sites.

Robinia pseudoacacia-dominated vegetation types of Southern Europe: Species composition, history, distribution and management

Knowledge of the species composition of invaded vegetation helps to evaluate an ecological impact of aliens and design an optimal management strategy. We link a new vegetation analysis of a large dataset to the invasion history, ecology and management of Robinia pseudoacacia stands across Southern Europe and provide a map illustrating Robinia distribution. Finally, we compare detected relationships with Central Europe.We show that regional differences in Robinia invasion, distribution, habitats and management are driven both by local natural conditions (climate and soil properties, low competitive ability with native trees) and socioeconomic factors (traditional land-use). Based on the classification of 467 phytosociological relevés we distinguished five broad vegetation types reflecting an oceanity−continentality gradient. The stands were heterogeneous and included 824 taxa, with only 5.8% occurring in more than 10% of samples, representing mainly hemerobic generalists of mesophilous, nutrient-rich and semi-shady habitats. The most common were dry ruderal stands invading human-made habitats. Among native communities, disturbed mesic and alluvial forests were often invaded throughout the area, while dry forests and scrub dominated in Balkan countries. Continuous, long-term and large-scale cultivation represent a crucial factor driving Robinia invasions in natural habitats. Its invasion should be mitigated by suitable management taking into account adjacent habitats and changing cultivation practices to select for native species. Robinia invasion has a comparable pattern in Central and Southern Europe, but there is a substantial difference in management and utilization causing heterogeneity of many South-European stands.

Silver nanoparticles reduced the invasiveness of redroot pigweed.

The differences in the growth performance between invasive species and native species might paly a key role in the effective invasion. The extensive use of silver nanoparticles (AgNPs) has created the concern of their release into environment. Thus, the possible effects of AgNPs on the growth performance of invading agents are critical to better illustrate the underlying mechanisms for effective invasion. This study aimed to assess the impacts of AgNPs with different concentrations [200 and 400 mg kg (soil)-1] and particle sizes (30 and 70 nm) on the growth performance and competitive ability of well known invasive Amaranthus retroflexus L. (redroot pigweed) and native A. tricolor L. (red amaranth). It was observed that the growth characteristics and supporting ability of redroot pigweed were significantly lower than those of amaranth. Results of the relative competitive intensity index and the relative dominance index also revealed that redroot pigweed exhibited lower competitive ability compared to red amaranth, especially under AgNPs. It can be assumed that the poor growth performance and competitive ability of redroot pigweed might prevent its invasiveness under AgNPs. The supporting ability, leaf photosynthetic area, leaf growing ability, leaf resource use efficiency and acquisition capability, and growth competitiveness of the two plant species were found to be significantly reduced under AgNPs. AgNPs with 30 nm at 400 mg kg (soil)-1 triggered more toxicity on the supporting ability and growth competitiveness of the two plant species than AgNPs with 30 nm at 200 mg kg (soil)-1. In addition, AgNPs with 30 nm imparted high toxicity on the leaf growing ability of red amaranth than AgNPs with 70 nm. However, the particle size of AgNPs did not address significant effects on the growth performance of redroot pigweed. Ag+ solution exhibited stronger toxicity on the supporting ability and leaf growing ability of the two plant species than AgNPs.

Competitive ability during mate competition relates to unique patterns of dopamine-related gene expression in the social decision-making network of male zebra finches

Aggressive interactions usually reveal individual differences in the competitive ability of contest participants. Individuals with higher competitive ability often gain priority access to resources such as food, territory, and/or mates. Individuals with lower competitive ability usually have reduced access to these resources and limited mating opportunities. Despite the importance of contest performance to the reproductive success of individuals, the neuroendocrine factors associated with individual differences in competitive ability have not been fully elucidated. Here, we investigate the relationship between dopamine (DA)-related gene expression and competitive ability during mate competition in male zebra finches. Males demonstrating high competitive ability (HCA) had higher tyrosine hydroxylase mRNA levels in the ventral tegmental area and higher D1 receptor (D1-R) mRNA levels in the preoptic area than low competitive ability (LCA) males. Additionally, HCA males had lower levels of D1-R mRNA in the anterior hypothalamus relative to LCA males. These data suggest that there are dynamic and region-specific changes in DA function that relate to variation in competitive ability during mate competition.

Competitiveness of generalist plant populations at a mine site

Plants inhabiting extremely stressful mine site environments tend to be specialized and localized, where they express lower performance than nonmine site plants from adjacent areas. However, such a cost may be concealed. In a previous study at a mine site, we found mine and adjacent nonmine plants of multiple species expressed similar performances in the absence of competition. However, a lower competitive ability may be a concealed driver. We aim to test whether costs under competition could explain specialization. In a glasshouse experiment, we measured the performance (i.e. vegetative and reproductive growth) of mine and nonmine potted plants under competition. The 6 herbaceous species tested were Anagallis arvensis L., Cirsium vulgare (Savi) Ten., Conyza sumatrensis Retz., Echium vulgare L., Oxalis chnoodes Lourteig, and Senecio diaschides D.G.Drury. We exposed individuals to interspecific competition using a local grass (Polypogon monspeliensis), as well as to intraspecific competition. Plants were grown alone for the control group. For all treatments, the mine plants expressed similar performances to the nonmine plants, except for mine site O. chnoodes, which had lower performance under intraspecific competition. Mine plants of A. arvensis and C. sumatrensis had higher performance than nonmine plants. Overall, there was no evidence of specialization in the mine site plants. These results indicate that, under some circumstances, inhabiting a stressful metal habitat does not promote specialization in multiple species. Future research may focus on assessing the environmental conditions and population genetics that promote the evolution of generalists that inhabit extremely stressful environments.

DEVELOPMENT POTENTIAL OF CONSTRUCTION COMPANIES: TECHNICAL AND ECONOMIC ASPECTS

Introduction: The construction industry represents the priority area of the economy, which affects the quality of life of the population and other industries as well. Currently, many construction companies in Russia show low competitive ability (in 2016, their competitiveness index was lower than 400). The value of this index depends on the ability to adapt the internal organizational structure and applied technologies to the requirements of the market, i.e. on the innovative activity. At the present time, introduction of technical as well as organizational and economic innovations is complicated. This is due to the fact that most Russian companies do not focus on qualitative changes in the production structure and processes as well as in the management practices applied. Those factors result in low labor efficiency as unqualified workers are engaged, long lead time, etc. Methods: Scientific novelty lies in the development of methods for innovation potential assessment at a construction company, based on technical and economic indicators. The originality of the paper lies in the fact that the results of the authors' research on construction companies in Russia are used for analysis. Results and discussion: The present paper analyzes key factors of construction companies' development and its barriers. The paper aims at substantiating resources facilitating development of construction companies. The research data obtained allow for qualitative and quantitative assessment of the construction industry state in Russia.

Daily energy expenditure of males following alternative reproductive tactics: Solitary roamers spend more energy than group-living males

In many species, males follow alternative reproductive tactics (ARTs), where one tactic (called bourgeois) has much higher reproductive success than alternative tactics followed by males with lower competitive ability. The extent to which ARTs differ in energetic costs is unknown, but it is important to understand the fitness payoffs of ARTs. We studied male African striped mice (Rhabdomys pumilio) which follow one of three ARTs: heavy bourgeois males defend harems of females and have 10 times higher reproductive success than smaller roamers, which have ten times higher reproductive success than philopatric males, which remain in their natal group and are the smallest males. Bourgeois and philopatric males live in social groups that defend one territory, while roamers are solitary and roam over larger areas. We predicted that roamers will face higher energetic costs compared to group-living males because they do not gain thermoregulatory benefits of huddling in groups and might travel larger distances as they have larger home ranges. We measured daily energy expenditure (DEE) of 30 males, resting metabolic rate (RMR) of 79 males, travel distances and daily ranges of 31 males and changes in body mass of 51 males. Roamers had higher DEE and higher RMR than both types of group-living males. Philopatric males had shorter travel distances and smaller daily ranges than both roamers and bourgeois males, which did not differ from each other. This indicates that the higher DEE of roamers compared to bourgeois males cannot be explained by larger travel distances. Philopatrics gained body mass faster than bourgeois males and roamers, thereby increasing their competitive ability and thus the probability of later switching to a tactic of higher reproductive success. Our results suggest that roamers suffer energetic costs that might reduce their ability of gaining body mass and thus the likelihood of switching to the bourgeois tactic, indicating evolutionary trade-offs between investing energy into roaming versus gaining body mass.

STRUCTURAL AND FUNCTIONAL MODEL OF THE STOCK-RAISING TERRITORY ON THE ECOLOGICAL BASIS (ON THE EXAMPLE OF STAVROPOL)

The leading sector of the South of Russia is crop production and livestock-raising with a relatively high risk. Animal husbandry in the region is facing a crisis; the structure and size of herds have sharply decreased. The cost of livestock products and the gap in the rate of its growth are constantly growing. There were problems with fodders and their structural and nutritional imbalance. There is a shortage of meat and dairy products. The volume of gross production for the period from 2005 to 2013 is provided by domestic and foreign meat imports which increased 3-fold. Methods. An analytical study on the state of animal husbandry is conducted on the basis of reports and statistical materials. The system "natural resource potential – industry sector" is described. Analysis of the current state of the industry is aimed at determining the methods of making decisions on land use management on the example of the structural and functional model of development of the agricultural enterprises. Results. At the present time, conditions arise when it is necessary to shift to a new scientifically grounded structural and functional model of the spatial organization of the enterprises. This will allow implementing the strategy of ecoadaptive intensification of grassland production, since the value of cultivated pastures is determined by high proportion of forage grasses in the feed balance and their huge ecological function. Conclusion. This structural and functional approach is based on the consolidation of the territory of agrarian enterprises and the phased subsequent replacement of biological species with different life cycle duration. In this case, the result is the rapid achievement of the maximum productivity of species with low competitive ability which will lead to short payback period.

Functional traits associated with plant colonizing and competitive ability influence species abundance during secondary succession: Evidence from subalpine meadows of the Qinghai-Tibetan Plateau.

It is widely recognized that colonists and competitors dominate early and late succession, respectively, with selected species having different colonizing and competitive abilities. However, it remains unknown whether colonizing and competitive ability can determine species abundance directly over succession. The data for five key functional traits were collected (photosynthesis rate, leaf turgor loss point, leaf proline content, seed mass, and seed germination rate), which are direct indicators of plant competitive and colonizing abilities including growth, drought and cold stress resistance, dispersal, and seed dormancy. Here, we tested the effects of colonizing and competitive abilities on species abundance, by employing a linear mixed‐effects model to examine the shifts in the relationship between species abundance and these five colonization and competition‐related traits in species‐rich subalpine secondary successional meadows (at 4, 6, 10, 13 years of age, and undisturbed, respectively) of the Qinghai–Tibetan Plateau. The abundant species at the early‐successional meadows tend to have high photosynthetic rate, high leaf proline content, low seed mass, and seed germination rate for having high colonizing ability, but low competitive ability. By contrast, late‐successional communities tend to be dominated by species with high competitive ability, but low colonizing ability, indicated by large seeds, high seed germination rate, low photosynthetic rate, and leaf proline content. The observed directional shifts in the relationships between traits (photosynthetic rate, leaf proline content, seed mass, and seed germination rate) and abundance with successional age, bring two new understandings of community assembly during succession of subalpine meadows in the Qinghai–Tibetan Plateau. First, it discloses that the differences in species abundance over succession can be directly attributed to differences in colonizing and competitive abilities of different species. Second, it expands the effects of multiple life historical differences including growth, resource competitive ability, cold stress resistance, dispersal, and seed germination strategy, represented by functional traits on community assembly along succession, that is, from the species to the community level.

The ecology of plant extinction: rates, traits and island comparisons

AbstractAlthough there is increasing evidence for a sixth mass extinction, relatively few plants have been officially declared extinct (<150 are categorized as Extinct on the IUCN Red List). The Red List, although the data are neither perfect nor comprehensive, is perhaps the most reliable indicator of extinction and extinction threat. Here, data collated from the Red List, of Extinct plant species and of Critically Endangered plant species with populations in decline, are examined to address three questions: (1) How do background, continental, and island plant extinction rates compare? (2) Are biological and physical island parameters associated with plant extinction? (3) Are any plant traits associated with extinction and if so do these differ between islands and continents? The background rate for plant extinction is estimated to be 0.05–0.13 E/MSY (extinctions per million species-years) and the Red List data are above these background rates and also above a higher extinction rate of 0.15 E/MSY. The data indicate that plant extinctions are dominated by insular species. The Red List extinction data are associated with lower competitive ability and lower climate change velocities, and anthropogenic factors. Analyses using only Critically Endangered species whose populations are in decline (arguably the species most at risk of extinction in the near future) largely mirrors this pattern and suggests that drivers of plant extinction may have an inertia that could last well into the future.

Ecogeographical Potential of the White Spruce (Picea glauca (Moench) Voss, Pinaceae), and the Possibility of Its Introduction into Northern Eurasia

We analyzed the factors limiting the distribution of the white spruce (Picea glauca) in North America and the ecological amplitudes of the species in relation to these factors. Based on these data, an ecogeographical model of spruce dispersal was built. It is shown that the northbound dispersal of White Spruce in North America is limited by heat supply. The species range is shaped at the southwestern border (from the central part to the Rocky Mountains) by the lack of humidification and at the southeastern border, presumably, by competitive relations with foliar edificators. For P. glauca, the northern limit of heat supply is about 1200°C. At the southern border of the range, the White Spruce has low competitive ability with deciduous trees, starting approximately from the sum of active temperatures of about 3000°C. The limits of species dispersal in arid zones are determined by the hydrothermal coefficient, the value of which should not exceed 1.2. Validation of the dispersion model for P. glauca shows a discrepancy between the actual and model range of ±50–100 km. Formerly unknown populations of P. glauca may be found, as affirmed by a new records of the White Spruce in the Noatak National Park, within the discrepancy zone, between the potential range and that ascertained by Little (1971). We compared the ecological boundaries of P. glauca dispersal with those boundaries of the genus Picea in Eurasia. It was found that ecogeographical model designed for P. glauca describes the dispersal of Eurasian spruce species with high accuracy. This was evidence that the ecological divergence between North American and Eurasian spruce species was not strong. Deviation of the modeling results for the White Spruce from the actual Eurasian spruce range was observed in the regions with permafrost and some others. Therefore, additional environmental factors are required for the ecogeographical model upon its introduction to another continent.