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1.
The results of research studies on the influence of high moss-and-lichen mosaicity typical for the northern taiga in Central Evenkia on the dynamics of radial growth of Gmelin larch trees (Larix gmelinii (Rupr.) Rupr.) are reported. Three sample plots were laid out in the larch ledum–cowberry–green moss forest on the northwest facing slope (8°–10°) in close proximity to each other; they differed in the proportions of area occupied by the principal components of a moss–lichen cover (Aulacomnium turgidum, Pleurozium schreberi, Cladonia rangiferina, and Hylocomium splendens), spatial distribution, and thermal properties of seasonally thawed soil layers. The worst thermal soil properties under the current climatic conditions have determined the comparatively low radial growth of trees in the sampling area, reduced response to air-temperature variations in the period of preseason cambium activity and at the beginning of the radial growth period, and heightened the response to this factor at the end of a season.  相似文献   

2.
Decaying logs are important seedbeds in boreal and subalpine forests. However, biotic and abiotic factors and their interactions related to seedling colonization patterns on logs remain unclear. In the present study, we evaluated the influence of bryophyte communities, wood decay type (white-, brown-, and soft-rot) owing to decomposer fungal activities, and environmental abiotic factors on seedling establishment in an old-growth subalpine coniferous forest in Japan. Among the tree species recorded on the conifer logs, Picea jezoensis var. hondoensis was the most dominant. Log surfaces were covered with distinctive patches of liverwort Scapania bolanderi and moss Pleurozium schreberi (approximately 33% cover for each). Redundancy analysis showed that brown-rot in sapwood significantly affects the bryophyte and seedling community on the logs. Generalized linear models suggested that the total bryophyte cover, Scapania cover, and white-rot in heartwood positively associate with Picea seedling density, whereas Pleurozium cover and basal area of adjacent Picea adults negatively associate with Picea seedling density. Results of structural equation modeling suggested that the brown-rot of sapwood positively associates with Scapania cover that has a positive effect on Picea seedling density. Furthermore, brown-rot of sapwood inhibited the Pleurozium cover, thus contributing to the Scapania dominance on the logs. These results suggest that fungal wood decomposer activities affect colonization of Picea seedlings in an indirect way via structuring bryophyte community on the logs.  相似文献   

3.
4.
Dominant canopy tree species have strong effects on the composition and function of understory species, particularly bryophytes. In boreal forests, bryophytes and their associated microbes are a primary source of ecosystem nitrogen (N) inputs, and an important process regulating ecosystem productivity. We investigated how feather moss-associated N2-fixation rates and contribution to N budgets vary in time and space among coniferous and broadleaf deciduous forests. We measured N2-fixation rates using stable isotope (15N2) labeling in two moss species (Pleurozium schreberi and Hylocomium splendens) in broadleaf deciduous (Alaska paper birch—Betula neoalaskana) and coniferous (black spruce—Picea mariana) stands near Fairbanks, interior Alaska, from 2013 to 2015. N2-fixation rates showed substantial inter-annual variation among the 3 years. High N2-fixation was more strongly associated with high precipitation than air temperature or light availability. Overall, contribution of N2-fixation to N budgets was greater in spruce than in birch stands. Our results enhance the knowledge of the processes that drive N2-fixation in boreal forests, which is important for predicting ecosystem consequences of changing forest composition.  相似文献   

5.
A review of geographic distribution, phylogenetic relationships, and evolutionary trends of six species of the South Palaearctic genus Haslundichilis Wygodzinsky is performed for the first time. Bristletails of the genus Haslundichilis are common in temperate forest and steppe open landscapes in the foothills and mountains of the East Caucasus, Central Asia, Northwest and East China, and South Korea. The genus originated in the forest landscapes of the West Stenopean (mixed) province wherefrom its representatives spread as far eastwards as South Korea and as far westwards as the mountains of Central Asia and the East Caucasus. The new species Haslundichilis daghestanicasp. n. is the closest to H. afghani, from which it differs in a greater body size, narrower eyes, and more developed sensory fields on the fore femur of the male.  相似文献   

6.
An investigation of the genetic structure of the Aporrectodea caliginosa-A. trapezoids diploidpolyploid complex of earthworms found in the Ukraine is performed by means of biochemical genetic marking with respect to six loci (Aat, Es-1,-2,-3, and-4, and Mdh) and karyotyping. All 646 individuals from 21 samples are analyzed at the biochemical gene level and karyotype samples are obtained from 70 specimens. As a result, diploid amphimictic A. caliginosa individuals (2n = 36), which form panmictic populations, and triploid (2n = 54) A. trapezoides individuals, represented by 19 hypothetical clones discovered in the course of an analysis of 157 specimens, are clearly differentiated. A clear trend towards dominance of the triploid forms in the steppe zone of Ukraine is discovered. Here they represent roughly 70% as against 12% of all A. (superspecies) caliginosa individuals in the northern forest regions. Based on the stated nature of the heterozygosity of the loci studied and the behavior of the chromosomes in meiosis, it may be claimed that the cloned forms are allotriploids, formed as a result of hybridization of a series of related forms, which, judging from the allelic pools, does not include amphimictic species that now inhabit the territory of Ukraine. That is, either the apomictic clones of A. trapezoides lack a local origin and their appearance among the fauna of Ukraine is a consequence of settlement in arid steppe regions that are unfavorable for earthworms or, on the other hand, amphimictic A. caliginosa is an invasive species.  相似文献   

7.
Conventional wisdom states Cannabis sativa originated in Asia and its dispersal to Europe depended upon human transport. Various Neolithic or Bronze age groups have been named as pioneer cultivators. These theses were tested by examining fossil pollen studies (FPSs), obtained from the European Pollen Database. Many FPSs report Cannabis or Humulus (C/H) with collective names (e.g. Cannabis/Humulus or Cannabaceae). To dissect these aggregate data, we used ecological proxies to differentiate C/H pollen, as follows: unknown C/H pollen that appeared in a pollen assemblage suggestive of steppe (Poaceae, Artemisia, Chenopodiaceae) we interpreted as wild-type Cannabis. C/H pollen in a mesophytic forest assemblage (Alnus, Salix, Populus) we interpreted as Humulus. C/H pollen curves that upsurged and appeared de novo alongside crop pollen grains we interpreted as cultivated hemp. FPSs were mapped and compared to the territories of archaeological cultures. We analysed 479 FPSs from the Holocene/Late Glacial, plus 36 FPSs from older strata. The results showed C/H pollen consistent with wild-type C. sativa in steppe and dry tundra landscapes throughout Europe during the early Holocene, Late Glacial, and previous glaciations. During the warm and wet Holocene Climactic Optimum, forests replaced steppe, and Humulus dominated. Cannabis retreated to steppe refugia. C/H pollen consistent with cultivated hemp first appeared in the Pontic-Caspian steppe refugium. GIS mapping linked cultivation with the Copper age Varna/Gumelni?a culture, and the Bronze age Yamnaya and Terramara cultures. An Iron age steppe culture, the Scythians, likely introduced hemp cultivation to Celtic and Proto-Slavic cultures.  相似文献   

8.
A typical feature of the populations of small mammals in different areas of the Saratov Trans-Volga region is the long-term and constantly increasing abundance of Sylvaemus uralensis and its wide distribution in a variety of habitats. The maximal abundance of S. uralensis is 72.0 individuals per 100 trap-days, and its share in catches is 73.0%. The abundance of Microtus arvalis tends to increase. It was shown that Lagurus lagurus has been found again in the steppe zone, on fallow lands and fields, after a prolonged depression in 2012–2013, the average density of species being 4.0 individuals per 100 trap-days. A high abundance of other typical steppe inhabitants (Allocricetulus eversmanni and Ellobius talpinus) was noted as well. The highest indices of species diversity (H = 1.18) are typical of fallow lands.  相似文献   

9.
Thirty-nine species of bugs, representing meso-and xerophilic inhabitants of open tundra, meadow, and steppe landscapes, were collected within the altitude range of 1260–1850 m above sea level in the upper Kyubyume River basin (63°13′N, 139°36′E, the Indigirka River basin). In the sub-golets sparse forest zone (up to 1550 m), 37 species were recorded, the dominant form being Chlamydatus pullus. The bugs were rare in most of the habitats; their species richness and abundance increased distinctly only on the south-facing slopes, reaching the maximum in the cryophytic steppe. The specific features of these complexes manifested themselves in the prevalence of Capnoda nigroaenea, a xerophilic species of alpine mountain steppes. The rest of the dominants comprised the ecologically flexible Emblethis brachynotus, Chlamydatus pullus, and Galeatus spinifrons. In the goletstundra zone, 8 species were found, half of them being arctic forms (Calacanthia trybomi, Orthotylus artemisiae, Ch. wilkinsoni, and Ch. opacus). Ch. wilkinsoni was the most common species. The species composition of bug groups in the dry lichen-dryad communities within this zone resembled that of similar communities of zonal tundra, whereas the humid habitats remained unpopulated, unlike their plain analogues. Comparison of the heteropteran fauna of mountain tundras in different regions of the Verkhoyansk-Kolyma mountain country attests to significant variations of its species composition. The possible reasons for these differences are discussed.  相似文献   

10.
Bromus tectorum can transform ecosystems causing negative impacts on the ecological and economic values of sagebrush steppe of the western USA. Although our knowledge of the drivers of the regional distribution of B. tectorum has improved, we have yet to determine the relative importance of climate and local factors causing B. tectorum abundance and impact. To address this, we sampled 555 sites distributed geographically and ecologically throughout the sagebrush steppe. We recorded the canopy cover of B. tectorum, as well as local substrate and vegetation characteristics. Boosted regression tree modeling revealed that climate strongly limits the transformative ability of B. tectorum to a portion of the sagebrush steppe with dry summers (that is, July precipitation <10 mm and the driest annual quarter associated with a mean temperature >15°C) and low native grass canopy cover. This portion includes the Bonneville, Columbia, Lahontan, and lower Snake River basins. These areas are likely to require extreme efforts to reverse B. tectorum transformation. Our predictions, using future climate conditions, suggest that the transformative ability of B. tectorum may not expand geographically and could remain within the same climatically suitable basins. We found B. tectorum in locally disturbed areas within or adjacent to all of our sample sites, but not necessarily within sagebrush steppe vegetation. Conversion of the sagebrush steppe by B. tectorum, therefore, is more likely to occur outside the confines of its current climatically optimal region because of site-specific disturbances, including invasive species control efforts and sagebrush steppe mismanagement, rather than climate change.  相似文献   

11.
We asked the following questions regarding gap dynamics and regeneration strategies in Juniperus-Laurus forests: How important are gaps for the maintenance of tree diversity? What are the regeneration strategies of the tree species? Thirty canopy openings were randomly selected in the forest and in each the expanded gap area was delimited. Inside expanded gaps the distinction was made between gap and transition zone. In the 30 expanded gaps a plot, enclosing the gap and transition zone, was placed. In order to evaluate the differences in regeneration and size structure of tree species between forest and expanded gaps, 30 control plots were also delimited in the forest, near each expanded gap. In the 60 plots the number of seedlings, saplings, basal sprouts and adults of tree species were registered. Canopy height and width of adult individuals were also measured. The areas of the 30 gaps and expanded gaps were measured and the gap-maker identified. Juniperus-Laurus forests have a gap dynamic associated with small scale disturbances that cause the death, on average, of two trees, mainly of Juniperus brevifolia. Gap and expanded gap average dimensions are 8 and 25 m2, respectively. Gaps are of major importance for the maintenance of tree diversity since they are fundamental for the regeneration of all species, with the exception of Ilex azorica. Three types of regeneration behaviour and five regeneration strategies were identified: (1) Juniperus brevifolia and Erica azorica are pioneer species that regenerate in gaps from seedlings recruited after gap formation. However, Juniperus brevifolia is a pioneer persistent species capable of maintaining it self in the forest due to a high longevity and biomass; (2) Laurus azorica and Frangula azorica are primary species that regenerate in gaps from seedlings or saplings recruited before gap formation but Laurus azorica is able to maintain it self in the forest through asexual regeneration thus being considered a primary persistent species; (3) Ilex azorica is a mature species that regenerates in the forest.  相似文献   

12.
Transformation of ecological factors on dumps of coal mines under the effect of Pinus sylvestris L. results in formation of three-zone phytogenous fields. The under-crown zone is characterized by a leveled temperature regime, low illumination, forest litter accumulation, and formation of abundant undergrowth. In the sufficiently moistened transitional zone, well-developed moss cover is formed, and the undergrowth occurrence is very low. The external zone, transitional to the background meadow communities, is characterized by well-formed grass cover, an abundance of species, and a group pattern of the undergrowth of P. sylvestris L. The reaction of herbaceous plants on the effect of phytogenous pine fields may be positive (adaptive) or negative. Most species are characterized by a negative reaction.  相似文献   

13.
Two new hybrid zones between sibling species of the Chorthippus albomarginatus group were described on the basis of the courtship song analysis. Not only the sounds emitted but also the accompanying stridulatory movements of the hind legs were analyzed, which allowed the temporal parameters to be classified in a more reliable way. One hybrid zone between Ch. albomarginatus and Ch. karelini was found in Ulyanovsk and Samara Provinces of Russia. The other hybrid zone, presumably between Ch. karelini and Ch. oschei, was found in the protected Askania-Nova steppe area in Kherson Province of Ukraine. Based on comparison of the natural and laboratory hybrids, a hypothesis on the structure and dynamics of the hybrid zones is proposed.  相似文献   

14.
Using chromosomal and molecular (cytb) markers, the specific identity of 78 individuals of cryptic species of voles of the subgenus Terricola was ascertained. The animal samples were obtained at 13 localities of the Caucasian region, from Krasnodar krai to North Ossetia in the Greater Caucasus and in the Stavropol Upland (forest island in the steppe) in Ciscaucasia, which had not been covered earlier in genetic studies. In the total sample, two chromosomal forms (cryptic species), namely, Microtus (Terricola) majori (2n = 54, NF = 60) and M. (T.) daghestanicus (2n = 54, NF = 58), were identified. The specific identity of most animals tested was confirmed by karyological means, and for individuals from two localities on the south slopes of the Greater Caucasus (Adlerskii district of Krasnodar krai), it was confirmed exclusively by means of molecular (cytb) markers. The last two records were used for evaluation of the differential role of sibling-species of the subgenus Terricola in circulation of the pathogen in mountain loci of hemorrhagic fever with renal syndrome (HFRS) in the Western Caucasus. For the first time, using the example of M. (T.) majori from the Ciscaucasia, which was compared with those of the mountain part of the species’ natural habitat, the role of isolation factors in morphogenesis of the subgenus Terricola was studied. As a whole, the results obtained specify the character of the geographical distribution and biotope attachment of cryptic species of the subgenus Terricola in the Caucasian region.  相似文献   

15.
The main threats to primates worldwide are the degradation, fragmentation, and loss of their habitats; hunting (especially for bushmeat); and illegal trade. For many species, the most important threat is forest fragmentation, resulting in small populations that are restricted to isolated forest patches. In this situation, primates are particularly vulnerable to disease. The Endangered blonde capuchin (Sapajus flavius) is now restricted to a few forest patches in Northeast Brazil. We investigated the occurrence of parasites and bacterial diseases in one of three free-ranging groups of S. flavius in a small forest patch in Paraíba state, Northeast Brazil. We tested for antibodies against Leishmania spp., Trypanosoma cruzi, Toxoplasma gondii, Leptospira spp. (24 strains), and Brucella spp.. We used molecular analysis to detect Plasmodium spp., and evaluated blood smears for the presence of hemoparasites. All individuals tested negative for Leptospira spp. and B. abortus, but 8 of 48 (16%) presented antibodies for both Leishmania spp. and T. cruzi. We identified antibodies to T. gondii in 12% of the individuals tested. Plasmodium brasilianum infection was present in 4% of the individuals tested, and blood smears showed microfilariae parasites in 46% of the individuals tested. The occurrence of these infectious diseases in S. flavius may pose a significant threat in terms of reduced recruitment and poor survival rates, and an understanding of the influence of pathogens is crucial for the management of small populations of primates.  相似文献   

16.
Ixodiae ticks have been counted and sampled in six distant locations within the Altai-Sayan Mountain Area and northern forest steppe in 2012. In total, 1829 individuals of I. persulcatus and 719 of I. pavlovskyi ticks were collected by flagging. I. persulcatus is found in all six examined locations and I. pavlovskyi is found in Western Altai, Northeastern Altai, and Northern Altai, as well as in forest parks near Akademgorodok of Novosibirsk. In total, 16S rRNA and COI sequences have been determined in 144 and 164 I. persulcatus individuals, as well as in 60 and 55 I. pavlovskyi. Selectively equivalent mutant forms are present in I. pavlovskyi populations of Northeastern Altai and Northern Altai. The hydrothermal regime in the forest parks near Novosibirsk is optimal for the I. pavlovskyi ticks. These ticks have recently colonized the forest parks near Novosibirsk and therefore are genetically close to I. pavloskyi from the Altai–Sayan Mountain Area populations.  相似文献   

17.
Glacial relicts have been regionally more common in glacial than in recent times. A rigorous assessment of which species are indeed glacial relicts is extremely difficult because direct evidence is untraceable or equivocal for many species. We aimed to identify species of the Western Carpathian flora (vascular plants, bryophytes and terrestrial lichens) that display apparent biogeographical and ecological symptoms, suggesting a wider regional or supra-regional distribution during glacial times, or at least before the middle-Holocene climate optimum. We worked with the premise that exemplary relict species should tolerate continental and/or arctic climates, should have large distribution ranges with disjunctions, being regionally rare and ecologically conservative nowadays, should be associated with habitats that occurred during glacial times (tundra, steppe, peatland, open coniferous forest) and should display a restriction of ecological niches in the study region. The assessed species were primarily those with boreo-continental or artcic-alpine distribution. We demonstrated a conspicuous gradient of glacial-relict symptoms, with Carex vaginata, Betula nana, Trichophorum pumilum, Nephroma arcticum, Saxifraga hirculus and Cladonia stellaris topping the ranking. Based on the arbitrary ranking, 289 taxa can be considered high-probability relicts. For only a minority of them, there are any phylogeographical and/or palaeoecological data available from the study area. Biogeographical and ecological symptoms of 144 taxa suggest that they retreated rapidly after the Last Glacial Maximum whereas other species probably retreated later. The first principal component of biogeographical symptoms sorted species from circumpolar arctic-alpine species of acidic peatlands and wet tundra to strongly continental species of steppe, steppe-tundra and mineral-rich fens. This differentiation may mirror the altitudinal zonation of glacial vegetation in the Western Carpathians.  相似文献   

18.
The distributions of most cosmopolitan invertebrate species are assumed to result from natural processes. Cryptic invertebrates with obscure biogeographic origins are often considered native by default, resulting in potentially severe underestimation of the extent of human-assisted invasions. This problem is exemplified by freshwater Bryozoa (Ectoprocta) and Entoprocta—small and widely distributed invertebrates commonly found in lakes and rivers. A benthic survey of a thermally modified section of the St. Lawrence River revealed the presence of two nonindigenous bryozoans: Carter’s moss animal Lophopodella carteri (Hyatt) and the crystal moss animal Lophopus crystallinus Pallas. Also discovered was a cryptogenic entoproct, the goblet worm Urnatella gracilis Leidy. These species were collected as statoblasts and (in the case of U. gracilis) colonial fragments downstream of the Gentilly-2 nuclear power plant at Bécancoeur, Quebec. Local densities of both U. gracilis and L. carteri increased by an order of magnitude at sites closer to the power plant. The occurrence of Lophopus crystallinus statoblasts in St. Lawrence River sediments is the first documented physical evidence of the species in North America. Contrary to the presumed natural Holarctic distribution of L. crystallinus, our literature review found that published historical records of L. crystallinus in the United States are erroneous or unsubstantiated. We propose that L. crystallinus is a western Palearctic species recently introduced to the St. Lawrence River, most likely as statoblasts discharged with ballast water from transoceanic ships.  相似文献   

19.
The results of the body-surface infrared thermography of rodents of the genus Lophuromys suggest that heat insulation of the black-clawed brush-furred rat L. melanonyx, a large specialized species of the AfroAlpine zone, is worse than that of the related smaller species, the golden-footed (L. chrysopus) and shorttailed (L. brevicaudus) brush-furred rats, that inhabit tropical forest and Erica shrub, respectively. A decrease in heat insulation of the alpine species may facilitate the use of solar radiation for supporting heat balance of these diurnal animals.  相似文献   

20.
Reconstruction of the dynamics of the range of Artemisia genus was carried out with the help of palynoareological method on the basis of the data of 97 pollen diagrams from the territory of Western Siberia and the Altai-Sayan mountainous region over the millennial time sections since the Late Glacial time till the present time. It was revealed that the maximal spread of the Artemisia steppe communities (probably of the cryoarid pattern) occurred at the territory under examination at 13–10 ka yr BP. After the time point of 9 ka yr BP a fundamental change in landscapes of Western Siberia occurred which resulted in the disintegration of previously continuous Artemisia steppe cover into separate blocks. Since 8 ka yr BP the Artemisia steppe communities of modern appearance occupied the zones of modern steppe and forest-steppe of Western Siberia and Northern Kazakhstan while over the taiga zone the Artemisia plant communities were spread occasionally under the extra zonal conditions and as the pioneering plant groupings on naturally disturbed soils. Since the time point of 4 ka yr BP till the present time the northern boundary of the steppe zone under-went pulsing shifts to the north and back and also broadening and narrowing of isolated insular steppes in Altai-Sayan mountain region took place. At present time we observe an increase in the role of plants of Artemisia genus in the tundra zone of Western Siberia and in the Altai mountains.  相似文献   

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