Middle Elevations Research Articles

The effect of passive smoking on bacterial colonisation of the upper airways and selected laboratory parameters in children.

SUMMARYExposure to tobacco smoke is associated with a higher risk of respiratory tract diseases. The aim of this study was to determine the influence of passive smoking on selected characteristics of children with adenoid hypertrophy. Sixty-one children with adenoid hypertrophy were enrolled in the prospective study. Differences in bacterial colonisation of middle nasal meatus and nasopharynx and changes in selected laboratory immune and inflammatory markers according to the tobacco smoke exposure were analysed. Exposure to tobacco smoke was associated with significantly higher colonisation of pathogenic bacteria and polymicrobial growth of pathogenic bacteria (≥ 2 bacteria) in middle nasal meatus compared to non-exposed children (P = 0.045, P = 0.032, respectively). Identification of pathogenic bacteria in the middle nasal meatus did not correlate with isolation of pathogenic bacteria in the nasopharynx in either group of children. Parameters of humoral immunity in serum, IgA and IgG, were detected at higher concentrations in children exposed to tobacco smoke (P = 0.047, P = 0.031, respectively). Differences in selected parameters of cellular immunity in peripheral blood according to passive smoking were not observed. Tobacco smoke exposure is related to increased colonisation by pathogenic bacteria in middle nasal meatus and elevation of IgA and IgG in peripheral blood, but does not seem to influence markers of cellular immunity parameters in children with adenoid hypertrophy. Avoidance of passive smoking could be recommended as a universal preventive strategy against microbial colonisation of the upper airways and development of various inflammatory diseases in children, e.g. adenoid hypertrophy.

Elevational and Possible Bushmeat Exploitation Effects on Dung Beetle (Scarabaeidae: Scarabaeinae) Communities on Mount Cameroon, West Central Africa.

Dung beetle species richness and abundance on Mt Cameroon were investigated to evaluate the effects of elevation. Surveys were done at five different elevations on the southwest facing slope from 216 to 2,102 m above sea level near the tree line at intervals of ~500 m. In total, 27 species and 1,886 specimens were collected during the study. No linear relationship between either species richness or beetle abundance and elevation was found with an expected highest diversity and abundance at low elevation and the lowest diversity and abundance at high elevation. Instead, both the highest diversity and abundance were discovered at the middle elevation (914-1,012 m) with 22 species and 48% of the total catch. The highest diversity indices (Shannon and Simpson) were found at the second lowest elevation (522-625 m). The lowest diversity found at the highest elevation (1,974-2,101 m) included only two species and represented only 4% of the beetles sampled. Unexpected low diversity and abundance at the lowest elevation are hypothesized to be due at least in part to the effects of bushmeat hunting in the more accessible lower elevations and the concomitant effects on dung beetles that mainly utilize mammal dung. The most similar faunas based on Morisita-Horn paired comparisons were those at the two highest and the two lowest elevations while the most dissimilar were the middle compared with the highest elevation. Faunas appear to be divided into high and low elevation communities with a boundary or division at c.1,500-1,750 m elevation.

Abundance–occupancy and abundance–body mass relationships of small mammals in a mountainous landscape

Mountainous landscapes are characterized by strong spatial heterogeneity, leading to increasing geographical isolation and decreasing area with elevation. Consequently, the colonization rate decreases from the low to high elevation zone, while the extinction rate shows the opposite. Due to such changes, we test whether (1) species occur at a declining number of sites (mountains) and have a less positive abundance–occupancy relationship (AOR) in a higher elevation zone; (2) a lower proportion of rare large-bodied species (less resistant to extinction) and a more positive abundance–body mass relationship (ABR) emerge in a higher elevation zone. Using the data of small mammals from 20 elevational gradients in the Mountainous Region of Southwest China, we compared the AORs and ABRs among the low, middle and high elevation zones. The AOR and ABR were fitted with linear and polynomial regression models. We compared endemic ratios among the different elevation zones. The AOR was best characterized by a linear model and positive in all elevation zones. Its slope decreased from the low to high elevation zone. The quadratic model performed the best in fitting the ABR in each zone. When fitted with linear models, both the R2 and slope of the ABR increased towards the high elevation zone. The endemic ratios were significantly higher in the middle and high elevation zones. Both the AOR and ABR in mountainous landscapes are strongly elevation-dependent. The increasing geographical isolation and decreasing area with elevation can have a high impact on macroecological patterns and processes.

A Review of Philenis Champion, 1906 (Coleoptera: Curculionidae: Conoderinae), with Descriptions of New Species from Central and South America

A brief review of the history of the taxonomic treatment of the genus Philenis Champion is presented and characters are discussed. Philenis flavipes Champion and P. fuscofemorata Champion, and 11 new species are described, including the first records from South America: P. anzaldoi new species (Costa Rica, Panamá), P. costaricensis new species (Costa Rica), P. laselvaensis new species (Costa Rica), P. auritibiae new species (Costa Rica), P. brunnea new species (Costa Rica, Panamá), P. muscamimetica new species (Panamá), P. chiriquiensis new species (Panamá), P. guyanensis new species (French Guiana), P. ferruginea new species (Ecuador), P. howdeni new species (Ecuador), and P. kuscheli new species (Colombia, Ecuador). A key is provided to separate the species, and an unusual type of “multifurcate” scale is reported for some species. Two species have been associated with plants of the family Araceae. Most collections of this genus by the Arthropods of La Selva (ALAS) biodiversity project in Costa Rica were made by passive trapping methods during the dry season and at lower to middle elevations along an altitudinal transect on the slopes of Volcan Barva. The coloration of some species in the genus is hypothesized to mimic social Hymenoptera or flies.

Effect of physiographic factors on woody species diversity in oak forests (case study: Sardasht forest -Iran)

Research on species diversity in different gradients of altitudes, aspect and slope is attempting to understand the interactions of vegetation and the non-living environment. The aim of this study was to examine the impact of altitude, slope and aspect variation on the woody species diversity in the Oak forests of Zagros (northern of Iran). 178 samples were taken by using of transect method with a fixed length of 50 m. Altitude, slope, aspect, woody species and diameter at breast height of all trees was recorded in each transect. Margalef richness index, Shannon and Simpson diversity indices and Shannon evenness index were calculated. The Means of the different diversity indices were compared with Kruskal- Wallis test. Results showed that altitude had significant impact on the diversity, richness and evenness of woody species and the middle elevation class (1400 - 1600 m) allocated maximum values of indices. Also, the highest species richness was observed in the (0 - 20%) and (20 - 40%) slope classes but the slope hadn’t effected on the woody species evenness and diversity. The lowest amount of species richness was observed in the east aspect than other aspects. In general, it can be concluded that the altitude had a large proportion of diversity variation than slope and aspect in the research area.J. bio-sci. 23: 19-27, 2015

Local trampling disturbance effects on alpine plant populations and communities: Negative implications for climate change vulnerability.

Global change is modifying species communities from local to landscape scales, with alterations in the abiotic and biotic determinants of geographic range limits causing species range shifts along both latitudinal and elevational gradients. An important but often overlooked component of global change is the effect of anthropogenic disturbance, and how it interacts with the effects of climate to affect both species and communities, as well as interspecies interactions, such as facilitation and competition. We examined the effects of frequent human trampling disturbances on alpine plant communities in Switzerland, focusing on the elevational range of the widely distributed cushion plant Silene acaulis and the interactions of this facilitator species with other plants. Examining size distributions and densities, we found that disturbance appears to favor individual Silene growth at middle elevations. However, it has negative effects at the population level, as evidenced by a reduction in population density and reproductive indices. Disturbance synergistically interacts with the effects of elevation to reduce species richness at low and high elevations, an effect not mitigated by Silene. In fact, we find predominantly competitive interactions, both by Silene on its hosted and neighboring species and by neighboring (but not hosted) species on Silene. Our results indicate that disturbance can be beneficial for Silene individual performance, potentially through changes in its neighboring species community. However, possible reduced recruitment in disturbed areas could eventually lead to population declines. While other studies have shown that light to moderate disturbances can maintain high species diversity, our results emphasize that heavier disturbance reduces species richness, diversity, as well as percent cover, and adversely affects cushion plants and that these effects are not substantially reduced by plant–plant interactions. Heavily disturbed alpine systems could therefore be at greater risk for upward encroachment of lower elevation species in a warming world.

Anthropogenic Warming Impacts on Today's Sierra Nevada Snowpack and Flood Risk

AbstractThis study investigates temperature impacts to snowpack and runoff‐driven flood risk over the Sierra Nevada during the extremely wet year of 2016–2017, which followed the extraordinary California drought of 2011–2015. By perturbing near‐surface temperatures from a 9‐km dynamically downscaled simulation, a series of offline land surface model experiments explore how Sierra Nevada hydrology has already been impacted by historical anthropogenic warming and how these impacts evolve under future warming scenarios. Results show that historical warming reduced 2016–2017 Sierra Nevada snow water equivalent by 20% while increasing early‐season runoff by 30%. An additional one third to two thirds loss of snowpack is projected by the end of the century, depending on the emission scenario, with middle elevations experiencing the most significant declines. Notably, the number of days in the future with runoff exceeding 20 mm nearly doubles under a mitigation emission scenarios and triples under a business‐as‐usual scenario. A smaller snow‐to‐rain ratio, as opposed to increased snowmelt, is found to be the primary mechanism of temperature impacts to Sierra snowpack and runoff. These findings are consequential to the prevalence of early‐season floods in the Sierra Nevada. In the Feather River Watershed, historical warming increased runoff by over one third during the period of heaviest precipitation in February 2017. This suggests that historical anthropogenic warming may have exacerbated runoff conditions underlying the Oroville Dam spillway overflow that occurred in this month. As warming continues in the future, the potential for runoff‐based flood risk may rise even higher.

Spring warming in Yukon mountains is not amplified by the snow albedo feedback

Decreasing spring snow cover may amplify Arctic warming through the snow albedo feedback. To examine the impact of snowmelt on increasing temperature we used a 5,000 m elevation gradient in Yukon, Canada, extending from valley-bottom conifer forests, through middle elevation tundra, to high elevation icefields, to compare validated downscaled reanalysis air temperature patterns across elevational bands characterized by different patterns of spring snowmelt. From 2000 to 2014 we observed surface warming of 0.01 °C/a·1,000 m in May (0.14 °C/a at 1,000 m to 0.19 °C/a at 5,000 m), and uniform cooling of 0.09 °C/a in June at all elevations. May temperature trends across elevationally dependent land cover types were highly correlated with each other despite large variations in albedo and snow cover trends. Furthermore, a clear dependency of infrared skin temperature on snow cover mediated albedo decline was observed in tundra, but this was insufficient to influence average diurnal air temperature. We observed negative June temperature trends which we attribute to increasing daytime cloud cover because albedo and snow cover trends were unchanging. We conclude that 8-day and monthly averaged Spring air temperature trends are responding to a synoptic external forcing that is much stronger than the snow albedo feedback in sub-Arctic mountains.

Past vegetation dynamics in the Yellowstone region highlight the vulnerability of mountain systems to climate change

AbstractAimReconstruct the long‐term ecosystem dynamics of the region across an elevational gradient as they relate to climate and local controls. In particular, we (1) describe the dominant conifers' history; (2) assess changes in vegetation composition and distribution; and (3) note periods of abrupt change versus stability as means of better understanding vegetation responses to environmental variability.LocationGreater Yellowstone Ecosystem (GYE; USA).Time period16.5 ka bp‐present.Major taxa studiedJuniperus, Picea, Abies, Pinus, Pseudotsuga.MethodsThe vegetation reconstruction was developed from 15 pollen records. Results were interpreted based on modern pollen–vegetation relationships estimated from a suite of regression‐based approaches.ResultsCalibrated pollen data suggest that late‐glacial vegetation, dominated by shrubs and Juniperus, lacks a modern counterpart in the area. Picea, Abies and Pinus expanded at 16 ka bp in association with postglacial warming and co‐occurred in mixed‐conifer parkland/forest after 12 ka bp. This association along with Pinus contorta forest, which was present after 9 ka bp, has persisted with little change at middle and high elevations to the present day. This stability contrasts with the dynamic history of plant communities at low elevations, where shifts between parkland, steppe and forest over the last 8,000 years were likely driven by variations in effective moisture and fire.Main conclusionsThe postglacial vegetation history of the GYE highlights the dynamic nature of mountain ecosystems and informs on their vulnerability to future climate change: (1) most of the conifers have been present in the area for >12,000 years and survived climate change by adjusting their elevational ranges; (2) some plant associations have exhibited stability over millennia as a result of nonclimatic controls; and (3) present‐day forest cover is elevationally more compressed than at any time in history, probably due to the legacy of the Medieval Climate Anomaly and the Little Ice Age.

Characterizing Drought Effects on Vegetation Productivity in the Four Corners Region of the US Southwest

The droughts striking the Colorado Plateau, where the Hopi Tribe and Navajo Nation Native American reservation lands are located, and their impacts have appeared slowly and relatively unnoticed in conventional national drought monitoring efforts like the National Drought Monitor. To understand the effect of drought-based drivers on vegetation productivity in the Hopi Tribe and Navajo Nation reservation lands, an assessment approach was developed integrating climate, land cover types, and topographical data with annual geospatially explicit normalized difference vegetation index (NDVI)-related productivity from 1989 to 2014 derived from 15-day composite multi-sensor NDVI time series data. We studied vegetation–environment relationships by conducting multiple linear regression analysis to explain the driver of vegetation productivity changes. Our results suggest that the interannual change of vegetation productivity showed high variability in middle elevations where needleleaf forest is the dominant vegetation cover type. Our analysis also shows that the spatial variation in interannual variability of vegetation productivity was more driven by climate drivers than by topography ones. Specifically, the interannual variability in spring precipitation and fall temperature seems to be the most significant factor that correlated with the interannual variability in vegetation productivity during the last two and a half decades.

Millennial scale climate-fire-vegetation interactions in a mid-elevation mixed coniferous forest, Mission Range, northwestern Montana, USA

AbstractMixed coniferous forests are widespread at middle elevations in the Northern Rocky Mountains, yet relatively little is known about their long-term vegetation and fire history. Pollen and charcoal records from Twin Lakes, in the Mission Range of northwestern Montana provide information on mixed-coniferous forest development and fire activity over the last 15,000 years. These data suggest an open parkland and minimal fire activity before 13,500 cal yr BP, consistent with cold, dry conditions. Increases inPinuspollen after 13,500 cal yr BP indicate a transition to closed forests, and a slight rise in fire activity as conditions warmed and fuel biomass increased. High levels ofArtemisiapollen between 10,000 and 6000 cal yr BP suggest an open forest during the early Holocene when conditions were warmer and drier than present. Low-severity fires likely maintained open forest/shrublands but produced little charcoal during this interval. Present-day mixed-coniferous forests were established in the last 6 ka and included forest taxa characteristic of low- (Pseudotsuga-Larix/Pinus ponderosa)and high-severity fire regimes (Picea/Abies). Increased climate variability and anthropogenic burning may have helped maintain heterogeneous, mixed-coniferous forests during the last several millennia when climate conditions became cooler and wetter.

Holocene vegetation history of the Jeseníky Mts: Deepening elevational contrast in pollen assemblages since late prehistory

AbstractQuestionsHow did the vegetation of a Central European mountain region with a fragmented alpine zone develop during the Holocene? When did human land use start to alter summit grasslands? Which gradient in pollen assemblages was strongest and was it consistent through time?LocationJeseníky Mountains, Czech Republic.MethodsSixteen pollen records were subjected to DCA in order to explore patterns of compositional similarities in the fossil pollen data. Because only the last 6,000 years were recorded in the study sites from mountain summits, we restricted further analysis to this period. Twelve radiocarbon‐dated pollen records were subjected to DCCA constrained by modelled calibrated age. Responses of individual pollen types to the principal DCCA gradients were tested with GAMs.ResultsIn the DCA, Early Holocene samples were located close to recent ones due to abundant pollen of herbs, Poaceae, Betula, Pinus sylvestris type and rare pollen of climax deciduous trees. In the DCCA for the last 6,000 years, the sorting of sites along the first unconstrained axis correlated with altitude, which is a complex factor corresponding to temperature and geomorphology (flat summits vs alluvia of mountain rivulets). This elevational differentiation became more pronounced after 2,250 cal BP when summit peatlands started to contain more Vaccinium, Calluna vulgaris, Amaranthaceae, Plantago lanceolata and Rumex acetosa type pollen. In contrast, mid‐elevation pollen spectra started to contain more meadow herbs (Caltha, Potentilla type, Cirsium/Carduus). Picea pollen was surprisingly more associated with mid‐elevation than high‐elevation sites, unlike Fagus.ConclusionIncreasing contrast between summits and middle elevation alluvia seems to be a major feature of vegetation development over the last 6,000 years. While alluvial areas were encroached by Alnus–Picea forests, and later locally transformed into wet grasslands, grazing and forest burning at summits gradually increased abundance of acidophytic dwarf shrubs and peatlands, especially since the Iron Age. Human impact might facilitate beech expansion at high elevations, with Picea‐dominated forests being restricted to alluvia and around mid‐elevation basin peatlands prior to establishment of modern Picea plantations.

Effects of removal of alien Spartina densiflora and restoration of native S. maritima on succession and zonation in European salt marshes

Although ecological zonation and succession are critical concepts to ecology and environmental management, little is known about their development in previously invaded ecosystems after ecological restoration. This present study analyzed plant zonation and succession and the maturation of the abiotic environment of restored Spartina maritima marshes compared to unrestored marshes invaded by Spartina densiflora during a period of 126 months in the Odiel Marshes (Southwest Iberian Peninsula). These restored marshes hosted seven native halophyte species, which were growing in three distinct bands parallel to the tidal line with contrasting abiotic and biotic development during their rapid maturation: a S. maritima non-successional monospecific band, a lower successional band characterized by increasing abundance of Sarcocornia perennis and an upper successional band characterized by rising abundance of the hybrid Sarcocornia perennis x fruticosa and Atriplex portulacoides. The restoration of these European marshes using S. maritima modified their sedimentary conditions, and the establishment of the native ecological zonation and the development of the ecological succession was successfully achieved. In contrast to this, in unrestored marshes, invaded by S. densiflora, only four native halophytes could be found, and their maturation was very slow. Most of the halophytes occupied a narrower range along the intertidal gradient in unrestored marshes than in the restored marshes. The invasion by S. densiflora altered the native zonation pattern, but this invasion seemed to have been limited by healthy growth areas of S. maritima at low elevations, and also by healthy growth areas of native Amaranthaceae species, at middle elevations.

Evaluation of lodgepole pine (Pinus contorta Dougl. ex Loudon) on a provenance plot situated in a formerly air-polluted area of the Krušné hory Mts. at the age of 34 years

The article evaluates 27 provenances of three subspecies of lodgepole pine on the Kovářská research plot (Krušné hory Mts.). The plot is part of a series of three established plots in various stand conditions. Two plots were already evaluated and the findings were published. At 34 years of age, we evaluated height, DBH, trunk shape, trunk forking, branch thickness, bark type, mortality, and defoliation. A total of 1,147 trees were measured. Above-average growth was achieved predominantly by the provenances of Pinus contorta subsp. latifolia (Engelmann ex S. Watson) Critchfield from middle elevations. In the Pinus contorta subsp. contorta Douglas ex Loudon, only the 2099 Port Orford provenance from Oregon demonstrated favourable results, and in the Pinus contorta subsp. murrayana (Balfour) Engelmann it was 2098 Chemult. High mortality was demonstrated mainly in the P. c. subsp. murrayana provenance from high mountainous elevations in California and P. c. subsp. contorta from coastal regions of Oregon. Provenances from middle elevations had relatively lower mortality, especially P. c. subsp. latifolia. The pines usually were of good quality although this was not the case for defoliation and branch thickness. In comparing all plots of the series, growth was fastest at the Sofronka location in western Bohemia and slowest at the south Bohemian Mláka location. Only the best provenances of lodgepole pine can equal the domestic Scots pine (Pinus sylvestris Linnaeus).

Combretum-Terminalia vegetation accumulates more carbon stocks in the soil than the biomass along the elevation ranges of dryland ecosystem in Southern Ethiopia

Dry land ecosystems including Combretum-Terminalia vegetation cover a wider area in the tropics. These resources are believed to greatly contribute for climate change mitigation in dry land ecosystems. Therefore, the objective of this study was to investigate biomass and soil carbon stocks of Combretum-Terminalia vegetation along the elevation ranges. A total of 60 nested sample plots of 20 m × 20 m were laid systematically along lower, middle and higher elevation ranges, representing 20 plots for each elevation. Within each nested sample plot inventory of woody species, litter and soil samples (0–15, 15–30 cm layers) were collected. The total carbon stocks (biomass plus soil) significantly (p < 0.05) differed among the three studied elevation ranges. The biomass carbon stocks were not significantly different between middle and higher elevations but both of them significantly (p < 0.05) differed from lower elevation, and also showed a decreasing trend from lower to higher elevations. However, inconsistence trends were observed for soil organic carbon and litter along the elevation ranges. It was concluded that woodland ecosystem has a potential to accumulate higher carbon stocks in the soil than the biomass and significantly vary along elevations.

A metabolic syndrome in terrestrial ectotherms with different elevational and distribution patterns

The metabolic performance of ectotherms is expected to be driven by the environment in which they live. Ecologically similar species with contrasting elevation distributions occurring in sympatry at mid‐elevations, provide good models for studying how physiological responses to temperature vary as a function of adaptation to different elevations. Under sympatry, at middle elevations, where divergent species ranges overlap, sympatric populations are expected to have similar thermal responses, suggesting similar local acclimation or adaptation, while observed differences would suggest adaptation to each species’ core range. We analysed the metabolic traits of sympatric species pairs from three ectotherm groups: reptiles (Reptilia: Lacertidae), amphibians (Amphibia: Salamandridae) and beetles (Coleoptera: Carabidae), living at different elevations, in order to test how adaptation to different elevations affects metabolic responses to temperature. We experimentally tested the thermal response of respiration rate (RR) and estimated potential metabolic activity (PMA) at three temperature regimes surrounding the groups’ optimal activity body temperatures. RR was relatively similar among groups and showed a positive response to increasing temperature, which was more pronounced in the high‐elevation species of reptiles and beetles. Relative to RR, PMA displayed a stronger and more consistent positive response to increased temperature in all three groups. For all three groups, the average biochemical capacity for metabolism (PMA) was higher in the range‐restricted, high‐elevation species, and this difference increased at higher temperatures in a consistent manner. These results, indicating consistent pattern in three independently evolved animal groups, suggest a ubiquitous adaptive syndrome and represent a novel understanding of the mechanisms shaping spatial biodiversity patterns. Our results also highlight the importance of geographic patterns for the mechanistic understanding of adaptations in physiological traits, including species’ potential to respond/adapt to global climate changes.

Beating cold by being tough: impact of elevation on leaf characteristics in Phleum himalaicum Mez. endemic to Himalaya

Effect of altitude on leaf responses in Phleum himalaicum populations was evaluated at three different elevation levels, viz. (Low 1200 m.a.s.l.), middle (1600 m a.s.l.) and high (1900 m a.s.l.) in western part of Himalaya. We hypothesized that physico-chemical properties of soil varied along elevation and Phleum populations located at high elevation would adapt more distinct morphological and physiological traits than those originating from middle and low elevation sites. Our study revealed that soil pH, Ec Mg, Ca, and P decreased at high elevation however, significant increase was recorded in soil K, organic matter, and total nitrogen along the elevation gradient. A significant correlation between leaf characteristics and elevation sites was recorded along the gradient. The outcomes of this study showed that highland population had better adjustments under low temperature and exhibited adaptive traits. These were, decreased number of leaves and leaf area, increased leaf blade thickness, intensive sclerification, and greater stomatal and trichome density. Apart from these, high elevation population had more physiological adjustment in terms of low stomatal conductance, low transpiration rate, high water use efficiency, and synthesis of more osmolytes in leaf. We argued that certain level of sugar and protein must be attained by high population to dodge the aggressive climatic forces in order to grow successfully at the highest elevation. Furthermore, altitude between 1600 and 1900 m was more likely an optimum zone for vigorous growth of P. himalaicum at the highest level of elevation.

No upward shift of alpine grassland distribution on the Qinghai-Tibetan Plateau despite rapid climate warming from 2000 to 2014

The distributions of many species show climate-driven shifts towards higher elevations, but evidence for elevational shifts is scarce for the alpine grasslands on the Qinghai-Tibetan Plateau. The upward shift of alpine grassland distribution from 2000 to 2014 was assessed with field measurements and satellite remote sensing data obtained across six elevational transects on the Qinghai-Tibetan Plateau. The aboveground biomass (AGB) of alpine grasslands varied with altitude and its data produced a bell-shaped curve. This was mainly due to the elevational dependency of climate change at the surface (i.e., producing drier climate at low elevations and wetter climate at middle elevations). The normalized difference vegetation index (NDVI) derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) exhibited a positive exponential relationship with the AGB of alpine grasslands. Overall, MODIS NDVI initially increased, then peaked at median altitude sites, then decreased with altitude on each elevational transect. MODIS NDVI at the upper limit of alpine grassland distribution did not show a significant increasing trend from 2000 to 2014, even though land surface temperature increased and precipitation remained approximately constant. High spatial resolution Landsat data supported this result. Further analyses of MODIS NDVI at all other sites found no general increase in AGB towards higher elevations. The results suggest that the distribution of alpine grasslands on the Qinghai-Tibetan Plateau did not show an upward shift despite rapid climate warming having occurred from 2000 to 2014.

长白山北坡不同海拔红松径向生长-气候因子关系对气温突变的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 长白山北坡不同海拔红松径向生长-气候因子关系对气温突变的响应 DOI: 10.5846/stxb201706171104 作者: 作者单位: 北京师范大学地理科学学部,北京师范大学地理科学学部 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金（41630750） Response of the relationship between radial growth and climatic factors to abrupt change of temperature along an altitudinal gradient on the northern slope of Changbai Mountain, Northeast China Author: Affiliation: Department of Geographical Sciences, Beijing Normal University,Department of Geographical Sciences,Beijing Normal University Fund Project: The National Natural Science Foundation of China (General Program, Key Program, Major Research Plan) 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:树木径向生长受复杂环境的影响。为预测气候变化背景下未来红松（Pinus koraiensis）径向生长动态变化，在长白山北坡采集3个海拔梯度（745、1134、1280 m）红松树轮样芯，运用树木年轮学研究方法，分析不同海拔红松径向生长-气候因子关系对气温突变的响应差异。结果表明：（1）通过对采样点附近气象站气温数据的M-K检验发现，年均温在1987年发生显著突变；（2）低海拔红松径向生长主要受当年生长季6-7月降水的影响，中、高海拔红松径向生长主要受当年7月平均最低气温的影响；（3）气温突变以后，低海拔红松径向生长-气候因子关系较为稳定，中海拔红松径向生长对前一年11月降水量的响应关系发生显著改变，高海拔红松径向生长对当年5月降水量的响应关系发生显著改变。因此，气温突变背景下，低海拔红松树轮年表更适用于区域气候重建等研究。同时随着气温持续升高，低海拔红松径向生长可能呈现下降趋势，中、高海拔红松径向生长可能呈现先增加后下降的趋势。 Abstract:The radial growth of trees is affected by complex environment. To predict the radial growth dynamics of Pinus koraiensis in the context of climate change, tree ring cores of P. koraiensis were collected from sampling sites at different elevations (745 m a.s.l., 1134 m a.s.l., and 1280 m a.s.l.) on the northern slope of Changbai Mountain. Using a dendrochronological method, we investigated the variability in the responses of radial growth to climatic factors and the temporal stability of the responses at different elevations. The results from the Mann-Kendall test showed that an abrupt change in annual mean temperature occurred in 1987. Tree growth at the low elevation was mainly influenced by the precipitation that occurred in June and July, whereas tree growth at the middle and high elevations was mainly affected by the mean minimum temperature of July. After the abrupt change in temperature, the growth-climate relationship was relatively stable at the low elevation; however, the response of radial growth to precipitation during November of the previous year at the middle elevation and to precipitation that occurred in May at the high elevation changed significantly. Therefore, in the context of an abrupt change in temperature, the chronology of P. koraiensis at low elevations is more suitable for the study of regional climate reconstruction. However, when the temperature continued to rise, the radial growth of P. koraiensis showed a downward trend at the low elevation, whereas at the middle and high elevations, tree growth first increased and then decreased. 参考文献 相似文献 引证文献

Migration of the Northern Boundary of the Siberian Silk Moth

Climate changes have induced the northward migration of outbreaks of the Siberian silk moth (Dendrolimus sibiricus Tschetv.), one of the most dangerous pests in the taiga. The initial outbreak of the Siberian silk moth began in 2014 in Siberian pine.fir stands within the Yenisei Plain on the southwestern flat slopes at elevations up to 200 m above sea level. Further, the outbreak extended to the parts of the forest with higher humidity, the northern slopes, and Yenisei Ridge at low and middle elevations. The northern limit of the outbreak zone shifted to 50 km (to 60°26′ N) northward from the historical boundary of formerly observed outbreaks. The outbreak was incited by an increase in aridity, the sum of positive temperatures (t > +10°C), and a decrease in soil moisture. It extended to an area of 800000 ha. Stand mortality was accompanied by the activation of secondary pests, including aggressive bark beetle species Polygraphus proximus. The outbreak under study is part of the panzonal outbreak that occurred in 2014–2017 on the territory of Siberia in Krasnoyarsk krai and Tomsk, Kemerovo, and Irkutsk oblasts. The increase in warming, aridity, and vegetative period provides opportunities for the Siberian silk moth to migrate to the northern dark-conifer taiga.