Difference In Mean Annual Temperature Research Articles

Understanding the drivers of β-diversity improves conservation prioritization for Central European dung beetles

The conversion and degradation of natural habitats has caused global declines in terrestrial insect diversity. Conserving insect diversity has therefore gained increasing attention in international conservation agendas. Dung beetles (Geotrupidae, Scarabaeidae) are diverse and abundant coprophagous insects who remove dung and enhance nutrient cycling. Today, half of Central European dung beetle species are threatened. While past research has concentrated on local (α-diversity) of dung beetles, the compositional differences between sites (β-diversity) have been largely neglected. However, maximizing the overall outcome of conservation measures requires a detailed understanding of the factors determining compositional differences between sites. We separated β-diversity of dung beetle communities, sampled across the Czech Republic, into independent components of spatial turnover and nestedness. We tested the relative importance of space, temperature, precipitation, elevation, season, grazing herbivore and antiparasitic treatment via multiple regressions for distance matrices to reveal which factors drive the β-diversity of dung beetle communities. Our results show that β-diversity of dung beetle communities is mostly driven by spatial distance, followed by similarly strong effects of season and mean temperature. Herbivore type and antiparasitic treatment had lesser influence than environment but can be influenced by conservation management. Nevertheless, antiparasitic treatment increased nestedness and resulted in an overall lower γ-diversity. Based on the principle of complementarity, we recommend – in order of decreasing importance – giving (1) conservation priority to the most distant sites, under (2) the largest differences in mean annual temperature, ensure (3) year-round grazing by (4) multiple herbivore species, and (5) avoid using antiparasitics.

Genetic diversity and differentiation of populations of Anthyllis vulneraria along elevational and latitudinal gradients.

The abundant centre model (ACM) predicts that the suitability of environmental conditions for a species decreases from the centre of its distribution toward its range periphery and, consequently, its populations will become scarcer, smaller and more isolated, resulting in lower genetic diversity and increased differentiation. However, little is known about whether genetic diversity shows similar patterns along elevational and latitudinal gradients with similar changes in important environmental conditions. Using microsatellite markers, we studied the genetic diversity and structure of 20 populations each of Anthyllis vulneraria along elevational gradients in the Alps from the valleys to the elevational limit (2500 m) and along a latitudinal gradient (2500 km) from Central Europe to the range margin in northern Scandinavia. Both types of gradients corresponded to an 11.5°C difference in mean annual temperature. Genetic diversity strongly declined and differentiation increased with latitude in line with the predictions of the ACM. However, as population size did not decline with latitude and genetic diversity was not related to population size in A. vulneraria, this pattern is not likely to be due to less favorable conditions in the North, but due to serial founder effects during the post‐glacial recolonization process. Genetic diversity was not related to elevation, but we found significant isolation by distance along both gradients, although the elevational gradient was shorter by orders of magnitude. Subarctic populations differed genetically from alpine populations indicating that the northern populations did not originate from high elevational Alpine ones. Our results support the notion that postglacial latitudinal colonization over large distances resulted in a larger loss of genetic diversity than elevational range shifts. The lack of genetic diversity in subarctic populations may threaten their long‐term persistence in the face of climate change, whereas alpine populations could benefit from gene flow from low‐elevation populations.

Dominated Taxonomic and Phylogenetic Turnover but Functional Nestedness of Wetland Bird Beta Diversity in North China

The decomposition of taxonomic, phylogenetic, and functional beta diversity into their turnover and nestedness components could provide novel insights into biodiversity conservation, e.g., provide implications for the Single Large Or Several Small reserves debate (SLOSS debate). Due to dramatic climate change and massive anthropogenic activities in recent decades in North China, the wetlands and the associated biodiversity in this region have declined significantly. This study applied the taxonomic, phylogenetic, and functional beta diversity decomposition for the first time in wetland bird communities in North China, aiming to propose scientific and comprehensive suggestions for bird diversity conservation in this region. A paired t-test was used to compare the differences between taxonomic, phylogenetic, and functional turnover, and their nestedness components. In addition, a spearman correlation analysis was used to assess the associations between each explanatory variable (differences in mean annual temperature and mean annual precipitation, as well as spatial distances) and each beta diversity index. A total of 546 bird species were found in 38 wetlands in North China, with three critically endangered species, 19 endangered species, 22 vulnerable species, and 61 near threatened species. The number of threatened species (critically endangered, endangered, and vulnerable) found in these lakes was about 30% of all threatened species in China. The results showed that taxonomic and phylogenetic beta diversity among wetland bird communities in North China was mainly dominated by turnover, while functional beta diversity was mainly dominated by nestedness. Importantly, the phylogenetic and functional results showed similar patterns even after controlling for the effects of taxonomic beta diversity. In addition, the taxonomic and phylogenetic turnover was more associated with both climate variables and spatial distances than other components. The contrasting patterns among the taxonomic, phylogenetic, and functional decompositions of wetland bird communities in North China indicate that distinctive conservation strategies should be considered for different biodiversity dimensions. Specifically, the conservation of taxonomic and phylogenetic bird diversity in this region should focus on multiple wetlands, while the conservation of bird functional diversity should focus on a single wetland with high functional diversity.

Temperature adaptation of soil microbial respiration in alpine, boreal and tropical soils: An application of the square root (Ratkowsky) model.

Warming is expected to stimulate soil microbial respiration triggering a positive soil carbon-climate feedback loop while a consensus remains elusive regarding the magnitude of this feedback. This is partly due to our limited understanding of the temperature-adaptive response of soil microbial respiration, especially over broad climatic scales. We used the square root (Ratkowsky) model to calculate the minimum temperature for soil microbial respiration (Tmin , which describes the temperature adaptation of soil microbial respiration) of 298 soil samples from alpine grasslands on the Tibetan Plateau and forest ecosystems across China with a mean annual temperature (MAT) range from -6°C to +25°C. The instantaneous soil microbial respiration was determined between 4°C and 28°C. The square root model could well fit the temperature effect on soil microbial respiration for each individual soil, with R2 higher than 0.98 for all soils. Tmin ranged from -8.1°C to -0.1°C and increased linearly with increasing MAT (R2 =0.68). MAT dominantly regulated Tmin variation when accounting simultaneously for multiple other drivers (mean annual precipitation, soil pH and carbon quality); an independent experiment showed that carbon availability had no significant effect on Tmin . Using the relationship between Tmin and MAT, soil microbial respiration after an increased MAT could be estimated, resulting in a relative increase in respiration with decreasing MAT. Thus, soil microbial respiration responses are adapted to long-term temperature differences in MAT. We suggest that Tmin = -5 + 0.2×MAT, that is, every 1°C rise in MAT is estimated to increase Tmin of respiration by approximately 0.2°C, could be used as a first approximation to incorporate temperature adaptation of soil microbial respiration in model predictions. Our results can be used to predict future changes in the response of soil microbial respiration to temperature over different levels of warming and across broad geographic scales with different MAT.

Sinusoidal growth, recruitment, mortality, yield-per-recruit analysis of Buried fan scallop Mimachlamys funebris (Reeve, 1853) and their implications for mariculture

This study described the growth, mortality, recruitment pattern and exploitation rate of the Buried fan scallop (Mimachlamys funebris) in Asid Gulf, Philippines. Monthly length-frequency data (N=3988) from April 2018 to March 2019 were used to examine population parameters using FISAT II. Two estimates of natural mortalities were used to compare variability of limit exploitation rates. Modelling through the oscillating von Bertalanffy growth function revealed that the species is fast growing (K=1.1 year–1) attaining SH∞ of 10.5 cm. Adequacy in the use of the sinusoidal version of the growth formula hinges on the mean annual temperature difference reported in the gulf to be 2°C. Recruitment pattern was continuous and bimodal throughout the year with two high pulses in April–May and September consistent with the reproductive seasonality reported for congeneric species. Fishing mortality coefficients (4.26 and 4.82 year–1) were higher than the natural mortality coefficients (0.543 and 1.1 year–1). Yield and biomass-per-recruit analysis showed that the current exploitation rates are 112% (Ecurr1 = 0.90) and 92% (Ecurr2 = 0.80) higher than the biological reference points adopted for the study particularly E50. These results demonstrate that M. funebris stock is overexploited, which necessitates effective management measures including mariculture.

Plant performance and survival across transplant experiments depend upon temperature and precipitation change along elevation

Abstract Understanding how plant individuals perform in non‐local sites is key in the context of contemporary range shifts along elevation. Transplant experiments conducted in mountain ecosystems are rising as key tools to measure the intraspecific response of individuals transplanted across contrasting elevations. However, a synthesis quantifying patterns of plant performance in response to changes in abiotic factors across different species and mountain ranges is still lacking. We conducted a meta‐analysis to quantitatively summarize patterns of plant species' performance variation in response to changes in temperature and precipitation within their elevation range across multiple transplant experiment studies. We compiled a dataset obtained from 38 studies and 49 vascular plant species in total addressing intraspecific performance variation in terms of survival, germination, biomass, height, number of vegetative organs, number of reproductive units, SLA and leaf size. We both compared pairs of transplanted individuals to those growing at their site of origin (‘away vs. home’) and to the local individuals found at the site of transplant (‘foreign vs. local’). Overall, individuals transplanted downward showed larger biomass and height compared to their site of origin but failed to adjust these traits and survival to that of local individuals. Individuals transplanted upward adjusted their traits by decreasing plant growth and number of reproductive units to that of local individuals but showed lower survival. Importantly, changes in survival, biomass, height, leaf size, number of vegetative organs and reproductive units increased linearly with the difference in mean annual temperature between site of transplant and site of origin in the ‘away vs. home’ comparison. Conversely, changes in biomass, leaf size, number of vegetative organs and reproductive units increased with mean annual precipitation difference between sites in the ‘foreign vs. local’ comparison. Synthesis. We detected common trends in survival and intraspecific trait variation across different species and transplant experiments conducted along elevational gradients. Because plasticity and adaptation play a crucial role in plant shift, establishment and persistence under non‐local environmental conditions, our meta‐analysis contributes to better understand how rapid plant shifts are constrained by climatic conditions within species' elevational range.

Insights into the Distribution Patterns, Habitat and Morphologic Differentiation of Cryptic Species of the Moss Hamatocaulis vernicosus in the Czech Republic

Manukjanová, A., Kouteckí, P., Štechová, T. & Kučera, J. 2019. Insights into the distribution patterns, habitat and morphologic differentiation of cryptic species of the moss Hamatocaulis vernicosus in the Czech Republic. – Herzogia 32: 183–199.We studied local distribution, morphological and ecological differences between the two cryptic species of Hamatocaulis vernicosus in the Czech Republic. Distribution was assessed at both regional scale and within localities using several barcoding methods including direct sequencing and PCR-RFLP of ITS region of nrDNA, as well as amplification of clade-specific SSR markers. The lineage known as clade 1 occurs on more than 90 % of the 70 investigated Czech localities, while clade 2 occurs at only about 10 % of localities, which moreover mostly support plants of both clades. Analysis of ITS sequences from Czech samples showed considerable variability in clade 1, while plants of clade 2 were invariable. Comparison of climatic characteristics did not reveal any significant differences in mean annual temperature, precipitation and frost days between localities of both clades, although clade 2 plants tends to grow at higher elevations. Statistical evaluation of morphometric data has not revealed any character which would morphologically distinguish plants of both clades.

Badania klimatu miejskiego w Toruniu prowadzone przez Katedrę Meteorologii i Klimatologii UMK – zarys historii i uzyskanych wyników

The article presents the history of research into the urban climate of Toruń initiated and conducted by the Department of Meteorology and Climatology of Nicolaus Copernicus University. Two periods of intensive research on the subject were identified: 1981–1993 and 2011–present. In the first period, measurements were taken at a significantly smaller number of points and covered a narrower scope than in the second period. The measuring equipment was also significantly different, with mercury thermometers and drum recorders (thermohygrographs) being used in the first period, and automatic meteorological stations in the second. Results from both periods, specifically from 1982 and 2012, confirmed the existence of an urban heat island (UHI) and significant differences in the spatial distribution of air humidity. In both analysed periods, differences in mean annual temperature and air humidity between the city centre and the reference station were about 1°C and 7%, respectively. The lack of changes in UHI intensity and spatial distribution of air humidity between the analysed years can be explained by the lack of significant changes in the development of Toruń’s Old Town.

Adaptive genetic potential of European silver fir in Romania in the context of climate change

Five provenance tests with twenty-six European silver fir autochthonous populations were used in order to assess the response of populations to climate change. Height growth and diameter at breast height of trees at age 31 years were considered as response variables and eight climate variables as predictors. Climatic variables for the trial sites and for origin location of provenances were calculated from 1961 to 2010. The experiments revealed a large genetic variability within species level and a plastic response to climate change, which certainly has a genetic basis. The transfer to warmer climate has resulted in an increase of the provenances growth, in the trial sites situated on the lower vegetation layer. But growth is significantly influenced by mean annual temperature and annual precipitation of planting site and also by the differences in mean annual temperature, annual precipitation, monthly mean temperature in July and July precipitation between provenance site and test site. These are the climatic factors which should be associated with risk in case of the transfer of forest reproductive materials. The provenance origin should be especially considered if the species will be planted outside of its current climate optimum. The best provenances in terms of total height and diameter at 1.30 m came from origin climate close to site climate, small transfer distances. Based on growth response functions and RCP4.5 scenario, we could project the shifts in species distribution for 2050s and 2100s and identify vulnerable populations.

Variability in mean size of phytoplankton in two floodplain lakes of different climatic regions

Phytoplankton size has an important functional role in ecosystem processes, such as nutrient production and cycling. It has been suggested that warmer temperatures may favor the smaller organisms in biological communities. We evaluate the mean size of the phytoplankton organisms and apply a morphology-based functional groups (MBFG) approach. We use time series of two floodplain lakes that present mean annual temperature difference of 10°C and similar hydrodynamic, area, and mean depth. We expected that a smaller mean size of MBFGs would be associated with higher temperatures. The Akaike Information Criterion was used to investigate environmental factors predicting the mean size of MBFGs within each lake. The mean size was most associated to nutrients and dissolved oxygen in the subtropical lake, and to temperature in the temperate lake. Large filaments with aerotopes and the small flagellated with siliceous exoskeletal structures showed high mean size at higher temperatures, thus contradicting temperature–size rules. Probably the high variability of mean size was provided by the high variability observed around environmental factors. Our findings reveal that other functional traits may be associated with the phytoplankters mean size, which result in adaptation to high variability of various environmental factors.

Identification of Floral Relicts Based on Spatial Distance of Isolation

The identification of climatic relicts is seldom straightforward. These species are threatened owing to current climatic trends, which underlines the importance of carrying out ecological and biogeographic investigations of them. Here we introduce a novel approach to improve the identification of climatic relicts. We are focusing on thermophilic relict plants of the Pannonian biogeographic region from the Holocene Thermal Maximum (HTM). We argue that a minimal mean annual temperature difference (MATD) of the HTM compared to the recent climate allowed a continuous northward expansion for the taxa investigated. We measured latitudinal distances between the recent occurrences of relicts and those of the main distribution found further south. Regarding estimates for MATD (1.0–2.5 °C), we only consider species with a distribution which has a 150–350 km North-South gap, since a latitudinally directed distance can be translated into temperature, showing a poleward cooling trend. Of the 15 selected species, 12 were recorded with values of 1.0–1.7 °C MATD, and three with values of 1.8–2.5 °C, some of which are presumably interglacial species. Woody species are over-represented among them (four species), using the Hungarian flora as a reference. The proposed method allows the prediction of potential climate-related changes in the future distribution of species, constrained by the topographic features of their habitats.

Anti-icing of road surfaces using Hydronic Heating Pavement with low temperature

A traditional method to mitigate slippery conditions on a road surface is to spread out sand and salt. This method results in corrosion of the road infrastructures and damage to surrounding vegetation. A renewable alternative method for anti-icing the road surface is to use a Hydronic Heating Pavement (HHP). The HHP consists of embedded pipes in the road. A fluid as thermal energy carrier circulates through the pipe. The energy is harvested in summer and saved in seasonal thermal energy storages. The harvested energy, as the only source of energy, is released in winter for snow/ice melting. The aim of this study is to investigate the anti-icing performance of the HHP system during cold periods. A two-dimensional numerical model was developed to investigate how different design options, such as distance between the pipes, affect the efficiency of the HHP systems. The annual required energy for anti-icing and remaining hours of the slippery conditions on the road surface were numerically calculated using a finite element model. The numerical model was validated for two cases: (i) for a road without pipes using a one year measured data of an existing road and (ii) for a road with embedded pipes using an analytical solution. The validation results for a road without pipes showed that the mean annual temperature difference of the road surface is 0.28°C with standard deviation of 3.53°C between the measured data and numerical calculation. The validation results for the road with embedded pipes showed that the maximum relative error associated with the thermal resistance between the pipes and surface is less than 1% between the numerical model and the analytical solution. In order to investigate the anti-icing performance of the HHP system, the climate data from Östersund, an area in middle of Sweden, were selected. The results revealed that the anti-icing performance of the HHP system improves when the pipes are placed closer, the depth of embedded pipes is reduced, large pipe sizes are used and when the road surface has a lower emissivity value. Among all options, the distance between pipes has the most significant effect on improving the anti-icing performance, so changing the pipe distances from 400mm to 50mm results in approximately four times shorter hours of the slippery conditions on the road surface.

A common thermal niche among geographically diverse populations of the widely distributed tree species Eucalyptus tereticornis: No evidence for adaptation to climate-of-origin.

Impacts of climate warming depend on the degree to which plants are constrained by adaptation to their climate-of-origin or exhibit broad climatic suitability. We grew cool-origin, central and warm-origin provenances of Eucalyptus tereticornis in an array of common temperature environments from 18 to 35.5°C to determine if this widely distributed tree species consists of geographically contrasting provenances with differentiated and narrow thermal niches, or if provenances share a common thermal niche. The temperature responses of photosynthesis, respiration, and growth were equivalent across the three provenances, reflecting a common thermal niche despite a 2,200km geographic distance and 13°C difference in mean annual temperature at seed origin. The temperature dependence of growth was primarily mediated by changes in leaf area per unit plant mass, photosynthesis, and whole-plant respiration. Thermal acclimation of leaf, stem, and root respiration moderated the increase in respiration with temperature, but acclimation was constrained at high temperatures. We conclude that this species consists of provenances that are not differentiated in their thermal responses, thus rejecting our hypothesis of adaptation to climate-of-origin and suggesting a shared thermal niche. In addition, growth declines with warming above the temperature optima were driven by reductions in whole-plant leaf area and increased respiratory carbon losses. The impacts of climate warming will nonetheless vary across the geographic range of this and other such species, depending primarily on each provenance's climate position on the temperature response curves for photosynthesis, respiration, and growth.

Tree species functional group is a more important driver of soil properties than tree species diversity across major European forest types

Summary The influence of tree species diversity and functional group on soil properties (carbon stock, pH and C/N ratio) has not been explored across major European forest types. We evaluated the relative importance of tree species diversity and functional group for soil carbon (C) stocks, C/N ratio and pH in major European forest types in the six regions Finland, Poland, Germany, Romania, Italy and Spain. We sampled soils in 209 permanent plots along a species diversity gradient from monocultures to five‐species mixtures. Carbon stocks in the topsoil (forest floor (FF), 0–10 cm and FF + 0–10 cm) were positively, but weakly, related to diversity across the regions. While the C/N ratio in the FF + 0–10 cm layer decreased significantly with increasing diversity in the Spanish region, pH was unrelated to species diversity across the regions. Tree species functional group (in terms of conifer proportion, CP) explained a larger proportion of the variability in soil properties than diversity. Conifer admixture increased C stock and C/N ratio, and decreased pH, but the impacts differed between the regions in some layers. Differences in mean annual temperature, actual evapotranspiration and soil texture between the regions were possible driving factors behind the different CP effects in Finland, Spain and Germany. The results imply that targeted selection of tree species with desired characteristics, e.g. complementary traits for resource use, is a preferred management approach for influencing soil C stock, C/N ratio and pH in mixed forests rather than increasing tree species diversity per se. A lay summary is available for this article.

Stable hydrogen isotope values of lignin methoxyl groups of four tree species across Germany and their implication for temperature reconstruction.

Stable hydrogen isotope ratios of lignin methoxyl groups (δ2HLM values) in wood have been shown to mirror the δ2H signatures of precipitation (δ2Hprecip values). Thus, δ2HLM values were suggested to serve as a potential paleotemperature proxy since δ2Hprecip values are dominantly controlled by air temperature in the mid-latitudes. A recent study where a significant δ2HLM-temperature relationship was found for a European transect with mean annual temperatures ranging from -4 to 17°C strengthened this assumption. However, using δ2HLM values as a paleotemperature proxy requires quantification of noise from site-, species- and biosynthetic-specific influences to determine the significance of recording smaller temperature changes. Here, we measured δ2HLM values of tree-ring sections covering 1981-1990 and 1991-2011 of four different tree species (European beech, English oak, Scots pine, Norway spruce) at 15 sampling sites across Germany. The maximum difference in mean annual temperature between sample sites was 5°C and all sites showed small temperature increases from 1981 to 1990 to 1991-2011 (mean Δ=0.7°C). For all species investigated, the maximum difference of δ2HLM within the tree was <10mUr or ‰ (median values) and between trees at a single site was ≤28mUr (median values). The general pattern of the spatial δ2HLM-temperature relationship found for the European transect was confirmed here although a significant correlation was lacking. This can be explained by the lower spatial δ2Hprecip-temperature correlation (R2=0.39) found for sampling sites in this study and the δ2HLM differences between trees. Nevertheless, the temporal changes in δ2HLM values of European beech trees correctly reflected within ±2°C the temperature change at every sampling site. Therefore, we suggest that δ2HLM values of European beech trees have considerable potential for reconstructing temperature changes when applied on tree-ring chronologies and consider this approach particularly suited for Late Holocene climate studies.

Analysis of asymmetric temperature fields for the duct-ventilated embankment of highway in permafrost regions

The heat capacity and polythermal effect of highway roadbeds with wide asphalt pavements have become increasingly significant, which causes their influences on engineering and permafrost issues to become prominent. A duct-ventilated embankment is a potential mean to proactively cool ground temperatures. This method is applied experimentally in a highway for the first time. According to a field testing in the Tibetan Plateau Highway Pilot Project, a duct-ventilated embankment has excellent cooling effect. The mean annual ground temperature reduction at the embankment/natural ground surface interface is 1.62°C. The mean annual temperature difference between the south- and north-facing slopes reaches 2.39°C. This difference results in the asymmetry of the underlying temperature field and longitudinal roadbed cracking. The asymmetric distribution of the duct-ventilated embankment temperature field is caused by differential sun exposure and the heat transfer process and intensity within the duct. Differential sun exposure is a major factor between the south- and north-facing sides, accounting for 84%, whereas the remaining 16% is ascribed to the different heat transfer processes within the duct. The amount of asymmetry is increased to 20% by the duct and slightly accentuated by the ventilation duct. To avoid this effect, future projects should focus on solving problems related to roadbed direction and the effect of slope temperature difference on ground temperature. Measures are recommended to be taken to regulate both slope temperature adjustment and ventilation ducts, and thus, effectively combine the advantages of both measures in embankment design.

Impacts of geographical distances and environmental differences on the beta diversity of plant communities in the dry-hot valley of the Yuanjiang River

Beta diversity is the difference in species composition between locations. Recently, much of the published biodiversity research has focused on the assessment of beta diversity because it can be used to investigate community assembly and maintenance of species diversity. In this study, we investigated the impacts of dispersal limitation and habitat on the beta diversity of communities by sampling 41 plots throughout the dry-hot valley of Yuanjiang River. Taxonomic beta diversity and phylogenetic beta diversity were quantified using Jaccard dissimilarity, mean nearest taxon distance (MNTD), and mean pairwise distance (MPD). These indices were then related to the differences in environmental characteristics between sample plots and the geographical distances separating sample plots using multiple regression on distance matrices (MRM) and variance partitioning. The results showed that taxonomic and phylogenetic beta diversity indices significantly increased with the spatial distance and difference in mean annual temperature between communities; ·研究报告· 400 生 物 多 样 性 Biodiversity Science 第 24卷 that taxonomic beta diversity and MNTD were most strongly influenced by spatial distance, whereas MPD was equally influenced by spatial distance and mean annual temperature difference between communities; and that only 11–13% of the variance in beta diversity was explained by the spatial distance and mean annual temperature difference between communities. These results highlight the effects of niche and dispersal limitations on beta diversity, and suggest that dispersal limitation may play a greater role than habitat differences between plant community locations. Additionally, human disturbances may greatly impact species composition along the dry-hot valley of the Yuanjiang River.

西藏高原草地生态系统丛枝菌根真菌的地理分布

PDF HTML阅读 XML下载 导出引用 引用提醒 西藏高原草地生态系统丛枝菌根真菌的地理分布 DOI: 10.5846/stxb201411192291 作者: 作者单位: 西藏大学农牧学院,西藏大学农牧学院 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金资助项目(41161043,41461054) Geographical distribution of arbuscular mycorrhizal fungi in the grassland ecosystems of the Tibetan Plateau Author: Affiliation: Agricultural and Animal Husbandry College,Tibet University,Agricultural and Animal Husbandry College,Tibet University Fund Project: 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:西藏高原是地球上极具特色的地理单元,对生物物种的形成与演化具有重要影响。基于孢子形态学鉴定,对从藏东南到藏西北(海拔高差 > 3500 m,年均温、年均降水量差异分别 > 20 ℃、 > 800 mm)高原热带、亚热带、温带、亚寒带和寒带环境下发育而成的热性草丛、暖性草丛、温性草原、温性荒漠、高寒草甸草原、高寒草原、高寒荒漠和高寒荒漠草原中的AM真菌群落进行研究,结果表明,不同类型草地间AM真菌的群落相似度普遍较低,环境对AM真菌群落具有重要影响。从藏东南到藏西北,不同类型草地间AM真菌的群落相似度呈下降趋势(Jaccard相似性系数从0.52降至0.20),AM真菌群落组成及结构变化渐趋加大,不同草地中的同种植物(包括广谱种、青藏高原特有种)AM真菌群落相似度亦不同。沿藏东南到藏西北环境梯度,随草地寒旱程度的逐步加剧,AM真菌种的丰度,特别是种数、Shannon-Weiner指数在总体上趋于显著(P < 0.05)下降,孢子密度则在总体上趋于显著提高,优势种比例、Shannon-Weiner指数亦表现出增加的趋势,表明AM真菌物种多样性虽趋于下降,但生存及对环境的适应能力趋于提高。海拔、土壤pH、有效磷和有机碳含量对AM真菌群落组成均具显著影响,但海拔对水热环境的影响决定着土壤环境的变化。因此,海拔和寒旱程度不断上升所导致的pH显著提高、土壤有机碳和有效磷含量显著下降的综合作用影响并决定着AM真菌的群落组成。研究结果对进一步理解西藏高原生物多样性的产生和维持机制等具有重要的参考价值。 Abstract:The Tibetan plateau is a unique geographical unit that plays important roles in the formation and evolution of biological species. On the basis of spore morphology, we preliminarily investigated arbuscular mycorrhizal (AM) fungal communities in tropical tussock (TT), warm tussock (WT), temperate desert steppe (TDS), temperate desert (TD), alpine meadow steppe (AMS), alpine steppe (AS), alpine desert (AD), and alpine desert steppe (ADS) environments in southeastern to northwestern Tibet (altitude > 3500 m; mean annual temperature difference > 20 ℃; mean annual amount of precipitation difference > 800 mm), including plateau tropic, subtropic, temperate, subfrigid, and frigid zones. The results showed that the community similarity of AM fungi in different types of grasslands was generally low, and the type of environment had an important effect on the AM fungal community. Community similarity of AM fungi in different types of grassland demonstrated a decreasing trend from southeastern to northwestern Tibet (Jaccard similarity coefficient decreased from 0.52 to 0.20). Changes in the composition and structure of the AM fungal community increased gradually. AM fungal community similarity for the same plant species (including a broad spectrum of species and species endemic to the Qinghai-Tibetan Plateau) in different grasslands was also different. With a gradually aggravated degree of cold and drought in the grasslands along the environmental gradient from southeastern to northwestern Tibet, the abundance of AM fungi species, especially the number of species, showed significantly decreasing trends, according to the Shannon-Weiner index (P < 0.05). At the same time, spore density demonstrated dramatically increasing trends, and the proportion of dominant species in relation to the Shannon-Weiner index also showed a tendency to increase. This indicated that although the diversity of AM fungi showed decreasing trends, their survival and adaptability to the environment tended to improve. The effects of altitude, soil pH, effective phosphorus, and organic carbon content on AM fungal communities were significant, whereas the effects of altitude on the hydrothermal environment determined the changes in the soil environment. Therefore, AM fungal community composition was determined by the comprehensive effects of a dramatic increase in pH and soil organic carbon and a dramatic decrease in effective phosphorus content due to the gradually increasing altitude and degree of cold and drought. Our results have an important reference value for the further understanding of the production and maintenance of organism diversity in the Tibetan Plateau. 参考文献 相似文献 引证文献

Distributions of carbon and nitrogen isotopes in Scotland's topsoil: a national‐scale study

SummaryThe land use and climate of Scotland are currently undergoing change. Concentrations of Natural abundance stable isotopes in ecosystems have been used extensively to help to understand a wide range of processes and functions. In the current study topsoil was collected from the intercepts of a 20‐km grid across the whole of Scotland (183 points), which encompass large differences in mean annual temperature (MAT,3.1–9.1°C), mean annual precipitation (MAP, 588–3470 mm) and land use (from arable land through grassland and woodland to less fertile moorlands and bogs). At each sampling point the natural abundance δ13C and δ15N values were measured. This paper describes for the first time the spatial distribution of these isotopes in the topsoil of Scotland. We applied linear modelling to assess the extent to which land use and climate can control the observed distributions. The more enriched topsoil δ13C values occurred in the northern and western regions of Scotland. Topsoil δ13C values were tightly constrained about the mean, and possibly because of this we were able to explain only 23.6% of the variance even after considering the potential effects of a wide range of abiotic factors and land uses. Precipitation and land use explained the greatest variance in topsoil δ13C, but individually this was only 10.4 and 9.9%, respectively. Topsoil δ15N values showed a more complex spatial arrangement. The main areas of the more enriched δ15N values were in the northern isles, along or near the coast on the eastern side of the country and in some areas of the western mainland. For topsoil δ15N, all explanatory variables together explained 55.7% of the variance, with land use alone explaining 45.4%. Soil under arable land and improved grassland, the more fertile sites, had the most enriched δ15N values, whereas woodland and bogs had the most depleted values. A positive relationship between topsoil δ15N and potential rate of nitrification suggested that this was due, at least in part, to greater losses of nitrate under arable land and improved grassland.

Are seed mass and seedling size and shape related to altitude? Evidence in Gymnocalycium monvillei (Cactaceae)

Several studies reported a negative relationship between altitude and seed mass. In cactus species, seed mass has been also related to seedling morphology (size and shape). Here we studied Gymnocalycium monvillei (Lem.) Pfeiff. ex Britton &amp; Rose, a cactus species with a wide altitudinal distribution, with the main aim of analyzing how altitude affects seed mass and seedling size (height and width) and shape (globose or columnar). We collected seeds from five sites along the entire altitudinal distribution of the species in the Córdoba Mountains (sites were located between 878 and 2230 m a.s.l.), encompassing a marked climatic gradient (6 °C of mean annual temperature difference between the extreme sites). Seed mass and seedling traits were measured in the laboratory. Seedling height increased with altitude, whereas seed mass was not related to this parameter. Seedlings became more globose (reduced surface/volume ratio) with decreasing altitude. Variation in seedling shape along the altitudinal gradient may be related to the contrasting climatic conditions to which seedlings are exposed, and could account for the wide altitudinal distribution of G. monvillei. Our results highlight the importance of seedling traits in the species’ response to climatic change.