Mountain Altitude Research Articles

The Forbush decrease observed by the SEVAN particle detector network in the 25th solar activity cycle

The temporal variations of cosmic-ray intensity, measured by ground-based detectors at various latitudes, longitudes, and altitudes, are related to the geophysical and solar phenomena. The latter are interplanetary coronal mass ejections and fast solar wind from coronal holes, which cause interplanetary magnetic field (IMF) abrupt variations near Earth. Interacting with the magnetosphere, they cause worldwide sudden decreases (Forbush decreases, FDs) of intensity followed by gradual recovery. The amplitude of the flux depletion depends on the type and energy of the registered particle, which in turn depends on geographical coordinates and the detector's energy threshold and selective power. SEVAN particle detector network with nodes in Europe and Armenia selects three types of particles that demonstrate coherent depletion and recovery and correspond to different energy galactic protons interacting with disturbed magnetospheric plasmas.On November 3–4, 2021, an interplanetary coronal mass injection (ICME) hit the magnetosphere, sparking a strong G3-class geomagnetic storm and auroras as far south as California and New Mexico. All detectors of the SEVAN network have registered an (FD) of ≈5% depletion in a 1-min time series of count rates. Approaching the maximum solar activity cycle, large variations of the particle flux intensity were registered on February 27, March 23, 2023, and March 24, 2024.In this work, we present measurements of these FDs performed on mountain altitudes on Aragats (Armenia), Lomnicky Stit (Slovakia), Mileshovka (Czechia), and at sea level DESY (Hamburg, Germany). We compared FD measurements made by SEVAN detectors and neutron monitors located on Aragats and Lomnicky Stit and made a correlation analysis of FD registration at different locations.

Increase in the count rates of ground-based cosmic-ray detectors caused by the heliomagnetic disturbance on 5 November 2023

This letter presents a rare physical phenomenon associated with solar activity, manifesting in anomalies within neutron, electron, and gamma-ray fluxes in the atmosphere. Conventionally, the Earth's magnetic-field disturbances reduce cosmic-ray intensity reaching the surface. However, a temporary surge in cosmic-ray flux occurs intermittently known as the magnetospheric effect (ME). Our observations reveal that this effect predominantly induces a count rate increase in particle detectors positioned at middle latitudes on mountaintops. On November 5, 2023, a 2–3% increase in neutron monitors at mountain altitudes and up to 5% increase in thin plastic scintillators registering electrons and gamma rays was observed. This flux escalation coincided with a southward orientation of the interplanetary magnetic field. Importantly, we present, for the first time, the energy spectrum of the Magnetospheric Effect observed at two mountaintops: Aragats and Zugspitze. Simulations of low-energy proton interactions in the terrestrial atmosphere affirm the augmentation of low-energy cosmic rays. Protons, typically restricted by the geomagnetic cutoff, reached the Earth's atmosphere, generating detectable particle showers on the Earth's surface. To sum up, 1) we measure an increase in the count rate of magnetospheric origin using particle detectors located at mountain altitudes and middle latitudes; 2) for the first time, we measured the energy spectra of the particle fluxes during the magnetospheric effect with spectrometers located on Mount Aragats and Zugspitze; 3) particle flux enhancement coincides with the depletion of the horizontal component of the geomagnetic field; 4) we explain why the magnetospheric effect was observed at mountain altitudes and not at sea level.

Assessment and Optimization of the Insecticidal Properties of γ-Al2O3 Nanoparticles Derived from Mentha pulegium By-Products to Xylosandrus crassiusculus (Carob Beetle).

This study concentrates on assessing the insecticidal attributes of the γ-Al2O3 nanoparticles derived from the remnants of Mentha pulegium, which include essential oil, ethanolic extract, and plant waste. The synthesis of the γ-Al2O3 nanoparticles was executed using a direct sol-gel procedure, affirming the crystal structure according to extensive physicochemical analyses such as UV-Vis, XRD, FTIR, and SEM. Evaluation of the insecticidal activity in vitro was conducted against Xylosandrus crassiusculus, a pest that infests carob wood, utilizing strains from diverse forests in the Khenifra region, situated in the Moroccan Middle Atlas. The lethal doses 50 ranged from 40 mg/g to 68 mg/g, indicating moderate effectiveness compared to the commercial insecticide Permethrin. Optimization of the conditions for the efficiency of the γ-Al2O3 nanoparticles was determined using experimental plans, revealing that time, humidity, and temperature were influential factors in the lethal dose 50 of these nanomaterials. Moreover, this study encompasses the establishment of correlations using Principal Component Analysis (PCA) and Ascending Hierarchical Classification (AHC) among various geographic, biological, and physical data, amalgamating geographic altitude and γ-Al2O3 nanoparticle insecticide parameters, as well as the attributes of the mechanical tests conducted on the carob wood affected by insects. The correlations highlight the close connections between the effectiveness of the insecticide, mountain altitude, and the mechanical parameters that were examined. Ultimately, these nanoparticles demonstrate promising potential as alternative insecticides, thus opening up encouraging prospects for safeguarding against carob wood pests.

Plant height variation and genetic diversity between Prunus ledebouriana (Schlecht.) YY Yao and Prunus tenella Batsch based on using SSR markers in East Kazakhstan.

Genetic differences between isolated endemic populations of plant species and those with widely known twin species are relevant for conserving the biological diversity of our planet's flora. Prunus ledebouriana (Schlecht.) YY Yao is an endangered and endemic species of shrub almond from central Asia. Few studies have explored this species, which is closely related and morphologically similar to the well-known Prunus tenella Batsch. In this article, we present a comparative analysis of studies of three P. ledebouriana populations and one close population of P. tenella in Eastern Kazakhstan in order to determine the particular geographic mutual replacement of the two species. The populations were collected from different ecological niches, including one steppe population near Ust-Kamenogorsk (P. tenella) and three populations (P. ledebouriana) in the mountainous area. Estimation of plant height using a t-test suggested a statistically significant difference between the populations and the two species (P<0.0001). DNA simple sequence repeat (SSR) markers were applied to study the two species' genetic diversity and population structure. A total of 19 polymorphic SSR loci were analyzed, and the results showed that the population collected in mountainous areas had a lower variation level than steppe populations. The highest level of Nei's genetic diversity index was demonstrated in the 4-UK population (0.622) of P. tenella. The lowest was recorded in population 3-KA (0.461) of P. ledebouriana, collected at the highest altitude of the four populations (2,086 meters above sea level). The total genetic variation of P. ledebouriana was distributed 73% within populations and 27% between populations. STRUCTURE results showed that two morphologically similar species diverged starting at step K=3, with limited population mixing. The results confirmed the morphological and genetic differences between P. tenella and P. ledebouriana and described the level of genetic variation for P. ledebouriana. The study's results proved that the steppe zone and mountain altitude factor between P. tenella and isolated mountain samples of P. ledebouriana.

The contribution of the frequency ratio model and the prediction rate for the analysis of landslide risk in the Tizi N'tichka area on the national road (RN9) linking Marrakech and Ouarzazate

Road infrastructure is vital for economic development, connecting various locations. However, in Morocco, landslides pose recurring challenges to road projects due to factors like lithology, climate, rift structures, and high altitudes in the High Atlas Mountains. Developing susceptibility maps for landslides is crucial to anticipate and take appropriate actions. National Road Number 9, particularly the Tizi N'tichka region in the High Atlas, experiences significant landslide issues. This study used frequency ratio (RF) and prediction rate (PR) techniques to map landslide susceptibility along this road section connecting Marrakech and Ouarzazate. By analyzing thirteen factors, including elevation, curvature, precipitation, slope, and land use, a landslide sensitivity index (LSI) was created. A landslide inventory of 214 locations was prepared, with 70% (150 events) used for model training and 30% (64 events) for validation. The resulting sensitivity map classified areas into five categories of landslide susceptibility. The model's effectiveness was evaluated using the receiver operating characteristic (ROC) curve technique, yielding an AUC value of 92.3% during validation. The findings demonstrate the efficacy of RF and PR methods in landslide susceptibility mapping. It helps identify high-risk areas along National Road Number 9 in the Tizi N'tichka region, enabling proactive measures for mitigating landslide impacts on road infrastructure. These outcomes serve as a foundational basis for conducting further research and verifying the performance of alternative methods such as the susceptibility index model (SII), the inventory validation (IV) model, and the weight of evidence (WoE) model Overall, this research contributes to better anticipation and management of landslides, ensuring the reliability and safety of road networks in the studied region and beyond the geographical boundaries.

Redhead, Paroissien, Parish &amp; Co.: British Field Science in early Independent RÍo de la Plata

This article explores the activities of those British travellers and settlers who carried out open field research in the Andean northwest of Río de la Plata during the 1820s. The focus is set upon Doctor Joseph Redhead, who became a regional expert on questions of mountain altitudes and natural portents such as giant fossil bones and large masses of native iron. Redhead was at the centre of a network of British doctors, entrepreneurs, adventurers and civil servants who crisscrossed the territory attracted by new mining ventures and the opening of trade, and driven by the need for geographical surveys implicit in the logic of empire. James Paroissien, Woodbine Parish, Joseph Pentland and others managed to combine research on the natural environment while engaged in their commercial, diplomatic or military missions. Particular attention is paid to the interactions of Redhead and his fellow countrymen with Humboldt and the kind of science cultivated by him, as well as to issues of scientific authority at the time of deciding on the cause of unexplained natural phenomena.

Milk Composition of Creole Goats Raised at Different Altitudes in an Extensive Production System in Northeast Mexico.

Goat milk composition is affected by feeding, and in semiarid rangeland, information on Creole goat milk physicochemical composition is lacking. For the fulfillment of this objective, three agroecological regions (AR) considering altitude (lowland 87, highland 779, and mountain 1309 m above sea level) with different botanical compositions were chosen. Every AR analyzed accounted for 30 goat herds, with a total of 90 herds. The results demonstrated that altitude had an influence mainly on density and protein. Milk density increases as altitude increases; conversely, milk protein increases as altitude decreases. On the other hand, in the mountain and lowland ARs, the salts and solids not fat (SNF) percentages were higher compared to that of the highland AR (p < 0.05). The freezing point (FP) was higher at highland altitudes compared to that of mountain and lowland ARs (p < 0.01). In the milk fatty acids (FA) profile, only the C14:1 value was affected by altitude, whereas goat milk at lowland and mountain altitudes had higher values compared to that at highland altitudes (p < 0.05). Additionally, late lactation stage fat, FP, and pH values were higher compared to early lactation values. The opposite effect was observed for salts and SNF. In the FA profile, late lactation values were higher for C10:0 and C8:0 compared to early lactation values. The opposite trend was observed for C18:2n6t. The thrombogenic index was significantly higher at lowland altitudes compared to highland altitudes, and similar to the mountain AR. These goat milk characteristics could be explained as a consequence of animal nutrition, as well as the goat's meat-type phenotype.

Non-native plants spreading fast into higher mountain altitudes, study finds

Non-native plants spreading fast into higher mountain altitudes, study finds

Studies of Anomalous Phenomena in the Development of Electron-Nuclear Cascades in the EAS Cores Registered by a Modernized Complex Installation at Mountain Altitudes

Phenomena have been observed in mountain high-energy cosmic-ray experiments, namely, a delayed absorption of high-energy cascades initiated by cosmic-ray hadrons in a lead absorber at E0≳ 1014 eV (so-called long-flying component), a coplanarity of most energetic particles in the central region of γ-ray−hadron superfamilies, and the so-called Tien Shan effect in EAS cores at E0≳ 1016 eV s&gt;5 TeV. These effects are not described by theoretical models. The coplanarity is explained by the process of coplanar generation of most energetic secondary particles in interactions of superhigh-energy hadrons with the nuclei of air atoms. The other two phenomena are possibly explained with a high cross section for fragmentation-region charmed-hadron generation. To investigate these phenomena, a cosmic-ray detector array, including a very thick ionization calorimeter, is being upgraded to study EAS cores.

Mapping reveals contrasting change patterns of rain-on-snow events in China during 2001–2018

Rain-on-snow (ROS) events can accelerate snow melting, which in turn leads to disasters such as floods, avalanches, and landslides. However, little is known about the characteristics of and changes in ROS events in China. In this study, the temporal and spatial variations of ROS days in China from 2001 to 2018 were investigated using the improved Moderate Resolution Imaging Spectroradiometer snow cover data, and China Meteorological Forcing Dataset. The results suggested that ROS days in China mainly occurred from November to June and were mainly distributed in northern Xinjiang (6.1 days/year), Qinghai-Tibet Plateau (2.8 days/year), northeast China (3.5 days/year), and east China (1.1 days/year). ROS days in each region have different seasonal distribution patterns. In the past 18 years, ROS days have shown a trend of increasing at higher latitudes and decreasing at lower latitudes in China, especially in northern Xinjiang and the Qinghai-Tibet Plateau. ROS days are decreasing below 3000 m in northern Xinjiang (-0.16 days/year) and below 4000 m in the Qinghai-Tibet Plateau (-0.21 days/year), which is explained by the decrease of snow days and rain days. ROS days are increasing at 3000–4000 m altitudes (0.15 days/year) in the Tianshan Mountains and 4000–5500 m altitudes (0.06 days/year) in the eastern Tibetan Mountains, mainly explained by more snowfall converted to rainfall. The ROS days along the Greater Khingan Mountains in Northeast China showed a decreasing trend (-0.12 days/year), and along the Changbai Mountains showed an increasing trend (0.07 days/year). The variation of snow cover days is the dominant factor. East China as a whole shows a decreasing trend (-0.1 days/year), explained by a decrease in snow cover time. In China, ROS days at low altitudes are negatively correlated with annual average temperature, and positively at high altitudes. The changes of ROS were also correlated with Arctic Oscillation and North Atlantic Oscillation. This study reveals the response of ROS to climate change in China, and provides an important reference for coping with the related disasters and changes caused by ROS events.

Regional peculiarities of specific immunity in inhabitants of different mountain heights of the Kyrgyz Republic

Kyrgyzstan’s challenging natural conditions and fragile mountain ecosystems can weaken the immune system of individuals residing permanently in high-altitude areas. Our study aimed to explore specific immune protection indicators in healthy populations from the Chui and Naryn regions at varying mountain altitudes. We assessed percentages of CD3+ (T-lymphocytes), CD20+ (B-lymphocytes), CD4+ (T-helper lymphocytes), CD8+ (cytotoxic T-lymphocytes), IRI (immunoregulatory index), CIC (circulating immune complexes), and quantified immunoglobulins of classes A, M, and G. Using immunofluorescent methods and monoclonal antibodies; we determined the percentages of CD3+, CD20+, CD4+, and CD8+. Radial immunodiffusion was used to quantify immunoglobulins of classes A, M, and G, while Falk’s method helped study CIC levels in blood sera. The participant count was based on statistical expert recommendations and G power analysis. The analysis revealed a decrease in the total number of T-lymphocytes (CD3+), primarily due to reduced T-helper and cytotoxic T-lymphocyte subpopulations. However, a significant increase in cytotoxic T-lymphocytes (CD8+) was observed among high-altitude residents. Mountain residents exhibited wide-ranging individual fluctuations for each immunoglobulin class. Our findings suggest varying degrees of immune mechanism disruptions, which maintain natural protection and internal environment constancy at different altitudes, resulting in a mixed type of cellular and humoral immunity suppression. These results emphasize the need for further research in the region and consideration of altitude when implementing disease prevention strategies related to the immune system for the local population.

Mountain Graticules: Bridging Latitude, Longitude, Altitude, and Historicity to Biocultural Heritage

The interdependence of biological and cultural diversity is exemplified by the new conservation paradigm of biocultural heritage. We seek to clarify obsolescent notions of nature, whereby cultural construction and identity markers of mountain communities need to reflect localized, situated, and nuanced understanding about mountainscapes as they are developed, maintained, managed, and contested in spatiality and historicity. Using the nexus of socioecological theory, we question whether a convergent approach could bridge montological knowledge systems of either different equatorial and temperate latitudes, western and eastern longitudes, hills and snow-capped mountain altitudes, or hegemonic and indigenous historicity. Using extensive literature research, intensive reflection, field observation, and critical discourse analysis, we grapple with the Nagoya Protocol of the Convention of Biological Diversity (COP 10, 2010) to elucidate the benefit sharing and linkages of biocultural diversity in tropical and temperate mountain frameworks. The result is a trend of consilience for effective conservation of mountain socioecological systems that reaffirms the transdisciplinary transgression of local knowledge and scientific input to implement the effective strategy of biocultural heritage conservation after the UN Decade of Biological Diversity. By emphasizing regeneration of derelict mountain landscapes, invigorated by empowered local communities, promoted by the Aspen Declaration, the UN Decade of Ecological Restoration, and the UN International Year of Mountain Sustainable Development, montological work on sustainable, regenerative development for 2030 can be expected.

Vertical Structures Associated with Orographic Precipitation during Warm Season in the Sichuan Basin and Its Surrounding Areas at Different Altitudes from 8-Year GPM DPR Observations

Global precipitation measurement (GPM) is one of the effective means employed to observe orographic precipitation, and its inversed GPM DPR data can be used to study the microphysical structure of precipitation particles. This study considers statistics on convective precipitation (CP) and stratiform precipitation (SP) events over three types of terrain (plains, mountains, and high mountains) using the DPR onboard the GPM Core Observatory from May to September of 2014–2021 to analyze the vertical structure of heavy CP and SP. In mountain areas and high mountain areas, the updraft rendered by topography or seeder-feeder mechanism is not only conducive to the collision and merger of raindrops into large raindrops, but also increases the concentration of small drops, which is the main reason why the occurrence probability of not only large but also small raindrops increases and the horizontal distribution domain of mass weighted average raindrop diameter (Dm) widens. For heavy SP, the occurrence probability of medium-diameter precipitation particles below the freezing height (FzH) over high mountains is greater than those over plains. The precipitation particles above 10 km altitude of high mountains have characteristics, such as lower droplet number concentration and larger diameter, compared with those over plains. Furthermore, the study also analyzed the correlation between storm top altitude (STA) and Dm, water vapor and STA respectively. This study is helpful to further understand the effect of topography on heavy precipitation through cloud microphysical processes and the vertical structure of precipitation.

Development of the relativistic runaway avalanches in the lower atmosphere above mountain altitudes

The comparative analysis of three thunderstorms on Aragats in May 2021 demonstrates that relativistic runaway electron avalanches (RREAs) can reach very low altitudes above the Earth’s surface on mountain altitudes. RREAs which reach the Earth’s surface are registered by the particle detectors as thunderstorm ground enhancements (TGEs) —large enhancements of electron and gamma ray fluxes, sometimes exceeding the fair-weather background fluxes up to a hundred times. By comparing the energy spectra of electrons and gamma rays it is possible to estimate the height above the ground where an RREA terminates and avalanche particles exit the accelerating field. For the several TGEs registered on Aragats, this estimate varied between 50 and 150 meters. The threshold electric field can reach on heights of . When a lightning’s active zone is above particle detectors RREAs last tens of seconds to a few minutes, until lightning flashes terminate electron acceleration. If the lightning activity is far from the detector site, TGEs are extended for a few tens of minutes and smoothly decay and TGE has a more or less symmetrical shape.

Sensitivity analysis of attenuation in convective rainfall at X-band frequency using the mountain reference technique

Abstract. The RadAlp experiment aims at improving quantitative precipitation estimation (QPE) in the Alps thanks to X-band polarimetric radars and in situ measurements deployed in the region of Grenoble, France. In this article, we revisit the physics of propagation and attenuation of microwaves in rain. We first derive four attenuation–reflectivity (AZ) algorithms constrained, or not, by path-integrated attenuations (PIAs) estimated from the decrease in the return of selected mountain targets when it rains compared to their dry weather levels (the so-called mountain reference technique – MRT). We also consider one simple polarimetric algorithm based on the profile of the total differential phase shift between the radar and the mountain targets. The central idea of the work is to implement these five algorithms all together in the framework of a generalized sensitivity analysis in order to establish useful parameterizations for attenuation correction. The parameter structure and the inherent mathematical ambiguity of the system of equations makes it necessary to organize the optimization procedure in a nested way. The core of the procedure consists of (i) exploring with classical sampling techniques the space of the parameters allowed to be variable from one target to the other and from one time step to the next, (ii) computing a cost function (CF) quantifying the proximity of the simulated profiles and (iii) selecting parameters sets for which a given CF threshold is exceeded. This core is activated for a series of values of parameters supposed to be fixed, e.g., the radar calibration error for a given event. The sensitivity analysis is performed for a set of three convective events using the 0∘ elevation plan position indicator (PPI) measurements of the Météo-France weather radar located on top of the Moucherotte mountain (altitude of 1901 m a.s.l. – above sea level). It allows the estimation of critical parameters for radar QPE using radar data alone. In addition to the radar calibration error, this includes the time series of radome attenuation and estimations of the coefficients of the power law models relating the specific attenuation and the reflectivity (A–Z relationship) on the one hand and the specific attenuation and the specific differential phase shift (A–Kdp relationship) on the other hand. It is noteworthy that the A–Z and A–Kdp relationships obtained are consistent with those derived from concomitant drop size distribution measurements at ground level, in particular with a slightly non-linear A–Kdp relationship (A=0.28 Kdp1.1). X-Band radome attenuations as high as 15 dB were estimated, leading to the recommendation of avoiding the use of radomes for remote sensing of precipitation at such a frequency.

Taxonomy and molecular phylogeny of Trametopsis (Polyporales, Basidiomycota) with descriptions of two new species.

Trametopsis is a worldwide genus belonging to Irpicaceae in the phlebioid clade, which can cause a white decay of wood. Previously, only three species were ascribed to the genus. In this study, we performed a morphological and phylogenetic study of Trametopsis. Molecular phylogenetic analyses of multiple loci included the internal transcribed spacer (ITS) regions, the large subunit nuclear ribosomal RNA gene (nLSU), the largest subunit of RNA polymerase II (RPB1), the second largest subunit of RNA polymerase II (RPB2) and the translation elongation factor 1-α gene (TEF1). Phylogenetic trees were inferred from the combined datasets of ITS+nLSU sequences and ITS+nLSU+RPB1+RPB2+TEF1 sequences by using maximum parsimony, maximum likelihood and Bayesian inference analyses. Combined with molecular data, morphological characters and ecological traits, two new species of Trametopsis are discovered. Trametopsisabieticola is characterised by its pileate, solitary or imbricate basidiomata, buff to buff-yellow pileal surface when fresh, becoming pinkish buff to clay-buff when dry, cream to buff pore surface when fresh, becoming pinkish buff to greyish brown upon drying, round to angular and large pores (0.5-1 per mm), cylindrical basidiospores (5.8-7.2 × 1.9-2.6 μm), distributed in the high altitude of mountains and grows on Abies sp. Trametopsistasmanica is characterised by its resupinate basidiomata, cream to pinkish-buff pore surface when fresh, becoming honey-yellow to snuff brown upon drying, cylindrical basidiospores (5.2-6.3 × 1.8-2.2 μm), and by growing on Eucalyptus sp. Detailed descriptions and illustrations of the two novel species are provided.

Determination of altitudes of the three main Ecuadorian summits through GNSS positioning

Determining the altitude of mountains is one of the most fundamental challenges for humankind. Therefore, the main objective of the study is to determine the altitudes of the three main summits in Ecuador through GNSS positioning, referring to the official vertical datum of Ecuador and the geopotential surface (Wo). The three peaks are active volcanoes named Chimborazo, Cotopaxi and Cayambe, all of which are known to be over 5700 m above sea level. Positioning GNSS was performed on the summit of the volcanoes, and the GPS leveling method was applied on nearby plates. At these summits, the correction of the potential difference between the mean sea level and Wo was used. The altitudes referred to the mean sea level were compared with other registered heights, and the results are more accurate than previous geodetic missions.

Antioxidant Activity and Chemical Characteristics of Sambucus nigra L. Blossom from Different Regions in Bulgaria

The aim of the current study was to investigate some bioactive compounds from Sambucus nigra L. blossoms and to evaluate the antioxidant potential of the obtained extracts. In this study, samples from four different regions of Bulgaria /Rhodopes, Plovdiv, Strandzha and Dobrich region/ from Sambucus nigra L. were collected and analyzed for total phenols, flavonoids, sugars and amino acids. The antioxidant activity of the extracts was evaluated by four assays based on different mechanisms. The sweetness index and total sweetness index of the extracts were also evaluated. The carbohydrate composition of the leaves and the blossoms was determined, with glucose and fructose predominating in both cases, as their contents were not above 3%. Nineteen amino acids have been identified in the composition of Sambucus nigra L., and glutamic, leucine and asparagine acids are predominant. The highest antioxidant activity and total content of phenols (49.2 ± 1 mg GAE/g) and flavonols (18.6 ± 0.5 mgQE/g) were found in the sample from the Rhodope region. Therefore, the higher altitude and lower temperature in mountains could influence the accumulation of secondary metabolites in blossoms of Sambucus nigra L., which improves the antioxidant potential of the samples.

Interspecific Association and Community Stability of Tree Species in Natural Secondary Forests at Different Altitude Gradients in the Southern Taihang Mountains

An interspecific association represents an inter-relatedness of different species in spatial distribution and combined with the altitude factor, is key for revealing the formation and evolution of an ecological community. Therefore, we analyzed the changes in interspecific association and community stability at different altitudes in the southern Taihang Mountains using the variance ratio (VR), χ2 test, association coefficient (AC), percentage of co-occurrence (PC) and Godron stability method. In total, 27 sample plots measuring 20 × 20 m were set up and were divided into lower altitude (700~1100 m), medium altitude (1100~1500 m) and higher altitude areas (1500~1900 m) into. The results showed that the overall interspecies association of communities exhibited an insignificant negative association in both the lower (VR = 0.79, W = 7.15) and higher (VR = 0.81, W = 7.36) altitude areas, while an insignificant positive association was observed in the medium (VR = 1.48, W = 13.34) altitude area. Besides, the χ2 test showed the ratio of positively and negatively correlated species pairs decreased as altitude increased with values of 1.39, 1.22 and 0.95 in the lower, medium and higher altitude areas, respectively. Moreover, the AC and PC indices stated that most species pairs had a weaker association in the three altitude areas, but the AC indices also suggested the number of positive association species pairs was more than that of negative association only in medium altitude area. Meanwhile, the Godron stability method showed the distances from the intersection point to the stable point (20 and 80) were still far away, with values of 22.53, 11.92 and 21.34 in the lower, medium and higher altitude areas, respectively, which indicated an unstable succession stage, though the community appeared steadier in the medium altitude area. This study can provide some guidance for effective afforestation and vegetation restoration.

Topographic controls in the distributions of tree species on the Karadağ Massif, NE Turkey

In this study, it was aimed to reveal the relationships between the distribution of tree species in the mountainous land on the Karadağ massif located in the transition zone of the Canik-Giresun mountains and the Trabzon mountains sites, and topographic variables. Results of independent t-test and PCA (Principal Component Analysis) indicated that Carpinus orientalis and Quercus petraea showed high ecological tolerance to humid-drought sites, whereas it limited the distribution of Castanea sativa in more humid areas. Although Alnus glutinosa, Fagus orientalis and Picea orientalis show similar ecological characteristics, it is likely that these species will be affected by the rainfall on the Canik-Giresun mountains along with the increasing fog in the upper altitudes of the Trabzon mountains. With increasing urbanization in sub-altitudes close to the coast, negative interventions may limit forests to steep slopes that are unsuitable for agriculture and settlement. Therefore, the drought-resistant Pinus sylvestris that can go down to the coast, the drought-resistant naturalized Robinia pseudoacacia, and Pinus pinea that is characteristic tree of the Mediterranean climate, which are distributed in the sub-altitudes of the Trabzon mountains site, are remarkable in terms of the impact of environmental variables. Given the current social-ecological dynamics, particularly in mountainous areas, which are highly fragile landscapes; understanding these relationships can help to guide appropriate future management strategy in the area and around. Key words: Eastern Black Sea region, environmental variables, sites, independent t-test, PCA&#x0D;