South Slope Research Articles

Ecotypic differentiation of leaf silicon concentration in the grass Brachypodium hybridum along a rainfall gradient.

Ecotypic differentiation, reflected in substantial trait differences across populations, has been observed in various plant species distributed across aridity gradients. Nevertheless, ecotypic differentiation in leaf silicon concentration, known to alleviate drought stress in plants, remained hardly explored. Here, we provide a systematic test for ecotypic differentiation in leaf silicon concentration along two aridity gradients in the grass Brachypodium hybridum in Israel. Seed material was sampled in 15 sites along a macroclimatic aridity gradient (89 - 926mm mean annual rainfall) and from corresponding north (moister) and south (more arid) exposed slopes (microclimatic gradient) at similar altitudes (mean north: 381m a.s.l., mean south: 385m a.s.l.). Plants were subsequently grown under common conditions and their leaf silicon concentration was analysed. Leaf silicon concentration increased with increasing aridity across the macroclimatic gradient, but did not differ between north and south slopes. The higher leaf silicon concentrations under more arid conditions can enhance the ability of plants to cope with more arid conditions by two mutually not exclusive mechanisms: (i) withstanding drought by reducing water loss and increasing water uptake or (ii) escaping drought by facilitating fast growth. Our study highlights that leaf silicon concentration contributes to ecotypic differentiation in annual grasses along macroclimatic aridity gradients.

Variation of CO2 concentration and its provenance in alpine on the south slope of Tomur Peak, Tianshan Mountains.

This study analyzes the characteristics of near-surface atmospheric CO2 concentrations on the southern slope of Tomur Peak from 2013 to 2022. Utilizing the Boughton two-parameter algorithm, we determined the CO2 background and non-background concentrations. Additionally, the Hysplit model was employed to investigate the potential contributing areas of the CO2 non-background concentration. Our findings that the CO2 concentration in the study area was approximately 17% lower than the global average, with an annual growth rate that was only about 47% of the global rate. The CO2 non-background concentration accounted for only 6.25% of the observed concentration, but was largely unaffected by near-ground meteorological factors. The source of the CO2 non-background was mainly controlled by the westerly belt, with potential source area mainly located in Central Asia. However, the WPSCF values in the modern ice and snow distribution area south of Tomur Peak and west of the monitoring station were significantly elevated, suggesting a strong wind transport of CO2 after accumulation under the influence of the elevated terrain. The local supplying path accounted for only 12.87%, indicating that human activities in the oasis areas of the Tarim Basin had a limited influence on the study area. Due to the blocking effect of the Baikal high-pressure system and the towering topography of the Tianshan Mountains, the influence of human emissions from higher latitudes was likely negligible.

Helechos y licofitas del Área Natural Protegida “Paisaje Protegido Cerro Mbororé” (Misiones, Argentina).

Background and aims: In this work, the ferns and lycophytes of the Paisaje Protegido Cerro Mbororé, Oberá, Misiones, Argentina are studied. The phytogeographic importance of the area is discussed, since it is located in the transition between the District of the Mixed Forests and the District of the Fields, in the Amazonian Domain from the country. M&M: The collected materials were deposited in the LP, BA, and SLP herbaria. For the identification of species, the Flora Argentina and local floras were used. The photographs taken in the field were uploaded to the iNarulatist platform. The herbarium specimens studied are mentioned in this section. Results: The study area has 32 species of ferns (nine families) and one species of lycophytes. The most diverse family is Pteridaceae, with six genera and 13 species, followed by Polypodiaceae, with three genera and four species. Four well-defined environments with particular associations of species are identified: the top of the hill, the high-altitude lagoon, the north slope and the south slope. Conclusions: The environmental heterogeneity, product of the steep relief, and the transitional position of the area, generate a complex community of ferns and lycophytes with an important environmental value, which must be protected from the danger of the advance of the agricultural frontier and forestry exploitation.

Hydrographic climatology of the South Brazil Bight continental shelf and slope

Hydrographic climatology of the South Brazil Bight continental shelf and slope

Mineralogy of Quaternary Sediments from the Valley of Vema Fracture Zone (Central Atlantic)

The content of sediment forming minerals in two cores from the eastern (ANS45-37) and western (ANS45-48) parts of the Vema transform fault valley is studied using the semi-quantitative XRD analysis of bulk powder sediment samples. The mineral composition of deep-sea sediments from the Amazone cone is also analyzed for comparison. It appeared that the average composition of the terrigenous component of both cores (according to prevailing quartz, secondary mica, plagioclase and potassium feldspar, as well as smectite, chlorite, kaolinite, illite) is quite similar and approximately corresponds to the composition of sediments from the Amazon cone. The ratio of four clay minerals suggests the supply of terrigenous material to the Amazon and Orinoco due to the erosion of the Andes and humid tropical weathering in the lower course of the rivers with further transportation of the suspended load to the ocean. This material was transported to the Vema transform valley due to the interplay between the gravity flows from the South American continental slope and the current of the Antarctic Bottom Water. Data on biogenic calcite (planktic foraminiferal tests, nannofossils) and opal A (radiolarians, sponge spicules) are obtained in addition. In the study area, several authigenic (diagenetic) minerals are identified. In particular, siderite and greigite are first found in the sediments from the Vema valley and Amazon cone, respectively.

Response of forest belt on the south slope of Tianshan Mountains in China to global warming during 1990–2020

Response of forest belt on the south slope of Tianshan Mountains in China to global warming during 1990–2020

Investigating soil properties on the north and south slopes at different elevations in Al-Jabal Al-Akhdar, Libya

This scholarly study investigated the physicochemical characteristics of soil in the Al-Jabal Al-Akhdar forest, Libya, with a specific focus on the influence of elevation and slope aspects. Fifty-six sample plots were established across varying elevations, each subdivided into four subplots, totaling 224. Soil samples were collected from each subplot at 0-15 cm depth. Results demonstrate significant variations in clay, silt, and sand content with elevation, indicating lower clay and higher sand content at higher elevations. Available water capacity (AWC) increased with altitude on the northern slope, while consistently lower values were observed on the southern slope. Bulk density (BD) decreased with increasing altitude, suggesting less compacted soils at higher elevations. Available phosphorus (Pav), available potassium (Kav), and pH values decreased with increasing altitude on both slopes. Cation exchange capacity (CEC) values varied at altitudes on the northern slope, with higher values observed at mid to high altitudes. Calcium carbonate (CaCO3) decreased with increasing altitude on the northern slope while showing inconsistent trends on the southern slope. Soil organic matter (SOM) content increased with altitude on both slopes. Pearson's correlation and Principal Component Analysis (PCA) examined relationships among soil properties, elevations, and aspects. Elevation positively correlated with AWC and SOM and negatively correlated with clay content, Kav, BD, and pH. PCA identified elevation, aspect, silt content, CaCO3, and electrical conductivity (EC) as primary influencers. SOM exhibited positive correlations with AWC and negative correlations with BD. Soil pH showed a negative correlation with SOM and a positive correlation with CaCO3. Additionally, CaCO3 content was positively correlated with the cation exchange capacity (CEC). These findings contribute to understanding soil property relationships, elevation, and aspect, emphasizing their role in shaping soil ecosystems and nutrient dynamics. Further research is warranted to explore additional factors influencing soil properties and to develop effective nutrient management strategies.

Diversity of the tropical easterly jet’s core location

The upper-tropospheric tropical easterly jet (TEJ) is one of the most important systems in modulating the Asian summer monsoon rainfall. In addition to the intensity variability that has been extensively studied, the TEJ’s core experiences remarkable changes in the zonal and meridional directions. The TEJ can be identified as three locational patterns using the cluster analysis: the east, northwest, and southwest modes. The frequencies of the three locational modes exhibit discernable changes on the monthly and the interannual-decadal time scales. While the anomalous zonal divergent circulation with the convergent/divergent center over the tropical Indian Ocean (IO) determines the zonal location of the TEJ’s core, the meridional temperature gradient between the Eurasian continent and the tropical IO distinguishes the meridional location of the TEJ’s core. It reflects the fundamental role of the large-scale east-west and north-south thermal contrasts in the movement of the TEJ’s core location. The variability of the TEJ’s core location has distinct impacts on the summer monsoon precipitation via redistributing the upper-level divergence and modulating the monsoon meridional circulation, especially in South, Southeast, and East Asia. In conjunction with the thermal effect of the Tibetan Plateau, the meridional shift of the TEJ’s core can affect the precipitation along the south slope of the Tibetan Plateau. These findings highlight the cause of the diversified TEJ’s core location and the significant impacts on the summer monsoon rainfall.

Variation in the surface heat flux on the north and south slopes of Mount Qomolangma

The distinctive conditions present on the north and south slopes of Mount Qomolangma, along with the intricate variations in the underlying surfaces, result in notable variations in the surface energy flux patterns of the two slopes. In this paper, data from TESEBS (Topographical Enhanced Surface Energy Balance System), remote sensing data from eight cloud-free scenarios, and observational data from nine stations are utilized to examine the fluctuations in the surface heat flux on both slopes. The inclusion of MCD43A3 satellite data enhances the surface albedo, contributing to more accurate simulation outcomes. The model results are validated using observational data. The RMSEs of the net radiation, ground heat, sensible heat, and latent heat flux are 40.73, 17.09, 33.26, and 30.91 W m−2, respectively. The net radiation flux is greater on the south slope and exhibits a rapid decline from summer to autumn. Due to the influence of the monsoon, on the north slope, the maximum sensible heat flux occurs in the pre-monsoon period in summer and the maximum latent heat flux occurs during the monsoon. The south slope experiences the highest latent heat flux in summer. The dominant flux on the north slope is sensible heat, while it is latent heat on the south slope. The seasonal variations in the ground heat flux are more pronounced on the south slope than on the north slope. Except in summer, the ground heat flux on the north slope surpasses that on the south slope.摘要珠穆朗玛峰南北坡独特的地形条件和复杂的下垫面, 导致了南北坡地表通量分布的显著差异. 本文利用地形增强地表能量平衡模式 (Topographical Enhanced Surface Energy Balance System (TESEBS)), 遥感数据和站点观测数据, 对季风和非季风期南北坡的地表热通量变化进行了研究. 首先, 把MCD43A3卫星数据加入TESEBS, 改进了地表反照率, 使模拟结果更准确. 受季风影响, 北坡季风期感热通量最大值出现在季风前期, 潜热通量最大值出现在季风期. 南坡季风期潜热通量最大. 全年北坡以感热交换为主, 南坡以潜热交换为主. 土壤热通量的季节变化在南坡比北坡更明显.

The influence of moisture transport processes on the stable isotopic compositions in precipitation on the South slope of the Himalayas

Understanding spatiotemporal variations in stable isotopes in precipitation (ẟ18O and ẟD) on the south slope of the Himalayas is crucial for comprehending moisture variations reaching the Tibetan Plateau (TP). Here, we analyze these variations at seven stations in Nepal spanning altitudes from 102 m to 5050 m above sea level in 2017. Our findings show no significant temperature or precipitation amount effect on isotopes, with synoptic precipitation exerting a strong influence. Non-monsoon precipitation primarily originates from the vicinity of the Koshi River basin and the Ganges River, while during the monsoon, the Bay of Bengal, the Koshi River basin, and the Ganges River contribute, with minimal input from the Arabian Sea. Convective activities significantly regulate inner-seasonal precipitation δ18O, with strong convection associated with low isotopic values. Increasing altitude leads to substantial differences in δ18O values, indicating modulation by higher condensation levels and lower temperatures. These findings underscore the impact of regional moisture transport on precipitation isotopic variability and offer insights into interpreting paleo-isotope records in the Indian Summer Monsoon region.

Variations in Maximum and Minimum Temperature in Mount Qomolangma during 1971–2020

Based on the daily maximum and minimum temperature observational data during 1971–2020, the variabilities of the maximum and minimum temperature of Mount Qomolangma are analyzed. The daily maximum temperature is 25.8 °C and the daily minimum temperature is −31.4 °C during the study period in Mount Qomolangma. Overall, there has been an upward trend with decadal laps for both maximum and minimum temperature. On monthly, seasonal, and annual scales, neither maximum temperature nor minimum temperature time series exhibit an increasing trend from 1971 to 2020. The increasing trends in monthly minimum temperature are even more pronounced than those in maximum temperature. Abrupt changes are noted in both monthly, seasonal, and annual maximum and minimum temperature time series. Specifically, an abrupt change in annual maximum temperature occurred in the 1980s, while an abrupt change in annual minimum temperature occurred in the 1990s. Differences between the north and south slope of Mount Qomolangma are evident, with temperature fluctuations of the north slope being more extreme than those of south slope. The seasonal and annual maximum temperature of the north slope is higher than that of the south slope, except for winter, and the seasonal and annual minimum temperatures of the north slope are all lower than those of the south slope. The tendences of maximum and minimum temperatures in the north slope are more dominant than those in the south slope. The findings are beneficial for understanding the characteristics of local climate change on the Tibetan plateau and to underscore the significant role of Mount Qomolangma in the context of global warming.

Changes in glacier surface temperature across the Third Pole from 2000 to 2021

Glacier surface temperature is not only an important indicator of climate change, but is also directly related to glacier physical processes and mass balance. Glaciers over the Third Pole have shown heterogeneous but accelerated mass loss over the past two decades. However, few studies have focused on changes of glacier surface temperature in this region. In this study, we investigate this change from 2000 to 2021 using an altitudinal area-weighting method based on Landsat surface temperature products. The results show that this method can robustly derive inter-annual variability and long-term trends of subregional glacier surface temperature. Over the entire Third Pole, glacier surfaces exhibited warming at the rate of +0.17 ± 0.35 °C dec−1 (p = 0.32). The warming had a distinct seasonal pattern: warming in autumn (+0.50 ± 0.53 °C dec−1, p = 0.06) but cooling in spring (−0.22 ± 0.36 °C dec−1, p = 0.23). Correspondingly, the ablation season 0 °C isotherm altitude has risen >100 m and the glacier area with GST ≥0 °C has expanded by 10%. Moreover, the GST changes displayed large spatial heterogeneity. In the westerlies-dominated regions (e.g., Karakoram and Kun Lun), glacier surfaces showed slight warming or even cooling on average (from −0.10 to +0.06 °C dec−1), while in the monsoon-dominated regions (e.g., East Himalaya, Southeast Tibetan Plateau and Hengduan Mountains), strong warming was observed (> +0.50 °C dec−1, p < 0.05). Glacier surfaces generally showed a faster warming at north slopes than south slopes, especially in the ablation season. These results emphasize that different magnitudes of glacier surface warming are important indicators for the contrasting glacier changes over the Third Pole. The method presented here opens the way to investigate long-term surface temperature change of global mountain glaciers, which can help us further understand the mechanisms of glacier response to global climate change.

Potential Regeneration and Spatial Distribution model of Saurauia pendula Blume in Mount Slamet, Central Java

Saurauia pendula Blume is a species of genus Saurauia and belong to Actinidiaceae family. Saurauia pendula spread over on several highlands or mountains in Java Island. Mount Slamet is the second highest mountain on Java with naturally good vegetations. The existence of several threats such as forest fires, destruction, deforestation and forest degradation has caused the condition of these plant species to begin to require attention. This study aims to determine the population of S. pendula, its potential regeneration and spatial distribution model in Mount Slamet area. The study was conducted on four (north, south, west and east) slopes in 2019-2020. Research on population conditions was carried out by following hiking trails and making new paths around the center of suitable habitat. Coordinate data is taken to make spatial analysis using Maximum Entropy (MaxEnt). The results showed that the number of S. pendula was found on the north, west and south slopes at an altitude of 1010-2024 masl. This species has a significant association with Saurauia microphylla de Vriese., Glochidion obscurum (Roxb. ex Willd.) Blume and Castanopsis argentea. The number of mature plants is 106 individuals, which have important role in the distribution of this plant. Analysis of the spatial distribution model shows that S. pendula is estimated to be widely distributed on the western slopes of Mount Slamet.

Digital mapping of soil organic carbon in volcanic soils after prolonged eruption Mt. Sinabung, Karo Regency, North Sumatra, Indonesia

Mount Sinabung (at Karo Regency, North Sumatra) has been considered as an active volcano since 2010, and after three years of inactivity, the volcano’s activity resumed in 2013. The deposition of volcanic ash buried everything on the soil surface with various thicknesses. Volcanic ash is a valuable inorganic material and consists mostly of primary minerals. But with time, these materials can initiate carbon storage through the revegetation process. This study investigates carbon storage and sequestration in volcanic soils affected by the intermittent eruptions of Mt. Sinabung. A total of 34 soil samples were collected from areas of 3 to 7 km from the eruptive vent. The samples were analyzed to determine labile-C, very labile-C, total-C, Organic-C, non-crystalline-C, and metal complex-C fractions. Regression kriging (RK) was applied to spatially predict the carbon distribution. The results showed that the highest labile-C was 1.65% found in the Southeast slope and the lowest, 1.20%, in the Southern slope. The highest value of very labile-C was in the Southeast (1.20%), and the lowest was in the Northern (0.46%). The highest (11.66%) and lowest values (8.84%) of total C were in the Northeast and South slopes, respectively. The highest Organic-C value was detected 7.42% in the Northeast volcanic soils, and the lowest, 5.74%, is in the South slopes soil. The lowest non-crystalline- C was found in the soils of Northeast slope (0.60%), and the highest was in the Southeast (0.82%) soil. While the highest metal complex-C value was 0.88% in the Southeast, and the lowest is 0.36% in the soil of South slope. These data show that the highest carbon storage is parallel with the direction of the ash distribution, which tends to the Southeast side of Mt. Sinabung. The results of this study demonstrated that volcanic regions have a strong resilience capacity to bounce back after devastating natural hazards. Volcanic deposits interact with atmospheric water to initiate vegetation regrowth and create a carbon pool within their particles.

Detection of pyroclastic material and deformation of the lava dome in Mt. Sinabung with multi-temporal analysis (2010-2020)

The persistent eruptions of Mt. Sinabung resulted in the lava dome’s deformation and blanketed the surrounding area with pyroclastic material. This research focused on determining the changes in Mt. Sinabung during the prolonged eruptions from 2010-2020. A total of 22 volcanic ash samples were collected following a 1x1 km grid interval spread over from the East to South slope of Mt. Sinabung. The studied area is the most affected by the volcanic eruption. Digital elevation models from the shuttle radar topographic mission and sentinel-1 were utilized to monitor deformations of the lava dome and the distribution of pyroclastic material on Mt. Sinabung. Sentinel Application Platform and Google Earth Engine were used as the main tools in multi-temporal digital elevation model (DEM) data processing. The eruption of Mt. Sinabung from 2010 to 2020 changed the height from 2,460 m to 2,404.3 m and created a new crater (5.35 ha). The lava dome volume from 2010 to 2020 is about 2,308,041 m3 and has collapsed to produce pyroclastic material which deposits to the surrounding area of Mt. Sinabung during the eruption. The distribution of pyroclastic material increased from 2010 to 2019, covered up an area of 103.27 ha (2010), 846.48 ha (2013), 1,029.74 ha (2016), 1,235.97 ha (2017) and 1,463.62 ha (2019). The thickness of the pyroclastic material deposits at Mt. Sinabung until 2020 varied from 13,24 cm to 219 cm. The findings from this study can be used as a reference for observing topographic changes due to volcanic activities and drawing a mitigation and contingency plan for a volcanic disaster program in the active volcanic region of Indonesia.

Acoustic diversity, bearing estimation, and localization of sound sources in shallow water and deep ocean off the U.S. Northeast coast using a coherent hydrophone array

An in-house developed 160-element large-aperture hydrophone array from Northeastern University was utilized for ocean monitoring in both the shallow waters of the Great South Channel (GSC) and the deep-water area off the continental slope south of Rhode Island in September 2021. Utilizing passive ocean acoustic waveguide remote sensing (POAWRS) technology, the system enabled real-time, broad-area surveillance of the oceanic environment. A novel multistage clustering was introduced for annotating the vast volume of underwater acoustic data, drawing inspiration from the human cognitive process of categorizing sounds. Initially, sounds are separated into broad groups, akin to a first human listening pass. Subsequent stages of clustering refine these categories, utilizing different sets of features to achieve a granularity of annotation that closely mirrors expert human annotation processes. It was found that the acoustic landscape of the GSC was primarily composed of diverse marine mammal sounds, such as fin whale 20 Hz pulses, humpback whale songs, minky whale buzz sequences, sperm whale and dolphin echolocation clicks, and unidentified whale calls. Conversely, the deep-water area off the continental slope featured predominantly fish sounds, chorus-like sounds, and dolphin vocalizations. Detailed analyses of the most prevalent vocalizations are presented, including their bearing-time trajectories and localizations.

Cephalopod paralarvae from the southeast–south Brazilian outer shelf and slope

Cephalopod paralarvae from the southeast–south Brazilian outer shelf and slope

Physical Properties, Chemical Components, and Transport Mechanisms of Atmospheric Aerosols Over a Remote Area on the South Slope of the Tibetan Plateau

AbstractThe physicochemical properties and origins of atmospheric aerosols in the Tibetan Plateau (TP) region are a research topic of great interest, but an in‐depth understanding of this topic is challenging, partially due to a lack of intensive in situ observations. Thus, a field campaign was conducted over Yadong, a remote area on the south slope of the TP from June 11 to 31 August 2021. The aerosol loading was low, with a black carbon mass concentration of 147.4 ± 98.4 ng·m−3. Aerosol single‐scattering albedo was low (0.73 ± 0.11 at 550 nm) and increased from 450 to 700 nm wavelength. Organic matter (OM) accounting for 69.6% of the total aerosol mass and relatively high secondary organic carbon ratios, highlighting the importance of secondary formation. An interesting phenomenon observed was that the evolution of aerosols was mainly characterized by diurnal variation, which could not be explained by large‐scale atmospheric processes such as Indian summer monsoon. Instead, it was found that regional mountain‐valley winds between the Himalayas and South Asia transported polluted air masses toward the TP, especially in the afternoon when regional valley wind are expected to be the strongest and the boundary layer in South Asia is deepest. Additionally, daytime local valley wind further elevated these aerosols to higher altitudes on the TP. This paper provides insights into the transport mechanisms of aerosols from South Asia to the TP. These findings are of great importance since aerosols exhibit significant diurnal variations in the TP region.

Simulation of Precipitation on the South Slope of the Tibetan Plateau by the HighResMIP Model

Simulation of Precipitation on the South Slope of the Tibetan Plateau by the HighResMIP Model

Edge Effects in Tree Diversity and Carbon Stock in South Slope at Phulchoki Forest, Lalitpur Nepal

The floral community changes in elevation. Due to the more diverse ecological characteristics, the diverse flora, and the number of landscape elements, there is a change in diversity called the edge effect. This study examines the role of altitude (1400–1800 m, 1800–2400 m, and above 2400 m) and how floral diversity changes with altitude variation. The aim of this study is to examine the carbon stock at which altitudinal range it is higher and why. One tree species (oak) was found at highest altitude (2650 m) followed by intermediate altitude (2100 m) further with greatest number of tree species at low altitude (1600 m). Higher species diversity (Shanon Index: 2.1863) and density (5575 individuals per hectares) was found at altitudinal range I (1400 to 1800 m) composed by Rhododendrum arborium, Quercus glauca, Myrica esculenta, and Myrsine capitellat. Whereas Rhododendron arboretum, Castanopsis tribuloides, and Quercus incana dominate altitudinal range II (1800m to 2400m) with diversity (Shannon Index: 1.759) and an average density (2150 individuals per hectare). In Altitudinal Area III (2400 m and above), the forest is dominated by Quercus semicarpifolia. The highest carbon stock was found in the altitudinal range (1800m to 2400m) compared to altitudinal ranges I and III. Edge effects shaped the community composition and affected tree diversity and carbon stock. In conclusion, the floral community and carbon stock were affected by forest edges, which led to conservation actions and mitigation of climate change in surprisingly different ways.