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This study presents a novel method for high-altitude terrain following photogrammetric mapping using Unmanned Aerial Vehicles (UAVs) that adapt their height to the terrain's morphology. Traditional grid missions in UAV mapping surveys use nadir photographs to cover an area of interest which is taken from a fixed height from the datum.Many times this leads to difficulties in flight mission and processing when hilly/undulated terrain is under consideration. The proposed solution addresses this by adjusting the UAV's flying height based on real-time terrain information gathered by a range detection sensor. This paper tests the proposed method in a hilly area in the Himalayas, capturing high-resolution images and processing them using UAV-based photogrammetry software. The pre-acquired terrain information ensures safe separation from obstacles and enables trajectory generation at lower altitudes when planning initial flights. The experimental results validate the effectiveness of the proposed method and highlight its potential for generating high-resolution photogrammetric products applicable to various UAV mapping tasks and monitoring scenarios. Overall, this research contributes to advancing the field of UAV mapping by providing a practical and effective solution for UAV based surveys in hilly and undulated terrains. The findings of this study have significant implications for various applications, including land surveying, environmental monitoring, landslide mapping and other scenarios that require detailed and accurate data acquisition from UAVs. [ABSTRACT FROM AUTHOR]

Flowering exhibits a significant relationship with environmental stimuli and changes. Effect of photoperiodism and vernalization have been well studied in flowering phenology; however, the effect of soil temperature on flowering is less explored which is one of the major factors of vegetation growth in alpine ecosystem. This study thus focuses on the effects of soil and air temperature on flowering response of Rhododendron arboreum Sm., a Himalayan tree species, which is also an indicator of spring initiation in high altitude regions. To monitor the flowering pattern, we employed automated phenocam, which was set up at 3356 masl in Tungnath (Indian Alpine region of Uttarakhand) for time-lapse photography of timberline ecotone. Soil and air temperature were recorded continuously at the timberline ecotone. Three years (2017 to 2020) of datasets were used for the present study. The phenocam observations displayed an interesting event in the year 2019–2020 with complete absence of flowering in R. arboreum population at Tungnath timberline ecotone. From the soil temperature data, an increase in winter (Dec–Jan, during which floral buds form) soil temperature, by > 1 °C, and no accumulation of freezing degree-days were found for the year 2019–2020. Air temperature however did not display any relationship with the failure of flowering, ruling out aerial chilling or frost injury of floral buds. From the results, a possible relationship between soil temperature and flowering can be suggested pointing towards necessary root apex vernalization stimulus in shallow rooted Rhododendrons. However, the dependency of flowering in Rhododendrons on winter soil temperature further requires continuous monitoring and more observations to make concrete inferences. [ABSTRACT FROM AUTHOR]

Globally, the treelines at higher elevations in mountains are reported to be advancing up-slope in response to recent climate warming. However, little is known about the treeline advancement in the Himalaya due to paucity of baseline vegetation data with which to compare, thus making their assessment and monitoring challenging. To fill this knowledge gap, the present study documented floristic and functional diversity of two treeline ecotone sites in Kashmir Himalaya. At each site, we conducted field sampling by laying five 20-m2 plots, with one at the highest limit (T0 plot), two plots below and two above the treeline and two nested subplots of 5-m2 for shrubs and five 1-m2 for herbs in each plot. We recorded 97 plant species belonging to 33 families from the two sites. We observed a considerable difference in species composition and distribution along the treeline ecotone. Majority of the species reported were perennial herbs. We observed a significant association of growth forms with the particular plots along the treeline ecotone. At both the sites, we recorded highest species richness at the T0 plot which was correlated well with the functional traits, thus indicating convergence of floristic and functional diversity at this transition zone. Interestingly, the T0 plot at both the sites showed maximum overlap of species with the plots above and below the treeline. In an era of climate warming, our study provides crucial baseline data that will facilitate assessment and monitoring of the Himalayan treelines. [ABSTRACT FROM AUTHOR]

We analyzed the tree-rings δ18O of Abies spectabilis (fir) growing at the subalpine treeline ecotone in the Magguchatti valley. The valley is located in the Indian summer monsoon (ISM) dominated region of western Himalaya and also receives snow precipitation derived by westerly disturbances (WDs) during the winter months. The 60 year developed (1960–2019 CE) tree-ring δ18O chronology revealed a strong positive correlation with the temperature of late winter and spring months (February to April). Strong negative correlations are also apparent for snowcover, soilmoisture, and relative humidity for the same spring season. Our findings partly contrast the significant correlation results of tree-ring δ18O with summer precipitation and drought indices recorded from other summer monsoon-dominated regions in the Himalayas. The spatial correlation analyses with sea surface temperatures (SSTs) and climate parameters showed subdued signals of tropical Pacific at the site, but with a shift to more moisture influx from the Arabian Sea during the last two decades. Moreover, a significant negative correlation with North Atlantic Oscillation further justifies the strongly captured spring temperature and snowcover signals and the weak effect of summer precipitation in fir trees. A temperature rising trend during the latter half of the 20th century and the elevation effect are taken as important factors controlling the moisture source at the treeline ecotone zones. [ABSTRACT FROM AUTHOR]

Globally, treeline in mountain landscapes is reported to be sensitive to projected warming by climate change. Betula utilis (Himalayan birch), a principal tree species defining the natural treeline in Himalayas, is a potential indicator species to track the signal of climate change. The present study models the ensemble distribution of B. utilis using Biomod2 package for present and future (RCP's 2.6–8.5 covering 2050 and 2070). The final ensemble model obtained had AUC = 0.886 and TSS = 0.655, thus indicating robustness of the model. We assessed change in the habitat suitability, area expansion and contraction based on ensemble model using SDM Toolbox. The highly suitable area for B. utilis is predicted to shift towards the eastern parts of Himalayas in future, with suitability declining towards the western part of Himalayas. The study, to our best knowledge, for the first time used Ecospat package to assess niche dynamics (i.e. overlap, similarity and equivalency) of B. utilis, which predicted the climatic niche of this treeline species is moderately shifting in future scenarios. Further, the PCA analysis indicated that significant variation (33.45% on PC1 and 24.63% on PC2) exists in the climatic conditions between current and future scenarios. The similarity and equivalency test revealed that B. utilis niche is similar but not identical between current and future climate change scenarios. Hopefully, the results from the present study will contribute significantly in understanding the impacts of climate change in Himalayas with wide implications for scientifically-informed adaptation and mitigation strategies. [ABSTRACT FROM AUTHOR]

Lichenometry is an extremely useful technique in dating moraine ridge and recent glacier retreat in polar and alpine regions. The study relates the size of the lichen thallus to the minimum age of the exposure of the surface on which it grows which consequently helps in assessment of the age of the boulders. The Lichenometric studies are carried out in Kupup and Thangu area of eastern Himalaya in Sikkim and Thajiwas glacier in Ganderbal district of north western Himalaya of Jammu and Kashmir with the help of diameters of a common crustose lichen Rhizocarpon geographicum growing luxuriantly on exposed boulder. The Thajiwas glacier showed retreat of 200 m in 279 years while in Thangu and Kupup area of eastern Himalaya the retreat was estimated as 200 m in 100 and 91 years respectively. The rate of retreat was slightly more faster in eastern Himalayan (20 mm/century) than the north-western Himalaya region (18.5mm/century). [ABSTRACT FROM AUTHOR]

The stratigraphic and tectonic setting in the northwest part of Himalayan belt is complex and thrusted due to the collision of Indian plate and the Eurasian plate. During the past, the Himalaya is divided into four parts; these are Outer Himalaya, Lesser Himalaya, Greater or Higher Himalaya and Tethys Himalaya. The appearance of basement rocks played a significant role in the Himalayan periphery for stratigraphic, structural and tectonic movement. The deformation pattern of the crustal rocks causing the rise of basement rocks which constitutes an integral part of crustal configuration during the evolutionary stages of the Himalaya. In this study, an attempt has been made to estimate the basement depth configuration using spectral analysis and Euler deconvolution technique of gravity data in the northwest Himalaya region. The elevation increases continuously from 500 m to 5100 m in SW to NE direction, however, Bouguer gravity anomaly decreases continuously from −130 mGal to −390 mGal in SW to NE direction due to the isostaic adjustment. Gravity anomaly is very low near Harsil, Badrinath and Joshimath area and observed higher elevation due to the deep rooted basement. However, there are extrusion of crystalline basement in and around the Badrinath area due to the resettlement of geologic process which are overlaid to the top surface of the sedimentary layers. Euler deconvolution technique has been applied to detect the direct basement depth and results show a good correlation with the average depth of the spectral analysis and other works carried by different authors. Three gravity profiles are selected in appropriate places orienting SW-NE direction with a profile length of 160 km, 150 km and 140 km respectively in the study area for calculating the average depth of the basement rock. The average basement depth calculated is around 11.27 km using the spectral analysis technique and results are well correlated with the results of various workers. Euler deconvolution studies along the three selected profiles have been interpreted. It has been observed that there are more number of cluster points falling between depth ranges of 10 to 15 km, dipping in SW to NE direction. Euler's study shows deep rooted connection near Main Frontal Thrust (MFT), Main Boundary Thrust (MBT), Main Central Thrust (MCT), Bearing Thrust (BT) and Vaikrita Thrust (VT) locations as per profile study. Based on these studies three geological models have been prepared along the profiles showing different tectonic resettlement and depth of crystalline basement. Crystalline rocks exposed at the surface may be due to uplift along the shear in the MCT zone by kinetic flow basically, Munsiayari Thrust (MT) and VT in the of NW-Himalaya region. [ABSTRACT FROM AUTHOR]

The article reports on a study performed by using remote sensing technology to monitor the alpine treeline shift in Himalayan Mountains in India. As mentioned, most of the previous research had limited geographical extent and this research used Normalized Difference Vegetation Index (NDVI) to detect the changes, greenness, and status of the vegetation. Several statistics based on the research in the form of tables are also presented.