Eastern Himalaya Research Articles

<i>Bulbophyllum brachypodum</i> Nom. Nov. with Two New Varieties

Cirrhopetalum brevipes is transferred to Bulbophyllum under the name of B. brachypadum. Further two new varieties, var. geei and var. parviflorum are described from Kameng District, and Bhutan in Eastern Himalayas respectively.

The Science of Vegetation with Reference to India

Pt. I Vegetation is the sum total of plant population covering a region and its descrete units circumscribed by characteristic environment, are communities. The species content is the flora. The physical and the biological surroundings characterise the environmental complex. Both plants and their environment are dynamic systems interacting within and with each other. The amplitude of variations in the environment is generally met with synchronised adaptive responses of the plants in time and space. Differentiation of ecads and ecotypes within the plastic species is the result. However, many forms and invaders may get eliminated also if the situation goes beyond their range of tolerance set by the genetic organisation as the factors may become critical at different stages of the life-cycle. The species around provide the genetic material for recruitment and ecesis within the community.pt. II Migration of species involving mobility of disseminules, their germination, aggregation, competition and final ecesis-ever continuing processes lead to colonisation and invasions. All these plant phenomena react upon the environment introducing changes therein. Thus newer community-environment-complex equilibria are set up in the dynamic system. The whole process is called, succession in relation to time and the series of succeeding communities for a given area, a sere. When it happens ‘de novo’ with no trace of plant present originally in the area, it is prisere as a result of primary succession and subsere with disturbed communities in which secondary succession is the rule. The mechanism of succession is driven by the reacting and changing environment consequential largely either to the plant processes themselves or to extraneous forces succession is autogenic in the former and allogenic in the latter case. In every case succession terminates into a more stable climax community generally dependant upon the climate and soil. The taxa used for classifying communities differ widely among ecologists but association is the basic unit accepted by all, though with varying concepts. The concept of ecosystem in relation to energy and matter within the community is the most acceptable basis for comprehending;vegetation types in India.Pt. III Since vegetation evolves out of the flora floristic regions of India should form the basis of its main divisions. For this purpose three main latitudinal belts viz. (1) Eastern and Western Himalayas, (2) Assam, Gangetic Plains and Rajasthan, and (3) Deccan and Malabar are recognised. The seven provinces with their distinct climate including photoperiod can be individually considered for the description of vegetation types along gradients of altitude, humidity-aridity, history and proximity of human settlements and soil fertility. Along these gradients closed, open and desert types of structure within forests, scrub and grass can be described with their combinations wherever necessary. Physiognomy, structure, function, composition, dynamics, habitat relations and history are the important diagnostic criteria of vegetation types. Size, texture and seasonal behaviour of leaves of dominant species may also be given. The hydrophytes can be described in each place as floating, suspended, submerged anchored, floating-leaved anchored and emergent anchored.

Comparative stress physiological analysis of aluminium stress tolerance of indigenous maize (Zea mays L.) cultivars of eastern Himalaya

Yield potential of maize having distinct genetic diversity in Eastern Himalayan Region (EHR) hill ecologies is often limited by Al toxicity caused due to soil acidity. Stress physiological analysis of local check exposed to 0–300 μM Al under sand culture revealed that 150 μM Al as critical and 200 μM Al as tolerable limit. Increase in Al from 0 to 300 μM reduced total chlorophyll, carotenoids by 74.8 % and 44.7 % respectively and enhanced anthocyanin by 35.3 % whereas LA, SLW and SL have reduced by 81.3%, 21.3 % and 47.8 % respectively. R/S ratio was 51.0 and 13.7 % higher at lower Al levels (50 μM and 100 μM) and photosynthetic, transpiration rate and TDM were 62.5 %, 42.9 % and 78.6 % lower at higher Al (300 μM) as compared to control. TRL, RSA, RDW and RV at higher Al (300 μM) were 92.6 %, 98.7 %, 78.7 and 97.5 % lower over control respectively. Root and shoot Al and PUpE at higher Al (300 μM) was 194.0, 69.2 and 830 % higher whereas PUE decreased to 88.5 % over control. Evaluation of 31 indigenous maize cultivars at 0, 150, and 250 μM Al in sand culture, alongside tolerance scoring and assessment, revealed that Megha-9, Megha-10, and MZM-19 exhibits high Al tolerance, Megha-1, MZM-22, and MZM-42 demonstrated moderate tolerance, whereas Uruapara, Sublgarh, and BRL Para were identified as Al-sensitive. Stress physiological parameters like SDW, TDM, TRL, SL and LA contributed 46.02 % of variability to PC1, whereas A, RV, RSA, anthocyanin and Chlorophyll_b, contributed 13.56 % of variability to PC2. Highest values of CMS, SL, LP, LA, TRL and anthocyanin were recorded in cluster I having sensitive cultivars while highest CMS, SL, LA, LP, TRL and RSA were found in cluster II having moderately tolerant cultivars and highest mean values for TRL, RSA, LP, LA, CMS and SL were recorded in cluster III having highly Al stress tolerant cultivars. The traits viz., A, RV, RSA, anthocyanin and Chlorophyll_b, total chlorophyll and TDM were emanated as physio-morphological for assessing Al toxicity stress tolerance in Maize with high divergence values. Tolerant cultivars showing 63.4 % and 22.4 % higher anthocyanin at 150 μM Al and 250 μM Al than moderately tolerant one in acid soil experiment with increased root Al, shoot Al, root P and shoot P by 42.6 %, 11 %, 95.1 % and 34 % respectively were emerged as promising for novel maize improvement under acid soils of EHR.

A Botanical Tour in the Sikkim State, Eastern Himalayas

The paper gives an account of the collections of Angiosperms and other lower group of plants made and studied by the author from the Sikkim State of the Eastern Himalayas during 1955. The area under study lies between 27°10'-28°5' N and 88°30'-89° E and includes the Lachen and Lachung river valleys, the upper Tista river valley and the neighbouring mountain slopes and meadows of the Northern Sikkim and the mountain ranges and meadow on way to Nathu La from Gangtok and Jelap La from Rongli, covering an altitude between 1400 and 4400 m. During the period under study, nearly 5000 specimens comprising 471 species of flowering plants, 6 species of Gymnosperms, 38 species of Pteridophytes and 14 species of algae, were collected. Notes on several medicinal and economic plants growing in wild condition, based on the data collected from the villagers and forest guards, are also incorporated in the paper.

Observations on the Pteridophytic Flora of Simla Hills (North Western Himalayas)

Ecological and distributional data about the Peteridophytic Flora of Simla Hills in the North Westan Himalayas is presented in this paper. Detailed observations on the habitat of various species have been made. In all, 121 species (9 Fern-Allies and 112 Ferns) were collected, out of which, 22 are new records for the area. Amongst the interesting and rare ones are, Cheilanthes chrysophylla Hook., Blechnum orientale Linn., Asplenium unilaterale Lam. Var. udum Atk., Phymatodes erythrocarpa (Mett, ex Kze.) Ching, Pyrrosia flocullosa (Don) Ching, Anogramma leptophylla (L.) Link, Selaginella subdiaphana (Wall.) Spr. and S. sanguinolenta (L.) Spr. forma aitchisonii (Hieron.) Alston. Simla combines the flora of the the Eastern and North Western Himalayas and it may be treated as the western limit for Blechnum orientale Linn., Sphenomis chinensis Maxon, Dennstaedtia scabra (Wall.) Moore, and Asplenium unilaterale Lam. Latest nomenclature has been used.

Anthropogenic disturbance produces divergent effects in the community structure and composition of tropical semi-evergreen forests in the Eastern Himalaya

Studies documenting anthropogenic disturbance-driven changes in forest communities of the Eastern Himalaya, a global biodiversity hot spot, are largely lacking. We studied six forest sites of tropical semi-evergreen forests in Arunachal Pradesh in the Eastern Himalaya to understand the effects of varying disturbance intensities on the forest community structure and composition. Based on the magnitude of disturbance, forest sites were classified as experiencing low, moderate and high disturbance. Mean species richness (SR) of trees and shrubs decreased from low disturbance to high disturbance. Mean SR of herbs was maximum in moderately disturbed forest sites. Maximum values of the Shannon-Wiener Diversity Index (SD) were recorded for trees at sites with low disturbance, for shrubs at sites with high disturbance and for herbs in moderately disturbed forests. Pilelou Evenness Index (EI) values were maximum for trees at sites with high disturbance, while maximum EI values for shrubs and herbs were recorded in the forest sites with low disturbance. The number of tree families decreased from 18 to 13 in the forests with low and high disturbance, respectively. Moderate disturbance led to increased herb species richness and diversity, while increasing disturbance produced contrasting effects on trees. High anthropogenic disturbance led to low species richness, but high diversity amongst shrubs. Our investigations suggest that the magnitude of disturbance elicits differential responses in different physiognomic classes in the forest ecosystems and further our understanding of the effects of disturbance in tropical forest ecosystems of a global biodiversity hotspot.

Correction: Structure, composition, and regeneration status of trees in non-protected forests of Eastern Himalaya

Correction: Structure, composition, and regeneration status of trees in non-protected forests of Eastern Himalaya

Acid mine drainage from coal mines in the eastern Himalayan sub-region: Hydrogeochemical processes, seasonal variations and insights from hydrogen and oxygen stable isotopes

Uncontrolled coal mining using non-scientific methods has presented a major threat to the quality of environment, particularly the water resources in eastern himalayan sub-region of India. Water bodies in the vicinity of mining areas are contaminated by acid mine drainage (AMD) that is released into streams and rivers. This study attempted to assess the impact of AMD, deciphering hydrogeochemical processes, seasonal fluctuations, and stable isotope features of water bodies flowing through and around coal mining areas. Self-organizing maps (SOMs) used to separate and categorize AMD, AMD-impacted and non-AMD impacted water from the different study locations for two sampling seasons revealed four clusters (C), with C1 and C2 impacted by AMD, C3 and C4 showing negligible to no impact of AMD. AMD impacted water was SO42− - Mg2+- Ca2+ hydrochemical type with sulphide oxidation and evaporation dominating water chemistry, followed by silicate weathering during both the sampling seasons. Water with negligible-to-no AMD-impact was Mg2+- Ca2+- SO42− to Ca2+ - HCO3− to mixed hydrochemical type with rock weathering and dissolution, followed by ion exchange as major factors controlling water chemistry during both the sampling seasons. Most of physicochemical parameters of C1 and C2 exceeded the prescribed limits, whereas in C3 and C4 water samples, parameters were found within the prescribed limits. Stable isotopes of hydrogen (δ2H) and oxygen (δ18O) during post-monsoon (PoM) varied between -41.04 ‰ and -29.98 ‰, and −6.60 ‰ to −3.94 ‰; and during pre-monsoon (PrM) varied between −58.18 ‰ and - 33.76 ‰ and −8.60 ‰ to −5.46 ‰. Deuterium excess (d-excess) ranged between 1.57 ‰ and 12.47 ‰ during PoM and 5.70 ‰ to 15.17 ‰ during PrM season. The stable isotopes analysis revealed that evaporation, mineral dissolution and mixing with rainwater are the key factors in study area.

Growth and production potential of buckwheat genotypes under organic farming in the Eastern Himalayan region of India

Growth and production potential of buckwheat genotypes under organic farming in the Eastern Himalayan region of India

The Concretions from the Middle Siwalik Group of Eastern Himalaya around Buxa Tiger Reserve (BTR), Alipurduar, West Bengal, India

The Concretions from the Middle Siwalik Group of Eastern Himalaya around Buxa Tiger Reserve (BTR), Alipurduar, West Bengal, India

Unique genetic architecture of prolificacy in 'Sikkim Primitive' maize unraveled through whole-genome resequencing-based DNA polymorphism.

'Sikkim Primitive' maize landrace, unique for prolificacy (7-9 ears per plant) possesses unique genomic architecture in branching and inflorescence-related gene(s), and locus Zm00001eb365210 encoding glycosyltransferases was identified as the putative candidate gene underlying QTL (qProl-SP-8.05) for prolificacy. The genotype possesses immense usage in breeding high-yielding baby-corn genotypes. 'Sikkim Primitive' is a native landrace of North Eastern Himalayas, and is characterized by having 7-9 ears per plant compared to 1-2 ears in normal maize. Though 'Sikkim Primitive' was identified in the 1960s, it has not been characterized at a whole-genome scale. Here, we sequenced the entire genome of an inbred (MGUSP101) derived from 'Sikkim Primitive' along with three non-prolific (HKI1128, UMI1200, and HKI1105) and three prolific (CM150Q, CM151Q and HKI323) inbreds. A total of 942,417 SNPs, 24,160 insertions, and 27,600 deletions were identified in 'Sikkim Primitive'. The gene-specific functional mutations in 'Sikkim Primitive' were classified as 10,847 missense (54.36%), 402 non-sense (2.015%), and 8,705 silent (43.625%) mutations. The number of transitions and transversions specific to 'Sikkim Primitive' were 666,021 and 279,950, respectively. Among all base changes, (G to A) was the most frequent (215,772), while (C to G) was the rarest (22,520). Polygalacturonate 4-α-galacturonosyltransferase enzyme involved in pectin biosynthesis, cell-wall organization, nucleotide sugar, and amino-sugar metabolism was found to have unique alleles in 'Sikkim Primitive'. The analysis further revealed the Zm00001eb365210 gene encoding glycosyltransferases as the putative candidate underlying QTL (qProl-SP-8.05) for prolificacy in 'Sikkim Primitive'. High-impact nucleotide variations were found in ramosa3 (Zm00001eb327910) and zeaxanthin epoxidase1 (Zm00001eb081460) genes having a role in branching and inflorescence development in 'Sikkim Primitive'. The information generated unraveled the genetic architecture and identified key genes/alleles unique to the 'Sikkim Primitive' genome. This is the first report of whole-genome characterization of the 'Sikkim Primitive' landrace unique for its high prolificacy.

Landscape modelling of the Yalong River catchment during the uplift of Southeast Tibet

Southeast Tibet is characterized by low-relief surfaces at high-elevation, showing very little exhumation during the India–Asia collision, as well as deeply incised rivers valleys. Understanding how these low-relief surfaces adjacent to the plateau's edge survived from regressive fluvial erosion is still an enigma, which is key to understanding the formation of the plateau. In the Three Rivers Region around the Eastern Himalayan Syntaxis, the squeezing of the Salween, Mekong and Yangtze rivers’ drainage basins in their middlestream, where numerous thrusts parallel to the river channels are observed, has been invoked as the key factor driving the river evolution. More to the east, in the Great Bends Region, no such squeezing of the drainage basins has been observed; the Yalong and Yangtze rivers flow perpendicularly across northeast-trending thrust belts, generating huge (>100 km) river course bends with steep channel slopes. These faults have significantly contributed to construct the high plateau margin, including the Yalong Thrust Belt (YTB), active during the Eocene (∼35–25 Ma) and reactivated in the Miocene (15–12 Ma). By applying state-of-the-art landscape modelling (FastScape) to the Yalong River catchment, with simplified rock uplift scenario deduced from fault activities, we show that strong monsoonal precipitation on the plateau (∼1 m/yr), even during only a short period such as the Mid–Miocene Climatic Optimum (17–14 Ma), produces wide rivers and destroys the plateau edge. In contrast, modelling the orographic effect with weak net precipitation (∼0.2 m/yr) above ∼2700 or 4000 m, preserves the plateau edge and reproduces the slope of the Yalong River, but with a width larger than in nature. To reproduce both the slope and narrowness of the Yalong gorge just upstream of the YTB, a combination of a rapid Miocene rock uplift leading to a regional surface uplift, which creates a significant orographic effect and preserves interfluve low-relief surfaces close to the plateau edge, and a water inflow in upstream, which deeply incises downstream river valleys, is necessary. Such an amount of upstream water is collected from the flat and expansive headwater, inherited from the inland endorheic zone of the plateau interior, on which the hillslope processes dominate the landscape evolution.

Vegetation browning trend progressively leading to forest degradation in eastern himalaya in response to climatic and anthropogenic drivers

Vegetation is a major natural resource that plays an important role in maintaining ecological balance. Vegetation in the eastern Himalaya has experienced severe consequences owing to deforestation, fragmentation, land use land cover (LULC) conversion and climate change. Disturbances in vegetation have a close connection to browning trend because they modify the terrestrial ecosystems. Remote sensing derived vegetation indices and the availability of long-term satellite data allowed us to infer greening and browning tendencies across the Northeast Region (NER) of India. The present study has employed almost four decades (1982–2020) of satellite data (i.e. NDVI and LAI) and climate data (precipitation, soil moisture, temperature, solar radiation) to deduce the spatial pattern of greening and browning trends over major vegetation ecosystems, namely forest, grassland and cropland. Statistical metrics such as the Mann–Kendall test (τ) and the Theil–Sen median trend were computed to understand the greening and browning including vegetation degradation. The key findings exhibited that a noticeable large-scale greening trend of forests persisted in the first period (1982–2000) and switched to browning in the latest period (2000–2020). The statistically significant areas of browning trends over forest regions in NER was 5.6% which increased to 10.7–15.6%. The browning trends over grassland were more pronounced in the southernmost part of NER. Such changes were ascribed mostly to persistent warming and declining soil moisture. This was further exacerbated by human-induced LULC change. Over croplands, greening was prominent in Assam in the latest period, whilst other regions switched to browning. Trend analysis gives critical information on temperature-induced moisture stress leading to browning that might have potential implications for the forest, grassland and agriculture ecosystems. Specifically, the areas at Ziro Valley of Arunachal Pradesh showed high risk of forest degradation (i.e. 19% of the total forest area of 1816.54 km2), whereas areas around the Loktak Lake in Manipur exhibited high risk of cropland degradation. The states in the southernmost part of NER showed high risk of grassland degradation. Nearly 20–27% of the areas were identified as high risk of degradation. The study underscores the potential areas of NER where land management strategies need attention in the context of complex climatic factors along the side of anthropogenic influences.

Patterns of forest community diversity, regeneration potential and carbon storages along an altitudinal gradient in Eastern Himalaya, India

This study showed changing patterns in the plant species composition, diversity, and carbon storage potential of different forests along altitudinal gradients (i.e. 100 – 1900 m) in Eastern Himalayan India. Different tree, shrub and herb species were sampled along the altitudinal gradients ranging from tropical to temperate forests through Nested Plot design. In each forest, vegetation sampling was made by establishing a permanent plot of 250 m × 250 m as per ISRO-GBP/NCP-VCP protocol. Individuals of trees ≥10 cm girth at breast height (GBH), shrubs and herbs were recorded in 4, 8 and 16 subplots of 31.62 m × 31.62 m, 5 m × 5 m and 1 m × 1 m, respectively. Community attributes such as species richness, density, basal area, diversity indices and biomass and carbon storages were computed for each study site. A total of 5 forest communities (2 each from tropical and subtropical and one from temperate forest) were identified. The woody species diversity was highest in the subtropical forest followed by tropical and temperate forest. Altitude played an important role in the Eastern Himalayan Mountains in the establishment and distribution of forest community. Forest community composition changes with elevation, for instance, the dominant communities like Dipterocarpus retusus–Phoebe goalparensis–Schima wallichii (D-P-S), Gmelina arborea–Schima wallichii-Duabanga grandiflora (G-S-D), Schima wallichii–Duabanga grandiflora–Alstonia scholaris (S-D-A), Alstonia scholaris–Terminalia myriocarpa–Bischofia javanica (A-T-B) and Acer thomsonii–Rhodendron arboreum–Quercus lamellose (A-R-Q) were present at elevational ranges of 100–300 m, 300–700 m, 700–1100 m, 1100–1500 m and 1500–1900 m, respectively. The study showed that about 41–57% of the tree species exhibited good regeneration followed by 23–30% as fair, 6–16% as poor, and 6–21% species did not show regeneration along the altitudinal gradient. The total biomass carbon (Mg C ha−1) varied from 84.74 to 163.56 in tropical, 103.12 – 156.41 in subtropical and 133.05 in temperate forest. In conclusion, community composition, regeneration pattern and biomass carbon storage changes along altitude because of altered biophysical characteristics. However, despite variations in elevation, factors for forest disturbance at different altitudes significantly contributed to the community attributes and overall accumulation of biomass carbon. Hence, the traditional management practices carried out by local communities also play a crucial role in shaping the structure, composition, and carbon dynamics of forest ecosystems. Understanding the impacts of these practices is essential for promoting sustainable forest management by conserving forests and preserving carbon stocks for mitigating climate change in future. This study emphasizes the importance of long-term forest monitoring to promote biodiversity conservation and formulate conservation strategies that support sustainable forest management policies to which ensure continuous provision of ecosystem services in the region.

Soil organic carbon fractionation, carbon index, and microbial activity under different agroforestry systems in North Eastern Himalayas, India.

The potential of soil organic carbon fractions for agroforestry systems (AFSs) is not well understood. Five distinct AFSs were tested for its impact on soil organic carbon fractionation, carbon index, and microbial activity in North Eastern Himalayas, India. The mean labile carbon (LC) ranged from 4.55 to 5.43kg soil-1 across the land use systems. Napier system observed the lowest very labile carbon (VLC) 12.36kg soil-1 in 60-75-cm depth. The mean non labile carbon (NLC) ranged from 15.67 to 16.83gkg soil-1 across the land use. Highest less labile carbon (LLC) was observed in agri-horti-silviculture (AHS) followed by agri-silvi-horticulture (ASH) land use system. The black gram + mandarin + Alnus nepalensis land use recorded higher lability index (1.66) followed by maize + Schima wallichii (1.65) in 0-15-cm depth. Among the different land use systems, carbon pool index increased in all the depths over buckwheat + mandarin. The mean carbon management index (CMI) value ranged from 167.02 to 210.12 among the land use system. The mean CMI was highest in black gram + mandarin + Alnus nepalensis (210.12) followed by soybean + Ficus hookerii + guava (191.56), maize + Schima wallichii (281.71), and lowest in buckwheat + mandarin (167.02). Among the AFSs, black gram + mandarin + Alnus nepalensis showed greater amount of carbon pool index, lability index, and carbon management index and, hence, considered the best sustainable agroforestry system to sequester more carbon in the Sikkim Himalaya. Such system also retained more different organic carbon fractions. The mean CMI value ranged from 167.02 to 210.12 among AFSs. Acid phosphatase activity was more during the rainy season followed by winter and summer season. Similar trends were followed by the urease activity in all the three seasons. Overall conclusion from this investigation is that SOC fractions, carbon index, and microbial activity levels are strongly influenced by the prevailing agroforestry systems.

A hydrous sub-arc mantle domain within the northeastern Neo-Tethyan ophiolites: Insights from cumulate hornblendites

Being a part of the large-scale Indus-Tsangpo suture zone ophiolites of the Alpine-Himalayan orogenic system, the Neo-Tethyan ophiolites of eastern Arunachal Himalaya, northeast India, are important in understanding the formation and evolution of the Neo-Tethyan lithosphere. This study focuses on the hornblendite dykes occurring within serpentinized peridotites of the Mayodia ophiolites in eastern Arunachal Himalaya, to ascertain the origin and evolution of such hydrous mineral cumulates within the ophiolite complex. Texturally and chemically, the hornblendites contain three types of amphiboles, Amp1 (pargasite), Amp2 (Mg-hornblende), and Amp3 (actinolite). The pargasites occur as large cm-sized phenocrysts and show cumulate textures while Mg-hornblende appears as both intercumulus grains between cumulus pargasites and surrounding partially resorbed clinopyroxene grains. Actinolite occurs along the breakdown zone of pargasite and is associated with other secondary minerals. The hornblendites are characterized by high MgO (~12–20 wt%) and low SiO2 (~42–44 wt%) with depleted light rare earth elements (REE) [(La/Sm)N = 0.29–0.52] and almost flat heavy REE [(Gd/Yb)N) = 0.89–1.11]. Moreover, the samples are characteristically depleted in high field strength elements (Nb, Ta, Ti, Hf) while being enriched in Pb. Geothermobarometric calculations yield high magmatic temperatures of ~950 and ~840 °C for pargasite and Mg-hornblende, respectively, and variable pressures with pargasite having the highest pressures (1.6–1.7 GPa) followed by Mg-hornblende (1.1–1.2 GPa) and finally actinolite (~0.55 GPa). Furthermore, fO2 calculations for the cumulus pargasites revealed highly oxidizing conditions (ΔNNO+2) and water content of parental melts (H2Omelt% = ~14.25 %). Parental melt calculations using whole-rock REE concentrations suggest formation from a hydrous sub-alkaline basaltic melt. Whole-rock initial SrNd isotopic ratios of the hornblendites reveal a primary signature for them, falling in the mantle array in proximity to the high-μ (HIMU) mantle reservoir. All these signatures point towards a magmatic arc affinity for these hornblendites. The host peridotite unit shows highly enriched REE concentrations (ƩREE = 18.13 ppm) with flat REE patterns compared to the other peridotites of the locality, which show depleted signatures. Olivine chemistry of the host peridotite unit depicts primary compositions falling in the mantle array. The olivine-liquid thermometer yields temperatures ~1000 °C, which are much lower than those of peridotites occurring in spreading centers (MOR or back-arc). These evidence suggest that the hornblendites and their host peridotite unit represent an island arc root complex, which further imply the hydrous nature of the Neo-Tethyan sub-arc mantle.

Barriers and corridors: Assessment of gene flow and movement among red panda populations in eastern Himalayas

Landscape features can impede dispersal, gene flow, and population demography, resulting in the formation of several meta-populations within a continuous landscape. Understanding a species' ability to overcome these barriers is critical for predicting genetic connectivity and population persistence, and implementing effective conservation strategies. In the present study, we conducted a fine-scale spatial genetic analysis to understand the contemporary gene flow within red panda populations in the Eastern Himalayas. Employing geometric aspects of reserve design, we delineated the critical core habitats for red pandas, which comprise 14.5 % of the landscape (12,189.75 Km2), with only a mere 443 Km2 falling within the protected areas. We identified corridors among the core habitats, which may be vital for the species' long-term genetic viability. Furthermore, we identified substantial landscape barriers, including Sela Pass in the western region, Siang river in the central region, and the Dibang river, Lohit river, along with Dihang, Dipher, and Kumjawng passes in the eastern region, which hinder gene flow. We suggest managing red panda populations through the creation of Community Conservation Reserves in the identified core habitats, following landscape-level management planning based on the core principles of geometric reserve design. This includes a specific emphasis on identified core habitats of red panda (CH-RP 5 and CH-RP 8) to facilitate corridors and implement meta-population dynamics. We propose the development of a comprehensive, long-term conservation and management plan for red pandas in the transboundary landscape, covering China, Nepal, and Bhutan.

Comparative Analysis of the Complete Mitochondrial Genomes of Three Sisoridae (Osteichthyes, Siluriformes) and the Phylogenetic Relationships of Sisoridae.

The family Sisoridae is one of the largest and most diverse Asiatic catfish families, with most species occurring in the water systems of the Qinhai-Tibetan Plateau and East Himalayas. At present, the phylogenetic relationship of the Sisoridae is relatively chaotic. In this study, the mitochondrial genomes (mitogenomes) of three species Creteuchiloglanis kamengensis, Glaridoglanis andersonii, and Exostoma sp. were systematically investigated, the phylogenetic relationships of the family were reconstructed and to determine the phylogenetic position of Exostoma sp. within Sisoridae. The lengths of the mitogenomes' sequences of C. kamengensis, G. andersonii, and Exostoma sp. were 16,589bp, 16,531bp, and 16,529bp, respectively. They all contained one identical control region (D-loop), two ribosomal RNAs (rRNAs), 13 protein-coding genes (PCGs) and 22 transfer RNA (tRNA) genes. We applied two approaches, Bayesian Inference (BI) and Maximum Likelihood (ML), to construct phylogenetic trees. Our findings revealed that the topological structure of both ML and BI trees exhibited significant congruence. Specifically, the phylogenetic tree strongly supports the monophyly of Sisorinae and Glyptosternoids and provides new molecular biological data to support the reconstruction of phylogenetic relationships with Sisoridae. This study is of great scientific value for phylogenetic and genetic variation studies of the Sisoridae.

Quantitative assessment of paclitaxel in Taxus wallichiana zucc. bark using HPTLC densitometry: Insights for germplasm selection and toxicological studies

Taxus wallichiana Zucc. [Synonym: Taxus baccata subsp. Wallichiana (Zucc.) Pilg.] or Himalayan Yew belonging to the evergreen gymnosperm family Taxaceae, grows in temperate regions and has been used in traditional medicines to treat cancer, bronchial disorders, colds, cough, etc. The plant is known to contain paclitaxel (PTX), a key bioactive component with anticancer properties. High-performance thin layer chromatography (HPTLC) was used in the present study to estimate paclitaxel from the bark of T. wallichiana obtained from 15 different geographical locations in the eastern and western Himalayas of India. HPTLC method was determined to be a reliable and efficient technique for the quantification of paclitaxel, offering rapid outcomes.The bark materials of T. wallichiana chemotype obtained from Sikkim (Samanden) contained the highest concentration of paclitaxel, followed by West Bengal (Sandakphu), Arunachal Pradesh (Dibang Valley), and respectively. The present study also examined the cytotoxicity and genotoxicity of the aqueous bark extract of the TW1 chemotype at various doses on the meristematic cells derived from the roots of Allium cepa L.. The bark extracts demonstrate considerable cytotoxic and mitotic properties. This study could be useful to the pharmaceutical industry for selecting elite (high paclitaxel-producing) chemotypes of T. wallichiana. The toxicological evaluation of the T. wallichiana chemotypes (using Allium cepa test) could also help to determine the genotoxic properties of the bark extract.

The transition from shifting cultivation to indigenous agroforestry as nature-based solution for land restoration in the Indian Eastern Himalayas

In the Indian Eastern Himalayas, shifting cultivation has long been a major cause of land degradation. However, indigenous communities, like the Hmar, have successfully transitioned from shifting cultivation to agroforestry systems such as pineapple agroforestry, leading to land restoration and increased household incomes. Despite these positive outcomes, little is known about how soil health indicators change during this transition. Thus, the present study aimed to investigate changes in selected soil health indicators and erodibility across different age classes of pineapple agroforestry systems (<5, 5–10, 11–15, and > 15 years old) compared to shifting cultivation and nearby natural forests. Soil samples were collected from six sites, including different stages of pineapple agroforestry systems, shifting cultivation phases, and a natural forest. At each site, three (10 × 10 m) quadrats were selected, and two (1 × 1 × 1 m) vertical soil pits were dug in each quadrat, sampling soil depths from 0 to 100 cm. The transition from shifting cultivation to pineapple agroforestry improved soil organic carbon (SOC) and stratification ratios while reducing soil erodibility. SOC stocks were estimated at 182.7 Mg C/ha for natural forest land and 188.2 Mg C/ha for the cropping phase in shifting cultivation. On the other hand, estimated SOC stocks for < 5, 5–10, 11–15 and > 15 years old stands of pineapple agroforestry system were 169.7 Mg C/ha, 157.2 Mg C/ha, 168.9 Mg C/ha and 177 Mg C/ha respectively. Thus, the estimated SOC stocks under > 15 years of pineapple agroforestry were comparable with adjacent natural forest land. The stratification ratios (SR > 2) for SOC and macronutrients indicated better soil quality in the pineapple agroforestry system than in the cropped land. The clay and modified clay ratios decreased with increasing age of pineapple agroforestry stands. The highest clay ratio was recorded in the topsoil of < 5-year-old pineapple agroforestry system, indicating a greater risk of exposure to rainfall events than in natural forest land and the cropping phase in the shifting cultivation cycle. It is concluded that transitioning from shifting cultivation to a pineapple agroforestry is a nature-based solution to restore degraded lands and presents an excellent opportunity for sustainable soil health and carbon sink management.