Eastern Himalayan Region Research Articles

Long‐term spatiotemporal variability in the surface velocity of Eastern Himalayan glaciers, India

AbstractInvestigation of spatiotemporal variation in glacier velocity is imperative to comprehend glacier mass and volume loss as a function of their sensitivity to climate change. The long‐term glacier velocity record for the Eastern Himalayan region is of utmost importance owing to its data scarcity and climate sensitivity. Here, we present a long‐term dataset spanning more than two decades (1994–2020) of glacier surface velocity for the entire Sikkim Himalaya by applying image correlation methods on the multi‐temporal Landsat images. Our results demonstrate an average glacier surface velocity decline from 15.7 ± 5.69 (1994/96) to 12.88 ± 2.09 m yr−1 (2018/2020), that is a decline of ~15% during the period of investigation. Trend analysis shows a decreasing trend in median velocity (32.2%) at a rate of 0.25 m yr−1. Despite the general decline in average glacier velocity, the rate of slowdown of individual glaciers is extremely heterogeneous (3.6–20 m yr−1). Our study shows that up to 32% of the observed heterogeneity in velocity variation can be explained by the variation in glacier size. The present study highlights that large glaciers with thick ice cover move faster compared to small glaciers (even those situated on steep slopes). The findings are significant and have direct implications for assessing future water availability scenarios and modelling glacio‐hydrology in the region.

Assessing the vulnerability of protected areas in the eastern Himalayas based on their biological, anthropogenic, and environmental aspects

Protected areas are the cornerstone for biodiversity conservation in present times. Considering this, the post-2020 global biodiversity framework aims to expand the network of protected areas to cover 30% of the earth's terrestrial surface by 2030. For effective biodiversity conservation, it is essential to bring in more areas under protection and systematically conserve the areas with greater biological diversity that are relatively more vulnerable to various environmental and anthropogenic stresses. In the present study, we assess the vulnerability of montane forest ecosystems in the protected areas of the eastern Himalayan region of India. Our study specifically classifies the protected areas by their relative vulnerabilities, using established methods based on the number of imperilled species, anthropogenic pressure, and the degree of climate change. The results show that a quarter of the protected areas contain a high species richness of imperilled species; 36% of the protected areas are highly affected by climate change, while only 10% are highly influenced by anthropogenic pressures. Outlining the specific vulnerabilities for protected areas would help determine the required management interventions and promote the judicious use of conservation resources. The analytical framework used in our study can be more widely applied to map the important sites for biodiversity conservation and identify the areas ideal for future expansion.

Variation in Moho topography and Poisson's ratio in the Eastern Himalayan arc

The eastern Himalaya comprised of Sikkim, Bhutan, and Arunachal Himalaya possess unique seismicity, which experienced small to great earthquakes due to the Indo-Eurasia collision tectonics along the Himalayan arc. Knowing the structure and composition of the crust is a vital way to a better understanding of crustal deformation and seismicity in this region. In this study, we present the results of teleseismic receiver functions to investigate the crustal thickness and VP/VS(k) ratio beneath the eastern Himalaya region. A total of 585 receiver functions were analyzed using teleseismic events recorded from 23 broadband seismograph stations distributed in the Brahmaputra valley plain to higher-Himalaya. We observed a wide range of variations with respect to crustal thickness among the seismic stations, owing to geographical regimes. The crustal thicknesses of high-altitude stations are thicker, mostly reaching 55–59 km in Bhutan High-Himalaya, and 35–39 km in the foredeep Brahmaputra valley. The high velocity lower crust exhibited in the Sikkim Himalaya to the Bhutan Himalaya agrees with previous geophysical studies. The Moho depths and average Poisson ratio were determined at each station using H-k stacking technique reveal higher Poisson's ratio near the major thrust belt region, and low to medium near the foredeep valley region.

Rangeland Conservation, Pastoralist Displacement, and Long-term Implications of a Grazing Ban in the Indian Himalaya

Conservation-induced displacement has been one of the major critiques of protected area management across South Asia. While there has been a steady increase in research on physical displacement, studies on loss of mobility remain limited. In 1998, a grazing ban was implemented in the state of Sikkim in the Eastern Himalayan region of India. Livestock herding in protected areas was restricted, and pastoral evictions were carried out across the state between 2000–2002. Fifteen years after the ban, we conducted this study to understand the long-term implications of the prohibition on grazing as well as that of the pastoral evictions in and around Khangchendzonga National Park (KNP). To do so, we assess eviction processes, document pastoral responses, and explore the complex social and perceived ecological outcomes of the grazing ban. Our study shows that pastoral evictions result in the further impoverishment of weaker sections of the pastoral community while powerful pastoralists appropriate benefits from conservation policies. Additionally, evictions do not necessarily aid in “biodiversity conservation”; instead, they give rise to social conflicts within the local community and lead to the emergence of new conservation challenges...

An assessment of the water quality index (WQI) of drinking water in the Eastern Himalayas of South Sikkim, India

The current research was performed to evaluate the Water Quality Index (WQI) from the South Sikkim district, India, in the Eastern Himalayan region. Due to the rapid development of the tourism industry in the region, water scarcity has become one of the significant issues in some parts of the South Sikkim district. The lack of sufficient spring water to meet their drinking water needs has forced the local people to depend on alternate sources such as surface or rainwater. The main aim of the current research is to determine the acceptability of drinking water sources using the Water Quality Index (WQI) values. The Bureau of Indian Standard (BIS 2012) was used to evaluate the WQI and evaluate the quality of water for the water sources. Physicochemical parameters such as potential of hydrogen (pH), hardness, alkalinity, iron (Fe), fluoride (F−), chloride (Cl−), nitrate (NO3−), and turbidity were analysed using standard devices and found that water is safe for drinking purpose. The presence of all these parameters did not affect the water quality as all are below the permissible limit. The water delivered after conventional treatment to individual households by local administration is free from contaminants and suitable for drinking. Based on WQI values, surface waterfalls under the projected area of South Sikkim district into two categories: excellent water and good water (ranging from 0 to 50). However, water scarcity continues to remain a major challenge. The current study concludes with some suggestions for proper planning and managing drinking water resources in the South Sikkim district and hilly areas.

Phytochemical, nutritional and antioxidant potential of Panax bipinnatifidus and Panax pseudoginseng: A study of two underutilized and neglected species from the Eastern Himalayan region of India

The world we live in today is rapidly inclining towards plant-based therapeutic and curative medicines. among these phytomedicines, the role of Ginseng's (Panax species) significance as a functional food or nutraceutical has piqued interest in recent years, with a growing market value. Keeping in mind, the present study was intended to analyse the phytochemical, nutritional content and antioxidant activity of two Indian species of Panax viz. P. bipinnatifidus and P. pseudoginseng from the East Himalayan region of India. HPLC studies revealed the presense of four predominant ginsenosides viz. Rg1, Re, Rb1 and Rd in both the Panax species. Analysis of phenolic compounds indicated higher values of gallic acid, chlorogenic acid, and vanillic acid in both species. The tuber contains a good amount of protein, dietary fibre and carbohydrates. Dominant content of arginine and glutamic acid were found with cysteine and methionine as limiting amino acids in both the Panax species. High levels of palmitic, oleic and linoleic acid were observed with higher values of poly-unsaturates in P. pseudoginseng. Analysis of minerals and trace elements reflected high content of phosphorus, potassium, magnesium and selenium in Panax species. The antioxidant study further confirmed the effective potential of these Panax species against several free radicals such as DPPH, ABTS, and superoxide anions. The present findings provide biochemical insights into the diverse aspects of east Himalayan Panax species coupled with their antioxidant potential. These findings could be used as a baseline model for enriching the herbal raw materials required for pharmaceutical as well as nutraceutical formulations. Moreover, a commercially oriented cultivation of these species may be developed by adopting effective conservation strategies to conserve these therapeutically important east Himalayan Panax species.

Screening of forest tree leaves from North Eastern Himalayan region as feed additives for modulating in vitro rumen fermentation and methanogenesis from total mixed ration

Screening of forest tree leaves from North Eastern Himalayan region as feed additives for modulating in vitro rumen fermentation and methanogenesis from total mixed ration

Next-gen precarity: gender and informal labor in the Eastern Himalaya

In the eastern Himalayan region of Sikkim and Darjeeling, India, young women migrate from within and outside the area to work in the expanding retail and service sector. This sector demands very little from them in terms of education, technical skills or financial literacy; the emphasis being on their youth, and supposed socio-cultural and gendered attributes of docility, flexibility and manageability. Simultaneously, technological and infrastructural advancements combined with the influx of cheap fakes of international brands have made borderlands prominent sites of low-end globalization. The informal sector thrives on the back of this rapidly expanding market, the unceasing supply of cheap, flexible and docile labor and the invisibility of laboring bodies and their inherent precarity. However, the informal sector and the attributes that it seeks also create room to maneuver, and negotiate precarity. Focusing on this newly formed but rapidly growing precariat in the eastern Himalayan borderland, and using qualitative data, this paper illustrates (a) how capitalism, through consumption, can create precarious lives and livelihoods (b) the emerging contradictions (empowerment, exploitation) in social and gendered relations as a result of informal employment and (c) the transformation of borderlands into new sites of low-end globalization.

OBSERVATIONS ON BENGAL MONITOR LIZARD, VARANUS BENGHALENSIS IN ITANAGAR, ARUNACHAL PRADESH, INDIA: A REPORT

Bengal Monitor Lizard, Varanus benghalensis, occurs on places, which are far from human settlements but in the present study, its presence was reported for the first time at three different public places in Itanagar, Papum Pare district, Arunachal Pradesh, the eastern Himalayan region. The sites of observation are parts of or adjacent to the Itanagar Wildlife Sanctuary, a global biodiversity hotspot of India. The size of the individuals observed was not large enough to attack any livestock. Moreover, conservation imbibed traditions among most local people suggested tolerance and offered a positive scenario for the survival of the species. However, the conservation of this 'Near Threatened' species seems necessary for the larger interest of biodiversity and humanity

Aerosols over the Foothills of the Eastern Himalayan Region during Post-monsoon and Winter Seasons

In this study a Microtops II sunphotometer is used for the first time over Birtamode, a rapidly growing city located in the eastern Himalayan foothills of Nepal, to measure aerosol optical depth (AOD). The average AOD for the observation period (October 2018–February 2019) was 0.68 ± 0.39 with the post-monsoon season having a higher value (0.74 ± 0.43) compared to the winter season (0.60 ± 0.32). The Angstrom exponent (α) for post-monsoon and winter are found to be 1.08 ± 0.10 and 1.11 ± 0.16 respectively. During the monitoring period, the majority of AOD values (47%) are above 0.60, indicating moderately polluted conditions in the region. Anthropogenic, biomass burning, and mixed aerosols are identified as the prevalent aerosol types in the study region. The observed aerosol classification is also explained in terms of CAMS near-real-time model datasets. The AOD values retrieved by MODIS, VIIRS, Himawari-8, and CAMS show a good correlation with the observed Microtops AOD with R2 values ranging from 0.60 to 0.94. Moreover, different MODIS aerosol products (DB, DT, and combined DB-DT) are evaluated based on a comparison of Collection 6.1 AOD with the ground truth obtained from Microtops. The spatial distribution of AOD as observed by various satellites are compared and the vertical distribution of aerosol is also explained with the extinction coefficient provided by the CALIOP lidar onboard CALIPSO and aerosol types provided by CAMS.

Season specific feed formulations for ameliorating climate stress in grower pigs reared under subtropical eastern Himalayan region

Thermal stress is an emerging issue for pig producers in tropical and sub-tropical Eastern Himalayan region. Thus, season specific feed was proposed to be formulated for amelioration thermal stress. Feeding experiment were conducted for both summer stress (May-August) and winter stress (November-February) in grower pigs (75% Hampshire and 25% Niang Megha). Forty-eight piglets for each experiment were selected and distributed by completely randomized design for these two experiments. The seasonal specific feed as well as standard feed were formulated and provided to the piglets as per the standard procedures. Blood cortisol was measured as indicator of stress, besides the body weight gain, average daily gain and feed conservation efficiency in the pigs. Results indicated that the grower pigs fed with summer specific feed had significantly (P<0.05) lower heat stress, higher body weight gain and better feed conversion ratio as compared to grower pigs fed with standard diet during summer season. Similarly, feeding of winter specific feed has significantly (P<0.05) lowered the cortisol level, improved the body weight gain and better feed conversion ratio in grower pigs. The study concluded that the feeding of season specific diet reduced thermal stress and improved body weight gain in growing pigs. Thus, season specific feed formulations are suggested as one of the strategies to alleviate thermal stress in the region under changing climate condition.

Major chemical constituents from Illicium griffithii Hook. f. & Thoms of North East India and their cytotoxicity and antimicrobial activities.

Illicium griffithii Hook. f. & Thoms is an endemic medicinal plant of North East India found in the Eastern Himalayan region of biodiversity mega centre. Herein, chemical investigation of I. griffithii, afforded five compounds and their structures were determined through extensive use of NMR, HRMS, and FT-IR spectroscopy. The complete proton-proton, proton-carbon coupling network of compound 1 was determined using 1H-1H COSY, HSQC and NOESY NMR experiments. All the compounds were evaluated for their cytotoxic activity by MTT assay and antimicrobial activity by Agar well diffusion method. Compound 1 exhibited significant cytotoxicity activity against Lung cancer (A549) and pancreatic cancer (MIAPaCa2) cell lines with IC50 values of 15.01 ± 2.69 μg/mL and 47.77 ± 2.38 μg/mL, respectively. Further, the compound 1 exhibited good antimicrobial activities against Escherichia coli and Candida albicans with MIC 7.50 ± 0.28 μg/mL and 7.50 ± 0.86 μg/mL, respectively. The other isolated compounds along with the extracts of I. griffithii also displayed moderate anticancer and antimicrobial activities against respective strains. To the best of our knowledge, this is the first study of isolation of compounds from bark, wood, and leaf along with cytotoxicity and antimicrobial activities of I. griffithii from the North Eastern region of India and could be a potential herbal medicine in near future.

Maize Yield Response to Zinc Fertilization in Farmer’s Field under Rainfed Condition in Hill Region of Assam, Eastern Himalayan Region

Zinc (Zn) is the micronutrient that most commonly limits maize yields but it receives much less attention than other inputs. The present field experiment was conducted to study the effect of Zn fertilizers on growth and yield of maize in farmer’s field under rainfed condition in hill region of Assam, Eastern Himalayan Region for authenticating Zn fertilizer application in increasing the yield of summer maize in actual farmer’s field condition. The experiment was carried out in 6 locations (as replication) of three villages with four treatments which consist of recommended dose of fertilizer (90:40:40 kg NPK kgha-1), recommended dose of fertilizer with ZnSO4 @15 kg ha-1, Farmers’ practice with ZnSO4 @ 15 kg ha-1 and Farmers’ practice (No application of fertilizers) as control. Maize responded positively to Zn fertilization where the yields increased from 4.62 t ha−1 without Zn to 4.91 t ha−1 with Zn under recommended dose of fertilizers. The yield response of maize to application of Zn only recorded 9.15 % increase in yield in case of farmers practice without any fertilizers. Zn application increased maize yield due to increased cob length, cob diameter, kernel numbers and kernel weight in Zn-deficient soils. The increase in grain yield in case of combined use of fertilizer and ZnSO4 (heptahydrate) was mainly due to significantly more number of kernels per cob (392) as well as kernel weight (120.3 g) over application of fertilizers only i.e. 368 and 108.4 g respectively. The result of the present study reveals that, basal soil application of Zn as ZnSO4 @ 15 kg ha-1 in maize crop along with recommended fertilizers is highly recommended for the soils of North Eastern Hill region of India.

Ethnomedicinal plants used by the indigenous tribal communities of Arunachal Pradesh, India: a review

Background: In the absence of modern healthcare facilities in remote rural localities, the indigenous tribal communities of Arunachal Pradesh in the Eastern Himalayan region of India continue to rely on plant-based ethnomedicine for the treatment of various ailments prevalent within their biocultural landscape. This review work has been carried out to document the ethnomedicinal knowledge of the indigenous tribal communities of Arunachal Pradesh by critically perusing the selected published literature. The exploration of ethnomedicinal knowledge of the tribal communities may provide clues for development of new drugs and can also help in the continuity and preservation of such important traditional healing practices. Methods: We downloaded 20 published ethnomedicinal literature (between 2005 to 2019) from online databases such as iMedPub, Academia.edu, ResearchGate, Semantic Scholar, Scopus, Web of Science, Publons, PubMed, etc. using keywords ‘ethnomedicine’, ‘tribes of Arunachal Pradesh’, and ‘North-East India’. The diversity of ethnomedicinal plants, types of ailments treated, herbal formulation, informant consensus and the species and family use values have been quantified using relevant statistical tools and techniques. Results: The present review have reported 358 species of medicinal plants belonging to 100 families used by the fourteen indigenous tribal communities for treating 107 specific types of ailments which are classified under 10 broad categories of ailments, namely, cardiovascular, dermatological, gastrointestinal, general health, gynecological, musculoskeletal, odontological, orthopaedic, respiratory, and urological disorders. Asteraceae has shown the highest use reports per family (86) while Acanthacaeae demonstrated the highest family use value index (UVf) of 4.90. The highest species use report was observed under gastrointestinal disorders with an Informant consensus factor (FIC) of 0.41 while the least species use report was observed under urological disorder (FIC 0.11). Conclusion: Plants showing higher UVf index and FIC in the present analysis should be useful for conservation priority. It will also help in prioritization for in-depth investigation of bioactive phytochemicals of potential medicinal plants effective against reported target ailment categories. Keywords: Ailments, Ethnomedicine, Family use value (UVf), Tribal communities, Informant consensus factor (FIC).

Agrobiodiversity and Natural Resource Management in Traditional Agricultural Systems of Northeast India

North-East India, which falls under the Indian Eastern Himalayan region and forms part of two global biodiversity hotspots, is well-known for its rich diversity of flora, fauna, cultures and traditional knowledge systems. Agriculture is the main occupation of the communities living in this region supplemented by utilization of wild useful species from the nearby forests. Traditional agriculture in North-East India follows mixed cropping pattern through multi-cropping, crop rotation, use of multipurpose nitrogen (N)-fixing trees, along with protection of semi-domesticated and wild biodiversity, including medicinal plants, wild edible fruits and vegetables, fodder plants and other useful species. Presently, there has been a gradual shifting from subsistence cultivation to commercial agriculture driven by market forces and modernization, leading to transition from traditional to intensive agriculture and monoculture of cash crops. This has resulted in reduced cultivation of local crop varieties and disappearance of the associated traditional ecological knowledge (TEK). Therefore, the present study attempts to review the contribution of traditional agricultural practices to agrobiodiversity conservation and sustainable natural resource management. Relevant traditional practices such as shifting (Jhum) cultivation systems, bamboo-drip irrigation, paddy-cum-fish cultivation, traditional agroforestry systems of different Indigenous communities residing in different states of North-East India were mentioned in this review. It is undeniable that TEK was developed by communities through many centuries by trial-and-error methods to conform to the local climate, topography, ecology and socio-cultural relevance to the concerned Indigenous communities. This knowledge, therefore, has a great scope for improvement by integration with scientific knowledge for transforming into sustainable agricultural systems in the face of climate change adaptation and mitigation of the vulnerable mountain communities of the Himalayan region.

Major ion chemistry and hydrochemical processes controlling water composition of Teesta River catchment, Sikkim Himalaya, India

ABSTRACT The study determines the major ion chemistry of the Teesta River catchment in the Eastern Himalayan region and evaluates hydrochemical processes controlling water composition of the catchment area. Water of the Teesta River basin was in neutral to alkaline condition. HCO3 −, Ca2+, Na+, Mg2+ and SO4 2- were identified as the dominant ionic species in the Teesta catchment water composition and Ca-Mg-HCO3 as the dominant hydrochemical facies. Higher contribution of (Ca2++Mg2+) and HCO3 − towards the TZ+ and TZ−, high ionic ratios of (Ca2++Mg2+)/(Na++K+), HCO3 −/(Cl−+SO4 2-) and low (Na++K+)/TZ+ ratio suggest carbonate weathering as a major contributor of dissolved ions in the Teesta basin water. Under-saturation with respect to both carbonate and sulphate phase minerals suggests that water can dissolve these minerals during water-rock interaction. Concentration of the analysed water quality parameters were well below the specified drinking and irrigation water limits.

Managing rice fallow lands of the Eastern Indian Himalayas: Impacts of residue management and varietal interventions on soil properties, carbon stocks, and productivity

AbstractDegenerating soil properties, low diversification, and productivity are the major issues for keeping large areas as fallow after rainy season rice (Oryza sativa L.) in Southeast Asia. Long‐duration rice cultivars along with conventional till farming and lack of irrigation facilities limit the chances of growing succeeding crops like pulses in rice fallow areas. Therefore, a field study was conducted to test the hypothesis that cultivating short‐duration rice and lentil (Lens culinaris Medic.) cultivars along with residue retention through mulching or standing rice stubble under no‐till (NT) farming for lentil can enhance the productivity in rice fallow areas and improve economic returns from the cropping system by conserving soil moisture and improving soil properties and carbon stocks. Two rice cultivars (namely, Shahsarang‐1: high yielding and medium duration; and Mendri: local, low yielding, and long‐duration variety), two high biomass lentil varieties (DPL‐81: early duration and IPL‐406: medium duration), and three rice residue management practices (namely, residue removal, 20 cm standing stubble, and mulching at 5 Mg ha−1 in lentil) were tested in the rice–lentil system. After harvest of rainy season rice, lentil was sown under NT using a manually operated furrow opener. Results of a 3‐year study revealed that rice residue retention as mulch at 5 Mg ha−1 and 20 cm standing stubbles (~2 Mg ha−1) conserved residual soil moisture and recorded significantly lower bulk density (1.10 and 1.09 Mg m−3), increased water‐holding capacity (57.05% and 55.14%), and improved water infiltration rate (3.47 and 3.30 cm hr−1) compared to residue removal. Soil organic carbon (SOC), soil microbial biomass carbon, dehydrogenase enzyme activity, available nitrogen, and phosphorus contents at 0–15 cm soil depth were significantly higher by 7.2%–11.1%, 3.9%–6.8%, 4.1%–6.7%, 2.7%–6.4%, and 2.7%–8.0%, respectively, under standing rice stubbles/mulching than residue removal. The SOC stock (25.3 Mg ha‐1) under mulching was significantly higher than that recorded under residue removal at 0–15 cm (23.4 Mg ha−1) and remained non‐significant at 15–30 cm depth. A significantly higher mean seed yield of lentil was obtained under mulching (1.68 Mg ha−1) and standing stubbles (1.49 Mg ha−1) than that under removal (1.27 Mg ha−1). Average productivity of lentil (1.53 Mg ha−1) after medium‐duration rice variety Shahsarang‐1 was greater than that grown after local long‐duration rice variety Mendri (1.43 Mg ha−1). The mean seed yield of early lentil variety DPL‐81 grown after medium‐duration rice was significantly higher (1.60 Mg ha−1) than medium‐duration lentil variety IPL‐406 (1.36 Mg ha−1). Thus, cultivating medium‐duration rice (Shahsarang‐1) followed by early‐duration lentil variety (DPL‐81) and rice residue retention either through mulching or standing rice stubble is recommended for improving soil properties, carbon stock, and productivity of lentil in rice fallow areas of the Eastern Himalayan region of India and other similar agro‐ecosystems.

Evaluation of ecosystem carbon storage in major forest types of Eastern Himalaya: Implications for carbon sink management

Forest's ecosystem is changing at an alarming rate and anthropogenic alteration of forests to other land use is a major driver of carbon (C) emission and biodiversity loss. We estimated ecosystem-level C stock and factors affecting C stock in six major forest types; tropical wet evergreen forest, montane subtropical forest, temperate forest, bamboo forest, quercus forest, and jhum land of the eastern Himalayan region (India). We determined ecosystem structure, biodiversity, and plant and soil C stock by laying random plots in each forest site. The average C stock was estimated in the range of 79.0–373.4 Mg C ha−1 and found significantly different among the forest types. Partitioning ecosystem C stocks in plant (24–55%), soils (43–75%), deadwood (1–4.8%) and litter (0.20–1.25%) components varied largely. Pearson correlation analysis shows a significant positive relation of basal area with species diversity, tree density, and ecosystem C stock. Linear mixed-effect model demonstrates the high influence of species density and soil moisture content on the ecosystem C stock. We recommend the inclusion of forest structural attributes and pedological characteristics while predicting synergies between C stock and future climatic conditions. Additionally, conversion of natural forests to jhum land should be minimized because they stored lesser ecosystem C stocks thus plays a minimum role in C accumulation and cycling. The study provides estimates of C stocks in major forests that can be useful in suggesting a path forward to partially fulfill India's commitments to REDD + policy.

Converting primary forests to cultivated lands: Long-term effects on the vertical distribution of soil carbon and biological activity in the foothills of Eastern Himalaya

The conversion of primary forests to cultivation brings a significant change in soil carbon (C) forms. In the foothills of the Eastern Himalayan Region of India (Manipur), such conversions are prevalent. However, little is known about the response of C forms, particularly in deep soil, to land use conversion in the region. We evaluated changes in soil C forms (total organic, inorganic, and pools) and microbiological properties (up to 1.0 m depth) mediated by C when the 45-year-old forest had been cultivated for 18–25 years. The cultivated land uses were tree-based agroforestry (LAF: legumes, NAF: non-legumes), horticultural fruits (WHF: woody, NHF: non-wood, mainly vegetables), and paddy agriculture system (AUS: upland, ALS: lowlands). Forest conversion significantly (p < 0.05) decreased the total carbon (TC) in the surface soil (0.0–0.15 m) from 4.88 % to 3.04–3.93 % in the tree-based land uses (LAF, NAF, and WHF). TC further declined to 2.05–2.81 % under seasonal crops (NHF, AUS, and ALS). Seasonal crop cultivation also caused a higher decline in microbial biomass carbon, soil enzymes, and carbon pools (active and passive) than the tree-based land use with the soil depth. The vertical distribution of C in the soil profile was inconsistent: organic C (including C pools) decreased, while inorganic C increased. The profile TC stock to a depth of 1.0 m in the forest was 358.8 Mg ha−1, of which 81 % were organic C, and 19 % were inorganic C. In comparison with forest soil, total soil C stocks (organic and inorganic) decreased more (−44.1 to −55.1 %) in seasonal crops than in tree-based (−15.4 to −36.3 %) land uses. The degradation index (DI) also confirmed that seasonal crop cultivation caused a larger decline in surface soil quality (DI: −423 % to −623 %) than tree-based land use (DI: −243 % to −317 %). The topsoil (up to 0.45 m) of seasonal crops was more degraded than that of the subsoil (>0.45 m–1.0 m). Forests converted to seasonal cultivation (upland rice and vegetables) caused higher degradation of soil C forms and overall soil health in the Himalayan foothills of northeastern India. We suggest the promotion of Agroforestry based on legumes (Parkia spp.) and woody fruits (mango/citrus/guava) in the uplands to minimize soil C degradation while ensuring nutritional security in the hill agro-ecosystems of the Indian Himalayas.

A review of forest fire and policy response for resilient adaptation under changing climate in the Eastern Himalayan region

This review paper presents the extent and magnitude of forest fires and adaptation responses to deepen our understanding of the dynamics of forest fires in the eastern Himalayan region. We used a narrative scooping review approach to narrate the present state of forest fires and resilient adaptation responses to guide the development of climate resilient adaptation pathways in the future. Our review concludes that forest fires (total mean fire incidence = 3,158.5) continue to destroy overwhelming areas of forests every year (mean area destroyed = 658,778.4 hectares), presenting significant threat to ecological integrity, human wellbeing, and global effort to fight climate change. Fire incidences are highest during and post dry winter months which quickly declines at the onset of monsoon. Adaptation and responding to ever growing size and frequency of forest fires are limited by lack of awareness, training on fire management, firefighting infrastructure, technology, and adequate policy and financial support. In addition, there is acute lack of scientific studies to understand forest fire dynamics in the eastern Himalayan region. Based on the forest fire literature we argue that policy makers and communities must quickly adopt policy strategies that support smart responses to forest fire management including allocating adequate funds to support capacity building and research. Such decision must be based on research into potentials for climate resilient pathways for adaptation response.