The Naga Hills Ophiolite(NHO) represents one of the fragments of Tethyan oceanic crust in the Himalayan Orogenic system which is exposed in the Phek and Kiphire districts of Nagaland, India. The NHO is composed of par...The Naga Hills Ophiolite(NHO) represents one of the fragments of Tethyan oceanic crust in the Himalayan Orogenic system which is exposed in the Phek and Kiphire districts of Nagaland, India. The NHO is composed of partially serpentinized dunite, peridotite, gabbro, basalt, minor plagiogranite,diorite dyke and marine sediments. The basalts are mainly composed of fine grained plagioclase feldspar, clinopyroxene and orthopyroxene and show quenching and variolitic textures. The gabbros are characterized by medium to coarse grained plagioclase, orthopyroxene and clinopyroxene with ophitic to sub-ophitic textures. The ultramafic cumulates are represented by olivine, Cpx and Opx.Geochemically, the basalts and gabbros are sub-alkaline to alkaline and show tholeiitic features.The basalts are characterized by 44.1-45.6 wt.% of SiO_2 with 28-38 of Mg#, and the gabbros by38.7-43.7 wt.% of SiO_2, and 26-79 of Mg#. The ultramafic rocks are characterized by 37.4-52.2 wt.% of SiO_2, and 80-88 of Mg#. In multi-element diagrams(spidergrams) both basalts and gabbros show fractionated trends with strong negative anomalies of Zr. Nb. Sr and a gentle negative anomaly of P.However, the rare earth element(REE) plots of the basalts and gabbros show two distinct patterns. The first pattern, represented by light REE(LREE) depletion, suggests N-MORB features and can be interpreted as a signature of Paleo-Tethyan oceanic crust. The second pattern, represented by LREE enrichment with negligible negative Eu anomaly, conforms to E-MORB, and may be related to an arc tectonic setting. In V vs. Ti/1000, Cr vs. Y and AFM diagrams, the basalts and gabbros plot within Island Arc Tholeiite(IAT) and MORB fields suggesting both ridge and arc related settings. The ultramafic rocks exhibit two distinct patterns both in spidergrams and in REE plots. In the spidergram, one group displays highly enriched pattern, whereas the other group shows near flat pattern compared to primordial mantle. In the REE plot, one group displays steeper slopes [(La/Yb)N = 4.340展开更多
There are many outcrops of the Tertiary sediments in northeast India and a large number of plant megafossils have been described from there. Among all, the Late Oligocene sedimentary basin of Makum Coalfield is very i...There are many outcrops of the Tertiary sediments in northeast India and a large number of plant megafossils have been described from there. Among all, the Late Oligocene sedimentary basin of Makum Coalfield is very important because there is no other exposure having such a rich palaeofloral assemblage not only from northeast India but also from the whole country. The assemblage is also important to confirm whether the suturing between the Indian and Eurasian plates was complete to facilitate plant migration or not. All the reported plant fossils clearly indicate the prevalence of tropical climate in the region during the deposition of the sediments. As the majority of taxa occur in tropical evergreen to moist deciduous and littoral and swampy forest, a warm and humid climate may be envisaged in Upper Assam during the Late Oligocene. The abundance of palms and pantropical megathermal plant families in the Makum Coalfield indicate that the cold month mean temperature(CMMT) was not less than 18°C. The quantitative palaeoclimate reconstruction indicates a monsoonal climate during the period with the same intensity as that of the modern day. The absence of Southeast Eurasian elements in the fossil assemblage provides clear evidence that suturing between the Indian and Asian plates was not complete till the Late Oligocene. Several modern analogues of the fossil taxa are now endemic to the Western Ghats which lies in the same palaeolatitude.展开更多
Nasopharyngeal cancer (NPC) is a rare disease in most parts of the world, except for Southeast Asia, some parts of North Africa and the Arctic. It is mostly seen in people of Chinese origin. In India, NPC is also rare...Nasopharyngeal cancer (NPC) is a rare disease in most parts of the world, except for Southeast Asia, some parts of North Africa and the Arctic. It is mostly seen in people of Chinese origin. In India, NPC is also rare, except for the Hill States of Northeast India, particularly Nagaland, Manipur, and Mizoram. The striking feature of NPC in Northeast India is that the incidence ranges over the complete spectrum from the lowest (as 0.5/100 000 to 2.0/100 000 among Caucasoid) to the highest (as ~20/100 000 among Cantonese/Zhongshan dialect Chinese). The age-adjusted rate of NPC in Kohima district of Nagaland State is 19.4/100 000, which is among the highest recorded rates. By contrast, in Assam, one of the so-called Hill States but not itself a hilly state, NPC is much less common. The Northeastern region is distinguished by a preponderance of the Tibeto-Burman languages and by variable mongoloid features among peoples of the region. The nature of the migratory populations who are presumed to be bearers of the mongoloid risk is unknown, but these NPC occurrence features provide an outstanding opportunity for NPC risk investigation, such as that of the hypothesis of Wee et al. for westward displacement of Chinese aborigines following the last glacial maximum.展开更多
Objective: To detect the prevalence pattern of Chikungunya virus in three states of Northeast India. Methods: A total of 1 510 samples were collected from different private and government hospitals of Assam, Arunachal...Objective: To detect the prevalence pattern of Chikungunya virus in three states of Northeast India. Methods: A total of 1 510 samples were collected from different private and government hospitals of Assam, Arunachal Pradesh and Meghalaya. Serum was tested for the presence of IgM antibodies against Chikungunya virus followed by RT-PCR for amplification of Chikungunya E1 gene region using specific primers. Results: Overall, 11.83%(172/1 454) clinical samples were positive by MAC-ELISA and/or RT-PCR assay. Asymptomatic infection was seen in 17.86%. Males were more affected than females and age group 16-30 years was mostly affected. Fever(100.00%) was the primary symptom followed by headache(72.03%) and arthralgia(41.53%). Only 118 Chikungunya positive cases could be traced, of which 25.42% complained about sequelae of infection. In entomological investigation, Aedes aegypti was more predominant(92.10%) than Aedes albopictus(7.90%). No mosquito pools could be incriminated for Chikungunya virus. Conclusions: In this study, Chikungunya was observed to be prevalent in Assam, Arunachal Pradesh and Meghalaya. Though Chikungunya is a selflimiting infection, increasing morbidity by CHIKV infection is affecting social and economic status of individual. Thus, a community empowerment to effectively control mosquito population by employing different mosquito control measures along with personal protection is mandatory to tackle future outbreak of the disease.展开更多
A study was conducted to assess growth, carbon stock and sequestration potential of oil palm plantations along a chronosequence in Mizoram, Northeast India for which a total of 148 oil palms drawn from different age g...A study was conducted to assess growth, carbon stock and sequestration potential of oil palm plantations along a chronosequence in Mizoram, Northeast India for which a total of 148 oil palms drawn from different age group plantations (1 to 11 years) were sampled for their biometric parameters and assessment of carbon stock through partial non-destructive methods. All the growth parameters of oil palm (trunk height, crown depth, total height, trunk diameter) and biomass drew from different parts of the palm showed a significant (p belowground biomass (BGB) > standing litter biomass > deadwood biomass > understorey biomass. AGB, BGB and deadwood biomass followed an increasing trend while understorey biomass decreased with age. An 11-year oil palm plantation accumulated 111.96 Mg ha-1 biomass with a carbon density of 49.90 Mg C ha-1 and could sequester 3.70 Mg C ha-1 year-1 in 10 years after planting in Mizoram, Northeast India. The findings showed considerable carbon storage with comparative higher values in oil palm plantations than shifting cultivation fallows. This will enable policy and decision makers in framing climate change mitigation and adaptation policies regarding the extension of oil palm plantations in Mizoram.展开更多
In view of the geographically closest location to Andaman archipelago, Myanmar was suggested to be the origin place of aboriginal Andamanese. However, for lacking any genetic information from this region, which has pr...In view of the geographically closest location to Andaman archipelago, Myanmar was suggested to be the origin place of aboriginal Andamanese. However, for lacking any genetic information from this region, which has prevented to resolve the dispute on whether the aboriginal Andamanese were originated from mainland India or Myanmar. To solve this question and better understand the origin of the aboriginal Andamanese, we screened for haplogroups M31 （from which Andaman-specific lineage M31al branched off） and M32 among 846 mitochondrial DNAs （mtDNAs） sampled across Myanmar. As a result, two Myanmar individuals belonging to haplogroup M31 were identified, and completely sequencing the entire mtDNA genomes of both samples testified that the two M31 individuals observed in Myanmar were probably attributed to the recent gene flow from northeast India populations. Since no root lineages of haplogroup M31 or M32 were observed in Myanmar, it is unlikely that Myanmar may serve as the source place of the aboriginal Andamanese. To get further insight into the origin of this unique population, the detailed phylogenetic and phylogeographic analyses were performed by including additional 7 new entire mtDNA genomes and 113 M31 mtDNAs pinpointed from South Asian populations, and the results suggested that Andaman-specific M31al could in fact trace its origin to northeast India. Time estimation results further indicated that the Andaman archipelago was likely settled by modem humans from northeast India via the land-bridge which connected the Andaman archipelago and Myanmar around the Last Glacial Maximum （LGM）, a scenario in well agreement with the evidence from linguistic and palaeoclimate studies.展开更多
Mizoram, a state situated in the northeast corner of India, is very rich in fossil woods belonging to the Tipam Group(Late Miocene-Early Pliocene in age). Four new fossil woods, namely Swintonioxylon hailakandiense Pr...Mizoram, a state situated in the northeast corner of India, is very rich in fossil woods belonging to the Tipam Group(Late Miocene-Early Pliocene in age). Four new fossil woods, namely Swintonioxylon hailakandiense Prakash & Tripathi, Bombacacioxylon tertiarum Mehrotra et al., gen. et sp. nov., Dipterocarpoxylon jammuense Guleria et al. and Bischofia palaeojavanica Awasthi are described from there. They resemble the modern taxa, namely Swintonia Griff.(Anacardiaceae), Dipterocarpus C.F. Gaertn.(Dipterocarpaceae), Bischofia Blume(Euphorbiaceae) and the taxa of the family Bombacaceae. The distribution of the modern equivalents of the present and previously described taxa indicates the existence of warm and humid climate in Mizoram during the depositional time.展开更多
Stratification in lowland rainforests of Meghalaya,India,which represent the westernmost limit of the rainforests north of the Tropic of Cancer,was studied in horizontal and vertical planes to elucidate the patterns i...Stratification in lowland rainforests of Meghalaya,India,which represent the westernmost limit of the rainforests north of the Tropic of Cancer,was studied in horizontal and vertical planes to elucidate the patterns in stacking of species diversity and community attributes,and to draw comparisons with rainforests of‘Indo-Malaya’ecozone(biogeographical realm).All individuals≥10 cm GBH(girth at breast height)were enumerated in six transects of 10 m width and up to 500 m length covering 2.45 ha area.The stratification of whole assemblage of species in vertical plane is referred to as‘storey structure’(=height class distribution),which explains structural complexity.In horizontal plane,it is typically referred to as‘stand structure’(=girth class distribution),which explains structural heterogeneity.The stratification of an individual species in vertical plane is referred to as‘loftiness’and in horizontal plane,it is frequently referred to as‘population structure’.The stand structure was characterized by a negative exponential relationship or a reverse J-shaped curve,which is typical of a well regenerating forest stand.The storey structure was characterized by the low stature of the rainforest(<30 m),subtle layering in the canopy with dearth of discrete multi-stories,narrower widths of the stories and a thick understory.The cluster analysis and‘candlestick charts’showed that the dominant species spatially segregated in canopy height to profile three strata,viz.,an understory of juveniles and shrubs below 5 m,a middle-storey of intermediate trees between 5 and 15 m,and an overstory of large trees between 15 and 25 m.Emergent trees of a few species may reach up to 30 m.The individuals tended to scatter in increasingly wider range of height classes from a lower to the next higher girth class,creating a‘torchlight scatter’pattern,with a tendency to concentrate towards smaller height classes due to stochastic factors,which potentially influence vertical growth proportionate to diametric growth展开更多
Northeastern India has high medicinal plant diversity due to variance in topography and physiognomy. We documented the uses of various medicinal plants by the Bengali people of West district and South district of Trip...Northeastern India has high medicinal plant diversity due to variance in topography and physiognomy. We documented the uses of various medicinal plants by the Bengali people of West district and South district of Tripura state for their own health care as well as for domesti-cated animals. Based on semi structured interviews, group discussions and information from local informants, a total of 93 species of medicinal plants of 52 families and 83 genera were documented. These plants were used to treat more than 55 different human diseases and 6 diseases of livestock. Sixty-eight plant species were used singly and the rest were used in combination with other species for therapeutic formulations of various diseases. Leaves of plants were most often used for most of the ethnobotanical preparations. Maximum consensus value of 96% was recorded for Chromolaena odorata （L.） King ＆amp;H. Rob., and the mini-mum was 15%for Bambusa balcooa Robx. Of the 93 plant species, 75 species showed pharmacological properties. Prospects for augmenting existing knowledge and enhancing the use of traditional medicinal plants are discussed.展开更多
Forests have significant economic and ecological value as a provider of ecosystem services, being home to much of the world’s biodiversity and supporting the livelihoods of many people. Reducing emissions from defore...Forests have significant economic and ecological value as a provider of ecosystem services, being home to much of the world’s biodiversity and supporting the livelihoods of many people. Reducing emissions from deforestation and forest degradation in developing countries (REDD) is a critical component of the overall greenhouse gas emission reductions and now the significance of REDD+ (which is not only about reducing emissions but halting and reversing forest loss), in delivering climate change mitigation benefits along with co-benefits, is increasingly being recognized in global climate negotiations. Northeast India provides a tremendous potential for harnessing REDD+ activities with about 66% of the total geographical area of the region being covered by forests. This paper attempts to explore this potential besides estimating the area available for different options under REDD+ as well as the mitigation potential using COMAP model, overcoming limitations of existing studies or a lack of them. Within this, the status of forests and biodiversity along with drivers of deforestation in north east India are documented and an assessment of the potential for taking up reducing deforestation and degradation and enhancement of carbon stocks and afforestation is conducted both at the state as well as district level. It was found that northeastern states have been experiencing net forest loss during the last few years along with significant scale forest degradation, with Nagaland followed by Arunachal Pradesh offering maximum potential for “reducing deforestation” option under REDD and the total incremental annual mitigation potential of the four REDD+ activities in northeast India being 29.2 MtCO2 for 2030.展开更多
The Miocene molassic Surma sandstones in parts of the Naga-Manipur hills,in and around Nungba,Northeast India have been studied for their tectonic provenance using petrography and heavy mineral contents.The poorly-to-...The Miocene molassic Surma sandstones in parts of the Naga-Manipur hills,in and around Nungba,Northeast India have been studied for their tectonic provenance using petrography and heavy mineral contents.The poorly-to-moderately-sorted sub-litharenite to lithicarkose type Surma sandstones display predominance of monocrystalline quartz(av.61%)and include undulose and non-undulose varieties and almost equal amounts of feldspars(av.22%)and rock fragments(av.17%).The heavy mineral suite of Surma sandstones is dominated by transparent varieties(96%)that include garnet,zircon,tourmaline,rutile,staurolite,scapolite,phlogopite,chondrodite,humite,wollastonite,hedenbergite,sphene,chlorite,sillimanite,glauconite,glaucophane,and chloritoid.These heavy minerals characterize the granitic and silicic metamorphic complexes(GM)as well as the basic metamorphic rocks(MT)like greenstones,green schist,and amphibolites relating to passive continental margin setup.The opaque grains constitute nearly 4%of the total heavy minerals.The presence of euhedral,as well as abraded heavy mineral grains,further supports a mixed provenance having substantial contribution from sedimentary and metamorphic rocks.A ZTR index of approximately 45%indicates mineralogically sub-mature nature of Surma sandstones.Based on the light and heavy mineral suites coupled with the type of terrain available in the vicinity of the study area,it may be visualized that the sediment supply was largely made by the Himalaya,the IMR,the Shillong plateau,and the Mikir Hills under the influence of semi-arid to semi-humid climatic conditions.An overall supply from a recycled orogen provenance has been envisaged.展开更多
Sandstones belonging to the Oligocene Barail Group and Miocene Surma Group of the Mizoram Foreland Basin have been studied geochemically to constrain their provenances,tectonic setting,and other sedimentary processes(...Sandstones belonging to the Oligocene Barail Group and Miocene Surma Group of the Mizoram Foreland Basin have been studied geochemically to constrain their provenances,tectonic setting,and other sedimentary processes(weathering and mineral sorting etc.).Based on their mineralogical compositions,these sandstones are classified as quartzarenite and sublithic-arenite.The sandstones of Barail and Surma Groups have similar contents of most of the major elements except for SiO2 and A12O3.The Barail sandstones are relatively more siliceous and less aluminous compared to the Surma sandstones.Barail and Surma sandstones were plotted in a singular array on different geochemical discrimination diagrams.The CIA and CIW values of the sandstones of Barail(69 and 77 respectively)and Surma Groups(68 and 77 respectively)suggest that the sandstones were derived from moderately weathered source rocks.In the A-CN-K diagram,the studied samples plotted along a roughly singular trend that originates from granodiorite as well as Trans-Himalayan granitoids and also confined within the field of Siwalik sediments.Chondrite・normalized REE patterns for the Surma and Barail sandstones are identical and are similar to upper continental crust,with moderate to high LREE enrichment and prominent negative Eu anomalies(*Eu/Eu for both Barail and Surma sandstone=0.69),indicating their derivation from a felsic magmatic source.The values of,*Eu/Eu(LaN/LuN),La/Sc,La/Co,Th/Sc,Th/Co,and Cr/Th ratios of Surma and Barail sandstones are also not significantly different,and the values are similar to finefractions derived from the weathering of felsic rocks.In the K2O/Na2O versus SiO2,Th-Sc-Zr/10 and Ti/Zr versus La/Sc tectonic discrimination diagrams the studied samples of Barail and Surma sandstones plot within the fields of greywacke from continental island arcs and active continental margin.The geochemical characteristics of the studied sedimentary rocks and their similarity with the Siwalik foreland sediments thus suggest were sourced from different fe展开更多
文摘The Naga Hills Ophiolite(NHO) represents one of the fragments of Tethyan oceanic crust in the Himalayan Orogenic system which is exposed in the Phek and Kiphire districts of Nagaland, India. The NHO is composed of partially serpentinized dunite, peridotite, gabbro, basalt, minor plagiogranite,diorite dyke and marine sediments. The basalts are mainly composed of fine grained plagioclase feldspar, clinopyroxene and orthopyroxene and show quenching and variolitic textures. The gabbros are characterized by medium to coarse grained plagioclase, orthopyroxene and clinopyroxene with ophitic to sub-ophitic textures. The ultramafic cumulates are represented by olivine, Cpx and Opx.Geochemically, the basalts and gabbros are sub-alkaline to alkaline and show tholeiitic features.The basalts are characterized by 44.1-45.6 wt.% of SiO_2 with 28-38 of Mg#, and the gabbros by38.7-43.7 wt.% of SiO_2, and 26-79 of Mg#. The ultramafic rocks are characterized by 37.4-52.2 wt.% of SiO_2, and 80-88 of Mg#. In multi-element diagrams(spidergrams) both basalts and gabbros show fractionated trends with strong negative anomalies of Zr. Nb. Sr and a gentle negative anomaly of P.However, the rare earth element(REE) plots of the basalts and gabbros show two distinct patterns. The first pattern, represented by light REE(LREE) depletion, suggests N-MORB features and can be interpreted as a signature of Paleo-Tethyan oceanic crust. The second pattern, represented by LREE enrichment with negligible negative Eu anomaly, conforms to E-MORB, and may be related to an arc tectonic setting. In V vs. Ti/1000, Cr vs. Y and AFM diagrams, the basalts and gabbros plot within Island Arc Tholeiite(IAT) and MORB fields suggesting both ridge and arc related settings. The ultramafic rocks exhibit two distinct patterns both in spidergrams and in REE plots. In the spidergram, one group displays highly enriched pattern, whereas the other group shows near flat pattern compared to primordial mantle. In the REE plot, one group displays steeper slopes [(La/Yb)N = 4.340
文摘There are many outcrops of the Tertiary sediments in northeast India and a large number of plant megafossils have been described from there. Among all, the Late Oligocene sedimentary basin of Makum Coalfield is very important because there is no other exposure having such a rich palaeofloral assemblage not only from northeast India but also from the whole country. The assemblage is also important to confirm whether the suturing between the Indian and Eurasian plates was complete to facilitate plant migration or not. All the reported plant fossils clearly indicate the prevalence of tropical climate in the region during the deposition of the sediments. As the majority of taxa occur in tropical evergreen to moist deciduous and littoral and swampy forest, a warm and humid climate may be envisaged in Upper Assam during the Late Oligocene. The abundance of palms and pantropical megathermal plant families in the Makum Coalfield indicate that the cold month mean temperature(CMMT) was not less than 18°C. The quantitative palaeoclimate reconstruction indicates a monsoonal climate during the period with the same intensity as that of the modern day. The absence of Southeast Eurasian elements in the fossil assemblage provides clear evidence that suturing between the Indian and Asian plates was not complete till the Late Oligocene. Several modern analogues of the fossil taxa are now endemic to the Western Ghats which lies in the same palaeolatitude.
文摘Nasopharyngeal cancer (NPC) is a rare disease in most parts of the world, except for Southeast Asia, some parts of North Africa and the Arctic. It is mostly seen in people of Chinese origin. In India, NPC is also rare, except for the Hill States of Northeast India, particularly Nagaland, Manipur, and Mizoram. The striking feature of NPC in Northeast India is that the incidence ranges over the complete spectrum from the lowest (as 0.5/100 000 to 2.0/100 000 among Caucasoid) to the highest (as ~20/100 000 among Cantonese/Zhongshan dialect Chinese). The age-adjusted rate of NPC in Kohima district of Nagaland State is 19.4/100 000, which is among the highest recorded rates. By contrast, in Assam, one of the so-called Hill States but not itself a hilly state, NPC is much less common. The Northeastern region is distinguished by a preponderance of the Tibeto-Burman languages and by variable mongoloid features among peoples of the region. The nature of the migratory populations who are presumed to be bearers of the mongoloid risk is unknown, but these NPC occurrence features provide an outstanding opportunity for NPC risk investigation, such as that of the hypothesis of Wee et al. for westward displacement of Chinese aborigines following the last glacial maximum.
基金supported by Indian Council of Medical Research,New Delhi(No.NER/23/2013-ECD-I)
文摘Objective: To detect the prevalence pattern of Chikungunya virus in three states of Northeast India. Methods: A total of 1 510 samples were collected from different private and government hospitals of Assam, Arunachal Pradesh and Meghalaya. Serum was tested for the presence of IgM antibodies against Chikungunya virus followed by RT-PCR for amplification of Chikungunya E1 gene region using specific primers. Results: Overall, 11.83%(172/1 454) clinical samples were positive by MAC-ELISA and/or RT-PCR assay. Asymptomatic infection was seen in 17.86%. Males were more affected than females and age group 16-30 years was mostly affected. Fever(100.00%) was the primary symptom followed by headache(72.03%) and arthralgia(41.53%). Only 118 Chikungunya positive cases could be traced, of which 25.42% complained about sequelae of infection. In entomological investigation, Aedes aegypti was more predominant(92.10%) than Aedes albopictus(7.90%). No mosquito pools could be incriminated for Chikungunya virus. Conclusions: In this study, Chikungunya was observed to be prevalent in Assam, Arunachal Pradesh and Meghalaya. Though Chikungunya is a selflimiting infection, increasing morbidity by CHIKV infection is affecting social and economic status of individual. Thus, a community empowerment to effectively control mosquito population by employing different mosquito control measures along with personal protection is mandatory to tackle future outbreak of the disease.
文摘A study was conducted to assess growth, carbon stock and sequestration potential of oil palm plantations along a chronosequence in Mizoram, Northeast India for which a total of 148 oil palms drawn from different age group plantations (1 to 11 years) were sampled for their biometric parameters and assessment of carbon stock through partial non-destructive methods. All the growth parameters of oil palm (trunk height, crown depth, total height, trunk diameter) and biomass drew from different parts of the palm showed a significant (p belowground biomass (BGB) > standing litter biomass > deadwood biomass > understorey biomass. AGB, BGB and deadwood biomass followed an increasing trend while understorey biomass decreased with age. An 11-year oil palm plantation accumulated 111.96 Mg ha-1 biomass with a carbon density of 49.90 Mg C ha-1 and could sequester 3.70 Mg C ha-1 year-1 in 10 years after planting in Mizoram, Northeast India. The findings showed considerable carbon storage with comparative higher values in oil palm plantations than shifting cultivation fallows. This will enable policy and decision makers in framing climate change mitigation and adaptation policies regarding the extension of oil palm plantations in Mizoram.
基金supported by grants from the Natural Science Foundation of Yunnan ProvinceNational Natural Science Foundation of China(Nos.30900797 and 30621092)
文摘In view of the geographically closest location to Andaman archipelago, Myanmar was suggested to be the origin place of aboriginal Andamanese. However, for lacking any genetic information from this region, which has prevented to resolve the dispute on whether the aboriginal Andamanese were originated from mainland India or Myanmar. To solve this question and better understand the origin of the aboriginal Andamanese, we screened for haplogroups M31 （from which Andaman-specific lineage M31al branched off） and M32 among 846 mitochondrial DNAs （mtDNAs） sampled across Myanmar. As a result, two Myanmar individuals belonging to haplogroup M31 were identified, and completely sequencing the entire mtDNA genomes of both samples testified that the two M31 individuals observed in Myanmar were probably attributed to the recent gene flow from northeast India populations. Since no root lineages of haplogroup M31 or M32 were observed in Myanmar, it is unlikely that Myanmar may serve as the source place of the aboriginal Andamanese. To get further insight into the origin of this unique population, the detailed phylogenetic and phylogeographic analyses were performed by including additional 7 new entire mtDNA genomes and 113 M31 mtDNAs pinpointed from South Asian populations, and the results suggested that Andaman-specific M31al could in fact trace its origin to northeast India. Time estimation results further indicated that the Andaman archipelago was likely settled by modem humans from northeast India via the land-bridge which connected the Andaman archipelago and Myanmar around the Last Glacial Maximum （LGM）, a scenario in well agreement with the evidence from linguistic and palaeoclimate studies.
文摘Mizoram, a state situated in the northeast corner of India, is very rich in fossil woods belonging to the Tipam Group(Late Miocene-Early Pliocene in age). Four new fossil woods, namely Swintonioxylon hailakandiense Prakash & Tripathi, Bombacacioxylon tertiarum Mehrotra et al., gen. et sp. nov., Dipterocarpoxylon jammuense Guleria et al. and Bischofia palaeojavanica Awasthi are described from there. They resemble the modern taxa, namely Swintonia Griff.(Anacardiaceae), Dipterocarpus C.F. Gaertn.(Dipterocarpaceae), Bischofia Blume(Euphorbiaceae) and the taxa of the family Bombacaceae. The distribution of the modern equivalents of the present and previously described taxa indicates the existence of warm and humid climate in Mizoram during the depositional time.
基金the Department of Biotechnology,Ministry of Science and Technology,Government of India,New Delhi through grant number BT/PR7928/NDB/52/9/2006 to the authorFinancial support for visit to China was received under the INSA-CAS Bilateral Exchange Programme 2018 from the Indian National Science Academy,New Delhi and Chinese Academy of Sciences,Beijing vide grant number INT/CAS/2017/01
文摘Stratification in lowland rainforests of Meghalaya,India,which represent the westernmost limit of the rainforests north of the Tropic of Cancer,was studied in horizontal and vertical planes to elucidate the patterns in stacking of species diversity and community attributes,and to draw comparisons with rainforests of‘Indo-Malaya’ecozone(biogeographical realm).All individuals≥10 cm GBH(girth at breast height)were enumerated in six transects of 10 m width and up to 500 m length covering 2.45 ha area.The stratification of whole assemblage of species in vertical plane is referred to as‘storey structure’(=height class distribution),which explains structural complexity.In horizontal plane,it is typically referred to as‘stand structure’(=girth class distribution),which explains structural heterogeneity.The stratification of an individual species in vertical plane is referred to as‘loftiness’and in horizontal plane,it is frequently referred to as‘population structure’.The stand structure was characterized by a negative exponential relationship or a reverse J-shaped curve,which is typical of a well regenerating forest stand.The storey structure was characterized by the low stature of the rainforest(<30 m),subtle layering in the canopy with dearth of discrete multi-stories,narrower widths of the stories and a thick understory.The cluster analysis and‘candlestick charts’showed that the dominant species spatially segregated in canopy height to profile three strata,viz.,an understory of juveniles and shrubs below 5 m,a middle-storey of intermediate trees between 5 and 15 m,and an overstory of large trees between 15 and 25 m.Emergent trees of a few species may reach up to 30 m.The individuals tended to scatter in increasingly wider range of height classes from a lower to the next higher girth class,creating a‘torchlight scatter’pattern,with a tendency to concentrate towards smaller height classes due to stochastic factors,which potentially influence vertical growth proportionate to diametric growth
文摘Northeastern India has high medicinal plant diversity due to variance in topography and physiognomy. We documented the uses of various medicinal plants by the Bengali people of West district and South district of Tripura state for their own health care as well as for domesti-cated animals. Based on semi structured interviews, group discussions and information from local informants, a total of 93 species of medicinal plants of 52 families and 83 genera were documented. These plants were used to treat more than 55 different human diseases and 6 diseases of livestock. Sixty-eight plant species were used singly and the rest were used in combination with other species for therapeutic formulations of various diseases. Leaves of plants were most often used for most of the ethnobotanical preparations. Maximum consensus value of 96% was recorded for Chromolaena odorata （L.） King ＆amp;H. Rob., and the mini-mum was 15%for Bambusa balcooa Robx. Of the 93 plant species, 75 species showed pharmacological properties. Prospects for augmenting existing knowledge and enhancing the use of traditional medicinal plants are discussed.
文摘Forests have significant economic and ecological value as a provider of ecosystem services, being home to much of the world’s biodiversity and supporting the livelihoods of many people. Reducing emissions from deforestation and forest degradation in developing countries (REDD) is a critical component of the overall greenhouse gas emission reductions and now the significance of REDD+ (which is not only about reducing emissions but halting and reversing forest loss), in delivering climate change mitigation benefits along with co-benefits, is increasingly being recognized in global climate negotiations. Northeast India provides a tremendous potential for harnessing REDD+ activities with about 66% of the total geographical area of the region being covered by forests. This paper attempts to explore this potential besides estimating the area available for different options under REDD+ as well as the mitigation potential using COMAP model, overcoming limitations of existing studies or a lack of them. Within this, the status of forests and biodiversity along with drivers of deforestation in north east India are documented and an assessment of the potential for taking up reducing deforestation and degradation and enhancement of carbon stocks and afforestation is conducted both at the state as well as district level. It was found that northeastern states have been experiencing net forest loss during the last few years along with significant scale forest degradation, with Nagaland followed by Arunachal Pradesh offering maximum potential for “reducing deforestation” option under REDD and the total incremental annual mitigation potential of the four REDD+ activities in northeast India being 29.2 MtCO2 for 2030.
基金funding the research programme through Inspire Fellowship No. IF140996
文摘The Miocene molassic Surma sandstones in parts of the Naga-Manipur hills,in and around Nungba,Northeast India have been studied for their tectonic provenance using petrography and heavy mineral contents.The poorly-to-moderately-sorted sub-litharenite to lithicarkose type Surma sandstones display predominance of monocrystalline quartz(av.61%)and include undulose and non-undulose varieties and almost equal amounts of feldspars(av.22%)and rock fragments(av.17%).The heavy mineral suite of Surma sandstones is dominated by transparent varieties(96%)that include garnet,zircon,tourmaline,rutile,staurolite,scapolite,phlogopite,chondrodite,humite,wollastonite,hedenbergite,sphene,chlorite,sillimanite,glauconite,glaucophane,and chloritoid.These heavy minerals characterize the granitic and silicic metamorphic complexes(GM)as well as the basic metamorphic rocks(MT)like greenstones,green schist,and amphibolites relating to passive continental margin setup.The opaque grains constitute nearly 4%of the total heavy minerals.The presence of euhedral,as well as abraded heavy mineral grains,further supports a mixed provenance having substantial contribution from sedimentary and metamorphic rocks.A ZTR index of approximately 45%indicates mineralogically sub-mature nature of Surma sandstones.Based on the light and heavy mineral suites coupled with the type of terrain available in the vicinity of the study area,it may be visualized that the sediment supply was largely made by the Himalaya,the IMR,the Shillong plateau,and the Mikir Hills under the influence of semi-arid to semi-humid climatic conditions.An overall supply from a recycled orogen provenance has been envisaged.
基金the financial support from UGC-NERO, Govt. of India [No. F.5-44/2013-14/(MRP/NERO)/281] to carry out the work
文摘Sandstones belonging to the Oligocene Barail Group and Miocene Surma Group of the Mizoram Foreland Basin have been studied geochemically to constrain their provenances,tectonic setting,and other sedimentary processes(weathering and mineral sorting etc.).Based on their mineralogical compositions,these sandstones are classified as quartzarenite and sublithic-arenite.The sandstones of Barail and Surma Groups have similar contents of most of the major elements except for SiO2 and A12O3.The Barail sandstones are relatively more siliceous and less aluminous compared to the Surma sandstones.Barail and Surma sandstones were plotted in a singular array on different geochemical discrimination diagrams.The CIA and CIW values of the sandstones of Barail(69 and 77 respectively)and Surma Groups(68 and 77 respectively)suggest that the sandstones were derived from moderately weathered source rocks.In the A-CN-K diagram,the studied samples plotted along a roughly singular trend that originates from granodiorite as well as Trans-Himalayan granitoids and also confined within the field of Siwalik sediments.Chondrite・normalized REE patterns for the Surma and Barail sandstones are identical and are similar to upper continental crust,with moderate to high LREE enrichment and prominent negative Eu anomalies(*Eu/Eu for both Barail and Surma sandstone=0.69),indicating their derivation from a felsic magmatic source.The values of,*Eu/Eu(LaN/LuN),La/Sc,La/Co,Th/Sc,Th/Co,and Cr/Th ratios of Surma and Barail sandstones are also not significantly different,and the values are similar to finefractions derived from the weathering of felsic rocks.In the K2O/Na2O versus SiO2,Th-Sc-Zr/10 and Ti/Zr versus La/Sc tectonic discrimination diagrams the studied samples of Barail and Surma sandstones plot within the fields of greywacke from continental island arcs and active continental margin.The geochemical characteristics of the studied sedimentary rocks and their similarity with the Siwalik foreland sediments thus suggest were sourced from different fe
