Vegetation history, monsoonal fluctuations and anthropogenic impact during the last 2330 years from Loktak Lake (Ramsar site), Manipur, north-east India: a pollen based study

Tripathi, Swati; Singh, Y. Raghumani; Nautiyal, C. M.; Thakur, Biswajeet

doi:10.1080/01916122.2017.1375441

Cited by 13 publications

(10 citation statements)

References 60 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The high frequencies of non-cereal pollen in the fossil record could be owing to the luxuriant herbaceous vegetation growing around the sampling provenance, and might have been transported from the nearby croplands situated at a distance of 100-300 m through varied media (wind, water, etc. ) to the lake basin (Quamar and Nautiyal, 2016;Tripathi et al, 2017).…”

Section: Palynological Signals Of Human Activity Detected In the Wetland Coresmentioning

confidence: 99%

Floristic and climatic reconstruction in the Indo-Burma region for the last 13,000 cal. yr: A palynological interpretation from the endangered wetlands of Assam, northeast India

Tripathi¹,

Thakur²,

Nautiyal³

et al. 2019

The Holocene

Self Cite

View full text Add to dashboard Cite

The present study deals with pollen analyses from two sedimentary sequences (280 and 150 cm deep) cored from wetlands in Deepor (Kamrup district) and Hasila (Goalpara district) in the western Brahmaputra flood plain of Assam. This region is a part of the Indo-Burma region and documents changes in vegetation, climate and alterations in the wetland level as well as of anthropogenic impacts as related to the fluctuating orientation of the southwest monsoon during the past 13,040 cal. yr. The presence of cool taxa, both trees and ferns, Schima, Ilex, Gleichenia dichotoma and Pteris pentaphylla, though present in small amounts, indicate cool and dry climatic conditions from 13,040 to 11,700 cal. BP. This is followed by a shift to warmer and moderately humid climate between about 8390–3450 cal. BP which coincides with the Holocene thermal maximum (8000–7000 yr BP) and could be attributed to an intensified southwest monsoon. A palynozone depicting less warm and humid climate was observed between 3450 and 2250 cal. BP because of the occurrence of low frequencies of Shorea and Terminalia along with marshy taxa. Climatic conditions were again improved from 2250 cal. BP onwards under warm and moderately humid climate owing to the proliferation of Sal and its associates and thereafter, between 1500 and 710 cal. BP, an increased humid climate is indicated by relatively high percentages of Shorea, Syzygium, Impatiens, Onagraceae and Myriophyllum indicating strong monsoonal conditions corresponding to Medieval Warm Period (MWP). Deterioration of the tropical mixed deciduous forest under a warm and relatively dry climatic regime has occurred since 710 cal. BP accompanied by accelerated human settlement, as shown by an abrupt increase in Poaceae > 45 µm along with typical ruderal pollen taxa.

show abstract

Section: Palynological Signals Of Human Activity Detected In the Wetland Coresmentioning

confidence: 99%

Floristic and climatic reconstruction in the Indo-Burma region for the last 13,000 cal. yr: A palynological interpretation from the endangered wetlands of Assam, northeast India

Tripathi¹,

Thakur²,

Nautiyal³

et al. 2019

The Holocene

Self Cite

View full text Add to dashboard Cite

show abstract

“…The divergence between R. e. eldii and R. e. siamensis took place around 0.4 Mya (95% HPD 0.3–0.5). During the Late Pleistocene and Early Holocene period, Northeast India was dominated by open grassland habitats 38 , 39 , which would have facilitated the dispersal of grassland dependent species during the period. The dynamic influences of climatic and environmental factors during the Pleistocene have significantly driven the divergence and phylogeographic structure of several species 40 .…”

Section: Discussionmentioning

confidence: 99%

“…The existing population of R. e. eldii inhabits the floating meadows of KLNP situated in the southern fringes of Loktak Lake in Manipur. The existing lake is the remnant of the original lake, which once occupied almost the entire Manipur valley 39 and is known to have originated around 25,000 Ybp 48 . Since the course of its formation, the Loktak Lake underwent a prolonged phase of hydrodynamic and morphological changes 48 .…”

Section: Discussionmentioning

confidence: 99%

“…The low estimates of effective population size during ~ 3000–5000 generations ago (median 383–420) around 15,000–25,000 Ybp are therefore consistent with the biogeographical history of the region. Subsequently, the appearance of open grasslands with aquatic herbaceous associates in the Loktak Lake region during Late Holocene 38 , 39 indicates the emergence of extensive habitat conditions favourable for grassland dependent species, such as R. e. eldii . As shown in our results, an increase in the ancestral population size during the past ~ 2500–300 generations (median 540–4876) (Fig.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

Population genetics and evolutionary history of the endangered Eld’s deer (Rucervus eldii) with implications for planning species recovery

Ghazi

Sharma

Tuboi

et al. 2021

Sci Rep

View full text Add to dashboard Cite

Eld's deer (Rucervus eldii) with three recognised subspecies (R. e. eldii, R. e. thamin, and R. e. siamensis) represents one of the most threatened cervids found in Southeast Asia. The species has experienced considerable range contractions and local extinctions owing to habitat loss and fragmentation, hunting, and illegal trade across its distribution range over the last century. Understanding the patterns of genetic variation is crucial for planning effective conservation strategies. This study investigated the phylogeography, divergence events and systematics of Eld's deer subspecies using the largest mtDNA dataset compiled to date. We also analysed the genetic structure and demographic history of R. e. eldii using 19 microsatellite markers. Our results showed that R. e. siamensis exhibits two divergent mtDNA lineages (mainland and Hainan Island), which diverged around 0.2 Mya (95% HPD 0.1–0.2), possibly driven by the fluctuating sea levels of the Early Holocene period. The divergence between R. e. eldii and R. e. siamensis occurred around 0.4 Mya (95% HPD 0.3–0.5), potentially associated with the adaptations to warm and humid climate with open grassland vegetation that predominated the region. Furthermore, R. e. eldii exhibits low levels of genetic diversity and small contemporary effective population size (median = 7, 4.7–10.8 at 95% CI) with widespread historical genetic bottlenecks which accentuates its vulnerability to inbreeding and extinction. Based on the observed significant evolutionary and systematic distance between Eld’s deer and other species of the genus Rucervus, we propose to classify Eld's deer (Cervus eldii) in the genus Cervus, which is in congruent with previous phylogenetic studies. This study provides important conservation implications required to direct the ongoing population recovery programs and planning future conservation strategies.

show abstract

“…Even a 1 -2 difference seems to matter owing to the topography. For example, some of these palynological studies suggest warmer and humid conditions during MCA and moderately humid LIA in the sampled locations of the NEI (Chauhan and Mandaokar, 2006;Bhattacharyya et al, 2007;Nautiyal and Chauhan, 2009;Basumatary and Bera, 2010;Tripathi et al, 2017); the authors attribute these changes to vagaries in monsoon. In contrast, a weakening of the Southwest Monsoon since 900 BP in lower Assam (Dixit and Bera, 2012), and a generally cold-dry to coldmoist oscillation of climate in the highland state of Sikkim, concurrent with the global LIA and MCA signals (Sharma and Chauhan, 1999) have been suggested.…”

Section: Introductionmentioning

confidence: 99%

Summer monsoon over northeastern India during the last millennium

Ashok

Soraisam

Tejavath

et al. 2021

Intl Journal of Climatology

View full text Add to dashboard Cite

Analysing three high resolution coupled model simulations for the Medieval Climate Anomaly (MCA) and Little Ice Age (LIA) regimes, available as the last millennium simulations of the PMIP3, we find that Northeastern Indian summer monsoon rainfall (NEISMR) did not change appreciably from the MCA to the LIA. This is in contrast to the signals in the rest of the Indian region. Our results from all the models suggest that, during the MCA, the simulated 100‐hPa tropical easterly jet (TEJ) becomes relatively more intense than that during LIA, due to a stronger Tibetan High. This strengthening of the TEJ results in an associated increase in relative vorticity at the 500 hPa over the Head Bay of Bengal and neighbouring east coast of the Bay of Bengal. This results in higher moisture availability and increased summer monsoon rainfall in the neighbourhood, including the central Indian region, during the MCA. However, the simulations do not show any such changes over northeastern India, indicating a relatively stable simulated NEISMR from MCA through LIA. Furthermore, just as the current day observations, the simulated correlations between the NEISMR with various concurrent ENSO indices are weak and statistically insignificant during the MCA and LIA regimes. Interestingly, an analysis of time‐slice simulations for the MCA and LIA from an atmospheric general circulation model broadly agree with the above conclusions, indicating that the tropical ocean and atmospheric coupling may not have played a major role in the northeast climate.

show abstract

Vegetation history, monsoonal fluctuations and anthropogenic impact during the last 2330 years from Loktak Lake (Ramsar site), Manipur, north-east India: a pollen based study

Cited by 13 publications

References 60 publications

Floristic and climatic reconstruction in the Indo-Burma region for the last 13,000 cal. yr: A palynological interpretation from the endangered wetlands of Assam, northeast India

Floristic and climatic reconstruction in the Indo-Burma region for the last 13,000 cal. yr: A palynological interpretation from the endangered wetlands of Assam, northeast India

Population genetics and evolutionary history of the endangered Eld’s deer (Rucervus eldii) with implications for planning species recovery

Summer monsoon over northeastern India during the last millennium

Contact Info

Product

Resources

About