Modern pollen dispersal studies from the phytogeographically and climatically different regions [the Peninsular and extra-Peninsular regions (the Himalaya), the Ganga-Brahmaputra Plain and the coastal regions] of India are summarised and reviewed in the present communication. We have incorporated all the works undertaken on modern pollen dispersal aspects in India. It must be noted that initial studies, though incipient in nature and content, helped in establishing the science of palynology, in the early days, across the varied regions of the vast country. Shorea robusta and Tectona grandis, despite being high pollen producers and dominant components of the deciduous forests, are under-represented in the pollen assemblages; however, Madhuca indica has comparatively good representation. Rhizophora, Aegiceras, Barringtonia, Excoecaria, Sonneratia and Avicennia are the important mangrove taxa recorded from the coastal areas, although their representation is less as compared to the extant vegetation. Mesua, Schima, Elaeocarpus, Ilex and Garcinia are represented well in the pollen spectra from the evergreen forests. Pinus pollen is highly over-represented in the Himalaya. Suggestions for overcoming limitations are also provided, which will improve the accuracy and understanding of modern pollen dispersal studies in the Indian scenario. Recommendations for future research mainly comprise adoption of the established protocols for vegetation surveys. Extended R-value (ERV) models may be applied for estimating the pollen productivity (PPEs) for further use in landscape reconstruction algorithm (LRA) approaches.

Pollen analysis and radiocarbon dating of a 1.4 m deep lacustrine sediment profile from Chhattisgarh State, central India, in the core monsoon zone (CMZ), has revealed the vegetation history, associated climate change and the Indian Summer Monsoon (ISM) rainfall variability during the Late-Holocene. The pollen evidence suggests that between ca. 3000 and 2600 cal year BP, tree-savannah vegetation occurred in the region having a comparatively lesser monsoon rainfall. The forest expanded and culminated into an open-mixed tropical deciduous forest between ca. 2600 and 2200 cal year BP under a warm and moderately humid climate with an increase in monsoon rainfall. Subsequently, between ca. 2200 and 2000 cal year BP, the existing open-mixed tropical deciduous forest transformed into a mixed tropical deciduous forest under a warm and humid climate with further increase in monsoon rainfall. Finally, between ca. 2000 and 1800 cal year BP, a dense mixed tropical deciduous forest occupied the landscape under a regime of a warm and relatively more humid climate with further strengthening of the ISM. The gradual warming, and the climatic amelioration with the intensification of the ISM, during the Late-Holocene (ca. 2600–1800 cal year BP; ~650 BC to AD150) corresponds to the Roman Warm Period (RWP), recorded globally between 2500 and1600 cal year BP (~550 BC to AD ~350). Human activities were present around the study area, which varied according to the ISM variations. The present study provides insights into the gradual intensification of the monsoon since the last ca. 2600 cal year BP (between ca. 2600 and1800 cal year BP), and an increase in the ISM strength in the CMZ of India, against the generally weakening trend during the Late-Holocene.

The present communication reviews the pattern of modern pollen-rain studies carried out in southwestern Madhya Pradesh, India. The study largely revealed that Tectona grandis (teak), despite being an enormous pollen producer (7500 average number of absolute pollen/flower) and the dominant forest constituent (80 to 95% of the total forest constituents), is recorded mostly in low frequencies, attributable to its low pollen dispersal efficiency as well as poor pollen preservation in the sediments. However, Madhuca indica (Mahua) and other dominant members of Sapotaceae (cf. Manilkara hexandra and Mimusops elangi) have always shown their typical behaviour in the pollen spectra and are represented in high frequencies, which are assigned to their local abundance around the provenance of the samples, coupled with high dispersal efficiency as well as good pollen preservation in the sediments. Meanwhile, the other usual and characteristic associates of teak (Tectona grandis) in the tropical deciduous forests, despite being the common elements of the forests, are under-represented, sporadically represented or not represented at all, which could be ascribed to their low pollen productivity owing to entomogamy. Various factors that affect the deposition pattern of the diverse constituents of the tropical deciduous forests dominated by teak (Tectona grandis) have been discussed and suggestions are also given while interpreting the pollen sequences generated from the sedimentary beds in terms of past vegetation and climate in a chronological order in the region during the Late Quaternary Period.

Quaternary palaeoclimatic studies in India, with reference to palynology, commenced in the early part of the twentieth century. Sporadic studies continued until the 1940s. A watershed in palynological research in the country occurred in the late 1940s, primarily with the inception of the Birbal Sahni Institute of Palaeobotany (recently renamed the Birbal Sahni Institute of Palaeosciences). Since then, other academic centres and universities have also steadily contributed in augmenting palynological research in India. Preliminary studies, though seemingly rudimentary, nonetheless helped in the expansion of the palynological database for the country. The pioneering workers, in spite of limited resources, did a creditable job in undertaking palynological studies across a vast territory. Earlier, studies were limited to local data generation; recent research has featured stronger global contextualisation. This includes the Last Glacial Maximum (LGM), Younger Dryas (YD), Holocene Climatic Optimum (HCO), Medieval Warm Period (MWP) and Little Ice Age (LIA). The recent progress of palynology in India, with reference to Quaternary palaeoclimatic studies, is discussed and reviewed in this article.

Pollen records from a 1.8-m deep sediment profile from Lakadandh Swamp, Baikunthpur Forest Range of Koriya District, Chhattisgarh (C'garh, central India), show the late Quaternary vegetation and climate history. Lakadandh Swamp occurs in the core monsoon zone of India. The study revealed that between ∼12,785 and ∼9035 cal. yrs BP, tree savannah vegetation, – composed of Poaceae, Amaranthaceae, Tubuliflorae along with the tree taxa Holoptelea sp. and Sapotaceae; sparsely distributed Acacia sp., Emblica officinalis, Lagerstroemia sp., Madhuca indica and Syzygium sp., thickets of Ricinus and Zizyphus sp. – occurred in the region under a cool and dry climate probably indicative of reduced monsoon precipitation. The early part of this phase is comparable with the Younger Dryas (YD) cold event which occurred between ∼12,800 and ∼11,500 yrs BP. Between ∼9035 and ∼4535 cal. yrs BP, the expansion of existing taxa Holoptelea sp., Sapotaceae, Madhuca indica, Ailanthus excelsa and Lagerstroemia sp. as well as the appearance of Acacia, and Shorea robusta, Acanthaceae, Rungia sp., and Ricinus sp., shows the tree savannah vegetation was replaced by open mixed tropical deciduous forest under a regime of warm and moderately humid climate with increased monsoon precipitation. Since ∼4535 cal. yrs BP to Present, owing to the improvement of most of the forest constituents, particularly Madhuca indica, Holoptelea sp., Sapotaceae and Lannea coromandelica, and also with immigration of Terminalia sp., Diospyros sp., Butea sp. and Maytenus sp., mixed tropical deciduous forest has taken over the space covered by open mixed tropical deciduous forest under a warm and relatively more humid climate, with further increase in monsoon precipitation. The existing cereal-based agricultural practice increased during the latter two phases, which could be attributed to increased monsoon precipitation.