Evaluation of Temperature and Precipitation Since 4.3 ka Using Palynological Data from Kundala Lake Sediments, Kerala, India

A comprehensive database of paleo vegetation from Kundala Lake, Kerala, was used for a palynological study in a 120 cm sedimentary profile from Kundala Lake (1700 mamsl), Palni Hills, to understand the climate and vegetation equilibrium during the last four millennia. On the basis of pollen assemblage and cluster analysis, a relatively high percentage of evergreen vegetation between 4.3 and 3.4 ka (phase I) was inferred to represent the relicts of middle Holocene vegetation during a warmer climate. Subsequently, in the periods of 3.4–2.3 ka (phase II) and 2.3–0.87 ka (phase III), herbs/shrubs dominated. A relative increase in the percentage of arboreals along with herbaceous taxa was again observed from 0.87 to 0.12 ka (phase IV). Later, in phase V (from 1820 AD to present), few new plant taxa were recorded. On the basis of the ‘coexistence approach’, the Mean Annual Temperature (MAT) was inferred to be 22 °C, 15 °C, 15 °C, 20 °C and 22 °C during phases I to V, respectively. The Mean Annual Precipitation (MAP)was 2660 ± 3700 mm from ~4.3 to 0.12 ka; however, it decreased to ~1750 mm between 3.4 and 2.3 ka. However, pollen evidence reveals short-term cooler spells during the 16/17th century AD, which is in concordance with the globally recorded cooler and arid climate that began sometime from ~5.0 to 4.0 ka. A thematic digital elevation map of vegetation reconstructed for the years 2005 and 2018 shows a reduction in evergreen plants and water bodies in the vicinity of Kundala Lake, which was correlated with the results of palynological studies and Indian meteorological data for the last ~100 years in the region.