Pollen rain deposition pattern in tropical deciduous Sal (Shorea robusta Gaertn.) forest in Shahdol District, Madhya Pradesh, India

Abstract

The pollen rain–vegetation relationship study, based on pollen analysis of 6 surface samples from tropical deciduous Sal (Shorea robusta Gaertn.) forest at Khanaudi, Shahdol District reveals the relatively lower frequencies of arboreal taxa in contrast to non–arboreal taxa. Among the arboreals, Shorea robusta, a dominant forest constituent, is not represented appropriately in the pollen–rain and encountered with av. 2% pollen only in the sediments. The under–representation of Shorea robusta pollen, despite being high pollen producer, could be attributed to its poor preservation in the sediments as well as low dispersal efficiency. On the other hand, the consistent presence of Madhuca indica, a common associate of Sal, and Sapotaceae with high frequencies of average 19% and 6%, respectively corresponds more or less with their frequent presence in the forest coupled with good preservation of their pollen in the sediments. However, a large number of other associates of Sal, viz. Terminalia, Lagerstroemia, Emblica officinalis, Syzygium, Holoptelea, Sterculia, etc. occurring appreciably in the forest, denote sporadic presence with av. 10% pollen only owing to their low pollen productivity, since they are entomogamous. Thus, av. 39% arboreal pollen including av. 37% trees and av. 2% shrubs, though scanty, represent the modern Sal forest in the region. The abundance of pollen of grasses, sedges, Tubuliflorae, etc. corresponds with their composition in the ground flora. The consistently moderate frequencies of Cerealia and Cheno/Am coupled with sporadic pollen of Artemisia, Cannabis sativa and Caryophyllaceae indicate the proximity of cultivated land.