Modern pollen assemblages from teak (Tectona grandis Linn. F.) dominated tropical deciduous forest in southwestern Madhya Pradesh, India
Keywords:Pollen analysis, Surface sediments, Mixed tropical deciduous forests, Hoshangabad, Madhya Pradesh, India
This paper gives an account on the modern pollen rain–vegetation relationships, based on the pollen analysis of 12 surface samples, 2 samples each collected from the southern, northern, eastern and western flanks of Amjhera Swamp as well as 4 from the mixed tropical deciduous forests dominated by teak (Tectona grandis) in Hoshangabad District, southwestern Madhya Pradesh, India. The pollen assemblages demonstrate the dominance of arboreals (trees and shrubs) over non–arboreals (herbs). Among the tree taxa, Madhuca indica is constantly represented with average pollen frequency of 37.36% in most of the samples which could be attributed to the good preservation of its pollen in the sediments coupled with its high pollen dispersal efficiency. Terminalia (av. 5.1%) is also retrieved steadily. However, Tectona grandis is untraced in the samples despite being an enormous pollen producer and dominant forest component, which could be due to its low pollen dispersal efficiency and differential pollen preservation. Besides, Adina cordifolia, Mitragyna parvifolia, Schleichera oleosa and Emblica officinalis are present with average pollen frequencies of 8.1%, 7.8%, 6.69% and 1.126%, respectively, but only in a few samples. Syzygium, Maytenus, Lagerstroemia, Lannea coromandelica, etc. are also intermittently recovered in almost all the samples, but in varying frequencies (< 0.5%–7.91%) despite their frequent presence in the forest. This erratic display of all these taxa could be inferred to their low pollen productivity, since majority of the tropical trees portray a strong tendency of entomophily. The partial preservation of their pollen in the sediments cannot also be denied. The relatively meagre representation of grasses, sedges, Malvaceae, Xanthium except Tubuliflorae and culture pollen taxa such as Cheno/Am, Caryophyllaceae, Brassicaceae and Cannabis sativa are suggestive of poor herbaceous cover around the swamp and also in the mixed tropical deciduous forest. However, the record of Cerealia and other culture pollen taxa stamps the proximity of cultivated land and human habitation in and around the investigation site. The abundance of trilete fern spore as well as Ceratopteris, monolete fern spore and trilete with perine, though in relatively low values envisages their origin from the local sources as ferns and their allies flourish well in moist and shady habitats.