Spatial Distribution, Population Structure and Neighbour Relation of Trewia nudiflora within Forested Vegetation of North-Eastern U.P., India

Abstract

Trewia nudiflora Linn. (Euphorbiaceae) is a soft wooded, fast growing multipurpose dioecious tree which grows within the moist semi-evergreen tropical forests of north-eastern Uttar Pradesh. Its spatial distribution, population structure and neighbour relation were examined within eight plots located at six different sites differing in the light regimes and soil moisture status. Loose sub-populations of male and female trees were recognized at all the sites and the distance between any two female sub-populations was greater than that between two male sub-populations. The mean inter-sub-population distance for same sex and for opposite sex was lesser in shaded and high moisture environment. The number of male trees per sub-population was greater under open environment with average soil moisture while that of female sub-populations was greater under high moisture environment. Further, the inter-tree distances for any two adjacent female trees was significantly greater than for the two adjacent male trees. Further, female individuals generally occurred in highly moist soil of low bulk density while male individuals occurred more on relatively lesser moist soil of higher bulk density. As regards to the population structure, the proportional share of seedlings and saplings was quite high under exposed and high soil moisture conditions. The proportional share of young as well as mature trees of T. nudiflora was always higher in open as compared to shaded condition and the number of mature trees showed gradual decrease with decreasing light intensity. Further, the sites having better light and moisture regimes showed greater proportion of females and juveniles. The neighbourhood analysis showed that the density of neighbouring species of all the three life forms-herbs, undershrubs and shrubs was generally greater within the neighbourhood zone of target male trees than that for the target female trees of Trewia under all the light regimes. More than 60 species occurred within the neighbourhood zone of T. nudiflora, which shows quite stable population and niche occupancy to cope up with the prevailing forest environment of the region.