Tropical Plant Research

Vivek Joshi* and Kusum Arunachalam

*School of Environment and Natural Resources, Doon University, Dehradun, Uttarakhand, India

DOI: https://doi.org/10.22271/tpr.2022.v9.i2.012

Abstract:
The present study was carried out in riverine ecotone of Tons and Pabber rivers which are tributary of river Yamuna in Garhwal Himalaya to understand the edge effect on distribution and structure of plant community patterns. The study was done at an altitude of 900 m to 1300 m to identify the plant diversity and community structure of riverine ecotone areas within a stretch of 64 km. In total Seventeen (N=17) tree species twenty one (N=21) shrub species, thirty-eight (N=38) species of herbs and three (N=3) species grasses were identified. Mallotus philippensis, Alnus nepelensis, and Pinus roxburghii were found to be dominant threes having 35.7%, 14.9% and 13.6% representation in total tree population. Out of nine (N=9), sample sites Mallotus philippensis and Pinus roxburghii were having the highest densities and relative densities in five (N=5) sites. Rubus elipticus was dominating shrub species with 16% representation followed by Zanthoxylum armatum 12.2%, Adhatoda vasica 10.3% and Agave cantula 9.3%. Rubus elipticus and Zanthoxylum armatum.were having the highest numbers in sites where the slope was gentle and soil conditions were not sandy. Whereas Adhatoda vasica was more uniformly distributed and was found growing uniformly in riverine sandy soil areas Agave cantula preferred the southern and western aspects with rocky slopes and poor soil conditions. In grasses, Carex infuscata was having highest dominance (43.64), in herbs Trifolium repens was having the highest dominance (21) followed by Cannabis sativa (20.92), Cynodon dactylon (17.8) and Verbascum thapsus (10.71). Species diversity indices used in the study was the Shannon Index, the value of diversity indicated by H' was 2.44 which indicates that the herb diversity in the ecosystem is uniformly distributed, no single herb species is dominant, whereas the dominance value which is 0.11 corroborate the diversity of the ecosystem. The value of Shannon wiener (H') index for shrub species was 1.58 which indicates that the majority of shrub (66.6%) species are distributed uniformly except Berberis lycium, Clerodendrum phlomidis, Euphorbia royleana, Indigofera heterantha, Lantana camara, Woodfordia fruticosa and Viburnum cotinifolium.