Diversity of naturalized plant species across different land use types in Kailali district, western Nepal
Date
2019
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
Department of Botany
Abstract
With the increasing movement of organisms directly and indirectly by human
activities across natural biogeographic barriers, the number of naturalized plant
species has been increasing both in disturbed and human-modified ecosystems. Due to
variation in propagule pressure of naturalized plant species, available resources,
disturbance regimes and species interactions, diversity of naturalized species may
vary across vegetation and land use types. Naturalized plants species richness
measured in different vegetation and land use types in Kailali district by using
Modified-Whittaker nested vegetation sampling method (50 m × 20 m) and five plots
were sampled in each of the seven land use types so, total number of sampling plots
were 35. We recorded 792 species including 22 pteridophytes, 1 gymnosperm and 769
angiosperms; among them 670 were native species, 87 naturalized species and
remaining 35 species were cryptogenic. Species richness of native, naturalized and
invasive species significantly (p<0.05) varied across land use types. Naturalized
species richness was the highest in roadside grazing land (17.2±1.35), followed by
agriculture land (11.4±2.11) and it was the lowest in Shorea-Terminalia forest
(3.6±1.43). Among invasive species Ageratum houstonianum was the most frequent
(41%), followed by Senna tora (33%). However, Senna tora had the highest cover
(64%) followed by Ageratum houstonianum (30%). The naturalized species richness
showed significant relation (p≤0.05) with grazing, native species richness, distance
from river, tree canopy cover, soil pH, distance from settlement area and distance
from road. Also, invasive species richness was significantly correlated with
naturalized non-invasive species richness, grazing, tree canopy cover, soil pH, native
species richness. Present study revealed the naturalized species were more colonized
in human-modified and disturbed land use types that provide propagules for further
spread to other vegetation and land use types in the region so, land use modification
and disturbance factors as major governing factors for the naturalized plant species
diversity. Therefore, the more modified and disturbed land use types should be
regularly monitored for early detection and eradication as a part of management
strategy for naturalized plant species.
Description
Keywords
Species richness, Disturbance, Alien species, Modified land use