QUANTITATIVE DESCRIPTION OF RAPIDLY CHANGING VEGETATION AROUND KARACHI

Abstract

A phytosociological survey was conducted at 30 sites on different habitats i.e. tidal area, saline, waterlogged, dry stream, flat sandy, nalas and hard rocky areas around Karachi. Plant communities, importance values of some dominant species and absolute values of different stands were presented. Importance values of 1 st three dominant species ranged from 43 to 271, 2 nd dominant species from 29 to 75 while 3rd dominant species occupied from 22 to 57 importance values. Overall 83 different species were recorded in this study. Stand density ranged from 3839 plants ha-¹ to 15000 plants ha-¹, while cover ranged from 7.78 m²ha-¹ to 92.85 m²ha-¹. Stand density and cover not related significantly while it was positively significantly related in some species. Alien species Prosopis juliflora supersede native species completely in 4 stands occupying 1st dominant position in 8 stands captured 2nd dominant position in 7 stands while present as a 3rd dominant species in 4 stands. It is anticipated that this species not only enhanced its domination in sandy and hard surface area but invade saline and coastal areas slowly. Present investigation also compares floristic composition and plant communities of past to those at present. Anthropogenic disturbances is also a main reason to alternative communities with the aggressive behavior of Prosopis juliflora.