Desert vegetation and vegetation-environment relationships in Kirthar National Park, Sindh, Pakistan

摘要

A survey of the desert vegetation of Kirthar National Park, Pakistan, recorded 466 plant species in 372 sample quadrats. Classification (Twinspan) and ordination (NMDS) of dry season vegetation data (using 368 species) identified nine 'natural' and one 'cultural' vegetation assemblages: (1) Wetlands, (2) Riparian woodlands, (3) Sandy riparian woodlands, (4) Plains woodlands, (5) Stony shrublands, (6) Stony foothills woodlands, (7) Rocky riverbed shrublands,(8) Rocky slopes woodlands, (9) Cliffs, peaks and canyons vegetation, and (10) Irrigated fields. Major differences in species composition of vegetation existed between mountains, plains, wetlands and riparian vegetation. The vegetation of mountains, cliffs and canyons showed higher species richness and lower human impacts (from livestock grazing and wood harvesting) than did that of riparian and plains habitats. Physical environmental factors likely to affect water availability (e.g. slope angle, rockiness) were more important than soil chemical and human impact factors in determining the distribution of the major vegetation types and species richness patterns. Mountain-tops and canyons are reservoirs of high species richness and rare species, and may have acted as long-term refugia for species of more mesic environments. Plant species and community conservation priorities for the park are identified.