干旱区生态环境知识资源中心

This study focuses on the population ecology of a desert summer annual, Ipomoea sindica Stapf, the abundant flora after the monsoon rains in Karachi, Sindh. Two sites were selected for the study, designated as site ’A’ and ’B’. Site ’A’ was thy having low water holding capacity, on the other hand, site ’B’ had high water holding capacity. Vegetation was comparatively sparse at site ’A’, whereas, relatively high water holding capacity and nutrient status of the soil ’B’, presumably enable the population to flourish with higher densities. I. sindica exhibited Deevey type I survivorship curves at both the sites. Plants inhabiting site ’B’showed better vegetative and reproductive growth than those surviving at site ’A’. Large quantity of seeds were present in the buried seed pool. Their number decreased after the monsoon rains i.e., after the germination of seedlings. Rise in the seed bank was observed after dispersal from the existing vegetation, thus exhibiting persistent type of seed bank. I. sindica produces heavy seeds in smaller numbers. That’s why the dispersal distance travelled by the seeds was less. Most of the seeds fall near the mother plant due to their heavy weight and horizontal growth of plants.