Microhabitat variations and seed bank-vegetation relationships in a desert wadi ecosystem

Published Date

December 2014, Vol.209(12):725–732, doi:10.1016/j.flora.2014.09.004

Title 

Microhabitat variations and seed bank-vegetation relationships in a desert wadi ecosystem

• Author 

• Nasr H. Gomaa ^,

• Department of Botany & Microbiology, Faculty of Science, Beni-Suef University, Beni-Suef, Egypt

Received 7 April 2014. Revised 11 September 2014. Accepted 12 September 2014. Available online 19 September 2014. Edited by Brigitta Erschbamer

Highlights

• •
  The floristic composition and structure of soil seed bank varied among wadi microhabitats.
• •
  The functional properties, diversity and size of seed bank differed among microhabitats.
• •
  The above-ground vegetation influenced the density and diversity of seed bank.
• •
  Differences in seed bank could be related to variations in disturbance and soil factors.

Abstract

Due to extreme variability in patterns of rainfall, plant seed banks are an important component of desert habitats. Here I report on effects of standing vegetation and three different microhabitats (channel, bank and terrace) on the soil seed bank of a desert wadi ecosystem in the Eastern Desert of Egypt. A total of 450 soil samples at 45 stands were collected to represent the different wadi microhabitats. The germinable seed bank was estimated by controlled counts of seedling emergence. The floristic composition, functional properties and diversity of the soil seed bank, as well as its similarity with the standing vegetation varied among wadi microhabitats. Such variation could be attributed to differences in disturbance intensity among microhabitats (terrace < bank < channel) and variation of soil factors along the microtopographic gradient. Channel showed the highest species richness and size of soil seed bank, followed by bank and then terrace. Moreover the Shannon index of diversity of the seed bank and its similarity with standing vegetation were significantly greater in both channel and bank microhabitats than in terrace. At the level of plant functional groups, number of seeds of annuals was higher in both channel and bank than in terrace. Shrubs were more abundant in seed banks of channel compared to terrace. The size and species richness of seed bank were increased with the total plant cover, annual/perennial ratio and species richness of the standing vegetation.

Keywords

• Disturbance
• Species diversity
• Species composition
• Soil variables

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