Species Composition and Structure of Isoberlinia Woodland of Shika, Zaria Nigeria

Abstract

This study was carried out to investigate the effect of farming activities on Isoberlinia woodland. This was achieved by assessing their composition and structural characteristics in two plots, 30 m x 30 m each, the plots were farming plot and a rested plot of minimum anthropogenic impacts (here called disturbed and undisturbed plot respectively). Data were collected from each plot, all woody species were identified and their height, diameter at breast height (dbh), basal area, volume, diversity and biomass were measured. In addition, herbaceous diversity and biomass were also determined. Dominance species were determined by the Importance Value Index (IVI). Soils were augured, collected and analyzed for physico-chemical parameters. A total of 71 species belonging to 36 families were identified. Shannon-wiener diversity index showed that the disturbed plot was 2.441 and equitability of 0.733 had higher diversity when compared to the undisturbed (2.331 and 0.685) respectively. These two plots were 66% similar in vegetal composition. Analysis of the importance value index revealed that the dominant species in the area was Isoberlinia doka. The total basal area and volume was very low at both plots. The woody biomass for the undisturbed was 0.015 ton/ha for the undisturbed and 0.001 ton/ha for the disturbed plot. The total herbaceous biomass for the undisturbed plot was 70.7 ton/ha and 49.7 ton/ha for the disturbed plot. The soils were characteristically alfisols and much degraded reflecting degrees of vegetal exploitation. The low woody volume and biomass though disturbing but not withstanding had high Isoberlina component hence, the woodland can still and better be called degraded Isoberlinia woodland.