Exploring the herbaceous plant height and dry matter relationship on a sub-humid rangeland in Zimbabwe

Abstract

A study was carried out at the University of Zimbabwe Farm, to assess and quantify the correlation between plant canopy height and biomass in the rangelands of Zimbabwe. Two range sites, bush grassland and grassland, were selected and three paddocks within each range site were sampled. Four 25 m long transects were drawn in the four cardinal directions from the paddock center. Five 0.25 m2 quadrants were located at 5 m intervals on each transect line. Common plant species in both bush grassland and grassland range sites were Sporobolus pyramidalis, Hyparrhenia filipendula, Cynodon dactylon, and Eragrostis curvula. There was a significant (P<0.05) linear relationship between plant height and biomass for both range sites. There was a significant (P>0.05) quadratic relationship between plant height and biomass for grassland but not for the bush grassland. Pearson Correlation Coefficient (r) was 0.929 for grassland and 0.717 for bush grassland. The regression equation was y = 15.82x – 0.02x2 for bush grassland and y = 15.88x – 0.27x2 for grassland. The coefficient of determination (r2) for grassland was 0.863 and 0.514 for bush grassland. Variation in plant height explained 86.3% of the variation in biomass for grassland and 51.4% for bush grassland accordingly.