Effects of soil type on density of trees and nutritive value of tree leaves in selected communal areas of South Africa

Abstract

This study aimed to describe the distribution and nutritive value of woody species growing in clay-loamy and red-brown sand from selected localities of North West, South Africa. Three 2.2 km transects, radiating from homesteads, which served as replicates, were established at each of four selected grazing areas. Nine 10 × 10 m homogenous vegetation units (HVU), 20 m apart, were marked in each transect. Woody plant density, height and canopy cover (CC), were recorded, and chemical properties and degradability via in vitro ruminal fermentation of harvested leaves were measured. Raisin bush (Grewia flava), Buffalo thorn (Ziziphus mucronata) and Camel thorn (Vachellia erioloba) were the common species across both soil types. Soil type influenced (P <0.05) plant density, CC, total tree equivalent (TTE) and plant height. Areas with red-brown sandy soil had higher (P <0.05) total plant density (827.7 plant/ha), CC (9.6%) and TTE (2886.4 TTE/ha) than those with clay-loamy soil. Vachellia erioloba leaves in clay-loamy soil had the highest (P <0.05) crude protein content (151.2 g/kg DM). Leaves of Searsia lancea species that were harvested from both the clay-loamy and red-brown sandy soils had the highest (P <0.05) amounts of condensed tannins (0.915 AU550/200 mg and 0.917 AU550/200 mg, respectively). Searsia lancea leaves had the lowest (P <0.05) in vitro ruminal nitrogen degradability values in both soil types. The leaves of Z. mucronata and G. flava leaves have potential as protein supplements for ruminants owing to their higher crude protein content and in vitro ruminal N degradability.
 Keywords: canopy cover, feeding value, plant height, semi-arid, species diversity, tree equivalent

Nutrients Profile of 52 Browse Species Found in Semi-Arid Areas of South Africa for Livestock Production: Effect of Harvesting Site

“…The nutritive content (Ash, CP, CF, ADL, NFC, DMD, DE and ME) in this study showed a wide significant variation among the browse species found in both soil types. These findings are consistent with Kraus et al [14] and Ravhuhali et al [2], who discovered that spatial variation has a great influence on the chemical composition of browse leaves. In this study, it was observed that the ash content from this study was higher in GM-L than AKS-CH, with a range between 35.7-136.7 g/kg DM.…”

“…Browse tree species have long been considered important for livestock nutrition, particularly where the quantity and quality of feedstuff are limited for prolonged periods [1,2,42]. In this study, variations were observed among species and harvesting sites and the interaction between species and harvesting sites.…”

“…The amount of acid detergent acid present in the substrates has a direct influence on the digestibility of the diets and most of the browse species in this study had higher DM digestibility values. These results can be influenceby different soil types and other environmental factors within various locations, as demonstrated by Kwaza et al [39], Ravhuhali et al [2] and Sariyidiz and Anderson [19]. Mlambo et al [6] stated that cell wall composition, lignin and tannins are some of the elements that may influence the variance in digestibility among browse species.…”

“…This is due to the fact that livestock mostly most rely on high fiber diets that have low nutrients such as protein, mineral, carbohydrates and vitamins. For livestock production in the Sub-Saharan areas, including South Africa, browse woody species have long been considered essential for livestock nutrition, particularly where the quantity (biomass) and quality of feedstuff is low for long periods [1,2].…”

“…Spatial variation is also one of the factors influencing the concentration levels of nutrient elements in browse species [2,13]. Spatial variation involves several attributes such as area temperature [14,15], light-and ozone-influencing photosynthesis processes on plants, altitude [16], soil moisture, type and the fertility of certain areas [2,[17][18][19].…”