Species richness and composition
In the study area, a total of 47 herbaceous species were recorded. The
herbaceous species richness was significantly higher (ANOVA: F = 60.61,
df = 2, p < 0.001) in the enclosure land sites compared to the
grazing and browsing sites. The Shannon diversity index for herbaceous
species was estimated at 3.07, 2.92, and 2.78 for the enclosure,
grazing, and browsing areas, respectively. On the other hand, the woody
species richness was significantly lower (ANOVA: F = 13.61, df = 2, p
< 0.001) in the enclosure land sites compared to the grazing
and browsing sites (Table 1). The Shannon diversity index for woody
species was estimated at 1.22, 1.36, and 1.25 for the enclosure,
grazing, and browsing areas, respectively.
The distribution of herbaceous species composition varied significantly
(ANOVA: F = 11.145, df = 2, permutations = 999, p < 0.001)
among sites with different grazing management practices. The CCA
analysis (Figure 3) showed some clear clustering of herbaceous species
in association with the different grazing management practices. Notably,Chrysopogon aucheri, Chlor is gayana, Digitaria
abyssinicum , and Themeda triandera species were widely
distributed in the enclosure management sites. Whereas Tragus
berteronianus and Eragrostis sp. species were highly distributed
in the open grazing sites. In contrast, Abutilon fruticosum,
Hibiscus asperhook , and Tragus racemosus species were more
prevalent in the browsing management sites (Figure 3).
The distribution of desirable herbaceous species was greater in the
enclosure’s sites than in other management sites (Table 2). Among
herbaceous species, desirable species of Chloris gayana,
Chrysopogon aucheri, Cynodon dactylon, and Themeda triandera were
distributed by 88.9%, 100%, 64.00%, and 93.33% respectively in the
enclosure sites. In contrast, the distribution of undesirable herbaceous
species was higher in grazing and browsing sites than in the enclosure
sites. In the browsing site the less desirable species of Tragus
racemosus and Sida sp were highly distributed by 56.67% and 46.67%
respectively.
Moreover, we identified a total of five Acacia species and one Vachellia
species. The composition of these woody species varied significantly
(ANOSIM: R = 0.58, permutations = 999, p < 0.001) depending on
the type of grazing management practices implemented in the area.Acacia etbaica was the dominant species in the browsing
(Bay) management sites. Whereas Acacia busie was the
dominant species in the enclosure and open grazing sites
respectively (Table 3).