Effect of exclosure on woody species diversity and population structure in comparison with adjacent open grazing land: the case of Jabi Tehnan district north western Ethiopia

Figures & data

Figure 1. Map of the study sites

DBH Class (cm) 1 = <2, 2 = 2–5.5, 3 = 5.5–8.5, 4 = 8.5–11.5, 5 = 11.5–13.5, 6 ≥ 13.5

Table 1. Specific study site description

	Keble (Peasant Association)
	Wega Guanaesa (WG)	Gay Webishet (GW)
Altitude	2000–2300 m.a.s.l	1833–1863 m.a.s.l
Topography	45% mountain, 30% hill, and 25% gentle slope/flat terrain.	0.75% mountain, 94% gentle/flat, and 5.25% valley
Size of exclosure	12.5 ha	13.5 ha
Size of open grazing land	14 ha	8.5 ha

Table 2. Woody species recorded in the Wega guanaesa and Gay webishet site

Scientific name	Family	Life form	Wega guanaesa					Gay webishet
			Gn	Og (n = 10)		Ex (n = 10)		Gn	Og (n = 10)		Ex (n = 10)
				Fr	Ab	Fr	Ab		Fr	Ab	Fr	Ab
Acacia abyssinica	Fabaceae	T	11	1	10	3	8	11	1	3	5	15
Acacia brevispica	Fabaceae	SH	11	–	–	1	1	–	–	–	–	–
Acacia decurrens*^+	Fabaceae	T	11	–	–	10	16	–	–	–	–	–
Acacia saligna*^+	Fabaceae	SH/T	11	–	–	1	5	–	–	–	–	–
Albizia gummifera	Fabaceae	T	18	–	–	1	1	20	–	–	10	16
Bersama abyssinica	Melianthaceae	T	4	8	32	10	17	4	2	2	10	5
Carissa spinarum	Apocynaceae	SH	2	4	5	10	16	2	5	6	1	3
Casuarina equisetifolia*^+	Casuarinaceae	T	3	0	0	4	4	3	–	–	8	8
Clutia abyssinica	Euphorbiaceae	SH	–	–	–	–	–	8	8	8	7	20
Cordia africana	Boraginaceae	T	20	–	–	1	1	23	1	2	4	4
Croton macrostachyus	Euphorbiaceae	T	17	8	32	2	6	19	10	70	4	19
Cupressus lusitanica*^+	Cupressaceae	T	19	1	1	10	25	22	–	–	4	6
Dovyalis abyssinica	Flacourtiaceae	SH	–	–	–	–	–	15	–	–	1	10
Eucalyptus camaldulensis*^+	Myrtaceae	T	5	1	1	–	–	0	–	–	–	–
Strychnos spinosa	Myrtaceae	T	–	–	–	–	–	–	–	–	0.9	0.7
Ficus thonningii	Moraceae	T	8	–	–	1	1	7	2	2	1	3
Grevillea robusta*^+	Proteaceae	T	12	–	–	10	20	12	–	–	5	10
Grewia ferruginea	Tiliaceae	SH/T	16	–	–	1	1	0	–	–	–	–
Inula decipiens	Asteraceae	T	15	5	6	3	6	16	1	4	6	18
Leucaena leucocephala*^+	Fabaceae	T	–	–	–	–	–	17	–	–	1	5
Maerua aethiopica	Capparidaceae	SH	10	–	–	2	2	10	1	1	5	187
Mangifera indica*^+	Anacardiaceae	T	–	–	–	–	–	18	–	–	3	10
Millettia ferruginea	Fabaceae	T	6	1	1	–	–	5	–	–	1	2
Osyris quadripartite	Santalaceae	T	14	4	16	10	88	14	–	–	1	8
Rhus natalensis	Anacardiaceae	SH/T	7	0	0	1	1	6	–	–	4	12
Rosa abyssinica	Rosaceae	SH/T	13	4	20	2	10	13	–	–	1	2
Sesbania sesban*^+	Fabaceae	SH	–	–	–	–	–	21	–	–	6	6
Terminalia brownii*	Combretaceae	T	1	1	4	4	10	1	6	6	7	19
Vernonia amygdalina	Asteraceae	SH/T	9	1	3	1	4	9	–	–	8	27
Vernonia auriculifera	Asteraceae	SH	9	10	70	10	184	9	3	3	4	10
Total				49	201	98	427		40	107	107	425

Fr = Frequency, Ab = Abundance, Gn = genera, Op = open grazing land Ex = Exclosure, T = Tree, SH = shrub. *Exotic; ⁺Planted.

Table 3. Mean ± SE basal area, density, and woody species diversity per plot

Land use	Wega guanaesa (WG)			Gay webishet (GW)
	Basal area (m^2)	Shannon diversity	Density (stem/ha)	Basal area (m^2)	Shannon diversity	Density (stem/ha)
Op (n = 10)	0.77^a ± 0.31	0.17^a ± 0.03	87.38 ± 25	0.42^a ± 0.04	0.11^a ± 0.04	61.8^a ± 43.3
Ex (n = 10)	2.17^b ± 0.57	0.3^b ± 0.05	109.8^b ± 33	1.47^b ± 0.45	0.29^b ± 0.07	506.7^b ± 203
P value	0.044	0.04	0.01	0.033	0.03	0.046

Means with the same letters across column are not significantly different (P > 0.05); Op = adjacent open grazing, Ex = Exclosure.

Figure 2. Population structure of woody species in adjacent open grazing land of Wega guanaesa site

DBH Class (cm) 1 = <2, 2 = 2–5.5, 3 = 5.5–8.5, 4 = 8.5–11.5, 5 = 11.5–13.5, 6 ≥ 13.5

Figure 3. Population structure of woody species in exclosure land of Wega guanaesa site

DBH Class (cm) 1 = <2, 2 = 2.5–5.5, 3 = 5.5–8.5, 4 = 8.5–11.5, 5 = 11.5–13.5, 6 ≥ 13.5

Figure 4. Population structure of woody species in adjacent open grazing land of Gay webishet site

Figure 5. Population structure of woody species in exclosure land of Gay webishet site

Table 4. Mean ± SE of woody species abundance, richness and evenness per plot

Land use	Wega guanaesa			Gay Webishet
	Abundance	Richness	Evenness	Abundance	Richness	Evenness
Open (n = 10)	20.1^a ± 1.95	1.3^a ± 0.15	0.086^a ± 0.2	10.7^a ± 2.98	1.1^a ± 0.1	0.045^a ± 0.009
Exclosure (n = 10)	42.7^b ± 3.36	2.2^b ± 0.4	0.095^a ± 0.01	42.5^b ± 10.46	2.4^b ± 0.4	0.08^b ± 0.01
P value	0.000	0.002	0.72	0.009	0.006	0.025

Means with the same letters across column are not significantly different (P > 0.05).

Table 5. List of woody species recorded with their density, frequency, abundance, dominance at Gay webishet site

Scientific name	Exclosure (n = 10)				Open Grazing land (n = 10)
	Den	Fre	Abu	Dom	Den	Fre	Abu	Dom
Millettia ferruginea	27.05	1	2	0.17	–	–	–	–
Strychnos spinosa	31.05	1	3	0.22	–	–	–	–
Rosa abyssinica	27.05	1	2	0.24	–	–	–	–
Dovyalis abyssinica	59.05	1	10	0.2	–	–	–	–
Carissa spinarum	94.05	1	3	0.32	425	5	6	0.11
Rhus natalensis	31.05	4	12	0.25	–	–	–	–
Cupressus lusitanica	23.05	4	6	0.36	–	–	–	–
Cordia africana	23.05	4	4	0.47	8	1	2	0.06
Croton macrostachyus	47.05	4	19	0.48	28	10	70	2.98
Grevillea robusta	69.05	5	10	0.39	–	–	–	–
Vernonia auriculifera	169	4	10	0.29	25	3	3	0.02
Inula decipiens	31.05	6	18	0.46	16	1	4	0.05
Osyris quadripartita	419	1	8	0.17	–	–	–	–
Acacia abyssinica	31.05	5	15	0.87	12	1	3	0.38
Sesbania sesban	44.05	6	6	0.76	–	–	–	–
Casuarina equisetifolia	69.05	8	8	0.59	–	–	–	–
Vernonia amygdalina	81.05	8	27	0.6	–	–	–	–
Clutia abyssinica	144	7	20	0.57	25	8	8	0.07
Terminalia brownii	119	7	19	1.01	25	6	6	0.29
Bersama abyssinica	89.52	10	5	0.33	25	2	2	0.04
Albizia gummifera	23.05	10	16	0.8	–	–	–	–
Maerua aethiopica	44.05	5	187	2.46	25	1	1	0.03
Mangifera indica	1352	3	10	1.77	–	–	–	–
Leucaena leucocephala	2019.1	1	5	0.93	–	–	–	–
Ficus thonningii	–	–	–	–	4	2	2	0.14
Total	5066.47	107	425	14.71	618	40	107	4.17

Where Den = density (Stem/hectare), Fre = Frequency, Abu = Abundance, Dom = Dominance (Basal area (m²) of woody species per hectares of land they cover); - is absent

Table 6. List of woody species recorded with their density, frequency, abundance, dominance at Wega guanaesa site

Scientific name	Exclosure (n = 10)				Open grazing land (n = 10)
	Den	Fre	Abu	Dom	Den	Fre	Abu	Dom
Acacia abyssinica	32	3	8	0.8	40	1	10	2.83
Acacia brevispica	4	1	1	0.7	–	–	–	–
Acacia decurrens	24	10	16	1	–	–	–	–
Acacia saligna	20	1	5	0.8	–	–	–	–
Albizia gummifera	4	1	1	0.7	–	–	–	–
Bersama abyssinica	39	10	17	1.1	32	8	32	0.34
Carissa spinarum	26.67	10	16	1.5	5	4	5	0.12
Casuarina equisetifolia	4	4	4	0.8	–	–	–	–
Cordia africana	4	1	1	0.7	–	–	–	–
Croton macrostachyus	12	2	6	1	16	8	32	2.34
Cupressus lusitanica	87	10	25	1	500	1	1	–
Ficus thonningii	68.49	1	1	0.7	–	–	–	–
Grevillea robusta	5.33	10	20	1	–	–	–	–
Grewia ferruginea	4	1	1	0.7	–	–	–	–
Inula decipiens	8	3	6	0.8	4.8	5	6	0.06
Maerua aethiopica	29	2	2	0.8	–	–	–	–
Osyris quadripartita	48	10	88	1.6	16	4	16	0.36
Rhus natalensis	8	1	1	0.7	–	–	–	–
Rosa abyssinica	15	2	10	0.9	20	4	20	0.21
Terminalia brownii	10	4	10	0.8	16	1	4	0.11
Vernonia amygdalina	16	1	4	1	16	1	3	0.21
Vernonia auriculifera	550	10	184	2.5	200	10	70	0.86
Eucalyptus camaldulensis	–	–	–	–	4	1	1	0.24
Millettia ferruginea	–	–	–	–	4	1	1	0.01
Total	1018.49	98	427	21.6	873.8	49	201	7.69

Where Den = density, Fre = Frequency, Abu = Abundance, Dom = Dominance; - is absent.