Research Article

Changes in Regulating Ecosystem Services following Establishing Exclosures on Communal Grazing Lands in Ethiopia: A Synthesis

Table 4

Average (±SE, ) of species composition and diversity in exclosures and communal grazing lands and their differences.

VariablesExclosure age (year)ExclosuresAdjacent grazing landsDifferencesaP valueb

Richnessc (number)520.0 (1.7)10.0 (0.3)10.00.01
1015.7 (1.8)6.7 (4.1)9.00.11
1530.0 (6.8)10.7 (2.7)19.30.02
2031.3 (4.2)11.7 (4.8)19.60.03

Diversity (Shannon-Wiener index)51.4 (0.1)1.3 (0.1)0.10.17
101.4 (0.1)0.7 (0.2)0.70.01
152.0 (0.1)0.9 (0.2)1.10.00
202.1 (0.1)1.4 (0.2)0.70.00

Evenness (Shannon-Wiener index)50.56 (0.04)0.78 (0.03) 0.01
100.67 (0.03)0.41 (0.10)0.260.00
150.67 (0.03)0.58 (0.12)0.090.44
200.72 (0.05)0.73 (0.04) 0.13

Herbaceous species
(number)
52.7 (0.3)0.7 (0.3)2.0 0.01
102.0 (1.2)1.3 (0.9)0.70.67
153.0 (0.6)0.7 (0.3)2.30.02
204.7 (1.5)1.3 (0.9)3.30.12

Shrub species (number)510.3 (1.7)5.3 (0.7)5.00.04
107.7 (0.9)3.7 (2.3)4.00.18
1515.7 (1.8)6.3 (1.7)9.30.01
2014.7 (1.8)6.7 (2.2)8.00.04

Tree species (number)54.0 (0.6)2.0 (0.6)2.00.07
104.0 (0.6)1.0 (0.6)3.00.02
158.0 (3.1)2.7 (0.7)5.30.16
208.0 (1.0)3.0 (1.0)5.00.02

Economically important species (number)56.3 (0.9)2.7 (0.9)3.70.04
105.0 (1.0)2.0 (0.6)3.00.06
159.0 (2.1)4.0 (1.5)5.00.12
208.0 (1.0)2.7 (1.2)5.30.03

Differences are calculated as exclosure values minus adjacent grazing land values. Differences in species richness are equivalent to the value of beta diversity provided that we did not encounter a species unique to the communal grazing lands. bThe P values are values obtained after paired t-test. cRichness refers the total number of plant species in an area including forbs, lianas, and grasses.