Woldu Goiteom, Solomon Negasi, Hishe Hadgu, Gebrewahid Hailemariam, Gebremedhin Mewcha Amha, Birhane Emiru
Institute of Geo-Information and Earth Observation Science, Mekelle University, P.O. Box 231, Mekelle, Ethiopia.
Department of Land Resources Management and Environmental Protection, Mekelle University, P.O. Box 231, Mekelle, Ethiopia.
Heliyon. 2019 Dec 31;6(1):e03121. doi: 10.1016/j.heliyon.2019.e03121. eCollection 2020 Jan.
Exclosures are established with the objective of rehabilitating degraded lands and restoring of woody vegetation. Various studies have been conducted to evaluate the success of exclosure on restoring woody species diversity. However, works focusing on the effect of topographic factors on woody species diversity are scarce. Understanding the factors that determine woody species diversity is important for management purposes. Therefore, this paper analyzes the effect of altitude, slope, and aspect as topographic variables on woody species diversity in Dawsura exclosure in northern Ethiopia. Data on species identity, abundance, slope, elevation and aspect were recorded from 58 sampling plots. Different diversity indices were used to analyze the data and one-way ANOVA and linear regression was conducted. There were a total of 34 woody species represented 15 families, of which 62% and 38% were trees and shrubs respectively. Altitude (r = 0.63, p = 0.000 and r = 0.794, p < 0.01) and slope (r = 0.57, p = 0.002 and r = 0.68, p < 0.01) correlated significantly and positively with Shannon diversity, whereas aspect (r = 0.12, p = 0.378 and r = 0.27, p > 0.05) did not correlate significantly with Shannon diversity. Woody species diversity at moderate (1.44) and high (1.85) altitudes was significantly different from that of low (0.86) altitude areas (p = 0.0013). Furthermore, significantly higher woody species diversity was recorded at steep slope (1.88) and moderately steep slope (1.62) areas as compared to the gentle slope (0.95) areas. No significant variation was observed in woody species diversity among the aspect categories (p > 0.05). The study concludes that woody species diversity is largely regulated by slope and altitude than aspect in the exclosure. We suggest other environmental and anthropogenic variables should be taken into consideration in future studies on woody species diversity.
建立围栏的目的是恢复退化土地并恢复木本植被。已经开展了各种研究来评估围栏在恢复木本物种多样性方面的成效。然而，关注地形因素对木本物种多样性影响的研究很少。了解决定木本物种多样性的因素对于管理目的很重要。因此，本文分析了海拔、坡度和坡向等地形变量对埃塞俄比亚北部道苏拉围栏内木本物种多样性的影响。从58个采样地块记录了物种身份、丰度、坡度、海拔和坡向的数据。使用不同的多样性指数对数据进行分析，并进行了单因素方差分析和线性回归。共有34种木本物种，分属15个科，其中树木和灌木分别占62%和38%。海拔（r = 0.63，p = 0.000；r = 0.794，p < 0.01）和坡度（r = 0.57，p = 0.002；r = 0.68，p < 0.01）与香农多样性显著正相关，而坡向（r = 0.12，p = 0.378；r = 0.27，p > 0.05）与香农多样性无显著相关性。中等海拔（1.44）和高海拔（1.85）地区的木本物种多样性与低海拔（0.86）地区显著不同（p = 0.0013）。此外，与缓坡（0.95）地区相比，陡坡（1.88）和中度陡坡（1.62）地区记录到的木本物种多样性显著更高。在不同坡向类别之间，木本物种多样性未观察到显著差异（p > 0.05）。研究得出结论，在围栏内，木本物种多样性在很大程度上受坡度和海拔的调节，而非坡向。我们建议在未来关于木本物种多样性的研究中应考虑其他环境和人为变量。
