Floristic diversity in fragmented Afromontane rainforests: Altitudinal variation and conservation importance

Abstract

Question: How does the floristic diversity of Afromontane rainforests change along an altitudinal gradient? What are the implications for conservation planning in these strongly fragmented forest areas that form part of the Eastern Afromontane Biodiversity Hotspot? Location: Bonga, southwestern Ethiopia. Methods: Based on evidence from other montane forests, we hypothesized that altitude has an effect on the floristic diversity of Afromontane rainforests in southwestern Ethiopia. To test this hypothesis, detailed vegetation surveys were carried out in 62 study plots located in four relatively undisturbed forest fragments situated at altitudes between 1600 m and 2300 m. Floristic diversity was evaluated using a combination of multivariate statistical analyses and diversity indices. Results: Ordination and indicator species analyses showed gradual variations in floristic diversity along the altitudinal gradient with a pronounced shift in species composition at ca. 1830 m. Upper montane forest (41830 m) is characterized by high fern diversity and indicator species that are Afromontane endemics. Lower montane forest (o1830 m) exhibits a greater diversity of tree species and a higher abundance of the flagship species Coffea arabica. Conclusions: Our results provide crucial ecological background information concerning the montane rainforests of Ethiopia, which have been poorly studied until now. We conclude that both forest types identified during this study need to be considered for conservation because of their particular species compositions. Owing to the high degree of forest fragmentation, conservation concepts should consider a multi-site approach with at least two protected areas at different altitudinal levels.

Relationship between fragmentation, degradation and native and exotic species richness in an Andean temperate forest of Chile

“…Thus, these results may be consistent to other studies documenting a decreasing invasion with altitude mediated by a increase in fragmentation and degradation levels (e.g. Wilson et al 1992, Schmitt et al 2010, Alexander et al 2011. The absence of a statistically significant correlation suggests that this may be a developing pattern while the invasion process occurs.…”

“…Then, this result is concordant to other studies documenting negative effects of fragmentation on native biodiversity (e.g. Saunders et al 1991, Soulé et al 1992, Gilliam et al 1995, Laurance et al 1998, Tabarelli et al 1999, Hersperger & Forman 2003, Lindenmayer & Fischer 2006, Echeverría et al 2007, Schmitt et al 2010. As with exotic species, environmental changes produced by fragmentation (Chen et al 1995, Murcia et al 1995 may be detrimental for some forest-specialist native species.…”

“…Saunders et al 1991, Soulé et al 1992, Gilliam et al 1995, Laurance et al 1998, Tabarelli et al 1999, Hersperger & Forman 2003, Lindenmayer & Fischer 2006, Echeverría et al 2007, Schmitt et al 2010, as well as increases in exotic species diversity and abundance (Brothers & Spingarn 1992, Hobbs & Huennecke 1992, Wilson et al 1992, D'Antonio 1993, Mooney & Hobbs 2000, Hobbs 2001, Rouget et al 2002, Pauchard & Alaback 2004, Sax et al 2005. These fragmentation effects may be related to micro-environmental changes in the new edges, such as increase of light, higher temperatures and the potential release of other resources (Saunders et al 1991, Brothers & Spingarn 1992, Chen et al 1995, Hobbs 2001).…”

“…This may produce a non-random distribution pattern of fragmentation, degradation, native diversity and plant invasion (Hobbs 2001, Lindenmayer & Fischer 2006, Alexander et al 2011. Lower altitude sites, where more productive habitats are found, have customarily been used for farming, logging and urban development, resulting in smaller remnant fragments that are more degraded and invaded by alien species than those in higher elevations (Pauchard & Alaback 2004, Schmitt et al 2010, Alexander et al 2011.…”

Homegardens (Aal-oos-gad) of the Basket People of Southwestern Ethiopia: Sustainable agro-ecosystems characterizing a traditional landscape

“…This number is comparable to the number of vascular plant species recorded from Yayu forest (217) (Senbeta 2006), buna forests in southwestern Ethiopia (220) (Woldemariam et al 2008), and Afromontane rainforests in Kafa (220) (Schmitt et al 2010). Basketo landscape species diversity is higher than that of Maji forest (146) (Senbeta 2006), Jibat humid Afromontane forest (183) (Burju et al 2013), and Masha forest (2013) (Assefa et al 2013).…”