Plant Community Analysis Along Environmental Gradients In Moist Afromontane Forest of Gerba Dima, South-Western Ethiopia

Abstract

Background: This study was carried out in Gerba Dima Forest, South-Western Ethiopia, to determine the floristic composition, species diversity and community types along environmental gradients. Ninety sample plots having a size of 25 X 25m (625m2) were laid by employing stratified random sampling. Nested plots were used to sample plants of different sizes and different environmental variables. All woody plant species with Diameter at breast height (DBH) ≥ 2.5 cm and height ≥ 1.5m were recorded in 25 m X 25 m plots. Hierarchical (agglomerative) cluster analysis was performed using the free statistical software R version 3.6.1 using package cluster to classify the vegetation into plant community types. Redundancy Analysis (RDA) ordination was used in describing the pattern of plant communities along an environmental gradient. Result: One hundred and eighty plant species belonging to 145 genera, 69 families and comprising of 15 endemic species were recorded. Of these, 52 species (28.9%) were trees, 6 species (3.33%) were Trees/shrubs, 31 species (17.22%) were shrubs, 76 species (42.22%) were herbs, and 15 species (8.33%) were Lianas. Rubiaceae, Acanthaceae and Asteraceae were the richest family each represented by 11 genera and 11 species (6.11%), 9 genera and 11 species (6.11%), 6 genera and 11 species (6.11%), respectively of total floristic composition. Cluster analysis resulted in five different plant communities and this result was supported by the ordination result. RDA result showed altitude was the main environmental variable in determining the plant communities. The ANOVA test indicated that the five community types differ significantly from each other with regard to Electrical Conductivity and Potassium. Conclusions: Description of floristic diversity of species in Gerba Dima forest revealed the presence of high species diversity and richness. The presence of endemic plant species in the study forest shows the potential of the area for biodiversity conservation.

Plant diversity and community analysis of Sele-Nono forest, Southwest Ethiopia: implication for conservation planning

“…It is said that there was uncontrolled forest exploitation during the past times since the 1950s in the southwest forest mainly for the purpose of timber and timber-related purposes (Chaffey 1979 ; Ersado 2001 ; Tadesse and Woldemariam 2007 ). Most of the species reported in this study to be preferred for timber and timber-related purposes by the local people were also mentioned in other southwest forests of Ethiopia (Chaffey 1979 ; EFAP 1994 ; Schmitt et al 2010 ; Desalegn et al 2012 ; Dibaba et al 2022 ). Some of these species are Pouteria adolfifriederici, Apodytes dimidiate, Celtis africana, Cordia africana, Croton macrostachyus, Ekebergiacapensis, Prunus africana, Olea welwitschii, Polyscias fulva, and Syzygium guineense .…”

“…The finding of this study also revealed that the Sele-Nono forest contains more species than the species reported for Bonga forest (220 species) by Schmitt et al ( 2010 ), Gura Ferda forest (196 species) by Denu ( 2006 ), Masha forest (130 species) by Assefa et al ( 2013 ), Yayu forest (220 species) by Woldemariam et al ( 2002 ), Sheko forest (374 species) by Senbeta et al ( 2007 ), Gesha and Sayilem forest (300 species) by Addi et al ( 2020 ), Gerba Dima forest (180 species) by Dibaba et al ( 2022 ). This indicates that the current study area is one of the richest forest ecosystems in the southwest forest of Ethiopia.…”

“…The richest plant families reported in the current study area are Asteraceae, Fabaceae, Acanthaceae, Euphorbiaceae, Rubiaceae, and the like. Most of these families are also among the top families in the flora of Ethiopia and Eritrea (Kelbessa et al 1992 ) in general and in the different vegetation patches of the moist southwest forests in particular (Yeshitela and Bekele 2002 , Woldemariam 2003 , Yeshitela and Bekele 2003 ; Senbeta et al 2005 ; Kelbessa and Soromessa 2008 ; Addi et al 2020 ; Dibaba et al 2022 ). The prevalence of the family Asteraceae in the study area indicate that the forest might have been under a certain level of disturbance as plants of the Asteraceae family are often ruderal (early colonizers); and normally prefer open and disturbed lands to grow (Malcolm 1994 ; Turner 1996 ; Tadesse 2004 ; Awoke et al 2022 ).…”

“…From these early efforts on, vegetation scientists did specific floristic studies and generated enormous data on the diversity, distribution, and conservation status of the existing patches of the area. Some of these studies include the work of Derero ( 1998 ), Kigomo ( 1999 ); Yeshitela and Bekele ( 2002 ), Woldemariam ( 2003 ), Yeshitela and Bekele ( 2003 ), Bekele ( 2003 ), Woldu and Yeshitela ( 2003 ), Berhan and Assefa ( 2004 ), Yeshitela and Shibru ( 2004 ), Ersado and Assefa ( 2004 ), Bekele et al ( 2004 ), Senbeta et al ( 2005 ), Denu ( 2006 ), Senbeta ( 2006 ), Schmitt ( 2006 ), Senbeta et al ( 2007 ), Kelbessa and Soromessa ( 2008 ), Hundera and Deboch ( 2008 ), Hundera and Gadissa ( 2008 ), Woldemariam et al ( 2008 ); Nune ( 2008 ), Gobeze et al( 2009 ), Schmitt et al ( 2010 ), Friis et al ( 2011 ), Assefa et al ( 2013 ), Hylander et al( 2013a , b ), Soromessa and Kelbessa ( 2013 ), Gebrehiwot and Hundera ( 2014 ), Mulugeta et al ( 2015 ), Addi et al ( 2016 ), Siraj et al ( 2017 ), Yasin et al ( 2018 ), Denu ( 2019 ), Addi et al ( 2020 ), Dibaba et al ( 2022 ). Despite these and many other related studies, the area still faces the challenge to conserve its vegetation and is becoming among the highly-threatened ecosystems in Ethiopia.…”