Pattern of functional diversity along the elevation gradient in the dry evergreen Afromontane forest of Hararghe Highland, Southeast Ethiopia

Abstract

Understanding plant species distribution patterns along environmental gradients is fundamental to managing ecosystems, particularly when habitats are fragmented due to intensive human land use pressure. The variation pattern of functional diversity of plant communities along the elevation gradient in the Dindin dry evergreen Afromontane forest was tested. Fifty four plots of 20 x 20 m (400 m2) were established at 200 m intervals starting 2,300–2,900 m a. s. l. and woody species composition, and environmental variables were recorded. Nine functional diversity indices based on functional distances were employed to esimate functional diversity. The mixed effect model was used to determine the effect of elevation, aspect and slope on functional diversity indices. The results showed that functional diversity in communities varied greatly; functional diversity revealed a decrease with increasing elevation and a‘‘humped’’ pattern, with peak diversity appearing at middle elevation. Functional diversity was significantly correlated with elevation, slope, and aspect. Functional diversity was significantly correlated with species richness and evenness. Environmental filtering was important to the functional diversity pattern; the nine indices were all successful in the analysis of functional diversity in the plant community with different effectiveness, and modified functional attribute diversity, plot-based functional diversity, community based functional diversity, functional richness, and community weight mean of woody density performed better than the other four indices in this study.

Functional and Species Diversity across Disturbance Levels and Environmental Variables in Yayu Coffee Forest Biosphere Reserve, Southwest Ethiopia

“…All of the functional diversity indices increased in a polynomial manner as species richness and diversity increased, which idicated that their relationships is direct but non-linear which has consistence with the previous studies [48,60,62,70]. The non-linear relations between functional diversity and species diversity proved that functional diversity can provide special information which is different from species diversity.…”

“…The non-linear relations between functional diversity and species diversity proved that functional diversity can provide special information which is different from species diversity. Because, the variation in species abundance and distribution can mainly explained through species diversity, however functional diversity can explain variations of species morphology, physiology, reproduction, ecology and phenology as already reported by [67] as cited in [70]. Previous findings pointed out [69], different functions will likely be maximized by functionally different species, and consequently diverse mixtures would provide combinations that maximize multiple functions.…”

Hydrological Season Can Have Unexpectedly Insignificant Influences on the Elevational Patterns of Functional Diversity of Riverine Macroinvertebrates

“…By assessing the role of environmental filtration in the changes of community composition, functional diversity becomes significant in understanding the changes of diversity and ecosystem processes [ 23 , 24 ]. A few studies have explored the elevational patterns of functional diversity, and their contradictory findings on the pattern of functional diversity along the elevation gradient have been presented [ 25 , 26 ].…”

“…Zhang et al [ 26 ] found a unimodal pattern with the highest functional diversity near the middle of the gradient. In the dry evergreen Afromontane forest of Hararghe Highland, Southeast Ethiopia, Teshome et al [ 23 ] found that most functional diversity indices decreased with increasing elevation, and their results suggested that elevation is the most critical environmental filter affecting species distribution and community structure.…”