Hindawi International Journal of Ecology Volume 2020, Article ID 1629624, 10 pages https://doi.org/10.1155/2020/1629624 Research Article Woody Species Diversity, Vegetation Structure, and Regeneration Status of the Moist Afromontane Forest of Agama in Southwestern Ethiopia Abyot Dibaba ,1 Teshome Soromessa,2 Alemayehu Kefalew,3 and Admassu Addi4 1Department of Biology, Debre Berhan University, Debre Berhan, Ethiopia 2Center for Environmental Science, Addis Ababa University, Addis Ababa, Ethiopia 3Department of Biology, Debre Markos University, Debre Berhan, Ethiopia 4Holeta Bee Research Center, Holeta, Ethiopia Correspondence should be addressed to Abyot Dibaba; [email protected] Received 29 November 2019; Revised 6 February 2020; Accepted 9 March 2020; Published 30 June 2020 Academic Editor: Panos V. Petrakis Copyright © 2020 Abyot Dibaba et al. *is is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. *is study was conducted in Agama Forest in Kafa Zone, Southwestern Ethiopia, to assess species diversity, vegetation structure, and regeneration status of woody species. A systematic sampling technique was employed to collect vegetation data. Sixty (60) sample plots of 25 m × 25 m were laid at 300 m intervals all along ten grids interspaced 800 m apart. Sample plots of 25 m × 25 m were used to record DBH and H of all woody plant species reaching a DBH >2.5 cm and height >2 m. For the inventory of seedling and sapling, two subplots of 2 m × 5 m were used at the beginning and the end of the baseline on opposite sides of the main quadrat. Vegetation data such as DBH, height, seedling, and sapling density of woody species were recorded in each plot. Altogether, 72 woody plant species of 65 genera and 35 families were identified. Analysis of selected tree species showed diverse population structures. *is study showed that small trees and shrubs dominated the Agama Forest, which revealed its status under a secondary regeneration stage. Study on the structure and regeneration of some woody species indicated that there are species that require urgent conservation measures. Sound management and monitoring, as well as maintenance of biodiversity and cultural and economic values of the forest, require conservation activities that encourage sustainable uses of the forest and its products. 1. Introduction deforestation and forest degradation at between 150,000 and 200,000 ha/year and this was associated with loss of forest Ethiopia’s highly variable ecology, topography, and climate structure, diversity, dynamics, and evolution. New invest- make it an internationally recognized centre of biodiversity ment opportunities in Southwestern Ethiopia are converting [1]. *e country has around 6000 higher plant species of these remnant forests into other land uses such as tea and which about 10% are endemic [2, 3]. *e vegetation of coffee plantations [7]. New settlers migrating from the Ethiopia has been classified into 12 types [4]. *e vegetation northern and central parts of Ethiopia have also contributed type at Agama Forest in Southwestern Ethiopia, the subject to land use changes and forest degradation [8, 9]. of this paper, is part of the moist evergreen Afromontane *e Shannon–Wiener index, H, is the most popular forest that is characterized by one or more closed strata of measure of species diversity because it scores for both species evergreen trees that may reach heights of 30 to 40 m. richness and evenness and is not affected by sample size Southwestern Ethiopia best represents remnant natural [10, 11]. In the analysis of vegetation structure, the growth forests but those are being destroyed at an alarming rate [5]. stages of trees as seedlings, saplings, and mature trees as well Human-induced loss of forest cover, structure, and biodi- as the distribution of size classes within a population can be versity is of global concern; in Ethiopia, [6] estimated rates of essential elements of diversity that permit or deny the 2 International Journal of Ecology likelihood of quick recovery after disturbances [12]. *e DBH ≤ 2.5 cm) within the subquadrats. Geographical coor- status and dynamics of woody-tree populations can be ex- dinates and altitudes were recorded for each quadrat using amined by conducting a size class distribution and seedling GPS. Plant specimens were collected, pressed, dried, and and sapling counts [13, 14]. Healthy natural populations brought to the National Herbarium (ETH), Addis Ababa with continuous regeneration exhibit an exponentially University, for taxonomic identification and nomenclature. decaying size class distribution, whereby trees in smaller size *ese were determined by comparison with authenticated classes are represented in greater numbers than in larger specimens housed at ETH and by referring to published classes. *e absence or rarity of seedlings can be considered volumes of the Flora of Ethiopia and Eritrea [20–25]. an indication of a declining population. *e population structure of a tree species is indicative of its history of past disturbance and can be used to predict its future status in the 2.3. Data Analysis. Species diversity was calculated using the forest [13]. *is study investigated the woody species di- Shannon–Wiener diversity index, H, as versity, structure, and regeneration status of the Agama s Forest in Southwestern Ethiopia. *e results will be used to H � − X pi ln pi; (1) set conservation and management strategies for this forest. i�1 where s is the number of woody species and pi is the pro- 2. Materials and Methods portion of individuals or the abundance of the ith species expressed as a proportion of the total. 2.1. Study Area. *is study was conducted in Gimbo district Shannon’s evenness, J, was calculated as the ratio of of the Kafa Zone in the Southern Nations’ Nationalities and observed diversity, H, to the maximum diversity, Hmax, using Peoples’ Regional State (SNNPRS), which is located 500 km the following equation: from Addis Ababa and 30 km from Bonga (Figure 1). *e H H area is centered at 7.16°N, 36.11°E, the altitudinal range is J � � ; (2) (s) H from 1800 m to 2370 m, and the topography is undulating, ln max with valleys and rolling plateaus [15]. *e size of the study where ln(s) � Hmax forest covers about 1872 hectares (Figure 1). *e structure of the vegetation was described using a *e climate data between the years 2005 and 2018 frequency distribution of H, DBH, and Importance Value recorded by the meteorological station at Bonga that is Index (IVI). Tree or shrub density and basal area values were located 20 km south of the study area was used to describe calculated on a per-hectare basis. For all species, IVIs were the climatic condition of the study area. *ere is a unimodal calculated as the sum of their relative density (RD), relative rainfall pattern with eight months between March and frequency (RF), and relative dominance (RDO) [10] where October with rainfall >100 mm/month [16]. *e mean an- the number of all individuals of a species nual rainfall is 1830 mm, and the monthly mean maximum RD � × 100; and mean minimum temperatures are 29.6°C and 9.5°C, the total number of all individuals ° respectively. *e mean annual temperature is 19.7 C. the number of plots where a species occurs *e major soil groups of the study area, according to the RF � × 100; FAO/UNESCO legend of soil classification, are Nitisols, the total occurrence of all species in all plots Acrisols, and Vertisols [17]. *e Nitisols are agriculturally the the basal area of a species most important and dominant type of soils in the Kafa Zone. RDO � × 100; *e Nitisols are clay-red in color and have moderate CEC and total basal area relatively high organic matter content and total nitrogen. (3) where the basal area of an individual wasπd2/4 (π � 3.14; d � DBH). 2.2. Vegetation Sampling. A preliminary survey was made Five IVI classes were established: I < 1; II � 1–10; from 30 April 2017 to 15 May 2017 to obtain an impression on III ≥ 10–20; IV ≥ 20–30; V > 30. the general physiognomy of the vegetation and identify Frequency (F) and density (D) were calculated as [26] sampling sites in the study area. *e actual field study was conducted from 10 December 2017 to 30 April 2018. *e no: of quadrats in which a species occurs F � × 100: (4) systematic sampling design was used to collect vegetation and total no: of quadrats examined environmental data [10, 18, 19]. Sixty (60) sample quadrats of 25 × 25 m were laid at 300 m intervals along ten grids Species were grouped into five frequency classes: interspaced 800 m apart. Seedling and sapling inventories of A � 0–20%; B � 21–40%; C � 41–60%; D � 61–80%; E � all woody-tree and shrub species were recorded in two 2 × 5 m 81–100%: subquadrats located on opposite sides of each quadrat. For all total no: of individuals of a species found woody species of height (H) ≥ 2 m and diameter at breast D � : (5) total area examined height (DBH) ≥ 2.5 cm, H and DBH were measured using a clinometer and diameter tape, respectively. Regeneration Species were classified into six density classes: A ≤ 1; patterns were assessed using the total count of seedlings B ≥ 1–10; C ≥ 10–20; D ≥ 20–35; E ≥ 35–50; F ≥ 50 individ- (H ≤ 50 cm and DBH ≤ 2.5 cm) and saplings (H > 50 cm and uals per hectare. International Journal of Ecology 3 N 36°2′0″E 36°4′0″E 36°6′0″E Ethiopia 504ha 1040ha N N ″ ″ 30 30 ′ ′ 7°17 7°17 328ha Southwest moist montane forest 012 4 km 36°2′0″E 36°4′0″E 36°6′0″E Elevation (meter) 1,700–1,900 Agama Forest 1,900–2,100 Sample plots 2,100–2,300 Figure 1: Map and sample plots of the study area.