International Journal of Modern Botany

p-ISSN: 2166-5206    e-ISSN: 2166-5214

2016;  6(2): 19-25

doi:10.5923/j.ijmb.20160602.01

 

Flora Diversity of Urhonigbe Forest Reserve, Edo State, Nigeria

Erhenhi A. H. 1, Obadoni B. O. 2

1Department of Botany, Delta State University, Abraka, America

2Department of Botany, Ambrose Alli University, Ekpoma, Nigeria

Correspondence to: Erhenhi A. H. , Department of Botany, Delta State University, Abraka, America.

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Copyright © 2016 Scientific & Academic Publishing. All Rights Reserved.

This work is licensed under the Creative Commons Attribution International License (CC BY).
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Abstract

Urhonigbe Forest Reserve is located in Edo State, Nigeria. The study area was conveniently divided into three sample areas (X, Y and Z). Each sample area had four sampling plots, each measuring 50 m x 50 m. nine quadrants were laid in a plot to sample for plant species. One hundred and sixty (160) plant species, belonging fifty six families and one hundred and thirty eight genera were identified. Their habits vary from trees, shrubs, herbs, sedges, grasses to climbers. Tree species contributed to 53.75% of the total plant species obtained in Urhionigbe Forest Reserve. This was followed by shrubs (25.63%), herbs (10.63%), climbers (7.50%), grasses (1.88%) and sedge (0.63%). The trees were the most represented whereas, the sedge was the least. Fabaceae was the most dominant plant family having fourteen species which accounted for 8.75% of the total plant species sampled in the fields. Also, Rubiaceae and Euphorbiaceae had by twelve species each and contributed 15% of the total plant species enumerated in the fields. Others include Apocynaceae and Meliaceae with nine species each contributed 11.25%; Annonaceae, Ebenaceae, Sapindaceae and Tiliaceae with five species each accounted 12.50%. Icacinaceae, Sterculiaceae, Ulmaceae with four species each contributed 7.5%, while Piperaceae, Poaceae, Araceae, Menispermaceae, Commelinaceae, Palmaceae, Moraceae and Myristiceae with three species each accounted for 15%. Rutaceae, Vebenaceae, Convolvulaceae, Clausiaceae, Irvingiaceae, Connaraceae, Burseraceae, Capparaceae, Combretaceae and Maranthaceae with two species each contributed 12.50%, while Anacardiaceae and the other families with one species each accounted for 17.50%.

Keywords: Flora, diversity, Forest reserve

Cite this paper: Erhenhi A. H. , Obadoni B. O. , Flora Diversity of Urhonigbe Forest Reserve, Edo State, Nigeria, International Journal of Modern Botany, Vol. 6 No. 2, 2016, pp. 19-25. doi: 10.5923/j.ijmb.20160602.01.

Article Outline

1. Introduction
2. Materials and Methods
3. Results
4. Discussion and Conclusions
ACKNOWLEDGEMENTS

1. Introduction

Biological diversity has taken the centre stage in the field of science as a result of the rate of exploitation of our natural resources. Biodiversity is the relationship between species and their pattern of richness (Young and Swiacki, 2006). Diversity is also a measure of heterogeneity of a site taking into consideration the number and density of individual species (Ogunleye et al., 2004). Forest diversity is increasingly threatened as a result of deforestation, fragmentation, climate change and other stressors. The rich flora diversity of plant species is a major source of raw plant materials that enable sustainability in the human communities now and in the future (Ogie-Odia et al., 2010)
Plant diversity could affect food web connectivity in a variety of ways (Gross et al. 2009; O'Gorman & Emmerson 2009). Higher plant diversity increases plant productivity and predator abundance (Haddad et al., 2009), which increases the amount of energy transfer among interacting species and thus increases food web connectivity. Few forest reserves have positive flora and fauna diversity where as many forest reserves diversity have been affected through anthropogenic and natural factors (Stock, 2007).

2. Materials and Methods

Sampling Technique
The study area was conveniently divided into three sample areas (X, Y and Z) based on the varying degrees of human interference. Each sample area had four fields, each measuring 50m x 50m. In a field, nine quadrats each measuring 10m x 10m giving total of one hundred and eight (108) sample units for the three sample areas were used. Sample area X represented Forest Re-Growth Area (FRA), while Y was Restricted Forest Area (RFA) and Z, Strictly Restricted Forest Area (SRFA).
In a field, line transects were cut diagonally and five (5) quadrats were laid along each diagonal leaving 2m at each edge to minimize edge effect. The distance between one quadrat (sample unit) and the other was 4m. The third quadrat at the centre was common to both diagonals. Sampling along the diagonals at close spacing ensured adequate coverage of the fields. A total area of 30,000m2 was sampled in the three sample areas. Plants encountered during surveys were collected. Some plant species were identified in the field while useful parts such as plant exudes (gums, resins) and leaves, preserved and taken to the laboratory to ease identification; besides the plants, their seeds, flowers, and barks were collected.

3. Results

One hundred and sixty plant species, belonging fifty six families and one hundred and thirty eight genera were identified. The family Fabaceae had fourteen species and contributed 8.75% of the total plant species encounted. Also, Rubiaceae and Euphorbiaceae were represnted by twelve species and contributed 15% of the total plant species enumerated in the fields. Others include Apocynaceae and Meliaceae with nine species each contributing 11.25%; Annonaceae, Ebenaceae, Sapindaceae and Tiliaceae with five species each contributed 12.50%. Icacinaceae, Sterculiaceae, Ulmaceae with four species each contributed 7.50%, while Piperaceae, Poaceae, Araceae, Menispermaceae, Commelinaceae, Palmaceae, Moraceae and Myristiceae with three species each accounted for 15%. Rutaceae, Vebenaceae, Convolvulaceae, Clausiaceae, Connaraceae, Irvingiaceae, Burseraceae, Capparaceae, Combretaceae and Maranthaceae with two species each contributed 12.50%, while Anacardiaceae and the other families with one species each accounted.
Figure 1. Schematic diagram of plant survey technique
Table 1. Plant families, scientific names and habits of plant species encountered in Urhonigbe Forest Reserve
     
The habits of the plant species showed eighty six trees, forty one shrubs, seventeen herbs, twelve climbers, three grasses and a sedge. Tree species contributed 53.75% of the total plant species obtained in Urhionigbe Forest Reserve. This was closely followed by shrubs (25.63%), herbs (10.61%), climbers (7.50%), grasses (1.88%) and sedge (0.63%). The trees were the most represented whereas, the sedge was the least represented (Fig 2).
Figure 2. Percentage composition of the plants based on habits in Urhonigbe Forest Reserve

4. Discussion and Conclusions

The different plant species collected from Urhonigbe forest reserve were one hundred and sixty species. The plant species vary in different plant habits which range from tree, shrubs, herbs, climbers, grasses and sedge. The flora diversity was highest in designated Strictly Restricted Forest Area (SRFA) due to the least anthropogenic activities (such as lumbering, grazing and farming) taking place there as compared to Forest Re-Growth Area (FRA) which has the most anthropogenic activities of these three designated areas. Similar but lower number of woody species was reported by Aremu et al., (2009) who enumerated seventy four (74) woody plant species belonging to thirty three (33) families in Gele-gele Forest Reserve. The difference in the number of woody species in both forest reserves was due to greater human interference at Gele-gele Forest Reserve.
Ihenyen et al., (2009) reported ninety-nine species of trees distributed into 36 families and 87 genera in Ehor forest reserve, Edo state, Nigeria. This report was quite similar to the results obtained in the present study due to closeness in latitudinal location of the two reserves studied. Also, Ogunleye et al., (2004) sampled Olokemeji Forest Reserve, located in Olokomeji, Ibadan, and identified 107 plants made up of sixty-nine trees and thirty six (36) shrubs. The more southern location of Urhonigbe Forest Reserve probably the higher number of tree species obtained may be due to the southern location of Urhonigbe Forest Reserve where there is sufficient rainfall annually, less farming activities and abundant coastal riparian vegetation as compared to Olokomeji Reserve located in the Western part of Nigeria where more farming activities take place as well as has lower annual rainfall.
Oduwaiye and Ajibode (2005) identified thirty five (35) trees, fifteen (15) shrubs and eight (8) climbers in thirty-three (33) families from Onigambari Forest Reserve, Ibadan in Oyo state. The low number of tree species encountered by the authors was expected as Ibadan is located in the forest/ savannah transition zone. Asyraf et al., (2012) recorded 325 plant species belonging to 68 families and 211 genera in Sabang Island, Aceh, Indonesia. The Sundaland countries are known for high species diversity due to their perculiar geographical location, high rainfall throughout most parts of the year, fertile soil and easy transfer of plant species from one area to another because of large land area.
Anthropogenic activities (cattle grazing, poor farming techniques, illegal encroachment as well as over dependence on the forest reserve resources) pose serious threats to the biodiversity as well as the plant community of the forest reserve.

ACKNOWLEDGEMENTS

We are very grateful to the Urhonigbe Forest Reserve foresters who assisted us to have access to carry out this work in the reserve.

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