EFFECT OF SELECTIVE LOGGING ON THE FLORA COMPOSITION IN THE RAINFOREST OF GHANA;

A CASE STUDY OF ASENANYO RIVER FOREST RESERVE

BY

ETSRA, HOPESON ELI

MAY, 2014

INTRODUCTION• Ghana forest area has been reduced through diverse

anthropogenic influences

• Timber exploitation has major impact on forest area and structure.

• Though only 3–10% of the trees are selectively logged for commercial use, 40–80% trees are destroyed by the creation of logging tracks, falling trees and heavy activity of forestry machinery (Putz, 2000)

JUSTIFICATION• The maintenance and conservation of ecological,

economical and socio-cultural benefits of the forest has become a matter of global, regional, national and local concern.

• Selective logging is actually a management tool being used by the Forestry Commission (FC) of Ghana in managing the natural forest to ensure sustainable production of its resources.

• There is therefore the need to find out the effect of selective logging on our forest reserves

JUSTIFICATION CONT.Objective:• To assess the composition and distribution of timber tree

species after selective logging in Asenanyo River Forest Reserve.

Specific Objectives:

• To determine Species composition/richness

• To determine Relative abundance of species

• To determine Species density and diversity

METHODOLOGYStudy Area:• Asenanyo River Forest Reserve is located within the

Nkawie Forest District of the Ashanti region

*Unproductive area include areas under research, conversion & protection

Gross Area (ha) Productive Area (ha)

Unproductive Area (ha)

Admitted Farms And Village Land (ha)

22,792.00 15,991.97 5,751.03 1,049.00

METHODOLOGY CONT.Research Plots:

• 3 Compts. comprising of 2 disturbed Compts (Compt. 52 and 109), logged 5 and 15 years ago respectively and an undisturbed compt. (Compt. 27).

• In each of the disturbed compartments, the areas where the actual felling operations had taken place were the areas that were identified and studied

METHODOLOGY CONT.Lying Of Plots/Research Setup:• Sixteen (16) 25m x 25m plots were laid in each study

site through stratified random sampling (a total sample plot of 1.00ha in each study site) but 5m off tracks to minimize edge effect.

• The compass and tape measure were used in laying the plots and an angle of 90° was added to the initial angle after a distance of 25m had been measured.

METHODOLOGY CONT.Data collection• Sapling and small trees that are greater than 5cm but

less than or equal to 15cm dbh or 1.3 m from ground were identified, measured and recorded in the sample plots.

• The enumeration team was made up of a recorder, a tree spotter and an assistant.

METHODOLOGY CONT.Data Analysis• Microsoft Excel - find means, Standard Deviations, etc

& make graphs, charts, etc

• Simpson’s Index of Diversity - show difference in species diversity among the study sites.

• Tree Importance Value Index (IVI) - show differences in relative dominance of timber species among the study sites.

RESULTSSpecies Composition/Richness

• In total, 1582 individual trees were counted in the study areas. Out of these, there were 104 different species belonging to 33 different families.

• The undisturbed site (compt. 27) had 68 species, followed by the disturbed site that has been left to fallow for 5 years (compt. 52) with 87 species, while the disturbed site that had been left to fallow for 15 years (compt. 109) had 90 species.

RESULTS CONT.Top ten (10) species families in the reserve• In total, 1582 individual trees were counted in the

study areas. Out of these, there were 104 different species belonging to 33 different families.

• The undisturbed site (compartment 27) had 68 species, followed by the disturbed site that has been left to fallow for 5 years (compartment 52) with 87 species, while the disturbed site that had been left to fallow for 15 years had 90 species.

FamilyDisturbed

Undisturbed5 Years 15 Years

Caesalipiniaceae 11 8 7

Sterculiaceae 9 8 8

Meliaceae 6 9 6

Moraceae 6 7 7

Mimosaceae 5 5 5

Ulmaceae 4 4 4

Sapotaceae 3 4 3

Annonaceae 2 4 3

Rubiaceae 3 3 2

Euphorbiaceae 2 3 2

RESULTS CONT.Relative abundance of Species (Top 5 Species)• In total, 1582 individual trees were counted in the

study areas. Out of these, there were 104 different species belonging to 33 different families.

• The undisturbed site (compartment 27) had 68 species, followed by the disturbed site that has been left to fallow for 5 years (compartment 52) with 87 species, while the disturbed site that had been left to fallow for 15 years had 90 species.

DisturbedUndisturbed

5 Years 15 Years

Triplochiton scleroxylon Triplichiton sclerxylon Triplochiton scleroxylon

Celtis mildbraedii Celtis mildbraedii Celtis mildbraedii

Celtis zenkeri Nauclea diderrichii Celtis zenkeri

Nauclea diderrichi Celtis zenkeri Khaya anthotheca

Canarium schweinfurthii Canarium schweinfurthii Pycanthus angolensis

RESULTS CONT.Species Density and Diversity• In total, 1582 individual trees were counted in the

study areas. Out of these, there were 104 different species belonging to 33 different families.

• The undisturbed site (compartment 27) had 68 species, followed by the disturbed site that has been left to fallow for 5 years (compartment 52) with 87 species, while the disturbed site that had been left to fallow for 15 years had 90 species.

Investigated ParametersDisturbed Area

Undisturbed5 Years 15 Years

Species Density

509 551 522

Simpson's Index (D) 0.05 0.05 0.06

Simpson's Index of

Diversity (1-D)0.95 0.95 0.94

DISCUSSIONSpecies Composition• The number of species counted was higher in the two

disturbed compartments, compartment 52 had 87 and compartment 109 had 90, than in the undisturbed compartment (compartment 27) which had 68.• Smith (1945) noted earlier that the most important

factors for plant growth are the kind and degree of both shading and root competition. In this light, the less vegetation left on the site, the greater will be the amount of light, soil moisture and nutrients available to the regenerating plant.

DISCUSSION CONT.Species Composition Cont.• The low number of individual species for

compartment 52 might be as a result of the damage caused during the felling operation, as observed earlier by Hawthorne (1993) that residual trees can be damaged during harvesting through the process of felling and skidding within the stand.

• Species that are dominant in the study area are Triplochiton scleroxylon and Celtis mildbraedii forming the Celtis-Triplochiton association, as classified by Taylors (1960)

DISCUSSION CONT.

Relative Abundance of Species

• In the first four species, the disturbed areas were dominated by Nauvlea diderrichi whiles the undisturbed area was dominated by Khaya anthotheca.

• This is because the seeds of Khaya anthotheca can germinate in full sunlight as well as under shades whiles the seeds of Nauvlea diderrichi germinate well in full sunlight (www.protoa.org)

DISCUSSION CONT.Species Diversity• The value of Simpson’s Index of diversity for

compartment 52, 109 and 27 were 0.95, 0.95 and 0.94 respectively.

• The index obtained for the various compartments indicated that species diversity within the compartments were very high and it was higher in the disturbed areas than in the undisturbed area.

• However, ANOVA performed showed that there was no significant difference between species density of the undisturbed area and disturbed area, at 0.05 confidence level.

CONCLUSION• The study showed that there were differences in the

flora composition of the logged and unlogged compartments of the Forest Reserve.

• A real Rainforest association of Celtis-Triplochiton species dominated the Asenanyo River Forest Reserve.

• Though there were differences in the values of the parameter obtained, analysis indicated a non-significant pattern at 0.05 confidence level.

• Thus, selective logging had no real impact on the composition and abundance of the trees in the Asenanyo River Forest Reserve.

RECOMMENDATIONS

• Sufficient felling cycle should be practiced to reinstate the same set of species that prevailed before logging

• Felling techniques should be improved to reduce the level of destruction caused by the operation

• Strict Policies and Legislations must be put in place to ensure the adherence of felling cycle and improved felling techniques

THANK YOU