Abstract
This study assessed the effects of exploitations in natural forest ecosystems on tree species diversity and environmental conservation. This was achieved by comparing tree species diversity and yield in an unlogged forest (Strict Nature Reserve) and a forest reserve where active logging is in progress in Ondo State, Nigeria. Eight plots (20 m × 20 m) were assessed in each site using systematic sampling techniques. All living trees with dbh >10 cm were identified, categorized into families with their diameter at breast height (dbh) measured in each plot. Shannon-Weiner and species evenness indices were used to assess and compare tree species diversity and abundance. The results show that the tropical humid forest is very rich in tree species, as a total of 54 different tropical hardwood species from 23 families were encountered in both forest types. There were 46 species distributed among 21 families in the unlogged forest and 24 species in 14 families in the logged forest. Shannon-Weiner diversity index of 3.16 and 3.03 and evenness index of .83 and .81 were also obtained for the unlogged and logged forest, respectively. Every variable computed had a higher value in the unlogged forest relative to the logged forest. In the unlogged forest, the species with the highest number of occurrence was Mansonia altissima A. Chev. (80 stems/ha). Caesalpinoidae and Sterculiaceae families had the highest number of species (6). In the logged forest, Triplochiton scleroxylon K. Schum. (18 stems/ha) had the highest frequency and Caesalpinoidae family has the highest number of species (4). The study concludes that exploitation has affected species diversity in the ecosystem and subsequently, the roles of trees in environmental conservation are affected.
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Claims 11
Claim · model-written summary
The two forest types contained 54 tropical hardwood species from 23 families.
Verbatim
e0“a total of 54 different tropical hardwood species from 23 families were encountered in both forest types”
e1“in Ondo State, Nigeria”
Claim · model-written summary
The unlogged forest contained 46 species.
Verbatim
e0“There were 46 species distributed among 21 families in the unlogged forest”
e1“tree species diversity and yield”
e2“in Ondo State, Nigeria”
Claim · model-written summary
The logged forest contained 24 species.
Verbatim
e0“24 species in 14 families in the logged forest”
e1“tree species diversity and yield”
e2“in Ondo State, Nigeria”
Claim · model-written summary
The unlogged forest had a Shannon-Weiner diversity index of 3.16, versus 3.03 in the logged forest.
Verbatim
e0“Shannon-Weiner diversity index of 3.16 and 3.03 and evenness index of .83 and .81 were also obtained for the unlogged and logged forest, respectively”
e1“tree species diversity and yield”
Claim · model-written summary
The unlogged forest had an evenness index of .83, versus .81 in the logged forest.
Verbatim
e0“evenness index of .83 and .81 were also obtained for the unlogged and logged forest, respectively”
e1“tree species diversity and yield”
Claim · model-written summary
All computed diversity variables were higher in the unlogged than logged forest.
Verbatim
e0“Every variable computed had a higher value in the unlogged forest relative to the logged forest”
e1“tree species diversity and yield”
Claim · model-written summary
Mansonia altissima A. Chev. was the most frequent species in unlogged forest at 80 stems/ha.
- Taxon
- Mansonia altissima A. Chev.
Mansonia altissimae0 - Outcome
- number of occurrencee0
- Direction
- higheste0
- Value
- 80 stems/hae0
- Setting
- unlogged foreste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the unlogged forest, the species with the highest number of occurrence was Mansonia altissima A. Chev. (80 stems/ha)”
Claim · model-written summary
Caesalpinoidae and Sterculiaceae each had the largest species counts in unlogged forest, at six species.
Verbatim
e0“Caesalpinoidae and Sterculiaceae families had the highest number of species (6)”
e1“In the unlogged forest”
Claim · model-written summary
Triplochiton scleroxylon K. Schum. had the highest frequency in logged forest, at 18 stems/ha.
- Taxon
- Triplochiton scleroxylon K. Schum.
Triplochiton scleroxylone0 - Outcome
- frequencye0
- Direction
- higheste0
- Value
- 18 stems/hae0
- Setting
- logged foreste0
Organisms pictured · Representative pictures of the matched species, not figures from the paper.
Verbatim
e0“In the logged forest, Triplochiton scleroxylon K. Schum. (18 stems/ha) had the highest frequency”
Claim · model-written summary
Caesalpinoidae had the most species in logged forest, with four.
Verbatim
e0“Caesalpinoidae family has the highest number of species (4)”
e1“In the logged forest”
Claim · model-written summary
The authors concluded that logging affected tree species diversity and their environmental conservation roles.
Verbatim
e0“exploitation has affected species diversity in the ecosystem and subsequently, the roles of trees in environmental conservation are affected”