Effects of human disturbances and plant invasion on liana community structure and relationship with trees in the Tinte Bepo forest reserve, Ghana

There are conflicting reports on the role of disturbances in maintaining liana community structure, and in determining their relationship with trees. The effects of plant invasion on these attributes of lianas are not known. The study investigated the effects of human disturbances and plant invasion on liana community structure and relationship with trees in the Tinte Bepo forest reserve, Ghana, in three distinct forest types to reflect both human disturbances and invasion: Undisturbed, Disturbed-Invaded and Disturbed Forests (UF, DIF and DF respectively). Trees ‚â•10 cm dbh were identified and their dbh measured in two 0.25 ha plots in each forest type. The trees were examined for the presence of lianas (\u3e2 cm dbh) and their dbh measured. A total of 380 lianas \u3e2 cm dbh belonging to 20 genera and 12 families were identified in the 1.5 ha forest. Twelve liana species were unique to the DIF suggesting the probable positive influence of plant invasion on their colonisation. Liana density differed significantly across the forest types (df = 2, p = 0.043) with the UF recording the greatest number. The mean liana stem diameter and basal area were greater in the DF. Large diameter lianas were absent in the UF. Tree density and number of trees hosting lianas were greater in the UF followed by the DIF and DF. Liana infestation was generally high with 90% in the DF, 88.2% in the UF, and 85.7% in the DIF. Both liana load per tree species and mean liana load per infested tree were highest in the UF followed by the DIF and then the DF. Liana density was highly dependent on tree density in all the forest types (df = 1, r2 = 0.50, p = 0.007; df = 1, r2 = 0.99, p = 0.000 and df = 1, r2 = 0.72, p = 0.000 in the UF, DIF and DF respectively). There was a significant positive relationship between liana dbh and host dbh in the UF (df = 1, r2 = 0.096, p = 0.000), DIF (df = 1, r2 = 0.11, p = 0.000) and DF (df = 1, r2 = 0.16, p = 0.008). There was no significant relationship between host dbh and liana loads in all the forest types

Floristic Composition and Vegetation Structure of The KNUST Botanic Garden, Kumasi, Ghana

The diversity, relative importance, canopy height and cover of plant species in the Kwame Nkrumah University of Science and Technology (KNUST) Botanic Garden were evaluated in five 1-ha plots using a stratified random sampling technique in order to build an understanding of its floristic composition and structure in two distinct parts of the garden (cultivated and uncultivated). We recorded 184 species which belonged to 146 genera, 51 families and six growth forms. The most dominant tree species in the garden were Elaeis guineensis Jacq., Hevea brasiliensis (Willd.) Muell.-Arg. and Parkia biglobosa (Jacq.) G. Don. with a combined importance index of 60.09 (20 % relative importance). The differences in importance value indices of species between the cultivated and uncultivated areas of the garden were statistically insignificant (p > 0.05), suggesting the presence of conducive growth environments for plants in both areas. The most dominant families were Fabaceae, Moraceae, Arecaceae and Euphorbiaceae whilst trees were the most predominant growth forms (62.5 %). Average crown height and percentage canopy were 28.8 ± 8.81 m and 66.4 ± 8.26 % respectively. These results show the floristic richness of the KNUST botanic garden and underscore the garden\'s potential as a centre for ex-situ conservation beside its traditional roles in education, research and recreation. Keywords: Floristic composition, structure, botanic garden, KNUST Journal of Science & Technology (Ghana) Vol. 28 (3) 2008: pp. 103-12

Diversity and Distribution of Climbing Plants in a Semi-Deciduous Rain Forest, KNUST Botanic Garden, Ghana

The diversity and distribution of climbing plants were investigated in two 1-ha plots in the KNUST botanic garden. Each plot was divided into sixteen 25 m x 25 m quadrats and all trees and shrubs ≥10 cm dbh were enumerated in each quadrat. All vines on tree species were identified and counted while all lianas ≥1.5 cm were enumerated. The mechanisms of climbing of the climbers were studied. A total of 951 climbing plants belonging to 82 species, 49 genera and 26 families were identified. These consisted of 72 liana and 10 vine species. Seven hundred and sixteen trees belonging to 77 species and 27 families hosted the climbers. Climbing plants made up of about 43% of all the species (except herbs) identified. Lianas alone constituted about 38% of the woody species. The commonest and most dominant species were Strophantus barteri Franch., Smilax species and Griffonia simplicifolia (Vahl ex DC.) Baillon. Most of the climber species showed clumped distribution. Stem twinning was the most predominant climbing mechanism. The number of climbers using the different climbing mechanisms differed significantly (p\u3c0.001). Host species, habitat and their interaction had significant (p\u3c0.001) effects on climber density

Liana species richness, abundance and relationship with trees in the Bobiri forest reserve, Ghana: Impact of management systems

Forest management practices which may represent various forms of disturbance regimes could influence liana species richness, abundance and relationship with their hosts. The study sought to determine the impacts of three management systems, namely, the Selection, Tropical Shelterwood and Post Exploitation Systems (SS, TSS and PES respectively) on liana species richness, abundance and relationship with trees in the Bobiri forest reserve, Ghana. Lianas with dbh ≥ 2 cm found on trees with dbh ≥ 10 cm were enumerated in 1 ha plot each in the SS, TSS and PES. All trees (dbh ≥ 10 cm) within the plots that did not carry lianas were also enumerated. A total of 640 liana individuals belonging to 27 species, 22 genera and 13 families were identified in the management systems. Griffonia simplicifolia (Vahl ex DC.) Baill., Motandra guineensis (Thonn.) A.DC. and Calycobolus africanus (G.Don) Heine were the abundant species in all the management systems. Unlike in SS, lianas in the TSS and PES were dominated by a few species. Larger diameter lianas were more abundant in the PES (32%) compared with the SS (18.3%) and the PES (13.1%). Liana diversity (H′) (species richness and abundance) was quantitatively higher in the SS (2.8) than the TSS (2.2) and the PES (2.0). The numbers of lianas carried by tree species differed significantly in the management systems (p \u3c 0.001 each). Liana infestation in the forest was high. The level of liana infestation did not reflect the extent of liana load per tree in the management systems. Larger trees carried significantly more liana individuals than smaller trees in the PES (p = 0.019, r2 = 0.15). There was a positive significant relationship between host dbh and liana dbh in the PES (p \u3c 0.001, r2 = 0.23) and TSS (p = 0.024, r2 = 0.11). Tree diversity appeared to have influenced liana species richness and abundance

Diversity and distribution of ferns on the campus of the Kwame Nkrumah University of Science and Technology (KNUST), Kumasi, Ghana

Identification and distribution of fern species on the Kwame Nkrumah University of Science and Technology campus were determined. A dichotomous key was constructed for the identification of ferns on the Kwame Nkrumah University of Science and Technology campus. The species were identified using keys, descriptions, pictures, figures, herbarium specimens and assistance of fern taxonomists. The distribution of the species was determined using the relative frequency. The relative frequency of the species was quantified by recording the presence or absence of the plant species in a set of ten randomly located quadrats (4 m x 4 m). The plot size in each site was 40 m x 40 m. Thirteen different fern species belonging to the following genera were identified: Nephrolepis, Pteris, Microsorum, Cyclosorus, Arthropteris, Thelypteris, Adiantum, and Pityrogramma. The family Pteridaceae was the most diverse in terms of species richness while the family Oleandraceae recorded the lowest number of species. The most widely distributed fern species were Arthropteris orientalis and Thelypteris microbasis. The distribution of the rest of the species was however low. The study also showed that ferns on the Kwame Nkrumah University of Science and Technology campus are distributed in two main habitats: open and shaded. More of the species occurred in the shaded habitats. The diversity and distribution of ferns were affected by human activities.Journal of Science and Technology(Ghana) Vol. 27 (1) 2007: pp. 35-4