COMPOSITION, STRUCTURE AND CONSERVATION POTENTIAL OF VEGETATION ADJOINING A WIRE-MESH PERIMETER...

Nigerian Journal of Weed Science Volume 28 2015

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COMPOSITION, STRUCTURE AND CONSERVATION POTENTIAL OF VEGETATION

ADJOINING A WIRE-MESH PERIMETER FENCE AT UNIVERSITY OF BENIN FARM

SITE, BENIN CITY, NIGERIA

AIGBOKHAN E. I. AND AGIANAKU, O. F.

Department of Plant Biology and Biotechnology, University of Benin,

P.M.B. 1154 Benin City, 300001 Edo State, Nigeria

Email: [email protected].

Abstract.

Artificial structures in urban environments such as wire-mesh fences when left undisturbed, often

support spontaneous vegetation which escape regular weeding interventions. This study describes the

vegetation composition, structure and conservation potential of the perimeter wire-mesh fence

surrounding the University of Benin Farm Project site in Benin City, located within the wet tropical

rainforest zone. Floristic composition and structure at different sides of the fence were obtained from

visual surveillance and triplicate sample quadrats measuring 300 cm x 10 cm (3000 cm2). Ordinal and

hierarchical cluster analysis of phytosociological (cover, sociability) and species presence or absence

data were used to determine relative similarities and infer extent of anthropogenic disturbance at

different sections of the fence. Collectively, 123 vascular plants were inventoried with all but one

verified to known taxa. The plants distributed into one fern and 44 angiosperm families had Fabaceae

(14.9%), Poaceae (7.4%) and Euphorbiaceae (7.4%) as most prevalent. Growth form distribution was:

shrubs (22.76%), vines (22.76%), herbs (20.33%), trees (15.44)% and lianas (8.13%). Majority (70%)

mailto:[email protected]


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were native plants while exotic and cosmopolitan plants accounted for 28% and 3% respectively. Up

to 26 (25.2%) were plants typical of a heavily farmed forest regrowth habitat. Structurally, the East-

facing section was most species rich, while the South facing section was most diverse and the North-

facing section least diverse. Four floristically distinct vegetation groups were revealed in both the

scatter and cluster plots and appeared to reflect degree of anthropogenic disturbance. The South section

was the most markedly different from other sections while the least accessible West and North sections

were most similar and distinctly different from the East and South sections which were located along

thoroughfares. Among the plants, 26 (21.13%) were recognized as rare to the urban environment,

suggesting that the fence may have protected them from weeding and grazing. This demonstrates that

fence precincts in urban areas could serve as conservation refugia for rare native plants and that routine

surveys of such sites may yield relics of rare, vulnerable or endangered native indigenous or endemic

plants in urban environments.

Keywords: urban habitat, spontaneous vegetation, fence plants, rare plants, forest ecosystem,

disturbance, Nigeria.

'Running Title'. Weeds colonizing a wire-mesh fence in Benin-City, Nigeria.


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INTRODUCTION

The study of urban ecology approaches and promotes a paradigm shift especially for landscape

professionals to take a non-judgmental look at the totality of the plant resources of cities and to

recognize that ruderal landscapes have the capacity to make significant contributions to the

ecological functionality of many cities, particularly those struggling to adjust to the reality of

negative economic growth and population loss (Tredici, 2010). The increasing spread of peri-urban

areas in the vicinity of metropolitan cities in many emerging and developing countries is often

accompanied by social, societal and environmental problems (Redman and Jones, 2005; Simmering

et al. 2013). The most obvious distinguishing aspect of urban environments is the ubiquitous physical

disturbance associated with the construction and/or maintenance of their infrastructure and the

habitats are characterized by high levels of disturbance, impervious paving, and heat retention. These

factors, acting in concert, alter soil, water, and air conditions in ways that promote the growth of

stress-tolerant, early successional vegetation on abandoned or unmaintained land (Tredici, 2010)

Abandoned ruderal landscapes consist of marginal or degraded urban land that receives little or no

maintenance. It consists of a cosmopolitan mix of species that grows and reproduces without human

care or intent. Ruderal landscapes are typically associated with the margins of transportation

infrastructure, abandoned or vacant residential, commercial, and industrial property, and the

interstitial spaces that separate one land-use function from another (Tredici, 2010). From a strictly

functional perspective, most vegetated urban land can be classified into one of three broad

categories: remnant native landscape, manage horticultural landscapes, and abandoned ruderal

landscapes (Kowarik, 2005, Kuhn, 2006; Whitney, 1985; Zipperer et al., 1997, Tredici, 2010). These

landscape types can be distinguished from one another on the basis of 1) their past land-use history;


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2) the types of vegetation they contain; 3) the characteristics of their soils; and 4) the levels of

maintenance they require in order to preserve their integrity (Tredici, 2010).

Plant diversity in urban areas is often surprisingly high because of a number of factors, including past

land-use history, habitat heterogeneity, shifting patterns of socio-economic activity, changing

climatic conditions, horticultural and agricultural activity by people, and the abundance of

disturbance-generated establishment opportunities (Knapp et al., 2010, Wittig 2004, Zerbe et al.,

2003; Tredici, 2010). Improvement of urban environment and conservation of ecosystem have been

identified as two of the most compelling reason to investigate the spatial distribution of vegetation in

urban areas on a regional scale (Kumagai, 2008).

Very few report exist on the nature of urban vegetation in major cities in Nigeria (Fuwape and

Onyekwelu, 2011; Al Amin and Dadan-Garba, 2014). According to Fuwape and Onyekwelu (2011),

trees and green spaces of urban forestry (plus spontaneous vegetation) include among others serve to:

help to keep cities cool, act as natural filters and noise absorbers, improve microclimates, conserve

biodiversity, protect and improve the quality of natural resources, including soil, water, vegetation

and wildlife. Trees further contribute significantly to the aesthetic appeal of cities, thereby helping to

maintain the psychological health of their inhabitants.

The knowledge of the state of vegetation in the urban environment will allow for the monitoring and

detection of ecosystem degradation, which will lead to assessing the effects of habitat loss of forest

in Nigeria. Artificial structures such as a wire-mesh fence in an open disturbed site often serve as

support for spontaneous climbing weedy plants as well as providing protection for opportunistic

plants against regular weeding interventions. The precinct of such fences would simulate such

conditions akin to what may obtain in a forest environment where young sapling present in a forest

gap support the growth of vines and lianas especially at forest edges. Little is known about the


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species composition, distribution and conservation potentials of such sites found in urban areas in

southern Nigeria.

This study therefore investigates the vegetation profile around a wire-mesh fence highlighting the

potential effects of anthropogenic disturbance on the species composition, as well as vegetation

diversity and structure. This study addresses the following objectives: (i) determine plants commonly

associated with wire-mesh fences in Benin City, (ii) establish if the vegetation composition and

structure at the different sides of the fence are similar and if different, to what extent are the

differences linked to the degree of exposure to anthropogenic influence, (iii) which plant family

groups and growth form classes most represented, (iv) the relative distribution of native species

compared to exotic species among plants colonizing the fence precinct, (v) the habitat class that most

of the plants at the fence associated and (vi) if the fence precinct is serving as sanctuary or refugia for

rare native plants that would otherwise not survive in urban environments.


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MATERIALS AND METHODS

Study Area

University of Benin is a public owned University founded in 1970 and located just outside the borders

of Benin City metropolis on the Lagos Benin Highway. Benin City is an urban centre located originally

in the moist evergreen Tropical lowland forest region which is now completely degraded with virtually

no trace of its high forest status. The study was conducted from April 2011 to October 2014 at the 500

m long wire-mesh perimeter fence surrounding the University of Benin Project Farm site. A schematic

illustration (Ikhuoria, 1995) and a Google Satellite Image (Google, 2003) of the site are depicted in

Fig. 1A and Fig 1B respectively. The farm site, established in 1985 is located at the Main Campus,

Ugbowo, Benin City and has a rectangular outlay with a plot area of 14712.5 m2 measuring 107 m x

137.5 m at the North-South and East-West wings respectively. The GPS coordinates at the two extreme

corners to the North are 06024' 14.43"N, 005

036' 35.35" and 06

024'15.08"N 005

038.19E. The

coordinates at the South wing are 06024' 10.01N, 005

0 36'36.82E and 06

0 24' 10.95", 005

0 36' 39.89"E.

The elevation is 116 m asl. The South facing section overlooks a mini shopping centre and its entire

length lies on a busy thoroughfare with frequent human traffic. About one-half of the East facing side

adjourns an open field/parking lot with moderate human traffic while the other segment is cordoned off

by another fence thus making it inaccessible or minimally accessible to human traffic. The North and

West facing precincts of the fence are minimally exposed to human traffic. A small farmland adjourns

the North wing while the West wing was initially flanked by an open fallow field but was in the

process of being fenced in at the onset of this study in April 2011.


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A

B

Figure 1. Schematic outlay of University of Benin, Ugbowo Campus Main Campus showing Farm

Project study site - arrowed top left (A). Google Earth Satellite imagery of the study site shown within

the white-bordered square (B).

Determination of species composition

Weekly visual reconnaissance surveillance around the wire-mesh fence precinct were conducted

beginning from May 2011 until October 2014. Plants found at different sections of the fence were

identified, classified and catalogued according to their taxonomic (species and family) names, growth

form and biogeographical status (native or exotic). The following literature: Hutchinson & Dalziel

(1954, 1963, 1968,-1972), Akobun

N


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du and Agyakwa (1998), Arbonnier (2004) and Aigbokhan (2014) were used for plant identification. A

checklist of all the plant taxa grouped by family and indicating presence or absence at each of the four

sections of the perimeter fence was collated. Species found in all or at least three of the fence sections

were designated as common while those found only in one or two sections and from previous

experience, new or rarely known to the investigators and not commonly encountered in the area were

designated as rare or uncommon.

Determination of vegetation community structure

Comparative status of the vegetation structure at the different sections of the wire-mesh fence were

assessed and characterized using phytosociological data obtained from rectangular quadrats

measuring 300 cm x 10 cm (3000 cm2) which were randomly placed in three replicates along each of

the four sections of the perimeter fence (North = B, C, D; South = E, F, G; East= H, I, J; West = K,

L, M). Estimates of percent relative cover and sociability were determined following Braun-Blanquet

scales (Barbour et al., 1980). The presence or absence of each plant at the different sections of the

fence was also used to generate another data matrix. Spatial dispersion and degree of variability

within and among all the sampling transects was determined from ordination and cluster analysis on

both the phytosociological and presence or absence data matrices using var-corr matrix on Principal

Component Analysis (PCA). Similarity clusters were generated using algorithms based on

Unweighted pair-group average (UPGMA) based on Simpson's similarity measure. Prior to analysis,

trace presence of a plant denoted by ―r‖ on the data matrix were substituted by 0.1 and absence by

―0‖. Eigenvector loadings from the PCA were used to identify species exacting the most influence in

separating the different groups, while dendrograms from the hierarchical cluster analyses were used

to determine the level of similarities between the fence sites. All the analysis were performed on

Paleontological Statistics Software Package for education and data analysis (PAST) version 2.09

(Hammer et al., 2001).

Habitat classification

To determine the most probable natural habitats to which each of the observed plant species at the

fence precinct belong, each identified plants was cross-referenced with available checklists of plant


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typical for each of the different vegetation zones in Nigeria using principally information from

Nielsen (1968) and Steentoft (1988).

Conservation potential

Common and uncommon or rare urban plants among those observed at the fence precinct were

determined based on frequency of occurrence of each plant at each of the different sections of the

fence combined with available records in literature and previous knowledge and experience.

Voucher specimens of such uncommon plants were prepared and deposited at University of Benin

PBB herbarium.


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RESULTS

Species composition

The summary of plants found around the four sides of the perimeter wire-meshfence is shown in

Appendix 1. A total of 123 plants were found and only 122 species could be verified to known taxa.

Identified plants were distributed in 46 families were recorded along. Members of the Fabaceae were

the most represented with 14 taxa (9.84%) followed by Apocynaceae 8 (6.57%), Euphorbiaceae 8

(6.57%), and Poaceae 7 (5.74%) (Figure 2).

Plant type/growth habit

Overall relative frequency distribution of the growth habit of the observed plants (Table 1) show that

shrubs and vines were the most predominant categories each with 28 species or 22.78%, followed by

herbs with 25 (20.3%), trees 19 (15.4%), lianas 10 (8.1%) while grasses, sedges and ferns had 7

(5.69%), 5 (4.07%) and 1 (0.81%) respectively. Collectively, climbers (vines and lianas) accounted

for 38 (30.9%), woody shrubs and trees 47 (38.2%), and herbaceous plants 38 (30.89%). Frequency

distribution of each growth form class along individual section of the perimeter fence is shown in

Figure 4.

Table 1. Distribution of growth forms of vegetation found at the wire-mesh perimeter fence.

Growth form/ habit No. of

species

Relative

(%)

Fern 1 0.81

Sedge 5 4.07

Grass 7 5.69

Liana 10 8.13

Tree 19 15.44

Vine 28 22.76

Herb 25 20.33

Shrub 28 22.76

Total 123


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Figure 4. Plant growth-form distribution at different sections of the wire-mesh perimeter fence.

0

5

10

15

20

25

North wing South wing East wing West wing

Tree

Vine

Liana

Shrub

Herb

Grass

Sedge


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Figure 2. Frequency distribution of family groupings of plants found growing around the perimeter-wire fence.

12

8 8 7

6 6 6 5 5

4 3 3 3 3 3 3

2 2 2 2 2 2 2 2 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1

0

2

4

6

8

10

12

14

Fab

ace

ae

Ap

ocy

nac

eae

Eup

ho

rbia

ceae

Po

ace

ae

Cu

rcu

bit

ace

ae

Dio

sco

reac

eae

Lam

iace

ae

Am

aran

thac

eae

Cyp

erac

eae

Mal

vace

ae

Ara

ceae

Ast

erac

eae

Co

mm

elin

ace

ae

Me

nis

per

mac

eae

Ph

ylla

nth

ace

ae

Ru

bia

ceae

Aca

nth

ace

ae

Co

mb

reta

ceae

Co

nvo

lvu

lace

ae

Icac

inac

eae

Mo

race

ae

Myr

tace

ae

Po

rtu

laca

eae

Vio

lace

ae

An

no

nac

eae

Are

cace

ae

Big

no

nia

ceae

Can

nab

inac

eae

Car

icac

eae

Car

yop

hyl

lace

ae

Ce

last

race

ae

Co

lch

icac

eae

Co

nn

arac

eae

Dry

op

teri

dac

eae

Irvi

ngi

ace

ae

Mu

sace

ae

Pan

dac

eae

Pas

sifl

ora

ceae

Pip

erac

eae

Po

lyga

lace

ae

Sap

ind

acea

e

Sola

nac

eae

Urt

icac

eae

Ve

rben

acea

e

Vit

acea

e

Fre

qu

ency

Plant family


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Native origin

Plant distribution based on native origin of the plants is shown in Figure 3. Native plants with

most represented with 70% and 27.27% were exotic while plants of cosmopolitan status

accounted for 2.73%. Among the exotics, five were identified as invasive (Table 3).

Figure 3. Phytogeographic status plants found within the precincts of a wire-meshperimeter fence

in Benin-City, Nigeria in 2013.

Table 3. Exotic, invasive plant species found around the wire-mesh fence showing their common

names and origin

Botanical name Common name1 Native (Origin)

1

Alternanthera brasiliana Brazilian joyweed Mexico, N. & S. America

Alternanthera sessilis perpétua, rabbit-meat, sessile joyweed Asia

Chromolaena odorata Siam weed, Parafin weed, Devil weed,

Jack in the bush

N. & S. America

Euphorbia graminea grassleaf spurge N. & S. America

Mimosa diplotricha Giant Sensitive plant Brazil

1 Aigbokhan (2014)

70

27.27

2.73

0

10

20

30

40

50

60

70

80

Native Exotic Cosmopolitan

%

freq

uen

cy

Phytogeographic profile


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Natural Habitat

All but one plant species observed within the precinct of the wire-mesh fence were typical to

seven natural habitat classes (High Forest, Secondary Forest, Forest regrowth, Forest thickets,

home gardens, Ornamentals and ruderal) and majority were of the high forest environment with

those commonly found in forest regrowth/heavily farmed secondary forests being the most well

represented (Table 2). Most (31) plant taxa are typical of a forest regowth or Heavily farmed

secondary forest while 22 plants were typical of different strata of a High Forest. For other

categories, forest thicket had 12, secondary forest (11), home gardens (7), ornamentals (5) and

ruderals (9).


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Table 2. Habitat classification of plants observed at the wire-mesh perimeter fence. High forest

Secondary forest

Forest regrowth /

Heavily farmed areas

Forest Thicket Home gardens/

Cultivated plants

Ornamental plants Ruderals

Emergent (upper storey)

Alstonia boonei a

Celtis zenkeri a

B. Lower canopy (8-30 m)

Alchornea cordifolia a

C. Small trees and shrubs

Bridelia micrantha b

Carpolobia lutea a

Combretum spp a

Microdesmis puberula b

Rauvolfia vomitora b

Rinorea welwitschii a

Sphenocentrum jollyanum a

D. Lianes

Clerodendrum formicarum b

Clerodendrum globuliflorum b

Clerodendrum splendens b

Clerodendrum volubile b

Combretum platypterum a

Leoseneriella africana a

Landolphia owariensis a

E. Smaller Climbers

Cissus spp (Cyphostemma

adenocaule) a

Mikania cordata b

Secamone afzelia b

F. Weeds (herbs, shrubs or

climbing species Aneileme beninense b

Palisota hirsuta b

Abrus precatorius a

Alcornea cordifolia a

Dioscorea smilacifolia.

Elaeis guineensis a

Ficus exasperata a

Icacina trachantha a

Irvingia gabonensisb

Landolphia owariensis a

Newbouldia laevis a

Rauvolfia vomitora a

Secamone afzelia b

Abrus precatorius a

Adenia lobata a

Albizia zygia a

Alchornea cordifolia a

Allophylus africanus

Anchomanes difformis

Baphia nitida a

Bambusa vulgaris a

Clerodendrum voluble b


Cyathula prostata a

Dalechampia ipomoeifolia b

Desmodium spp a.

Ficus exasperata a

Laportea aestuans a

Gloriosa superba a

Glyphaea brevis a

Icacina trachantha a

Leoseneriella africana a

Mallotus oppositifolius a

Manniophyton fulvum b

Microdesmis puberula b

Milletia thonningii a

Momordica charantia a

Monodora tenuifolia a

Newbouldia laevis a

Palisota hirsuta b

Rauvolfia vomitora a

Solanum donianum a


Talinum triangulare a

Abrus precatorius a

Baphia nitida a

Cnetis corniculata


Ficus exasperata a

Gloriosa superba b

Glyphaea brevis a

Mallotus oppositifolius a

Mikania cordata a

Rauvolfia vomitoria a

Solanum donianum a


Carica papaya

Colocasia esculenta

Elaeis guineensis

Manihot esculenta

Musa var. sapientum

Psidium guajava

Telfairia occidentalis

Allamanda

cathartica

Delonix regia

Eugenia uniflora

Quisqualis indica a

Thevetia neriifolia

(Cascabela thevetia)

Ageratum conyzoides

Amaranthus hybridusa

Amaranthus spinosusa

Commelina erecta

Drymaria cordata

Euphorbia hirta

Ipomoea involucrata

Laportea aestuans

Plastosoma africanum

22 11 31 12 7 5 9

Habitat class listings based on prevalence under natural settings within selected vegetation zones in of Nigeria according to a

Nielsen (1965); bSteentoft (1988)


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Community Profile Analysis

Most of the trees, vines and lianas were found on the East wing while majority of the shrubs were

found at the precincts of both East and West wings. The South wing had the least number of lianas

and was the only site where sedges were represented. Most of the herbs were found on the West

wing.

Species diversity

Estimates of plant community structure using different parameters is shown in Table 4. Fewer

number of plant taxa (2.7) and fewer individuals (21) were recorded from the West facing section

of the fence than in others sections. More individuals were recorded from the North side while the

South facing section had the highest number of plant taxa (6.3). Both the Shannon Weaver and

Simpson’s indices indicate that the highest plant diversity (1.615) was evident at the South side

while the lowest plant diversity was observed at the West facing section which also was more

uniform because it had the most dominance( i.e dominance exerted by a specific taxa).

Table 4. Summary of mean estimates of different vegetation indices derived from three transects

samples at the different sections of the wire-mesh fence.

Vegetation index NORTH SOUTH EAST WEST

Taxa_S 5.333 6.333 4.667 2.667

Individuals 44.333 40.333 31.333 21.000

Dominance_D 0.493 0.232 0.351 0.566

Shannon_H 1.060 1.615 1.210 0.707

Simpson_1-D 0.507 0.767 0.649 0.434

Evenness_e^H/S 0.585 0.806 0.734 0.788

Spatial dispersion

Scatter plots of the sampling transect of phytosociological data and binary (presence or absence)

data from species composition projected onto the principal components are shown in Figures 5

and 6. Dispersion among sampling transects from principal component analysis (PCA) (Fig. 5)

cumulatively accounted for 55.9% of the variation (PC1=37.1%, PC2 = 18.8%). The dispersion

pattern clearlysegregated the different sections of the perimeter fence along distinct sections of the


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quadrants. The PCA loadings, indicate that dispersion along PC1 axis was mainly influenced

mostly due to the presence or absence of two plant species: Alchornea laxiflora (-0.3478) and

Platostoma africanum (0.7372), whilethe presence or absence of three plant species:Alchornea

laxiflora (-0.4208), Commelina erecta (0.2466) and Secamone afzelli (0.5319) accounted for

dispersion observed along PC2 axis. Variability within samples obtained from the same transect at

each section however showed that samples from transects at West side was most uniform (precise)

than those from the North, South and East in increasing order of variability(Figure 5). Relatively

high variability in the transects samples obtained within each of the East and North facing sections

were apparent. PCA cluster analysis (Figure 5) showed that transects samples obtained from the

West facing side of the fence to be spatially more closely aggregated indicating less variability or

more evenness than in samples from other sections. The South facing section was also more

closely aggregated that either the East or North facing section where the transects were more

widely dispersed from one another.

Figure 5. Principal components analysis comparing spatial displacement of the different sides of

the perimeter wire-mesh fence based on data matrix derived from phytosociological data of

observed plant taxa estimated from 12 relevés. Percentage of total variation explained is 37.1%

for component I and 18.8% for component II.


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Figure 6. Principal components analysis comparing spatial displacement of the different sides of

the perimeter wire-mesh fence based on presence or absence of plant taxa. Percentage of total

variation explained is 39.5% for component I and 34.89% for component II.

The PCA plot shown in Figure 6 accounted for a cumulative variability of 74.4% (PC1 =

39.503%; PC2 = 34.893%). The Eigen value for PC1 was 12.41 and PC2 was 10.96. Dispersion

along PC1 were influenced mainly by the presence of Thunbergia alata, Gloriosa superba,

Dioscorea alata, Baphia nitida, Hibiscus surattensis, and Psychotria benthamiana while on PC2

dispersion the main influences were due the presence of Allamanda cathartica, Pleioceras barteri,

Culcasia scandens, Colocasia esculenta, Drymaria cordata, Quisqualis indica, Dioscorea

praehensilis and Dalechampia ipomoeifolia.

Similarity profile:

Community structure:

The phytosociological profile matrix generated using the Braun-Blanquet method for 12 sample relevés

from the perimeter fence is shown in Appendix 2. Hierarchical cluster from this data shown in Figure 7


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reveal that all transects within each of the respective fence site showed close uniformities but

marked differences between sites. Both the West and North facing sides were most similar at the

0.75 similarity index level with the south facing section of the fence being most unique and

markedly different from all the other sections of the fence with shared similarity with other

sections only at the 0.25 similarity index. The East facing section was also distinctive with index

of similarity to the West and North facing sides at the 0.38. Similar clustering pattern were

obtained from cluster diagram using matrices derived from presence or absence of individual

species (Figure 8).

Figure 7. A dendrogram showing classification of different sites each with three sample relevés

along the perimeter wire-meshfence based on similarities from Bray-Curtis distanced average

linkage hierarchical agglomerative algorithm. The cut off point is set at 10.5%.


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Figure 8. A cluster diagram showing classification of different sites using presence or absence of

cumulative species composition at each section of the perimeter wire-mesh fence based on

similarity estimates based on Simpson index using paired group algorithm. The cut off point is set

at 0.323

Conservation potential

Table 5 lists 25 common ruderal weeds and 26 uncommon plants rare to the urban environment of

Benin City metropolis among the plants found growing within the perimeter fence area. Among

the rare plants, the following eight species were considered as extremely rare as they had not been

previously observed by the authors anywhere in the Benin City metropolitan area:

Craterispermum schweinfurthii (Rubiaceae), Dalechampia ipomoeifolia (Euphorbiaceae),

Decorsella paradoxa (syn. Gymnorinorea abidjanensis) (Violaceae), Dioscorea smilacifolia

(Dioscoreaceae), Rhaphiostylis beninensis (Icacinaceae), Rinorea welwitschii (Violaceae),

0.4

0.5

0.6

0.7

0.8

0.9

1

Sim

ilarity

East West North SouthEast West North South

Sim

ilari

ty


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Talinum paniculatum (syn. Portulaca paniculata) (Portulacaceae), Thunbergia alata

(Acanthaceae)

Table 5. Common weedy ruderals and uncommon plant species found within the precincts of a

perimeter fence of University of Benin Farm Project Site, Benin-City, Nigeria.

Common weedy ruderal species Uncommon plant species

Ageratum conyzoides

Alternanthera brasiliana

Alternanthera sessilis

Asystasia gangetica

Axonopus compressus

Chromolaena odorata

Clerodendrum splendens

Coccinia barter

Commelina erecta

Dioscorea alata

Eragrostis tenella

Ficus lutea

Gloriosa superba

Glyphaea brevis

Hibiscus surattensis

Icacina trichantha

Ipomoea involucrata

Lagenaria breviflora

Mimosa diplotricha

Momordica charantia

Momordica cissoides Newbouldia laevis Secamone afzelli

Solenostemon monostachyus

Triclista patens

Allophylus africanus

Anchomanes difformis

Anthonotha macrophylla

Baissea welwitschii

Bombax costatum

Celtis zenkeri

Clerodendrum formicarum

Clerodendrumn globuliflorum

Cnetis corniculata

*Craterispermum schweinfurthii

Culcasia scandens

Cyphostemma adenocaule

Dalbergellia welwitschii

*Dalechampia ipomoeifolia

*Decorsella paradoxa (syn. Gymnorinorea abidjanensis)

Dioscorea praehensilis

*Dioscorea smilacifolia

Landolphia owariensis

Perichasma laetificata (syn. Stephania laetificata)

Pleioceras barteri

Quisqualis indica

*Rhaphiostylis beninensis

*Rinorea welwitschii

Securinega virosa

*Talinum paniculatum (syn. Portulaca paniculata)

*Thunbergia alata

* Plants not previously seen in Benin City area by the authors.


22

DISCUSSION

According to Fuwape and Onyekwelu (2008), urbanization in the West Africa is mostly a

recent phenomenon because the current trend of urbanization in the region is linked with

colonization that developed new centres for control, administration and export of exploited natural

resources. Most urban centres in West Africa were nurtured by great empires which developed

large settlements for commercial and religious purposes (Chandler, 1994). The urban metropolis

of Benin City combines attributes on the new and old as it was nurtured by the famed Benin

empire. This study present a partial checklist of the spontaneous flora that would dominate any

unmanaged urban landscapes in a university campus site in Benin City. A report similar to this

study (Modi and Dudani, 2013), showed the conservation potentials of green spaces at Gujarat

University campus in Ahmedabad, India. Among the few reported studies on urban vegetation in

Nigeria is Al-Amin. and Dadan-Garba, (2014) who reported using satellite imagery an almost

complete obliteration of indigenous native tree species on the urban vegetation of Kaduna

metropolis. This study provides a checklist of plants associated with a wire-mesh fence in Benin

City. It presents representative flora that would populate fences or free-standing structures capable

of supporting plant growth in forest zone of southern Nigeria. The spectrum of vegetation around

the fence precinct comprising native, cultivated agricultural or horticultural plants and

unintentionally introduced exotic or disturbance adapted weeds supports observations previous

observations that abandoned ruderal landscapes is often populated by introduced, disturbance

adapted weeds (Tredici, 2010).

Plant composition at the perimeter-fence precinct reflect what Tredici (2010) describes as

spontaneous vegetation—a cosmopolitan mix of species that grows and reproduces without

human care which are often found in marginal or degraded urban land that receives little or no

maintenance. The array of plants found represent vegetation common in a 5-8 year old forest

regrowth fallow which therefore suggests that the wire-mesh fence may have been abandoned for


23

this length of time. Many of the plants such as: Icacina sp, Cyathula prostata, Mormodica

charantia, have previously been shown to be typical of forest regrowth and small climbers like

Mikania cordata, Secamone afzelii are typical for secondary forests (Nielsen, 1965; Steentoft,

1988). Eleven (11) shrubs and tree species and one climber observed along the fence were also

previously reported at the Botanical Garden of Obafemi Awolowo University (Muoghalu and

Okeesan, 2005). Comparatively, 18 of the 41 (44%) of the plants observed at the precinct of

perimeter fence were also found on a farmland abandoned for 20 years in Imo state, Nigeria (Dike

and Obajuwana, 2012). This implies that the spontaneous vegetation found around the fence

reflect one that would be found in regrowth (abandoned) circumstances after 10 years. According

to Steentoft (1988), when fallow periods lasts from two to four years, a reduction of plant species

occur and a thicket is formed before the end of the next or disturbance period which supports

species such as: Alchornea cordifolia, Icacina trichantha, Mallotus oppositifolius, Ficus

exasperata and Rauvolfia vomitoria and all these plants were represented on the perimeter fence.

Taxonomically, the most dominant plant families represented around the fence were the

families: Fabaceae, Apocynaceae, Euphorbiaceae and Poaceae. Several findings support this

observation: Soromessa et. al., 2004, reports that the vegetation of Gamo Gofa zone, southern

Ethiopia, Fabaceae was the most prominent family represented by 33 species (15%), Addo-

Fordjour et. al., 2008, on a semi- deciduous rain forest in Ghana in which the most diverse family

in terms of species richness was Fabaceae (17.1%), Gentry, 1991; Schnitzer and Bongers, 2002,

reports that the most species rich climber families are Rubiaceae, Fabaceae, Celestraceae and

Apocynaceae while Rajendra, et al (2011) showed that Poaceae, Fabaceae and Asteraceae were

the dominant family groups in disturbed lands of North Gujarat Region (NGR), India by their

nature as seasonal plants (annuals) that generate large number of seeds with a wide range of

ecological tolerances and good dispersal efficiency.


24

The prevalence within the fence precinct of native plants and few cultivated and

ornamental crops including ruderals confirms observations by Kowarik (2005) that spontaneous

vegetation are most likely to be: 1) native to the area; 2) formerly or currently cultivated for

agricultural or horticultural purposes; and 3) unintentionally introduced, disturbance adapted

weeds. The opportunity for these regrowth plants to thrive may have been occasioned by

regeneration of viable propagules from relics from the natural vegetation that was in place before

urban encroachment. Although the vegetation around the wire-mesh fence may appear

aesthetically undesirable, from an ecologically standpoint it sustains the biodiversity of the area,

and as such, may serve as potential refugia sites for the exploration, exploitation of medicinal as

well as rare plants, and thus should be protected.

Ornamental and cultivated food plants are commonly observed in urban environments

especially where aesthetic use of plants and home gardens are common practices. The incidence

within the fence precincts of Delonix regia, Allamanda cathartica, Thevetia nerifolia, Eugenia

uniflora suggest relics from ornamental hedge plants that may have been deliberately cultivated to

demarcate the farm site perimeter before the wire-mesh fence was constructed. Fuwape and

Onyekwelu (2008) had identified D. regia as one of the trees cultivated for landscape

enhancement and environmental protection in the tropical rainforest zone. The occurrence of fruit

and food crops like Telfaria occiedentalis, Dioscorea alata, Dioscorea dumetorum around the

fence may have resulted from escape from cultivated plots within farm plots which now mingles

and formed part of spontaneous weedy plants that are protected from regular weeding by the

opportunity of its proximity to the fence.

According to Tredici (2010), urban ecology can be distinguished from its natural systems

counterpart by the inseparable blend of human culture and natural history. The occurrence around

the fence precinct of plants commonly associated with heavily farmed secondary forest regrowth

with few species characteristic of mature forest, gallery forests or fallow regrowth forest habitat


25

including garden crops and plants of significant cultural relevance to the Bini's culture appear to

support this position. The primary use of the farm site for the cultivation of garden crops and the

possibility that these crops with time, escaped or dispersed into the fence precinct. Plants such as

Newbouldia laevis (Ikhimi), Glyphaea brevis (Uwerhiontan) and Alstonei boonei (Ogiegbukhu)

when encountered, are often skipped during weeding process due to special cultural and sacred

reverence sometimes attached to them by the local population in Benin City. Rauvolfia vomitora

(Akata) is preserved for its medicinal value. The cultural uniqueness of these plants in the ancient

Benin Kingdom were previously documented in Melzian Benin Dictionary (Melzian, 1937,

Aigbokhan et al., 2013).

The presence along the fence precinct of invasive exotic plants such as Mimosa

diplothrica, Althernanthera brasiliana and Euphorbia graminea indicate the opened and disturbed

nature of the fence site. The first two are sun-loving (heliophytes) and widely distributed

(Aigbokhan et al 2011, Uyi et al., 2014) while the shade-loving (sciaphyte), E. graminea was

restricted only to the north and west facing sections of the perimeter fence which suggests the

abundance of shade at the microenvironment at these sites and also points to their relative less

disturbed status. This fact therefore suggest that E. graminea may have the potential in becoming

a serious invasive threat to shaded and less disturbed areas such as the forest understory

(Aigbokhan and Ekutu, 2012).

According to Fuwape and Onyekwelu (2011), the common trees grown in urban forests

located in rainforest ecological zones in West Africa were predominantly exotic plantation and

ornamental trees such as Gmelina arborea, Terminalia catappa, Tectona grandis etc. The

presence within the precinct of the fence of native trees such as Alstonia boonei, Celtis zenkeri

and Alchornea cordifolia suggests the immense conservation potentials such locations hold for

reviving the re-vegetation of urban centers with indigenous plants. The ratio of shrubs (22.8%),

herbs (20.3%) and climbers (30.86%) around the perimeter fence succession are mostly persistent


26

shrubs, small climbers and herbs and account for up to 20% of species. The higher estimates

observed especially of the perennials may suggest that the fence site may be well past its early

succession phase.

The preponderance of native plants, some exotic cultivated plants and very few

cosmopolitan assemblage of plant species among the spontaneous vegetation at the fence precinct

suggest that few exchanges with fewer biological immigration from all corners of the globe or the

inability of introduced propagates to successfully adapt, establish, thrive and proliferate. The

occurrence of typical forest undergrowth plant species such as Palisota hirsuta and Culcasia

scandens in the West or East facing sections of the perimeter fence suggest higher moisture levels

in the microenvironment which may have arisen from the shading effect from the tree crowns.

The patchy nature of vine distribution was in contrast to findings reported by workers reporting on

older sites. Addo-Fordjour et. al., ( 2008), worked on a 52 years old forest and found that 72 of

the 951 climber species were lianas and only 10 were vines, and Muoghalu and Okeesan, 2005,

worked on a 59 years old forest in which the climber species were made predominantly of 35

lianas and 14 vines. The result of this study differs from the hypothesis stated above that the

climber species would be comprised more of lianas this could be as a result of the short period of

time since the last major disturbance, as compared to the age of the forests reported above.

The abundance of herbs and sedges which accounted for 44.7% of the overall species

count is indicative of the open nature of the fence precinct and the influence of frequent

disturbance activities which tend to promote the development of ruderal vegetation. The structure

and composition of plants on the four sides of the fence suggests differential responses to varying

disturbance influences. Few climber species such as Momordica charantia, M. cissoides, Ipomoea

involucrata and Icacina trichantha which occurred all the four sides of the fences may be due to

their ability to withstand varying levels of stress conditions due to disturbance while the

occurrence of Amaranthus hybridus, A. spinosus, Cyathula prostrata and Platostoma africanum


27

on at the south section suggest their high stress tolerance common in highly disturbed

environments.

Estimates of species richness from this study was however higher than 102 species

reported for the Biological Gardens of Obafemi Awolowo University, Ile Ife (Muoghalu and

Okeesan, 2005). Biswas and Malik (2010) observed that species richness and species diversity

peaked at moderate disturbance while Connell (1978) and Binelli et al., 2000, confirmed that

intermediate levels of disturbance promoted higher levels of diversity. The high range of species

richness (45-64) observed in this study may be attributed to the high to intermediate level of

disturbances resulting from farming activities and other human influences occasioned by activities

from the thoroughfare, routine hand weeding and the occasional grazing from domestic animals.

Other possible disturbance factors include shading from tall trees and predation. Armesto and

Pickett, (1983) have shown from on an old-field community that species tend to increase with

intensity of disturbance, resulting in maximum richness at the highest disturbance intensity

disturbance. According to Suding (2001) and Calvo et al., (2011), disturbance favours the

colonization of new herbaceous species, and the effect of this is an increase in species richness

with increasing light availability at the ground level of the forest, and an increase in species

richness brought about by creation of gap in the forest due to disturbance.

The distinctive dispersion of the different sections of the perimeter fence in both the

cluster and PCA plots suggests their structural differences. Close association between West and

North facing sides which incidentally were also the sections that were least exposed to

anthropogenic disturbances demonstrate that analytical procedures used for both

phytosociological and the species presence of absence data were sensitive enough to precisely and

accurately detect the variations inherent within plant composition and structure at the different

segments of the fence. Additionally, it was also able to accurately detect that the most accessible

(most disturbed) south facing section as the most unique than all the other sections. These


28

evidences suggests that species found at the South section represent ruderals that are more adapted

to highly disturbed areas. Application of procedures used in this study is recommended for the

prediction of vegetation disturbance especially in areas with unknown history of anthropogenic

interference.

Structurally, vegetation appear to reflect degree of exposure to anthropogenic influences.

The south facing section of the fence and to a lesser extent, the East facing section had high

specie, a phenomenon which may be linked to disturbance attributable to direct human impacts as

these locations were accessible and used as thoroughfares which made them markedly different

from the west and north facing sections which were somewhat sheltered from such human

influences. This corresponds with observations by Tredici (2010) that increases in plant diversity

was due to habitat heterogeneity arising from abundance of disturbance-generated establishment

opportunities linked to human activities such as: land-use history, habitat heterogeneity, shifting

patterns of socio-economic activity, changing climatic conditions, horticultural and agriculture.

This study providence evidence that direct exposure anthropogenic influences could markedly

alter the composition and community structure of vegetation.

There have been recommendations that spontaneous vegetation be actively conserved for

the role they play in generating and maintaining urban biodiversity (Savard et al. 2000, Maurer et

al. 2000; Kowarik 2005; Muratet et al. 2007; Rink 2009; Tredici 2010, Modi and Dudani, 2013).

Zapfack et al. (2002) showed evidence that secondary forests serve as refuge areas for primary

forest plant species which may function as a starting point for possible regeneration of original

biodiversity. The presence at the perimeter fence of mature and saplings of large emergent forest

trees such as Bombax costatus, Alstonii boonei and Celtis zenkri suggests that these are probably

relics from past forest vegetation (see Nielsen 1968) which may have sequestered and then only

germinated and thrived because their presence by the fence precinct shielded them from trampling

and weeding. Similar arguments may also be advanced for the occurrence around the fence


29

precinct of as many as 26 native plant species some of which are rare and somewhat uncommon in

both urban, peri-urban and even in the wild environment around Benin City. Some of most

outstanding among the rare plants are: Anthonotha macrophylla, Baissea welwitschii, Celtis

zenkeri, Clerodendrum formicarum, Clerodendrumn globuliflorum, Cnetis corniculata,

Craterispermum schweinfurthii, Dalechampia ipomoeifolia, Decorsella paradoxa (syn.

Gymnorinorea abidjanensis), Dioscorea smilacifolia, Landolphia owariensis, Rhaphiostylis

beninensis, Rinorea welwitschii, Talinum paniculatum (syn. Portulaca paniculata) and

Thunbergia alata. It is therefore imperative to suggest that the perimeter fence may be serving as

a refugia for rare native plants species and therefore potentially of high conservation value.

Routine surveillance of such sites in urban areas is recommended to recover relics of rare

indigenous native plants for further conservation action.

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35

Appendix 1: Checklist and growth form of plants colonizing North, South, East and West sections

of the perimeter wire-mesh fence of University of Benin Farm Project Site, in Benin City, Nigeria

(Ordered alphabetically by family).

Species Growth

form*

Location of sampling plot

North South East West

ACANTHACEAE

1. Asystasia gangetica (L.) T. Anderson H + + +

2. Thunbergia alata Bojer ex Sims V +

AMARANTHACEAE

3. Alternanthera brasiliana (L.) Kuntze H + + +

4. Alternanthera sessilis (L.) DC H + + +

5. Amaranthus hybridus L. H +

6. Amaranthus spinosus L. H +

7. Cyathula prostrata (L.) Blume H +

8. Platostoma africanum P. Beauv. H +

ANNONACEAE

9. Monodora tenuifolia Benth. T + +

APOCYNACEAE

10. Allamanda cathartica L. SH +

11. Alstonia boonei De Wild. T +

12. Baissea welwitschii (Baill.) Stapf L +

13. Landolphia owariensis P. Beauv. V + +

14. Pleioceras barteri Baill. SH +

15. Rauvolfia vomitoria Afzel. SH + + +

16. Secamone afzelli (Schulfes) K.Schum. L + +

17. Cascabela thevetia (L.) Lippold

(Syn. Thevetia neriifolia Juss ex Steud.) SH +

ARACEAE

18. Anchomanes difformis (Bl.) Engl. H +

19. Culcasia scandens P. Beauv. V +

20. Colocasia esculenta (L.)Schott H +

ARECACEAE

21. Elaeis guineensis Jacq. T +

ASTERACEAE

22. Ageratum conyzoides L. H + + +

23. Chromolaena odorata (L.) R. King & H. Rob SH

24. Mikania cordata (Burm. f.) B. L. Rob. V +

BIGNONACEAE

25. Newbouldia laevis Seem. ex Bureau T +

CANNABINACEAE (ULMACEAE)

26. Celtis zenkeri Engl. T +

CARICACEAE

27. Carica papaya L. H

CARYOPHYLLACEAE

28. Drymaria cordata (L.) Willd. Ex Roem. & Schult. H +

CELESTRACEAE

29. Leoseneriella africana (Willd.) R.Wilczek ex N. Halle L + +

COLCHICACEAE

30. Gloriosa superba L. V + + +

COMBRETACEAE

31. Combretum platypterum (Welw.) Hutch. & Dalziel L + +

32. Quisqualis indica L. L +

COMMELINACEAE


36

Species Growth

form*



33. Aneilema beniniense (P.Beauv.) Kunth H + +

34. Commelina erecta L. H + + + +

35. Palisota hirsuta (Thunb.) K. Schum. ex Engler H + +

CONNARACEAE

36. Cnetis corniculata Lam. L + +

CONVOLVULACEAE

37. Ipomoea involucrata P. Beauv. V + + +

38. Ipomoea quamoclit L. V +

CURCUBITACEAE

39. Coccinia barteri (Hook.f.) Keay V + +

40. Lagenaria breviflora (Benth.) Roberty V + + +

41. Luffa aegyptiaca Mill. (syn. Luffa cylindrica M. Roem) V + +

42. Momordica charantia L. V + + +

43. Momordica cissoides Benth. V + + +

44. Telfairia occidentalis Hook. f. V +

CYPERACEAE

45. Cyperus esculentus L. S +

46. Cyperus rotundus L. S +

47. Kyllingia bulbosa P. Beauv. S +

48. Mariscus alternifolius Steud. S +

49. Mariscus longibracteatus Cherm. S +

DIOSCORACEAE

50. Dioscorea alata L. V + + +

51. Dioscorea bulbifera L. V + +

52. Dioscorea dumetorum (Kunth) Pax. V +

53. Dioscorea praehensilis Benth. V +

54. Dioscorea sansibarensis Pax V + +

55. Dioscorea smilacifolia De Wild. & Th. Dur. +

EUPHORBIACEAE

56. Alchornea laxiflora (Benth.) Pax & K. Hoffm. SH + +

57. Alchornea cordifolia (Schum. & Thonn.) Muell. Arg. SH +

58. Dalechampia ipomoeifolia Benth. V +

59. Euphorbia graminae Jacq. H + + +

60. Euphorbia hirta L. H +

61. Hevea brasiliensis (A. Juss.) Mull. Arg. T +

62. Mallotus oppositifolius (Geiseler) Mull. Arg. SH +

63. Manihot esculenta Crantz. SH +

64. Securinega virosa (Roxb. ex Willd.) Baill. (use Flueggea

virosa (Roxb. ex Willd.) Voigt) SH +

FABACEAE (PAPILIONOIDEAE)

65. Abrus precatorius L. V + +

66. Baphia nitida Lodd. SH + + +

67. Calopogonium mucunoides Desv. V + +

68. Centrosema pubescens Benth. V + +

69. Dalbergellia welwitschii Guill. & Perr. L + +

70. Milletia thonningii (Schumach. & Thonn.) Baker SH +

71. Mucuna pruriens (L.) DC. V + +

FABACEAE (CAESALPINOIDEAE)

72. Anthonotha macrophyllaP. Beauv. SH + +

73. Delonix regia (Hook.) Raf. T +

74. Senna occidentalis (L.) Link. SH +

FABACEAE (MIMOSOIDEAE)


37

Species Growth

form*



75. Albizia zygia (DC.) J.F. Macbr T + +

76. Mimosa diplotricha C. Wright V + + +

ICACINACEAE

77. Icacina trichantha Oliv. L + + + +

78. Rhaphiostylis beninensis (Hook.f. ex Planch.) Planch ex

Benth L + +

IRVINGIACEAE

79. Irvingia gabonensis (Aubry-Lecomte ex Rorke) Baill. T +

LAMIACEAE

80. Clerodendrum formicarum Gürke SH +

81. Clerodendrumn globuliflorum B.Thomas SH +

82. Clerodendrum splendens G.Don SH +

83. Clerodendrum volubile P.Beauv. SH + +

84. Solenostemon monostachyus (P. Beauv.) Briq. H +

MALVACEAE

85. Bombax costatum Pellegr. & Vuillet T +

86. Hibiscus surattensis L. SH + + +

87. Glyphaea brevis (Spreng.) Monach. SH + +

88. Sida urens L. SH +

MENISPERMACEAE

89. Perichasma laetificata Miers (syn. Stephania laetificata

(Miers) Benth.) L +

90. Sphenocentrium jollyanum Pierre SH + +

91. Triclista patens Oliv. L + + +

MORACEAE

92. Ficus exasperata Vahl T + +

93. Ficus sur Forssk.(syn. Ficus capensis Thunb.) T + +

MUSACEAE

94. Musa sapientum Var. H +

MYRTACEAE

95. Eugenia uniflora L. SH +

96. Psidium guajava L. T +

PASSIFLORACEAE

97. Adenia cissampeloides (Planch. Ex Hook.) Harms V + +

PANDACEAE

98. Microdesmis puberula Hook. f. ex Planch. SH + +

PHYLLANTACEAE

99. Bridelia micrantha (Hochst.) Baill. T + +

100. Phyllanthus amarus Schumach. & Thonn. H + +

PIPERACEAE

101. Peperomia pellucida (L.) Kunth. H + +

POACEAE

102. Axonopus compressus (Sw.) P. Beauv. G + + + +

103. Bambusa vulgaris Schrad. ex J.C. Wendl. G + +

104. Eleusine indica (L.) Gaertn. G +

105. Eragrostis tenella (L.) Roem. & Schult. G + + + +

106. Panicum maximum Jacq. (syn. Megathyrsus maximus

(Jacq.) B. K. Simon & S. W. L. Jacobs) G +

107. Setaria barbata (Lam.) Kunth G +

108. Zea mays L. G +

POLYGALACEAE +

109. Carpolobia lutea G. Don SH + +


38

Species Growth

form*



PORTULACACEAE

110. Talinum triangulare (Jacq.) Willd H + +

111. Talinum paniculatum (Jacq.) Gaertn. (syn. Portulaca

paniculata Jacq.) H +

RUBIACEAE

112. Craterispermum schweinfurthii Hiern T +

113. Psychotria benthamiana Hiern (syn. Chasalia kolly

(Schumach) Hepper) H + + +

114. Psydrax subcordatum (DC.) Bridson (syn. Canthium

subcordatum DC.) T + +

SAPINDACEAE

115. Allophylus africanus P. Beauv. T +

SOLANACEAE

116. Solanum donianum Walp. SH +

URTICACEAE

117. Laportea aestuans (L.) Chew (syn. Fleurya aestuans

(L.) Gaud. ex Miq.) H +

VERBENACEAE

118. Duranta erecta L. SH +

VIOLACEAE

119. Decorsella paradoxa A. Chev. (syn. Gymnorinorea

abidjanensis (Aubrev. & Pellgr.) Keay) SH +

120. Rinorea welwitschii (Oliv.) Kuntze SH +

VITACEAE

121. Cyphostemma adenocaule (A.Rich.) Desc. ex Wild&

Drum (syn. Cissus adenocaulis A.Rich.) V + +

122. UNIDENTIFIED (2) L +

LOWER PLANTS

DAVILLIACEAE

123. Nephrolepis biserrata (Sw.) Schott H? +

Column

Total 45 48 64 61

*Growth form codes: Tree (T), Shrub (SH), Herb (H), Liana (L), Vine (V), Sedge (S), Grass (G)


39

Appendix 2: A data matrix table of 12 relevés showing phytosociological status of plants found at

the North, South, East and West wings of the perimeter fence, based on Braun-Blanquét's method.

(tenths and unit digits represents cover and sociability ratings, r = absent or trace). NORTH SOUTH EAST WEST

SPECIES Relevé code B C D E F G H I J K L M

Albizia zygia r r 1.1

Alchornea laxiflora r r 1.1 2.1 r r 2.1 2.1 2.1

Anchomanes difformis r r 1.1

Asystasia gangetica 2.1 1.1 r

Axonopus compressus 1.2 2.2 r

Centrosema pubescens 1.1 2.1 r

Chasalia kolly r 2.1 r

Colocasia esculentus r r 1.1

Combretum platypterum r 1.1 r

Commelina erecta r 1.1 2.2

Delonix regia r r 1.1

Dioscorea prehensilis r r 1.1

Hevea brasiliensis 1.1 1.1 1.1

Icacina tricantha r 1.1 1.1 1.1 r 1.1 1.1 r 1.1 1.1 2.1 1.1

Ipomoea involucrata r 1.2

Mallotus oppositifolius r r 1.1

Mariscus alternifolius r r 1.1

Palisota hirsuta r 2.2 r

Panicum maximum r 1.1 1.1

Peperomia pellucida r 2.2 r

Platostoma africanum 3.3 3.5 2.2 2.2 2.2 2.5

Portulaca paniculata r r 2.2

Secamone sp 1.2 r 1.2 3.2 2.2 1.2

Setaria barbata 1.1 r 1.1 r 1.2 r

Tragia polygonoides r 1.1 r

Triclista patens r 1.1 r 1.1 r r

Plate 1. The only unidentified plant found in the precinct of East (Left) and

Baissea welwitschii (Right) from the West sections of the wire-mesh perimeter

fence.

COMPOSITION, STRUCTURE AND CONSERVATION POTENTIAL OF VEGETATION ADJOINING A WIRE-MESH PERIMETER...

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