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Journal of Agriculture and Ecology Research International 21(10): 25-37, 2020; Article no.JAERI.63899 ISSN: 2394-1073 Floristic Response of Herbaceous Flora to Intensive Cropping Systems: A Case of Ajibode-sasa Arable Agroecosystem, Ibadan, Southwest Nigeria Olayanju, Folasayo Micheal1 and Olubode, Oluseun Sunday1* 1Department of Crop Protection and Environmental Biology, University of Ibadan, Ibadan, Nigeria. Authors’ contributions This work was carried out in collaboration between both authors. Author OOS conceptualized the study. Authors OOS and OFM designed the study, performed the statistical analysis, managed literature searches, and wrote the first draft of the manuscript. Author OOS managed the revisions of manuscript. Both authors read and approved the final manuscript. Article Information DOI: 10.9734/JAERI/2020/v21i1030171 Editor(s): (1) Dr. Nhamo Nhamo, Marondera University of Agricultural Sciences and Technology, Zimbabwe. (2) Dr. Chandra Shekhar Kapoor, Mohan Lal Sukhadia University, India. Reviewers: (1) Lim Hwee San, Universiti Sains Malaysia (USM), Malaysia. (2) Andri Wibowo, University of Indonesia, Indonesia. (3) Hari Om, Bihar Agricultural University, India. Complete Peer review History: http://www.sdiarticle4.com/review-history/63899 Received 11 October 2020 Accepted 19 December 2020 Original Research Article Published 31 December 2020 ABSTRACT Agriculture a most significant land use types which alter natural ecosystem dynamics. Arable farming exerts much pressure on plant biodiversity, especially when practiced intensively in urban centers. There is dearth of information on floristic changes due to intensive arable farming in urban agroecosystems in developing countries. The study therefore assessed floristic changes resulting from and intensive farming practices at Ajibode-Sasa agricultural landscape. Ajibode-Sasa agroecosystem is a complex mix of arable cropping system between latitude N07°28′, E003°53′ and longitude N07°28′, E003°54. Comparative floristic surveys were conducted in 2016 and 2020 using quadrats (1 m2) systematically laid on 18 Transects ranging from 50 – 250 m long. A total of 224 and 184 quadrats were laid in 2016 and 2020 respectively. Reduction in numbers of quadrats laid resulted from physical anthropogenic development after the 2016 survey. Species identification followed standard procedures, and quantitative occurrence data were collected for determination of species composition and computation of relative importance values (RIV) and diversity indices. _____________________________________________________________________________________________________ *Corresponding author: E-mail: [email protected]; Micheal and Sunday; JAERI, 21(10): 25-37, 2020; Article no.JAERI.63899 Land-use changes over four years period was determined using Google earth and QGIS. Herbacous plant composition with 123 cumulative number of species in both years reduced from 98 species in 2016 to 85 species in 2020 species RIV of species ranged from 0.038 – 14.803. Tridax procumbens had the highest RIV (14.803) in 2016, while it was Acmella brachyglossa (13.248) 2020. Species richness and floral diversity was high with Shannon-Weiner Index (3.081 and 3.088) and Dominance (0.09388 and 0.08746) in 2016 and 2020 respectively. Intensive cultivation favoured introduction and spread of invasive species like Tridax procumbens and Tithonia diversifolia. Eight introduced and invasive species were newly enumerated in 2020, with a total of 38 herbaceous species no longer encountered in 2020. Concerted efforts should be made to conserve native flora on the agroecosystem through sustainable practices like crop rotation and short fallow. Keywords: Ecosystem dynamics; arable farming; landscape fragmentation; invasive species; sustainable agriculture. 1. INTRODUCTION fragmentation thus affects terrestrial biodiversity in way that affect species richness patterns, Man has dramatically transformed much of the because species richness is related to landscape earth’s natural ecosystems through various structure [14]. activities [1] and agriculture remains one of the major contributing factors [2]. Of the 13.2 billion However, as more than 50 percent of world hectares global land area, 1.6 billion hectares population now reside in cities [15], which that represent 12 per cent is currently in use for justifies the need for urban agriculture agricultural production [3] and this interferes with intensification to ensure food security [16,17], ecosystem services provided by natural concerns have developed long term sustainability resources [4]. Alteration of natural ecosystems and environmental consequences of the has been ongoing for millennia – but it has intensification of agricultural systems [18]. accelerated sharply over the last centuries, and Agricultural intensification can have negative in the last several decades [5]. Expansion of local consequences, such as increased erosion, agricultural land which for some time was lower soil fertility, and reduced biodiversity; justified as a need to ensure food security has negative regional consequences [19], such as led to habitat fragmentation [6] which is one of pollution of the ground water and the four major threats to world biodiversity [7] eutrophication of rivers and lakes; and negative and their life-sustaining services [8]. Agricultural global consequences, including intensification in both rural and urban impacts on atmospheric constituents and climate centers as an adaptation to increasing human [20]. population has however, continues to disrupt ecosystem integrity of natural environment [9] The roles of agriculture in spreading invasive leading to great negative consequences species have also been well documented [21]. [10]. This [4] anthropogenic effect [1] together with climatic and geological factors determines Urbanization encourages fragmentation of biological composition and services rendered by habitats of plants into patches that contain ecological system within space and time [22]. subsets of species inhabiting different habitat However, there is dearth of information on subsets [11]. Species occupancy is related to the quantitive floristic changes occasioned by specificity of the habitat, if habitat is defined intensive arable agriculture in many according to Hall et al. [12] and Lindenmayer and urban regions of developing countries in Fischer [13], where ‘habitat’ constitutes the Africa. resources and conditions present in an area that produce occupancy for a particular species. The Therefore, there is need to critically appraise habitat fragments are usually anthropogenic, effects of intensive cropping of urban lands on where it can constitute threats to biodiversity health and community structure of herbacous [11]. The anthropogenic nature of the patchiness flora. Hence this study was carried out to assess may be in the form of a number of built structure response of floral composition and flora invasion or like in the case of this study, more agriculture- of Ajibode-Sasa arable landscape to intensive related in the form of patches of different cropping practices in the area over a period of cropping systems intensively operated The four years. 26 Micheal and Sunday; JAERI, 21(10): 25-37, 2020; Article no.JAERI.63899 2. MATERIALS AND METHODS end. We observed a clearance or 5 m to the beginning and end of each transect in order to 2.1 The Study Site give due consideration to edge effect from the main road and the river. The transect lengths The Ajibode-Sasa arable landscape is located in ranged from 50-260 m with which a total of 225 quadrats were laid in 2016 and 184 in 2020 the University of Ibadan, Nigeria on N07°28′, 2 E003⁰53′ and N07°28′, E003°54′ with elevation respectively. A 1 x 1 m square quadrat was laid ranging from 189-193 m above the sea level. It at an interval of 10 m along each transect for covers an area of 0.1685 km² (16.85 ha) of enumeration of herbaceous plants that are farmlands with diverse cropping systems, and rooted in the quadrat. Quantitative values of bounded by two streams to the south and to the number of individuals in each quadrat was west with a rich river valley soil (Fig. 1, 2). It is recorded in a species x attribute data matrix bordered by the forest of the International Institute for Tropical Agriculture and Ajibode- The vegetation components of the quadrats were Sasa road to the north and east respectively. The identified using A Handbook of West African area receive a mean annual rainfall of 1280 mm Weeds [23] and Weeds of Rice in West Africa and mean annual minimum and maximum [24]. Species that could not be identified temperature of 21°C and 30°C respectively. The immediately were preserved and later taken to site was selected because of its location as a the Department of Botany Herbarium, University complex of crop farms in Ibadan metropolis. It is of Ibadan for identification. important to the livelihood of especially Yoruba and Hausa populations in Ajibode, Sasa, Orogun 2.3 Data Analyses and University of Ibadan communities, being in close proximities to them. The farm complex is Analysis of Relative Important Value (RIV) of coordinated by a Farmers’ Association. The farm species followed Kent, (2011) [25] and (Olubode complex is comprised of various combinations of et al., (2011) [26]; arable crops that are farmed on a small-holder basis. The farms were so close that many were where: separated by footpaths, increasing possibility of weed infestation, introduction and spread of Relative Importance Value

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