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Data from: The abundance and distributional (in)equalities of forageable street tree resources in Lagos Metropolis, Nigeria

Cite this dataset

Adeyemi, Opeyemi; Shackleton, Charlie (2024). Data from: The abundance and distributional (in)equalities of forageable street tree resources in Lagos Metropolis, Nigeria [Dataset]. Dryad. https://doi.org/10.5061/dryad.pzgmsbcwf

Abstract

Foraging for wild resources links urban citizens to nature and biodiversity while providing resources important for local livelihoods and culture. However, the abundance and distributional (in)equity of forageable urban tree resources have rarely been examined. Consequently, this study assessed the abundance of forageable street trees and their distribution in Lagos metropolis, Nigeria. During a survey of 32 randomly selected wards across 16 local government areas (LGAs) in the metropolis, 4,017 street trees from 46 species were enumerated. The LGA with the highest number of street trees was Ikeja, with 818 trees, while Lagos Island had the lowest count, with two trees. This disparity in tree numbers could be attributed to variations in human population density within each LGA. Ninety-four percent of the street trees surveyed had at least one documented use and 76 % had two, and thus were potentially forageable. However, the most common species had relatively low forageability scores. Only 5.6 % of the total street tree population was rated as highly forageable, with a usability score of at least 11 out of 15. The most forageable street trees were fruit trees and non-native species. The forageable street trees in the LGAs showed a significant disparity in their distribution, as evidenced by a Gini coefficient of 0.81. Overall, richer neighbourhoods had a higher street tree abundance, richness, and forageability potential. To meet greening and foraging goals and address the current inequitable distribution, we suggest allocating more funds for greening, particularly in low-income neighbourhoods. Further research should evaluate forageable species from other sites to acquire a detailed understanding of the distribution and abundance of forageable resources in Lagos metropolis.

README: The abundance and distributional (in)equalities of forageable street tree resources in Lagos Metropolis, Nigeria

https://doi.org/10.5061/dryad.pzgmsbcwf

Description of the data and file structure

The data contains street tree data in the Lagos metropolis. Thirty-two wards (32) were selected in Lagos Metropolis. Each worksheet was labeled by the ward name, making 32 worksheets in the Excel workbook. 

Each Worksheet represents:

S/N – the serial number of species surveyed in a particular ward

Family – this is the family the species belongs to

Latin name – this represents the scientific name or full name of the species. Genus and specific epithet

Common name - this is the name known to the general public

BC (cm) - means basal circumference, the measurement of a tree at 4.5ft above the ground

Pi = 3.142

BA (cm) - means basal diameter, calculated by dividing the BC by Pi

ud - represents an unidentifiable stem

Methods

All 16 LGAs were chosen and two wards from each LGA were randomly sampled, resulting in a total of 32 wards. Street trees were defined as "trees located in or near roads or streets" (Thomsen et al. 2016) for the purpose of this research. The road network dataset for Nigeria, which includes main roads, was obtained from the OpenStreetMap data and prepared by the World Food Programme (WFP) following the United Nations Spatial Data Infrastructure standards. This dataset was used to count and identify all trees on both sides of every street in the selected wards. The size, or basal diameter, of trees on the left side of the street was subsequently measured. The location of each tree was recorded using a handheld Garmin GPS 64x device. Furthermore, the usability ratings (edible, medicinal, and other uses) of the surveyed species were recorded based on the information provided by the “Useful Tropical Plants Database” (https://tropical.theferns.info/). The edible and medicinal usability ratings of useful tropical plants (2022) provide notable information about the extent to which Lagos street trees are forageable. The database employed a five-point rating scale (Table 1).

Microsoft Excel was used to manage and analyse the data. The total length of street inventories for each ward was determined using the distance measurement tool from Google Earth, and the total length for each LGA was calculated using the attribute data of OpenStreetMap from the WFP. Three uses were used to measure the usability (edible, medicinal, and other uses). Each of these can have a maximum rating of five, and therefore the total maximum rating for a particular species is 15 (only in the case where the species is exceptionally useful for food, medicine, and other uses). To calculate the total usability rating of species per LGA, we summed the usability ratings of all the species surveyed in each LGA. The maximum usability rating per LGA was calculated by multiplying the total species count by 15. The percentage usability rating per LGA indicates the proportion of the total usability score of the species that is achievable, relative to the usability score available for each LGA. The Gini coefficient (GC) and forageability potential (FP) were used to assess the equity in the distribution of forageable street trees because they are more effective in visualising inequality (Kabisch & Haase, 2014). The GC ranges from 0 to 1, with 0 indicating that the forageable trees are evenly distributed (perfect equity) across all the LGAs of the metropolis and 1 denoting a small number of LGAs with a disproportionately high share of forageable street trees.

The calculation is as follows:

The accumulated population density for each LGA is represented by , while the accumulation of street tree abundance is represented by

forageability Potential (FP) is summation of the usability score per species multiplied by the number of individual species in each LGA. Species richness was determined by counting the number of individual species surveyed in each LGA

Funding

National Research Foundation