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Browsing by Author "Yrjölä, Veikko"

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  • Yrjölä, Veikko (2023)
    While the effects of agricultural land use on biodiversity are beginning to unravel in Europe and North America, Africa remains poorly studied. Biodiversity in a broad sense provides ecosystem functioning and services, whose importance has become obvious to humankind in the quickly changing modern world. In Ghana, the practice of mango farming continues to grow in popularity due to suitable climate and potential source of livelihood. With increased demand and production of mango, natural habitats, namely savannahs, are being converted to plantations. The effects of such habitat conversion on local biodiversity are unknown for most taxa, thus providing an interesting study system for biodiversity research. Given the direct relation between functional diversity and ecosystem services, in this work I compare the taxonomic and functional diversity of ground-living spiders between mango orchards and savannah. I chose spiders (Arthropoda; Araneae) as model organisms as they critically contribute to several ecosystem services, such as biological pest control and nitrogen cycling, while being ubiquitous and abundant, thus easy to collect in the field. Spiders were captured with pitfall traps from six mango and four savannah areas in the Northern region of Ghana. A total of 424 individuals and 53 (morpho)species were identified and counted. Additionally, six morphological and four ecological traits were quantified for each (morpho)species. With these data, I calculated taxonomic richness and evenness, functional richness, dispersion, and evenness, and beta diversity of the different assemblages in the R environment. These metrics were then compared between spiders collected from mango orchards and savannah. Mango orchards showed lower taxonomic and functional evenness than savannah, contrary to all other alpha diversity measures. The two habitat types share many of the same diversity of ground-living spiders, but species and traits are distributed less evenly in mango orchards due to incomplete niche differentiation between species. Both taxonomic and functional beta diversity were significantly different between habitat types indicating that mango orchards sustain a similar richness of species as savannah, but the species composition is different. In conclusion, mango orchards have the potential to conserve some aspects of the original diversity, but species composition and the way species interact are substantially different. We should strive to find the best practices to produce mango without radically changing the natural biodiversity patterns.