Abstract:
Progress is required in response to how cities can support greater biodiversity. This calls
for more research on how landscape designers can actively shape urban ecologies to deliver contextspecific
empirical bases for green space intervention decisions. Design experiments offer opportunities
for implemented projects within real-world settings to serve as learning sites. This paper explores
preliminary ecological outcomes from a multidisciplinary team on whether purposefully engineered
native grassland gardens provide more habitat functions for insects than mainstream gardens in
the City of Tshwane, South Africa. Six different sites were sampled: two recently installed native
grassland garden interventions (young native), two contemporary non-native control gardens (young
non-native) on the same premises and of the same ages as the interventions, one remnant of a more
pristine native grassland reference area (old native), and one long-established, non-native reference
garden (old non-native). Plant and insect diversity were sampled over one year. The short-term
findings suggest that higher plant beta diversity (species turnover indicating heterogeneity in a site)
supports greater insect richness and evenness in richness. Garden size, age, and connectivity were not
clear factors mediating urban habitat enhancement. Based on the preliminary results, the researchers
recommend high native grassland species composition and diversity, avoiding individual species
dominance, but increasing beta diversity and functional types when selecting garden plants for urban
insect biodiversity conservation in grassland biomes.
