Background: The impacts of disturbance history on the floristics of Northern Coastal Forest (NCF; South Africa) are unknown.Objectives: This study compared the floristics of three remnant patches of NCF (in KwaZulu-Natal) with contrasting disturbance histories: a primary forest with low levels of disturbance (Hawaan), a primary forest with high levels of disturbance (Umdoni) and a secondary forest (Twinstreams) that was rehabilitated with presently low disturbance levels.Method: Transects and quadrats were used to assess species composition and diversity at each site.Results: Collectively, 688 species, 400 genera and 113 families were found, but only 21.95% of the species were shared by the three forests. The most speciose families were Fabaceae Asteraceae Rubiaceae. The species richness was highest at the disturbed primary forest and notably lower at the primary forest. Diversity indices exhibited a similar trend. Cluster analyses and ordinations indicated that the secondary forest was intermediate between the two primary forests, with the disturbed primary forest and secondary forest being more similar.Conclusion: The disturbed and secondary forests maintained a NCF floristic affinity. The dissimilarity between Hawaan and other forests is most likely the product of differing disturbance histories and rehabilitation efforts. The findings suggested that NCF patches are likely to be different in richness, but not in structure and affinity. Anthropogenic related pressures and disturbance appear to be major causes of floristic differences amongst patches. This leads to higher levels of richness by accommodating opportunistic, atypical and alien species, and possibly the creation of novel NCF types.

Aim of the study: Alien and indigenous species emergence patterns within canopy gaps in urban subtropical forests are poorly understood. This study compared canopy gap floristics in relation to abiotic and physical characteristics across three subtropical urban forests differing in disturbance history.Area of study: Three Northern Coastal Forests of varying disturbance histories found in coastal subtropical urban KwaZulu-Natal (KZN), South Africa (SA).Materials and methods: Closed canopy ( n = 15 quadrats per forest ) and four gaps from three size classes (‘small’ < 25 m2, ‘medium’ 25 - 45 m2; ‘large’ > 45 m2) were surveyed for each forest using classical vegetation sampling techniques. Soil moisture content and air temperature were measured within each gap.Main results: Cumulatively all forests hosted 198 species. Species richness was highest in the primary highly disturbed forest followed by the primary least disturbed forest and lowest in the transitional highly disturbed forest. Alien taxa cover within gaps was correlated with higher indigenous seedling emergence in the primary forests. Species richness was positively correlated with gap size and soil moisture content, and negatively correlated with air temperature.Research highlights: Gap floristic patterns are influenced by size, abiotic factors, disturbance and forest successional status. Alien taxa may facilitate indigenous seedling emergence within gaps in primary forests. Floristic, abiotic and physical characteristics of canopy gaps should be monitored within urban forests as they can influence gap infilling regarding species composition and rate. This can inform management strategies including species reintroduction and enrichment planting.