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Abstract South Africa’s urban population is increasing, and in parallel, urban green infrastructure has shown an increase in alien tree species, e.g., mulberry (Morus sp.), oak (Quercus spp.) and plane trees (Platanus spp.) to name a few. This causes ecological problems since alien trees are often more water-demanding and competitive than indigenous trees, but they also increase the abundance of respiratory diseases often triggered by an allergic reaction towards the pollen of those alien taxa. In the current study, utilizing 7-day volumetric spore traps, we illustrate that the most abundant tree pollen in the two largest cities of South Africa, Cape Town and Johannesburg, is produced by alien trees with a high risk of allergenicity. This adds another aspect related to public health when evaluating plant species composition in urban forestry and urban ecology, which underlines the urgency of more intense monitoring. More importantly, this—for South Africa—newly emphasized risk for public health underlines the applicability of current directives [i.e., Spatial Development Frameworks (SDFs), localized Precinct Plans, Land Use Schemes (LUSs)] and implementation options in urban planning. Here, we present ideas that may be implemented in such a framework. From both a public health and an ecological perspective, it is recommended to plant indigenous trees like Combretum erythrophyllum, Vachellia and Senegalia spp. that have fewer ecosystem disservices, like a lower impact on public health due to lower allergenicity/lower pollen occurrence and providing more ecosystem services such as lower water needs.

Abstract Background Pollen monitoring has been discontinuously undertaken in South Africa, a country with high biodiversity, a seasonal rainfall gradient, and nine biomes from arid to subtropical. The South African Pollen Monitoring Network was set up in 2019 to conduct the first long‐term national aerospora monitoring across multiple biomes, providing weekly reports to allergy sufferers and healthcare providers. Methods Daily airborne pollen concentrations were measured from August 2019 to August 2021 in seven cities across South Africa. Updated pollen calendars were created for the major pollen types (>3%), the average Annual Pollen Index over 12 months was calculated, and the results were compared to available historical data. Results The main pollen types were from exotic vegetation. The most abundant taxa were Poaceae, Cupressaceae, Moraceae and Buddleja. The pollen season start, peak and end varied widely according to the biome and suite of pollen taxa. The main tree season started in the last week of August, peaked in September and ended in early December. Grass seasons followed rainfall patterns: September–January and January–April for summer and winter rainfall areas, respectively. Major urban centres, for example, Johannesburg and Pretoria in the same biome with similar rainfall, showed substantive differences in pollen taxa and abundance. Some major differences in pollen spectra were detected compared with historical data. However, we are cognisant that we are describing only 2 years of data that may be skewed by short‐term weather patterns. Conclusions Differences in pollen spectra and concentrations were noted across biomes and between geographically close urban centres. Comparison with historical data suggests pollen spectra and seasons may be changing due to anthropogenic climate change and landscaping. These data stress the importance of regional and continuous pollen monitoring for informed care of pollinosis.

Recent sediments from the coastal environment of Lagos East, Nigeria, were used to make a palynological reconstruction of the vegetation of the study area and to draw inferences about its palaeoclimate. A total of 8456 palynomorphs were recovered, dominated by pollen grains of Poaceae (13.96%), Cyperaceae (6.23%), Alchornea cordifolia Müll-Arg (8.36%) and Elaeis guineensis Jacq (2.41%). Others were Cyclosorus afer Ching (2.18%), Rhizophora sp. (0.45%), Nephrolepis sp. (1.03%), Celtis sp. (0.25%) and Pteris sp. (0.13%). The composition of the recovered palynomorphs suggests that the past vegetation was predominantly a mosaic of freshwater swamp, with open to dry climate, as indicated by the records of Cyperaceae, Alchornea cordifolia, Elaeis guineensis, Arecaceae, Asteraceae, Acanthaceae and Chenopodiaceae/Amaranthaceae. Radiocarbon dates obtained from two depths (surface and deepest) indicate that the sediments were deposited around the last 103.8 ± 0.4 pMC (percentage Modern Carbon) and 111.9 ± 0.4 pMC, hence in the late Holocene. The study identified fluctuations between wet and dry climatic conditions in the Holocene of this area.

Pollen and fungal spores (aerospora) are the major atmospheric bioaerosols. Aerospora occurrence and concentration vary by geographical region and blossoming period, and with meteorological factors. Allergic respiratory diseases affect about 20 million South Africans, with pollen and fungal allergens amongst the leading triggers. Asthma triggered by aerospora can be life threatening; allergic rhinitis causes considerable morbidity and carries financial implications for individuals and health systems. Thus, knowledge about geographical variation, seasonal timing and intensity, as well as annual aerospora fluctuations in South Africa, where climate and vegetation are exceptionally diverse, is essential for effective diagnosis and treatment of allergies. Unfortunately, there is a lack of continuous aeropalynological data from South Africa. The longest annual monitoring exists for Cape Town (~20 years), with almost no data out of the Cape since the 1990s, and many parts of South Africa have never been monitored. In this brief review, we highlight the cross-disciplinary need for strengthened and expanded continuous aeropalynological study in South Africa, the history of efforts to date, and the introduction of the interdisciplinary South African Pollen Network (SAPNET). SAPNET was launched in seven major cities in August 2019 in order to monitor weekly variations of aerospora, and provide online data for allergy sufferers and health-care providers (www.pollencount.co.za) with the aim to establish regional pollen calendars. Significance: • The significance of aerobiology as the study of airborne organic particles which include pollen, spores of fungi and cryptogams, plant hair, insect remains etc. especially as agents of allergic rhinitis (commonly known as hay fever) is outlined. Cases of allergic rhinitis are globally increasing due to current climate change. • Very limited pollen monitoring data are available for South Africa; such data are a prerequisite for establishing pollen calendars to help medical practitioners and allergy sufferers. SAPNET (South African Pollen Network) addresses this lack of data. Since August 2019, seven 7-day volumetric spore traps have been operating in South Africa in major cities, and are continuously gathering data about the pollen and spore contents in a country which is highly affected by allergic rhinitis.