Fact or fiction – Pine pollen pollutes our waterways and is an allergen
It's pine pollen season again, and those that live in areas around Radiata pine forests will notice the deposits of yellow pollen on many outdoor surfaces such as puddles, decks, driveways and cars. Because pine pollen is large, yellow and visually obvious, it often gets unfairly blamed for a variety of ills.
One strongly viewed person recently opined to the editor that pine pollen was causing serious problems polluting our beautiful lakes and rivers with high-nutrient (nitrogen) pollen. This disturbed the author greatly as he had always viewed forestry as good for soil and water. A search on the web revealed a report by Environment Bay of Plenty Pollen and Rotorua Lakes which concluded that current scientific agreement is that nitrogen input from pollen on a lake is of minor significance when compared with other nitrogen inputs into a lake. The perception of pollen as a "massive input of nutrients" is increased by its bright (yellow) colour, it floats on water and can get concentrated on surfaces by wind effects. And it all gets produced over a relatively short period of time which seems to concentrate its effect. However, the pollen particles only contain 2.2% nitrogen. The actual effects on lake nutrient levels are small in comparison to other nutrient sources.
What about pollen as an allergen? Again, the way pollen looks has more to do with how people perceive it, rather than its actual effect. This topic was covered well in Wood Matters September 2011 and in a media release from the Forest Owner's Association titled Pines get unfair rap for early winter spring hay fever.
In summary, pines (alone) may cause reactions in a very small proportion of the population. Overseas research and local experience confirm a somewhat larger proportion can also react but the research suggests this is because they are already sensitised by, and reacting to, other less visible but strongly reactive pollens from grasses and other tree species. Common agricultural grasses, olives, garden trees such as silver birch, privet, ash, and cedars are all strong initiators. For this reason, for those who do suffer, removing some local pine trees or planting alternative species may not provide the relief wanted.