COS 6-2
Allergies on the Rise: Spatial correlations between management, plant populations and airborne pollen concentration for ragweed
Pollen allergies are one of the most common health problems in the United States, and over 20% of Americans are sensitized to ragweed (Ambrosia artemisiifolia L.). Despite the importance of allergenic pollen to public health, little has been studied on the processes leading to pollen exposure; moreover, little research has linked land use and plant populations to spatial heterogeneity in airborne pollen concentrations.
To examine the heterogeneity in ragweed pollen exposure, we collected pollen counts from various sites in Detroit (Michigan, USA). We also conducted vegetation surveys to assess vacant lot management regimes. This study addressed the following questions: 1) What land use has the highest ragweed population? 2) Is ragweed pollen concentration a function of ragweed abundance at a local scale (10m) and land use at a neighborhood scale (1km)? 3) What management methods can help remedy the disproportionate amount of allergies and ragweed sensitization in minority populations in Detroit?
To quantify these relationships, we surveyed ragweed stem density as a function of land use. 34 pollen collectors were deployed throughout the city, and ragweed cover was recorded in the immediate vicinity of each pollen collector. Each pollen collectors was placed 1.5 meters from the ground and at least 10 m from the nearest building. We then assessed vacant lots to quantify the management regime, characteristics of the vegetation, and ragweed presence and stem density.
Results/Conclusions
We found that ragweed populations are highest in vacant lots. There was also a significant relationship between ragweed pollen concentration as function of ragweed abundance on both a local and neighborhood scale. Both of these variables predict a large portion of airborne ragweed pollen concentrations (R2=0.48). These results display an link of pollen production within the urban context, and shows that management of allergenic pollen producing plants must be considered at a local and neighborhood level.
Additionally, our findings show that management choices, which influence plant composition, can increase allergenic pollen exposure to people living near these plant populations. We also conclude that ragweed is not present in vacant lots where maximum vegetation height is more than 2 m. We therefore recommend one of the two alternative management regimes for vacant lots: either mow frequently (multiple times a growing season) or do not mow them at all; both approaches will reduce ragweed prevalence in vacant lots and reduce allergenic pollen exposure for those people who live near vacant lots.