Species site matching: Selecting palms (Arecaceae) for urban growing spaces

Abstract Palms ( Arecaceae ) are part of many urban environments in warmer climatic zones where they are mainly planted for their aesthetical value. Due to physiological and morphological characteristics they provide many common services at lower levels than trees, putting them in danger of being replaced. To avoid this, it is necessary to adequately match them to available sites so that costs remain small in comparison to their benefits. To determine what factors might be related to palm health, and therefore aesthetic value, information on the total palm population in Olhao, Portugal, was collected and statistically analysed for relationships between crown state and variables like palm height, distance to the nearest road or objects located within a species-specific growing space. While city-scape related variables showed no or only very weak correlations, it was found that the three most common species differed significantly from each other as comparatively many Phoenix canariensis palms were in poor state due to red palm weevil damage. The results of the study suggest that, in order to reduce financial inputs required to create high levels of desired benefits, a focus should be on macro-environmental conditions which cannot easily be manipulated or only with considerable costs associated. In addition to often discussed general climatic suitability of different species it is also necessary to consider the factor ‘pests and diseases’ when evaluating the appropriateness of certain plant types for designated growing spaces.