Allocating species in Grime’s strategy space: an alternative to trait-based approaches

Abstract

Background:  The three primary-strategy theory proposed by Grime identifies stress and disturbance as key environmental factors leading to the emergence of distinct plant strategies. These are defined by a combination of stress and disturbance tolerance. Plant strategies are usually inferred from sets of traits, but this may lead to circular reasoning and artificial restrictions to species’ distribution in strategy space.  Question: Can measurements of stress and disturbance tolerance be used to estimate the position of different species relative to each other in Grime’s strategy space? Data description: Stress, disturbance, and abundances for 50 species at 25 0.5 ha sites. Study site and dates: Semiarid grassland, Oaxaca, Mexico, 2014. Methods: Species’ tolerance to stress and disturbance were inferred from abundances, and used to allocate species in Grime’s space. We tested if some attributes of our study species changed over the strategy space according to theoretical expectations. Results: Most species were allocated towards high disturbance and low stress intensities. Species attributes were in line with the trends expected from their position in the strategy space.  Discussion: Perhaps because of a long grazing history, most species were tolerant to disturbance. The allocation of species in the strategy space using stress and disturbance measurements seemed correct based on their attributes. Thus, our measurements seem to reflect the basic principles proposed by Grime. Our method provides relative positions in the strategy space, and (as previous work) requires defining somewhat arbitrary limits to such space if we wish to label species as ruderals, competitors or stress-tolerant.