A tale of two grasslands: how belowground storage organs coordinate their traits with water-use traits

Purpose Plant belowground storage traits are important for mediating environmental stress, but their role in response to water availability and their coordination with above-ground traits is largely unknown. We predicted a coordination of conservative above- and belowground traits and preferential storage of water-soluble carbohydrates in the drier grassland and acquisitive traits and preferential storage of starch in the wetter grassland. Methods We examined the relationship between plant preference/response for water availability (habitat preference, intrinsic water use efficiency, and leaf relative water content deficit) and the traits of belowground storage organs (morphological, anatomical, and storage carbohydrate concentration) in 37 perennial herbs from a wet and a dry temperate grassland in the Czech Republic. Results Species from the dry grassland preferred lower moisture, had greater water use efficiency than those from the wet grassland, and were also more conservative in their morphological and leaf traits. Although dry grassland plants preferentially stored oligo- and polysaccharides, their water-use efficiency increased with greater concentrations of starch. Leaf relative water content deficit did not vary significantly between the grasslands and additionally, the relationship to plant economy was not always in accord with other measures of preference for water availability. Conclusion Our results imply that belowground storage organs play a role in the response to reduced water availability. The strategies employed are further dependent upon the habitat and phylogeny of the species.