Endemic Mimosa species can serve as mycorrhizal "resource islands" within semiarid communities of the Tehuacán-Cuicatlán Valley, Mexico

Abstract

This paper explores if Mimosa species (Fabaceae-Mimosoideae) can serve as arbuscular mycorrhizal (AM) and nutrient "resource islands" in six plant communities in the semiarid valley of Tehuacán-Cuicatlán, Mexico. Spatial heterogeneity related to the occurrence of Mimosa species results in temporal differences in AM-fungal spore numbers and soil nutrients. A higher number of AM-fungal spores were found in the soil below the canopies of six endemic Mimosa species than in the soil from non-vegetated areas. For four species, Mimosa adenantheroides, Mimosa calcicola, Mimosa luisana and Mimosa polyantha, the soil below their canopies had more AM-fungal spores than the soil in non-vegetated areas during the wet season than during the dry season. Two species, Mimosa lacerata and Mimosa texana var. filipes, however, had more spores under their canopies during the dry season than during the wet season. Although physical differences are present within and between sites, in general the soil below the canopies of Mimosa species had significantly higher nutrient levels than the soil from non-vegetated areas. Mimosa species thus form "resource islands" that are not only rich in nutrients but also in mycorrhizal propagules. Mimosa species can serve as mycorrhizal "resource islands" by directly affecting AM-fungal spore dynamics and/or by serving as spore-traps. A range of plants associated with Mimosa species may benefit from the higher number of AM propagules. We believe that the use of Mimosa resource islands as an option for biodiversity conservation and for land restoration ought to be considered in the Valley.