Seed bank dynamics of Lachemilla pinnata (Rosaceae) in different plant communities of mountain grasslands in central Argentina

We studied the soil seed bank of Lachemilla pinnata (Ruiz & Pav.) Rothm. (R osaceae) in the main vegetation patches that make up mountain grasslands on granitic substrate in central Argentina: moist swards, tall-tussock: grass lands and stony grasslands. Ten compound soil samples from each community a t two soil depths (0-5 cm and 5-10 cm) were taken. In general, the density of the germinable seed bank of L. pinnat a was larger in autumn after the s eed rain, increased with its relative cover in the established vegetation, and sharply decreased with soil depth. The seed bank of L. pinnata was clas sified as short-term persistent. Its density was higher in moist swards, wh ere it was abundant and could produce flowers and fruits, than in stony gra sslands where its cover was very low, or tall-tussock grasslands, where no flowering events were recorded. On those bases, moist-sward patches are exp ected to play a more important role than, tall-tussock grasslands or stony grasslands in the maintenance of local populations of L. pinnata.