Seed production, dispersal and seed bank in Lupinus montanus Kunth at the upper limit of its altitudinal distribution in the Nevado de Toluca

Abstract

Introduction: In response to climate change, plants can adapt, migrate or die; however, migration by natural dispersion of seed can be very slow. Objective: To determine productive potential, dispersal distance and seed bank of Lupinus montanusKunth (lupine) at the upper limit (4 200 m) of its natural distribution at the “Nevado de Toluca” mountain. Materials and methods: The seed bank was estimated in an area of 1.88 m2. Three sampling sites were established with plants in reproductive stage (15 plants) isolated from other adult plants. Seed production was determined in traps placed at the four orientations of each plant and spatial pattern of dispersal was also determined. Results and discussion: Seedbank density was 4.26 seeds∙m-2 of soil. Lupinus montanus produced over 5 500 seeds per plant in one reproductive cycle; its seed potential was associated with plant height and number of stems. The number of seeds collected varied significantly (P < 0.0001) with respect to distance from the mother plant. The dispersion curve was adjusted (P < 0.01) to a negative exponential model (R2 = 0.849). Dispersal in the four orientations was symmetrical; 97 % of the seeds fell at a distance ≤2 m from the mother plant. Conclusions: Only 3.2 % of the seeds of L. montanus reached a distance greater than 2 m from the mother plant; however, dispersal is uniform in all orientations, therefore soil slope does not represent a limiting factor for the altitudinal migration of species.