Plant characteristics are poor predictors of microsite colonization during the first two years of primary succession.

摘要

Questions: Do plant characteristics predict microsite colonization in severe habitats dominated by abiotic factors? Specifically, does colonization of microsites differ among shrubs, forbs and grasses or between wind- and water-dispersed plants, non-native and native plants, or N-fixing and non-N-fixing plants? Location: Kowhai River floodplain, Kaikoura, South Island, New Zealand. Methods: Five microsite characteristics were measured for >1000 individuals representing 27 colonizing plant species on a two-year old surface of a primary succession on a New Zealand floodplain. The microsite characteristics included surface contour (convex, concave, or flat), the position of the plant (e.g., upstream, downstream) relative to the closest rock with >20 cm maximum dimension, the distance to that same rock, the depth of the base of the stem below the surface of a plane resting on the adjacent microrelief, and soil particle size (gravel, pebbles or sand). Results: All plants preferred concave microsites near large rocks relative to systematically placed null points. We found no clear preferences for microhabitats by dispersal mode, native vs. non-native status, or plants with or without nitrogen-fixing symbionts, but grasses preferentially colonized fine soil particles. Highly variable responses among species contributed to these results. Better predictability of microsite preference was obtained for individual species than for plants grouped by characteristics. Conclusions: Our results suggest that in severe habitats with strong abiotic filters and low microsite availability, such as found in early primary succession, coarse categories of species characteristics are poor predictors of colonization success..