Regeneration microsites and tree species coexistence in temperate rain forests of Chiloé Island, Chile

Abstract

Summary 1 We studied the importance of fallen logs as recruitment sites for tree species, their role in species coexistence, and also the influence of canopy openness and litter depth on tree species establishment in mid-successional and old-growth temperate rain forests of Chiloe Island, southern Chile. 2 Old-growth (OG) stands showed significantly more fallen logs than mid-successional (MS) stands. Concomitantly, the proportion of seedlings and saplings established on logs was significantly greater in OG than MS stands. 3 Of 13 tree species found at our study sites, eight showed a significant bias towards establishment on logs, especially those in advanced stages of decomposition. 4 In some stands, all seedlings of Eucryphia cordifolia , Laureliopsis philippiana , Nothofagus nitida , Tepualia stipularis and Weinmannia trichosperma occurred on decaying logs, whereas all Podocarpus nubigena seedlings were found on undisturbed soil sites. 5 Small-seeded species were more common on logs, whereas large-seeded trees occurred on soil. 6 On soil, litter depth negatively affected local abundance of log-dependent seedlings, suggesting that variation in litter accumulation influences species distributions across the forest floor mosaic. 7 The density of shade-intolerant seedlings was more enhanced by the presence of fallen logs under closed canopy than by the occurrence of canopy gaps over soil sites. 8 Seed size plays an important role in successful establishment of species across the mosaic of fallen logs and different litter depth on the forest floor. We suggest that this mosaic of microsites is an important factor for species coexistence.