Experimental establishment of big-leaf mahogany (Swietenia macrophylla King) seedlings on two soil types in native forest of Pará, Brazil

摘要: Abstract Research into the mechanisms underlying edaphic associations reported for many tropical forest tree species, including those in Meliaceae, has paid little attention to earliest post-dispersal life stages. We conducted a reciprocal sowing experiment examine germination and establishment rates of big-leaf mahogany ( Swietenia macrophylla King) during first seedling growing season two local habitats southeastern Amazonia. In this region, adult populations are restricted primarily low-ground soils associated with seasonal streams, but rarely found on high-ground soils. Soil analyses revealed that at study site were silty loams whereas clays. High-ground less acidic more fertile than soils, especially respect total nitrogen, Mg, sum basic cations. October 2003, 30 locations evenly split between soil types, we added 40 seeds paired canopy gap closed understory plots low- Two months after sowing, no significant differences types proportion seeds: (1) ungerminated yet viable, (2) still germinating, (3) already established, or (4) surviving (variables 1, 2, 3 combined). Nearly twice as seedlings had established (43%) gaps (24%), overall survival was lower (46% vs. 58%, respectively). Seven similar understory; however, recruitment nearly (38% 20%, respectively; P  = 0.006). Localised flooding drowned four (16 plots). Difference performance weakened when these flooded discarded (corresponding 38% 27%,  = 0.083). On average, showed small leaf damage, numbers, foliar conditions habitats. As expected, leaves greater between-census compared conditions. Collectively, evidence enhanced early mahogany's preferred type region. Any ecological processes driving association presumably emerge beyond season.