DOI: 10.5061/dryad.h44j0zpnh
title: Wind dispersal and 1-year survival of Vataireopsis iglesiasii (Fabaceae) seedlings in a Neotropical lowland rain forest

description: Populations of many tropical tree species are regulated by negative
 distance- and density-dependent processes (NDD), yet most studies on the
 effects of conspecific seedling and adult neighbours on seedling survival
 have focused on animal-dispersed species. Species with seeds dispersed by
 wind may not be moved as far on average as seeds dispersed by animals, but
 some seeds may be dispersed a lot further, suggesting that knowledge of
 dispersal mechanism may help in our understanding of NDD. In this study,
 we took advantage of a high-fecundity reproductive event that occurred for
 an individual isolated canopy tree of Vataireopsis iglesiasii in a
 tropical lowland rain forest site in Amazonian Ecuador to document seed
 dispersal and seedling survival to 1-year post-dispersal. Most seeds did
 not disperse far: 86% of germinated seedlings were found within 100 m.
 Mortality was high: only 49 of the 1732 monitored seedlings survived one
 year and only five survived a further four years. We found a significant
 negative effect of conspecific seedling density (but no effect of distance
 from the parent tree) on 1-year survival. Rare long-distance dispersal
 events may increase the probability of a seed reaching specific habitats,
 such as high-light patches, and surviving beyond one year, thereby
 shifting the population recruitment curve outwards away from adult trees
 and maintaining diversity in species-rich forests.
description: The 50-ha Yasuni Forest Dynamics Plot (FDP, 0°41’ S, 76°24’ W) is
 situated in tropical lowland rain forest, Amazonian Ecuador, wherein all
 trees &gt;1 cm diameter at breast height (DBH, 1.3m) have been marked,
 mapped, and identified regularly since 1994 (Valencia et al. 2004). The
 dominant vegetation type is evergreen terra firme forest with a canopy
 height of 10–30 m. Emergent trees can reach 50 m in height. The climate
 has is aseasonal with a mean annual rainfall of 2800 mm and no month’s
 rainfall averages less than 100 mm (Pérez et al. 2014). Mean monthly
 temperature is 25–27°C (Valencia et al. 2004).
 Vataireopsis iglesiasii Ducke (Fabaceae, Faboideae) is a large
 emergent tree that occurs in lowland rain forest from Colombia to Brazil.
 It has large single-seeded samara fruits that are wind dispersed (Figure
 1). The species is locally rare in western Amazonian forests. In the
 Yasuni 50-ha plot, it is represented by only two individuals &gt;1 cm
 DBH; a mature adult tree of 84.4 cm DBH and a juvenile tree of 4.3 cm DBH
 located about 170 m away (Figure 2). In early March 2016,
 the adult tree (tag = #400565, DBH = 84.4 cm in 2015, x = 807.2, y =
 464.1) released fruit during a period of strong wind. Many fruit were
 dispersed widely across the 50-ha plot. In 22–26 May 2016, we censused
 transects of 20×20m quadrats running in each of the 8 cardinal and ordinal
 directions from the base of the fruiting tree to the edges of the plot,
 corresponding to the FDP gridlines. Transects running NW, N, NE, and E
 were extended outside the FDP boundaries until no more seedlings were
 found. Several additional 20×20 m plots were also surveyed following the
 prevailing direction of the wind (Figure 2). Within each 20×20 m section
 of the transects (or 20×20 m plot), we counted the number of newly emerged
 Vataireopsis iglesiasii seedlings and the number of leaves on each
 seedling. In 5–9 December 2017, we censused the same transects for
 Vataireopsis iglesiasii seedlings again, recording the number of surviving
 seedlings and the number of leaves on each one. On 7 November 2021, we
 checked these few surviving seedlings again.