Differences in allometry and population structure between native and invasive populations of a tropical tree

Abstract

Introduced species can establish self-replacing populations in introduction sites despite climatic differences between these sites and the native range. Schizolobium parahyba (Fabaceae) is a fast-growing tree from the Atlantic Forest in Brazil and is invasive in semideciduous forests. We studied the allometry and population structure of S. parahyba within its native and invaded ranges. We expected to find differences in allometric relationships and ontogenetic stage sizes between forest types. We measured individuals within native and invaded ranges and analysed height : diameter allometry using standardised major axis regression. We used the chi-squared test and permutational multivariate analysis of variance to compare the frequencies of individuals of each ontogenetic stage between native and invasive populations. We found that allometry differed between forest types for seedlings, but only marginally for adults. The population structure differed between ranges and suggests active recruitment of juvenile and subadult plants in invaded sites, where the species is naturalising.

Intraspecific allometries reveal hyper‐slender stems in forest gaps and the impact on tree growth from insect herbivores

“…Becoming taller by sacrificing some mechanical stability would increase woody plants' fitness more than gains in whole-body biomass per se (Moncrieff et al, 2014), by enabling them to position new leaves higher from the ground, in better-lit conditions and above nearby competitors (Kohyama & Hotta, 1990;Poorter et al, 2005). Similarly, using ground-level diameters, higher-than-predicted (>1) slopes were also found in unbranched saplings of the pioneer Rhus trichocarpa in secondary temperate forest (Osada, 2005); in juveniles of the fast-growing Fabaceae tropical tree, Schizolobium parahyba (Sampaio-e-Silva, Tiberio, Dodonov, & Silva Matos, 2015); in four of seven woody species in cerrado (Dodonov, Lucena, Leite, & Silva Matos, 2011), as well as juvenile palms of Euterpe edulis (but not E. oleracae) in the Atlantic rainforest (Tiberio, Sampaio-e-Silva, Dodonov, Garcia, & Silva Matos, 2012); but not for saplings of 12 species in gaps of Amazon cattinga forest whose POM was taken at a 0.5-m-stem height (pooled slope = 0.73; Coomes & Grubb, 1998). That the three Korup tree species all became more slender to the same degree (Table 1: overlapping 95% CI of control populations), despite pronounced differences in their shade-tolerance traits, is consistent with the finding of increases in LMA and leaf nitrogen being similar among eight tree species varying in branching form (lateral vs. vertical-growth) and successional status in response to canopy openings in a temperate forest (Takahashi, Seino, & Kohyama, 2005), and likewise for the changed LMA among African tree species' (nonpioneer subset) seedling responses to higher irradiance (Veenendaal et al, 1996).…”