Higher survival drives the success of nitrogen‐fixing trees through succession in Costa Rican rainforests

Abstract

SummaryTrees capable of symbiotic nitrogen (N) fixation ('N fixers') are abundant in many tropical forests. In temperate forests, it is well known that N fixers specialize in early-successional niches, but in tropical forests, successional trends of N-fixing species are poorly understood.We used a long-term census study (1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013) of regenerating lowland wet tropical forests in Costa Rica to document successional patterns of N fixers vs non-fixers, and used an individual-based model to determine the demographic drivers of these trends.N fixers increased in relative basal area during succession. In the youngest forests, N fixers grew 2.5 times faster, recruited at a similar rate and were 15 times less likely to die as nonfixers. As succession proceeded, the growth and survival disparities decreased, whereas N fixer recruitment decreased relative to non-fixers. According to our individual-based model, high survival was the dominant driver of the increase in basal area of N fixers.Our data suggest that N fixers are successful throughout secondary succession in tropical rainforests of north-east Costa Rica, and that attempts to understand this success should focus on tree survival.

Demography of Symbiotic Nitrogen-Fixing Trees Explains Their Rarity and Successional Decline in Temperate Forests in the United States

“…This contradicts our expectation, given that N fixers are typically thought to be fast growers [34,39]. Robinia and Alnus , in particular, can grow rapidly, especially in their juvenile stages [40–42].…”

“…Whereas N-fixing trees in the coterminous U.S. grew slower and survived worse than their co-occurring non-fixers, N-fixing trees in Northeastern Costa Rica grew faster and survived better than non-fixing trees, particularly early in succession [34]. N-fixing trees in the canal region of Panama also grew faster than non-fixers early in succession, and had higher net recruitment (recruitment compared to mortality) [39].…”

“…[34]. In the coterminous U.S. FIA dataset, there are five rhizobial ( Olneya , Robinia , Acacia , Prosopis , and Albizia ) and three actinorhizal genera ( Alnus , Cercocarpus , and Elaeagnus ).…”

“…To understand how successional dynamics of N-fixing vs. non-fixing trees depend on each demographic process, we used an individual-based simulation model, following Menge and Chazdon [34]. We initially ran the simulation using the maximum likelihood functions fit to each type (“all demographic effects”).…”

Interaction between invasive and potentially invasive shrub species does not influence relationships between their ecological success and distance from propagule sources

“…Tree species (both alien and native) influence light availability (Knight et al 2008;Niinemets 2010), mineral nutrient cycling (Augusto et al 2002;Reich et al 2005;Dauer et al 2007;Mueller et al 2012), soil acidity (Binkley and Valentine 1991;Binkley and Giardina 1998;Mueller et al 2012), decomposition rate (Hobbie et al 2006(Hobbie et al , 2010, fine root and leaf lifespans (Withington et al 2006), ectomycorrhizal infections (Dickie et al 2006;Trocha et al 2012), and soil biota (Mueller et al 2015(Mueller et al , 2016. Modifying effects of invasive woody species on habitat was also reported from several biomes across the world (e.g., Vitousek 1990; Ehrenfeld 2003;Stohlgren and Rejmánek 2014;Castro-Díez et al 2014;Menge and Chazdon 2016). Among woody species, some guilds are especially responsible for ecosystem change, e.g., nitrogenfixing species (e.g., Ehrenfeld 2003; Rice et al 2004;Castro-Díez et al 2014;Jo et al 2015) or coniferous trees planted on sites typical to broadleaved trees (e.g., Binkley and Valentine 1991;Augusto et al 2002;Zerbe and Wirth 2006;Jagodziński et al 2015).…”