Frugivory underpins the nitrogen cycle

Abstract

1. Tropical rainforests are populated by large frugivores that feed upon fruit-producing woody species, yet their role in regulating the cycle of globally important biogeochemical elements such as nitrogen is still unknown. This is particularly relevant because tropical forests play a prominent role in the nitrogen cycle and are becoming rapidly defaunated. Furthermore, frugivory is not considered in current plant-large herbivore-nutrient cycling frameworks exclusively focused on grazers and browsers. 2. Here we used a long-term replicated paired control-exclusion experiment in the Atlantic Forest of Brazil, where peccaries and tapirs are the largest native frugivores, to examine the impact of large ground-dwelling frugivores on modulating soil nitrogen cycling, considering their effects across a gradient of abundance of a hyper-dominant palm. 3. We found that both large frugivores and dominant palms play a substantial role in modulating ammonium availability and nitrification rates. Large frugivores increased ammonium by 95%, which also increased additively with palm abundance. Nitrification rates increased with palm abundance in the presence of large frugivores, but not on exclosure plots. Large frugivores also stimulated the regulation of the functions of soil-nitrifying microorganisms, and modulated the landscapescale variance in nitrogen availability. Such joint effects of large frugivores and palms are consistent with the notion of 'fruiting lawns'. 4. Our study indicates that frugivory plays a pivotal role in zoogeochemistry in tropical forests by regulating and structuring the nitrogen cycle, urging to accommodate frugivory in plant-large herbivore-nutrient cycling frameworks. It also indicates that defaunation, deforestation and illegal palm and timber harvesting seriously affect nitrogen cycling in tropical forests, that play a prominent role in the global cycle of this nutrient.

Frugivore zoogeochemistry in tropical forest ecosystems

“…Villar et al (2020) observed strong evidence for impacts of frugivores on N cycling in their system. Overall, total N in soil was higher in the presence of frugivores than in the absence of these animals.…”

“…Villar et al (2020) begin to fill the gap in frugivore zoogeochemistry with an experiment of ungulate frugivore effects on elemental cycling in the Atlantic Forest of Brazil. Specifically, the authors report on an 8‐year control‐exclusion (i.e.…”

“…Given frugivores are widespread both taxonomically and geographically frugivores may play an important role in zoogeochemical cycles. Villar et al (2020) begin to fill the gap in frugivore zoogeochemistry with an experiment of ungulate frugivore effects on elemental cycling in the Atlantic Forest of Brazil. Specifically, the authors report on an 8-year control-exclusion (i.e.…”

Using recent baselines as benchmarks for megafauna restoration places an unfair burden on the Global South

“…An increasing number of studies support a strong connection between rewilding as a restoration strategy and sustainable human development, noting that the promotion of rewilding in policy and decision-making would strongly support the post-2020 biodiversity goals (Perino et al 2019, Pereira et al 2020, Svenning 2020, Pasgaard et al Under revision). Trophic rewilding (Svenning et al 2016) recognizes the key role that megafauna species have on ecosystems processes, from seed dispersal, frugivory, herbivory and nutrient cycles (Pérez-Méndez et al 2016, Villar et al 2020, Enquist et al 2020)— to effects on fauna and flora communities (Galetti et al 2017), vegetation structure (Sandom et al 2014, Riesch et al 2020) and carbon storage (Bello et al 2015). The long-history of coevolution with extant species and the disproportionate impact they have on the environment (Enquist et al 2020) make megafauna species a potentially key element in our efforts to restore biodiverse and resilient ecosystems (Svenning et al 2016, Fernández et al 2017, Perino et al 2019, Schowanek et al 2021).…”

Wild pigs mediate far-reaching agricultural impacts on tropical forest soil microbial communities

“…However, these edge effects have rarely been documented beyond a few hundred meters (10,14,15). Wildlife plays an important role moderating nutrients like nitrogen and phosphorus, and soil biota through deposition of excrement and carcases (16-19). Wildlife also affects soil physical environments through biopedoturbation (20-22) and plant-soil interactions via herbivory or nest building (23-26).…”