Secondary dispersal by ants promotes forest regeneration after deforestation

Abstract

Summary1. Many remnants of tropical forests are surrounded by deforested areas dominated by successional vegetation. Although secondary dispersal by scatter-hoarding rodents and ants may influence seed predation and seedling recruitment, very little is known about its importance in degraded forest ecosystems. 2. We studied the effects of secondary dispersal on seed predation, germination and seedling recruitment of the primarily bird-dispersed tree Clusia trochiformis in a tropical montane forest in Bolivia. We carried out exclosure experiments that allowed or excluded access to seeds by vertebrates in three habitat types (forest interior, degraded habitat close to and degraded habitat far from the forest margin) in a spatial block design at six sites. We offered a total of 1440 seeds (both with and without an aril) and marked half of them with a thread to follow their fate after 48 h and after 1 month. 3. We found that secondary dispersal by ants was highest in the forest interior but was also frequent in degraded habitats close to and far from the forest edge. Secondary dispersal significantly increased seedling recruitment, particularly in the degraded habitats, probably because seeds were often dispersed to sites beneath the leaf litter. Recruitment success increased significantly with dispersal distance. High recruitment of secondarily dispersed seeds in the degraded habitat was due to the combined effect of reduced predation and increased germination of seeds that had been moved by ants. 4. Synthesis. In the absence of secondary dispersal, seed germination and seedling recruitment were very low in degraded habitats. Seed dispersal by ants substantially increased natural regeneration in the deforested habitats. Our experiments thus demonstrate that the effects of biotic interactions on plant demography can vary across habitat boundaries at small spatial scales and that secondary dispersal is a crucial and overlooked process that can aid the regeneration of deforested habitats in the tropics.

The Curious Case of the Camelthorn: Competition, Coexistence, and Nest-Site Limitation in a Multispecies Mutualism

“…Interactions vary from facultative to obligate and range from mutualism to parasitism. Plants benefit from ants via services including seed dispersal (Gallegos et al 2014), pollination (de Vega et al 2009), nutrient enrichment (Wagner and Fleur Nicklen 2010), and protection against herbivory (Trager et al 2010). In exchange, myrmecophilic plants provide food to ants, a process that is taxonomically widespread (Weber and Keeler 2013).…”

Post‐dispersal seed removal of Carduus nutans and C. acanthoides by insects and small mammals

“…It would therefore be more correct to refer to these thistle species as not only wind-dispersed and human-dispersed, but, within populations, also as ant-dispersed. Within-population secondary dispersal by ants and other invertebrates has been shown to have the potential to increase seed performance through higher germination and seedling survival rates due to lower seed densities, seed handling and directed dispersal (Hammond 1995;Gó -mez and Espadaler 1998;Wenny 2001;Ohnishi et al 2013;Gallegos et al 2014). Other animals like slugs have been shown to be important seed removers in some other studies (e.g.…”

As formigas poneromorfas do Brasil

“…Além disso, colônias que recebem dieta suplementada com o elaiossomo de sementes mirmecocóricas apresentam larvas maiores, como em Myrmica ruginodis Nylander, 1846 (Myrmicinae) (GAMMANS et al, 2005). Larvas maiores apresentam maior sobrevivência, o que também pode afetar o fi tness das colônias (ELMES;WARDLAW, 1981).…”

“…As taxas de remoção de diásporos e a distância de remoção por formigas aumentam com a idade e estágio sucessional na Mata Atlântica (ZWIENER et al, 2012;. Há evidências de que as poneromorfas podem ser empregadas como aliadas na restauração passiva de áreas degradadas nos arredores de fragmentos, com as formigas gradativamente incrementando a deposição de sementes e acelerando a regeneração natural destas áreas (GALLEGOS et al, 2014). Há inclusive sugestões do emprego de técnicas de implantação de arilos artifi ciais em sementes, simples e de baixo custo, antes do emprego da semeadura em áreas de restauração.…”