The natural grasslands in South America have soils with low phosphorus (P) availability (1.0 to 7.5 mg kg−1), possibly altering the absorption and accumulation of P in grasses. We evaluated the chemical fractionation of P in the leaves of the most important grasses present in these grasslands to better understand the mechanisms involved in the storage of P. The grasses studied were Axonopus affinis and Paspalum notatum (fast tissue cycling and high nutrient demand) and Andropogon lateralis and Aristida laevis (slow tissue cycling and low nutrient demand). They were grown in pots filled with an Ultisol with two levels of P: control, and addition of 50 mg P kg–1. The main P fractions were the inorganic soluble (44%) and P in RNA (26%). Addition of P increased the total P concentration, following the order A. affinis (140%) > P. notatum (116%) > A. lateralis (81%) > A. laevis (21%). In conclusion, the species A. affinis and P. notatum responded to P fertilization with high variation and accumulating P in less-structural chemical forms, such as inorganic P. The species A. lateralis and A. laevis showed low variation in the concentration of P forms, with higher P concentrations in structural forms.

Many plant traits might explain the different ecological and network roles of fruit-eating birds. We assessed the relationship of plant productivity, fruit traits (colour, seed size and nutritional quality) and dietary specialization, with the network roles of fruit-eating birds (number of partners, centrality and selectivity) in the Atlantic Forest, Brazil. We classified bird species according to their dietary specialization into three categories: obligate, partial and opportunistic fruit-eating birds. To test if network roles changed according to dietary specialization, fruit productivity and traits, we used a generalized linear model analysis. The selected 14 species of plant interacted with 52 bird species, which consumed 2199 fruits. The most central and generalist fruit-eating bird, Turdus albicolis, interacted with plants that produced more fruits, such as Miconia cinerascens, and had, on average, larger seeds, such as Myrcia splendens. The most selective birds interacted with fruits with a higher concentration of lipids and less intense colour, and plants that produced fewer fruits. Obligate fruit-eating birds, such as Patagioenas plumbea, were more selective than partial and opportunistic birds. Different plant traits are therefore related to the different network roles of fruit-eating birds in the Atlantic Forest, which are also dependent on bird dietary specialization.

Large frugivores provide critical seed dispersal services for many plant species and their extirpation from forested ecosystems can cause compositional shifts in regenerating plant cohorts. Yet, we still poorly understand whether large seed-dispersers have complementary or redundant roles for forest regeneration. Here, to assess the functional complementarity of large-bodied frugivores in forest regeneration, we quantified the effects of varying abundance of hornbills, primates and the forest elephant on the density, species richness and the mean weighted seed length of animal-dispersed tree species among seedlings in five sites in a forest–savanna mosaic in D. R. Congo, while accounting for percentage forest cover and the local presence of fruiting trees. We found that the abundance of primates was positively associated with species richness of seedlings, while percentage forest cover was negatively associated (R2 = 0.19). The abundance of hornbills, the presence of elephants and percentage forest cover were positively associated with mean seed length of the regenerating cohort (R2 = 0.13). Spatially explicit analysis indicated that some additional processes have an important influence on these response indices. Primates would seem to have a preponderant role for maintaining relatively high species richness, while hornbills and elephant would seem to be predominantly responsible for the recruitment of large-seeded trees. Our results could indicate that these taxa of frugivores play complementary functional roles for forest regeneration. This suggests that the extirpation of one or more of these dispersers would likely not be functionally compensated for by the remaining taxa, hence possibly cascading into compositional shifts.

In the tropics, limestone caves in karstic areas are known for their unique biodiversity. However, many caves remain unstudied and little is known about underlying gradients that determine diversity and biomass in aquatic microhabitats. Here, we sampled zooplankton and benthos in a set of 12 aquatic caves, locally called closed cenotes in Yucatán, Mexico. Our aim was to explain diversity patterns and differences in biomass with particular attention for correlations between bat colony characteristics and other biota. Compared with caves that support photosynthesis, diversity was low with an average of four planktonic and two benthic species in these dark caves. Undetectable phosphorus concentrations in the water suggest this nutrient is limiting. Several associations hint at a potential link between bat abundance and functional guild composition, water quality and aquatic biota. As such, more bats were linked to higher nitrate concentrations. Yet this was not translated to higher invertebrate biomass, probably since phosphorus is limiting. Overall, the trends found in this survey suggest that bats could be important as fertilizers of the caves although mechanistic links that mediate the flux of nutrients need to be confirmed experimentally.

Ground-dwelling ants are active foragers that may extend their foraging area into the vegetation, although the factors affecting their diversity in the suspended litter of understorey plants remain overlooked. To evaluate the influence of the distance between strata, litter biomass and plant size on the ant fauna, the litter ant assemblage of the suspended stratum was compared with the ground immediately below the understorey treelet Erythrochiton brasiliensis (Rutaceae) in an Atlantic Forest, south-eastern Brazil. We collected 1364 ants from 26 ant species. The suspended litter ant assemblage represented a subset of the ground-dwelling ants present in soil litter. The beta diversity results primarily from the high ant species turnover among individual suspended-litter samples, and among ground-litter samples, while species turnover among suspended-ground pairs is lower. Additionally, plant height was not important in determining the species turnover between strata. However, plant height positively correlated with ant species richness, probably because of the increased number of microhabitats. These results suggest that suspended litter in the forest understorey can provide the conditions for ground-dwelling ants to forage and nest, functioning as a vertical extension of resources and microhabitat conditions present in the ground litter.

Addressing what affects predation among caterpillars, we conducted an experiment in a Bornean rain forest on 212 clay models of Tortricidae caterpillars (the herbivore) and 53 trees of Kopsia pauciflora (the host), located either in the open or under closed canopies. We predicted that the frequency of predatory attacks towards caterpillars increases (1) in canopy gaps and (2) on leaves damaged by herbivory, but (3) decreases among caterpillars that wrap their body in leaves. Each plant with caterpillar models was consecutively allocated to one of four treatments: caterpillars artificially rolled in leaves vs caterpillars on unrolled leaves, and caterpillars on artificially damaged vs undamaged leaves. Each time, caterpillar models were placed on the plants for 48 h, and then replaced with new models that were subjected to a new treatment. On average, our caterpillar models had a 21% chance of being attacked per 24 h. More attacks were performed by insects (81.6%) than birds. The attack frequency did not depend on the canopy cover or on leaf damage, but decreased among models rolled in leaves. This pattern was mainly attributable to insect attacks, which were also more frequent than bird attacks. Overall, the Tortricidae caterpillars seem to suffer comparable predation rates in the open and under closed canopies irrespective of the herbivory damage of leaves, but their leaf-rolling behaviour might reduce predation.