The present study aimed to investigate the relationships among stem circumference growth, phenology and abiotic variables, of three mangrove tree species of southern Brazil. Species circumference growth, measured using dendrometer bands, and phenological events were followed for 12 months. Data were correlated with day length, temperature and precipitation using a model based on the method of least squares, taking into account temporal autocorrelation of the data. During the study period, temperature influenced the fruiting of Avicennia schaueriana Stapf and Leechm. ex Moldenke, while it was strongly related to the production of leaves and flowering in Laguncularia racemosa (L.) Gaertn and Rhizophora mangle L., respectively. Monthly precipitation was related to the flowering of only R. mangle. No abiotic variable (day length, temperature and rainfall) was correlated with stem growth for the L. racemosa and R. mangle during the period. However, the highest rate of increase in stem circumference for all three species occurred during the period of highest temperature and rainfall. Our results demonstrate that the reproductive phenophases are more intense in wetter and hotter conditions. Combined with endogenous factors, these abiotic variables influence vegetative and reproductive phenophases and stem circumference growth. Stem growth rates were different for each studied species, but they all exhibited high peaks of stem growth concomitant with periods of higher temperature and precipitation. Phenological events, and how they correlate with the analysed abiotic variables, differed among the three species and stem growth showed a direct relationship with phenophases during the study period only for A. schaueriana.
In ombrophilous forests, light stratifi cation provokes diff erent adjustments by plants for better use of the environmental conditions of each stratum. Among the morphological traits that vary with strata, the presence of bundle sheath extensions (BSEs) is related to water transport, photosynthesis, and leaf mechanical support and classifi es leaves as homobaric or heterobaric. Th is study analyzed the proportion of these types of leaves in a Lowland Ombrophilous Dense Forest (LLODF) and a Mixed Ombrophilous Forest (MOF), and among the strata of each forest type. Th e morphological leaf traits of 89 LLODF tree species and 57 MOF tree species were examined. Th e proportion of homobaric and heterobaric leaves did not diff er between forests. However, in both forest types, the distribution of species with heterobaric or homobaric leaves depended on strata, with heterobaric species occurring mainly in higher strata, and homobaric species in lower strata. Th us, light stratifi cation acts as an ecological fi lter on the composition of the vegetation of these forests, favoring heterobaric species in places with higher light intensity and temperature, such as the highest strata of canopy. On the other hand, homobaric species are more frequent in lower strata, where light is less available and humidity higher.
Individual behavior, and local context are processes that can influence the structure and evolution of ecological interactions. In trophic interactions, consumers can increase their fitness by actively choosing resources they are able to explore. The effect of active choice on interaction network structure and their coevolution is not well known. Using an individual-based model, we modeled a community of several species that interact antagonistically. The trait of each individual is modelled explicitly and subjected to the interaction pressure. Besides, each consumer can actively choose to interact with resources that maximize its fitness. We show that active consumer choice can generate coevolutionary units, that is, the modules are formed by coevolution and stay stable over time. Besides, inside each module resource traits converge which promotes attack dilution: when resources converge their traits, the pool of options for a consumer increases and the chance of a specific individual being attacked decreases. We also observed that active consumer choice impacts network structure, with networks more modular and specialized and less connected and nested as the number of consumer choices increase. Thus, we emphasize that the consumers'ctive choice behaviour plays an important role in the ecological and evolutionary aprocesses that structure these communities.
Shade plants of ombrophilous forests are subjected to light-limiting conditions and need to invest in architectural structures associated with leaf symmetry to increase light capture. This study investigated the leaf architecture of six Araucaria forest tree species with distinct symmetry: Cupania vernalis, Casearia sylvestris, Schinus terebinthifolius, Piper gaudichaudianum, Roupala brasiliensis and Cedrela fissilis. We hypothesized that symmetry, associated with other traits, minimizes self-shading. Asymmetry index, petiole length, total leaf area, leaf angle, internode length and stem diameter were measured. The asymmetry index did not indicate a clear distinction between asymmetric and symmetric leaves. Leaves classified as asymmetric had higher values for the asymmetry index in the median and basal regions of the leaf, while symmetrical leaves had higher values in the apical region. The results also indicated an adjustment among structural leaf traits that facilitated a three-dimensional organization that produced an advantageous arrangement for light capture, which seems to be a response to selective pressure by the heterogeneous light conditions of the ombrophilous forest understory.
Ecological interactions build the architecture of biodiversity in biological communities (Bascompte, 2009). In trophic interactions such as parasitism, parasitoidism, predation or herbivory, individuals of one trophic level (consumers) exploit individuals of the trophic level below, as food resources. Consequently, these interactions result in increased consumer fitness at the expense of resource fitness. A foraging consumer will generally encounter different kinds of resources, and they can decide which one to choose according to some 'currency' of biological fitness (e.g. rate of net energy intake, handling time, predator avoidance; MacArthur & Pianka, 1966; Pyke & Choe, 2019). This decision-making process known as 'active choice' leads the consumers to use some resources more often than others, given an encounter with each type of resource (Sih & Christensen, 2001), e.g. birds that typically eat molluscs of particular sizes or species (Nagarajan et al., 2015); nest parasites that use the host's nests whose eggs are similar to their own (Avilés et al., 2006;
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.