Ingestion and dispersal: direct and indirect effects of frugivores on seed viability and germination of Corema album (Empetraceae)

Germination and First Stages of Growth in Drought, Salinity, and Cold Stress Conditions of Plasma-Treated Barley Seeds

Numerous works have demonstrated that cold plasma treatments constitute an effective procedure to accelerate seed germination under nonstress conditions. Evidence also exists about a positive effect of plasmas for germination under environmental stress conditions. For barley seeds, this work studies the influence of cold plasma treatments on the germination rate and initial stages of plant growth in common stress environments, such as drought, salinity, and low-temperature conditions. As a general result, it has been found that the germination rate was higher for plasma-treated than for untreated seeds. Plasma also induced favorable changes in plant and radicle dimensions, which depended on the environment. The obtained results demonstrate that plasma affects the biochemical metabolic chains of seeds and plants, resulting in changes in the concentration of biochemical growing factors, a faster germination, and an initially more robust plant growth, even under stress conditions. These changes in phenotype are accompanied by differences in the concentration of biomarkers such as photosynthetic pigments (chlorophylls a and b and carotenoids), reactive oxygen species, and, particularly, the amino acid proline in the leaves of young plants, with changes that depend on environmental conditions and the application of a plasma treatment. This supports the idea that, rather than an increase in seed water imbibition capacity, there are clear beneficial effects on seedling of plasma treatments.

The effect of lizards on the dispersal and germination of Capparis spinosa (Capparaceae)

Seed dispersal is a key component of the interactions between plants and animals. There is little research on the effects of lizard seed dispersal, which is more common on islands than elsewhere. In this study, the effects of the passage of Capparis spinosa seeds through Teratoscincus roborowskii lizard digestive tracts on the seed coats, water uptake rates and germination rates were investigated. In addition, the spatial patterns of fecal deposition by lizards in various microhabitats were assessed. Our results showed that the mean retention time (MRT) of mealworms was significantly longer than that of C. spinosa seeds in both adult and juvenile lizards. The defecation rate of C. spinosa tended to be lower than that of mealworms, which might be beneficial for seed dispersal. It was determined that the longer MRT of C. spinosa seeds enhanced the permeability of the seed coats, which promoted fast water uptake, broke seed dormancy and increased the seed germination rate. Furthermore, the seeds that passed through the digestive tracts of lizards were deposited in favorable germination microhabitats. By enhancing seed germination and depositing intact and viable seeds in safe potential recruitment sites, the lizard T. roborowskii acts, at least qualitatively, as an effective disperser of C. spinosa.

Defaunation as a trigger for the additional loss of plant species in fragmented landscapes: considerations on the state of Espírito Santo, southeastern Brazil

Abstract Here we present a brief review on how the loss of fauna can cause a concomitant loss in plant diversity in the state of Espírito Santo, focusing on the context of current habitat loss and fragmentation and the importance of the mutualistic interactions between animals and plants. We discuss the main groups of fauna that are involved in pollination and seed dispersal, especially those that are found in the state of Espírito Santo. These ecological processes were selected due to their relevance for population dynamics and population genetics of plants. In Atlantic Forest, important pollinators include a variety of insects (especially bees), along with many species of birds and bats. Seed dispersers also include many taxonomic groups, from ants to large mammals. Each of these groups contribute in their own unique and complementary, rather than redundant, way. Habitat fragmentation causes a variety of problems for habitat integrity and the reduction of species diversity, and smaller fragments tend to support fewer species and smaller populations. As a consequence, pollinators and seed dispersers are lost or their activity is reduced, thereby reducing even further the reproductive success of the plants, leading to a vicious cycle of reduction of species diversity.

Corema album: unbiased dioecy in a competitive environment

Corema album is a dioecious coastal shrub. Dioecious plants growing in these resource-limited habitats may present spatial segregation of the sexes (SSS) or demographic biases because of the different reproductive effort between sexes. In these environments facilitation is a more common interaction between plants than competition. To assess factors determining the distribution of C. album male and female plants, we investigated the influence of habitat type (sand dunes and coastal woodlands), assessed the occurrence of SSS or demographic biases and also a possible role of these shrubs as nurse plants. We selected three C. album populations with the two habitat types. All C. album individuals were sexed, mapped and measured in three plots (20 m × 20 m) per population/habitat type. Presence and abundance of all plant species were recorded under five female and five male C. album plants as well as in equivalent open ground area in each of 15 plots. According to Ripley's K function result, C. album did not display SSS. Generalised linear mixed models (GLMM) show that differences in plant size were not related to plant sex. Plant inventory correspondence analysis showed that species composition and abundance were influenced by habitat type, population and the presence of a C. album individual, but not by its sex. GLMM indicated a detrimental effect of C. album on the co-occurring plants. Our results show that sexual dimorphism has allowed C. album to adapt to the environment avoiding SSS or significant demographic bias, suggesting a positive outlook for its conservation.

Strong dependence of a pioneer shrub on seed dispersal services provided by an endemic endangered lizard in a Mediterranean island ecosystem

The accelerating rate of vertebrate extinctions and population declines threatens to disrupt important ecological interactions, altering key ecosystem processes such as animal seed dispersal. The study of highly specialized mutualistic interactions is crucial to predict the consequences of population declines and extinctions. Islands offer unique opportunities to study highly specialized interactions, as they often have naturally depauperated faunas and are experiencing high rates of human-driven extinctions. In this study, we assess the effect of seed dispersal on seedling recruitment of Ephedra fragilis (Ephedraceae) on a Mediterranean island ecosystem. We used field data and stochastic simulation modeling to estimate seed fate and recruitment patterns of this pioneer shrub typical of arid and semiarid areas, and to estimate the dependence of recruitment on the lizard Podarcis lilfordi (Lacertidae), its only known seed disperser. Ephedra fragilis recruitment highly depended on lizards: lizards produced 3.8 times more newly-emerged seedlings than non-dispersed seeds and no seedlings from undispersed seeds survived the study period. Seed dispersal by lizards was mostly to open sites, which was key for the increased success observed, while undispersed seeds, falling under mother plants, suffered higher predation and lower seedling emergence and survival. The ability of this pioneer shrub to get established in open ground is crucial for vegetation colonization and restoration, especially on degraded lands affected by desertification, where they act as nurse plants for other species. Lizards are key in this process, which has important consequences for community structure and ecosystem functioning.

Germination and Clonal Propagation of the Endemic Shrub Corema album, a Vulnerable Species with Conservation Needs and Commercial Interest

In this study, we aimed to explore regeneration possibilities of Corema album (L.) D. Don by determining germination mechanisms and testing vegetative propagation methods. We analyzed seed viability under natural conditions, carried out germination treatments and a greenhouse experiment to study clonal propagation. We confirmed that C. album seeds present physiological dormancy, broken by ingestion by natural dispersers (rabbits and foxes), and that seed viability under natural conditions is lost after one year. In vitro germination was better achieved with a 200 ppm gibberellic acid treatment. Clonal propagation proved to be a successful technique for the production of C. album. Treating cuttings with IBA 0.2, w/v, at 20% resulted in the highest rooting percentage, while planting rooted cuttings in a substrate of perlite with vermiculite 1:1 was essential for plant survival. Our results show that both germination pretreatments and cutting propagation are powerful tools for the production of this valuable species. Both methods could be incorporated for population regeneration in natural habitats, and for the potential establishment of the species as a new crop for consumption and pharmacological purposes.