Anthropogenic factors are stronger drivers of patterns of endemic plant diversity on Hainan Island of China than natural environmental factors.

The roles of natural and anthropogenic factors in contributing to the organization of biodiversity at large and small scales have long been challenging to disentangle, and doing so has never been attempted for the island province of Hainan in China based on patterns of taxonomic and phylogenetic diversity. Therefore, in this study, we evaluated the taxonomic and phylogenetic diversity of endemic plants on the island as a function of anthropogenic and natural variables based on non-metric multi-dimensional scaling (NMDS) ordination and generated generalized linear models (GLMs). We found that the highest phylogenetic diversity (1006) and the lowest mean phylogenetic distance (515.5) was in the provincial capital, Haikou. The NMDS analyses indicated that taxonomic diversity was significantly correlated with industrial revenue (p = 0.006) and population (p = 0.004). Furthermore, most phylogenetic diversity indices were strongly correlated with population and agricultural revenue, while the sampled natural environmental variables were not significantly correlated with plant diversity indices. These findings indicate that anthropogenic factors are the main present-day driving forces of plant diversity in Hainan, though we did detect a significant latitudinal diversity gradient of richness that likely reflects the historical roles of natural environmental factors in the organization of biodiversity on the island. Overall, our results are alarming for biodiversity of the island and indicate that conservation and sustainable use of endemic plant species must be made a critical priority.

Contribution of Light and Electron Microscopy to Identification of Bark from Frangula azorica, an Azorean Medicinal Plant.

Frangula azorica V. Grubow is a Macaronesian flora medicinal plant, endemic from Azores islands and inscribed on the International Union for the Conservation of Nature (IUCN) Red List of Threatened Species. This species, known as "sanguinho," belongs to the family Rhamnaceae, the same as Frangula alnus Mill. and Frangula purshiana (DC.) J. G. Cooper, two widely used official laxative herbal medicines of the western Pharmacopoeias constituted by the dried barks of each species. Morphological and chemical studies on F. azorica dried bark are scarce although it is potentially recognized as a Portuguese laxative herbal medicine. Macroscopically, the bark occurs in quills or nearly flat pieces. A channeled external surface with transversely elongated lenticels is characteristic. When the outer phellem layer is removed, a bright purple inner phellem layer is disclosed. Light and electron microscopy observations revealed flattened phellem cells with slightly thickened walls, cortical parenchyma with secretory ducts and groups of sclereids, phloem with groups of fibers and sheaths of parenchymatous cells containing druses or more frequently prismatic crystals of calcium oxalate, and parenchymatous medullary rays one to three cells wide with spherical starch grains. Observation of these botanical characteristics must be included in quality monographs of F. azorica bark herbal medicine.

Relationships between intra-specific variation in seed size and recruitment in four species in two contrasting habitats.

Large seeds contain more stored resources, and seedlings germinating from large seeds generally cope better with environmental stresses such as shading, competition and thick litter layers, than seedlings germinating from small seeds. A pattern with small-seeded species being associated with open habitats and large-seeded species being associated with closed (shaded) habitats has been suggested and supported by comparative studies. However, few studies have assessed the intra-specific relationship between seed size and recruitment, comparing plant communities differing in canopy cover. Here, seeds from four plant species commonly occurring in ecotones between open and closed habitats (Convallaria majalis, Frangula alnus, Prunus padus and Prunus spinosa) were weighed and sown individually (3200 seeds per species) in open and closed-canopy sites, and seedling emergence and survival recorded over 3 years. Our results show a generally positive, albeit weak, relationship between seed size and recruitment. In only one of the species, C. majalis, was there an association between closed canopy habitat and a positive seed size effect on recruitment. We conclude that there is a weak selection gradient favouring larger seeds, but that this selection gradient is not clearly related to habitat.

Ant behaviour and seed morphology: a missing link of myrmecochory.

Seed dispersal by ants (myrmecochory) is mediated by the presence of a lipid-rich appendage (elaiosome) on the seed that induces a variety of ants to collect the diaspores. When seeds mature or fall onto the ground, these ant species transport them to their nest. After eating the elaiosome, the seed is discarded in nest galleries or outside, in the midden or farther away, where seeds can potentially germinate. The final location of seeds with their elaiosomes removed was evaluated to assess the importance of possible handles (structures that ants can grasp to carry) in transporting ants during re-dispersal experiments of seeds from nests of six species of ants. The results indicate that seeds remained within the nest because the ants were not able to transport them out of the nest. As a consequence of the elaiosome being removed, small ant species could not take Euphorbia characias seeds out of their nests. Only large ant species could remove E. characias seeds from their nests. Attaching an artificial handle to E. characias seeds allowed small ant species to redistribute the seeds from their nests. On the other hand, Rhamnus alaternus seeds that have a natural handle after the elaiosome removal were removed from the nests by both groups of ant species. If a seed has an element that acts as a handle, it will eventually get taken out of the nest. The ants' size and their mandible gap can determine the outcome of the interaction (i.e. the pattern of the final seed shadow) and as a consequence, could influence the events that take place after the dispersal process.