Fern endemism and its correlates: contribution from an elevational transect in Costa Rica

We studied the distribution patterns of endemic ferns along an elevational gradient of 3400 m in Costa Rica, Central America. We related the endemism patterns of the whole species set and separated for life forms and microhabitats according to topography and environmental factors. Fern species were surveyed in 156 plots each with an area of 400 m², with up to five plots at every elevational step of 100 m. Global range size for every species was compiled from literature data, and species restricted to the mountain range from Costa Rica and adjacent western Panama were defined as endemic (24.5% of all species recorded). We found patterns of endemism rates mostly peaking at mid-elevation, but when separated for different life forms and microhabitats, some deviations from the overall pattern emerged. High constant humidity and reduced surface area were closely related to high levels of endemism. High humidity is discussed as a general predictor for high endemism rates in concert with highest overall richness. Restricted area of elevational belts, indicating a fragmented habitat, leads to a higher degree of population isolation and thus species differentiation. However, both interpretations were not fully supported by our data. Most importantly, endemism rates were fairly low on mountain tops that have the smallest available area in a topographically highly fragmented setting. In contrast, endemic species were more common than widespread species at the highest elevations. History and climatic shifts are assumed to play a role in this respect.     

Revision of the neotropical species of Triplophyllum (Tectariaceae)

This paper re-examines the species of Triplophyllum in the neotropics. The indument of the laminae (hairs and glands) provides many characteristics for distinguishing the species. Nine species are recognized, including three new ones: T. boliviense, T. chocoense, and T. glabrum. New combinations are made for T. hirsutum and T. perpilosum . A key is provided to distinguish the species, and all species are described and illustrated. The spores of the neotropical species are like those from African and Madagascan species. As such, they offer no evidence to determine whether the neotropical species form a monophyletic clade within the genus.     

宜溧山区药用蕨类资源调查

据调查统计,宜溧山区现有蕨类植物26科、44属、82种,其中40种左右有药用价值.对这些药用蕨类的生境、药用功效、利用现状等作了简要阐述,并就其开发和利用提出了相关的建议.     

Ethnobotanical studies on some pteridophytes of Southern Nigeria

Southern Nigeria represents one of the richest zones of vegetational wealth of Nigeria. The land surface is dominated by plants under 200 m.a.s 1. Folk utilization of pteridophytes by the southern Nigerians was studied. The results of this survey display an interesting diversity and distribution of ferns and fern-allied plants used as medicines, food, cosmetics, and manure in southern Nigeria. The data were compiled from frequent field trips conducted in 40 local government areas (LGAs). A total of 36 plant species belonging to 22 families were identified. Plant specimens and information were collected directly from the local inhabitants in villages and periurban towns. Our literature survey showed little or no documentation of ethnobotanical studies on pteridophytes of this region. Therefore, the present communication serves to bridge the gap. Thus, these pteridophytes could provide a vital source for healthcare and economic revenue after appropriate pharmacological analysis by patents.     

Conservation of pteridophytes in São Tomé e Príncipe (Gulf of Guinea)

Twenty-two pteridophytes (13 endemic and 9 non-endemic) from São Tomé e Príncipe (Gulf of Guinea) are evaluated as regards their rarity and conservation status. IUCN Red List Categories are assigned to these taxa. Eight taxa are Critically Endangered (CR), eleven taxa are Vulnerable (VU) and three taxa are Endangered (EN). Specific measures to conserve these rare pteridophytes are outlined.     

Distribution and Diversity of Pteridophytes and Melastomataceae along Edaphic Gradients in Yasuní National Park, Ecuadorian Amazonia1

We documented the floristic composition of pteridophytes (ferns and fern allies) and Melastomataceae in Yasuní National Park, Amazonian Ecuador. Our main questions were: (1) Are the density of individuals, species richness, and/or species diversity (measured with Shannon's H′) of the two plant groups related to edaphic differences? and (2) How many of the pteridophyte and Melastomataceae species are non–randomly distributed in relation to a soil base content gradient within terra firme (non–inundated forest). To answer these questions, we sampled 27 line transects of 500 × 5 m distributed in an area of ca 20 × 25 km. The study area included a permanent 50 ha plot established to monitor forest dynamics; thus, our results also provide information on landscape–scale floristic variability to which results from within the plot can be compared. A total of 45,608 individuals and 140 species of pteridophytes, and 4893 individuals and 89 species of the Melastomataceae, were counted in the transects. Both with pteridophytes and with Melastomataceae, a clear negative correlation was found between the amount of extractable bases in the soil and the number of plant individuals encountered in a transect. With Melastomataceae, species richness and species diversity also were negatively correlated with soil base content, but with pteridophytes they were not. More than 50 percent of the common species of both pteridophytes and Melastomataceae were nonrandomly distributed along the soil cation content gradient within terra firme. We conclude that while the species richness patterns observed in one plant group are not indicative of similar patterns in other plant groups, it seems likely that a substantial (but unknown) proportion of species belonging to other plant groups will be found to show distribution patterns that reflect edaphic preferences within terra firme forests.     

Edaphic and Floristic Variation within a 1‐ha Plot of Lowland Amazonian Rain Forest1

Several studies in lowland tropical rain forests have documented effects of local‐scale topographic variation on plant species distribution and abundance patterns. Few studies have compared the distribution patterns of more than one plant group, however, and even fewer have related these to measured physical and chemical soil characteristics. Here, we document such soil characteristics within a square 1‐ha plot in Amazonian Ecuador, and compare them to the distribution patterns of terrestrial pteridophytes, angiosperm ground herbs, and palms. Substantial variation in soil properties was found within the plot. The three plant groups showed highly correlated floristic patterns within the 1‐ha plot even after the effect of geographical distances had been taken into account. Mantel tests yielded significant correlations between edaphic patterns, as measured by distances in various soil and topographic characteristics, and floristic patterns. For all three plant groups, differences in elevation within the plot were highly correlated with floristic distances, and for terrestrial pteridophytes and palms, distances in soil calcium content and sand content were also important. Our results resembled those obtained at wider spatial scales with the same plant groups, which indicates that soil factors may play an important role for distribution and beta diversity of plants, even at the local scale.     

Mesoscale Gradients of Herb Richness and Abundance in Central Amazonia1

There are few hypotheses to explain local understory diversity patterns. There is a consensus that climate and soil fertility affect understory density and diversity at large scales, but few studies addressed the mechanisms controlling density and diversity locally. Here, I examine patterns of abundance and diversity of three understory herb groups along gradients of soil nutrients and topography at the mesoscale (64 km²) in a wet tropical forest, and possible factors causing them. Herb richness, diversity, density, and cover were measured in fifty‐nine 250 × 2 m plots systematically distributed over Reserva Ducke, Manaus. Herb groups responded differently to environmental gradients. Whereas density and cover of pteridophytes increased with altitude and slope, Marantaceae density and cover decreased. Density of sedges increased with altitude, but did not vary with slope. Density and cover of Marantaceae and sedges but not pteridophytes increased with the soil cation content. Pteridophyte richness increased with slope whereas Marantaceae richness decreased, richness of both groups increased with cation content. Diversity increased with altitude for Marantaceae and decreased for pteridophytes. Some of these patterns agree with what is expected from herbs, such as the greater abundance of Marantaceae and sedges in flat and low altitude plots, where water availability is higher and probably also light, and the greater richness of Marantaceae and pteridophytes in higher nutrient plots. The unexpected results of higher abundance and richness of pteridophytes in slopes, instead of in bottomlands, suggest that biotic or litter‐mediated controls may be important to set these patterns.     

Pteridophyte fungal associations: Current knowledge and future perspectives

Current understanding of the nature and function of fungal associations in pteridophytes is surprisingly patchy given their key evolutionary position, current research foci on other early-branching plant clades, and major efforts at unravelling mycorrhizal evolution and the mechanisms underlying this key interaction between plants and fungi. Here we provide a critical review of current knowledge of fungal associations across pteridophytes and consider future directions making recommendations along the way. From a comprehensive survey of the literature, a confused picture emerges: suggestions that members of the Lycopsida harbour Basidiomycota fungi contrast sharply with extensive cytological and recent molecular evidence pointing to exclusively Glomeromycota and/or Mucoromycotina associations in this group. Similarly, reports of dark septate, assumingly ascomycetous, hyphae in a range of pteridophytes, advocating a mutualistic relationship, are not backed by functional evidence and the fact that the fungus invariably occupies dead host tissue points to saprotrophy and not mutualism. The best conclusion that can be reached based on current evidence is that the fungal symbionts of pteridophytes belong to the two fungal lineages Mucoromycotina and Glomeromycota. Do symbiotic fungi and host pteridophytes engage in mutually beneficial partnerships? To date, only two pioneering studies have addressed this key question demonstrating reciprocal exchange of nutrients between the sporophytes of Ophioglossum vulgatum and Osmunda regalis and their fungal symbionts. There is a pressing need for more functional investigations also extending to the gametophyte generation and coupled with in vitro isolation and resynthesis studies to unravel the effect of the fungi on their host.