Ethnobotanical survey on wild alpine food plants in Lower and Central Valais (Switzerland).

ETHNOPHARMACOLOGICAL RELEVANCE: Swiss Alps have an ancestral tradition with regard to the use of wild plants as medicines and food. However, this knowledge is falling into oblivion, and is nowadays confined to village areas. Aim of the study was to identify wild edible plants used today and during the last two centuries by the alpine population of Valais (Switzerland). MATERIAL AND METHODS: Data were collected by means of semi-directed interviews made in four different lateral valleys of Valais (Val d'Anniviers, Val d'Entremont, Val d'Hérens, and Val d'Illiez). Wild food plants were classified according to their uses (salads, cooked vegetables, spices, raw snacks, teas, alcoholic drinks, sirups, and jams). Books and reports written in the XIXth century were consulted to identify uses of wild plants which have fallen in oblivion meanwhile. RESULTS: A total of 98 edible wild plants, distributed into 38 botanical families, were identified during the interviews. Several plants were highly cited (e.g. Taraxacum officinale, Chenopodium bonus-henricus). The most frequent usage was as tea (18%), followed by uses as cooked vegetables (16%), jams (16%), and raw snacks (16%). A strong association was observed between food and medicinal uses of plants. Wild food plants were of critical importance in times of food scarcity. Meanwhile, they have lost their relevance as vital components of the diet and are nowadays rather perceived and appreciated as delicacies. CONCLUSIONS: This study provides for the first time comprehensive data on present day and historical uses of wild plants as food in Lower and Central Valais. Besides being of historical interest, this ethnobotanical information can be used to identify species which may provide interesting opportunities for diversification of mountain agriculture.

Arbuscular mycorrhizal symbiosis can counterbalance the negative influence of the exotic tree species Eucalyptus camaldulensis on the structure and functioning of soil microbial communities in a sahelian soil.

The hypothesis of the present study was that bacterial communities would differentiate under Eucalyptus camaldulensis and that an enhancement of arbuscular mycorrhizal (AM) density would minimize this exotic plant species effect. Treatments consisted of control plants, preplanting fertilizer application and AM inoculation. After 4 months of culture in autoclaved soil, E. camaldulensis seedlings were either harvested for growth measurement or transferred into containers filled with the same soil but not sterilized. Other containers were kept without E. camaldulensis seedlings. After 12 months, effects of fertilizer amendment and AM inoculation were measured on the growth of Eucalyptus seedlings and on soil microbial communities. The results clearly show that this plant species significantly modified the soil bacterial community. Both community structure (assessed by denaturing gradient gel electrophoresis profiles) and function (assessed by substrate-induced respiration responses including soil catabolic evenness) were significantly affected. Such changes in the bacterial structure and function were accompanied by disturbances in the composition of the herbaceous plant species layer. These results highlight the role of AM symbiosis in the processes involved in soil bio-functioning and plant coexistence and in afforestation programmes with exotic tree species that target preservation of native plant diversity.

The geographical pattern of speciation and floral diversification in the neotropics: the tribe sinningieae (gesneriaceae) as a case study.

The geographical pattern of speciation and the relationship between floral variation and species ranges were investigated in the tribe Sinningieae (Gesneriaceae), which is found mainly in the Atlantic forests of Brazil. Geographical distribution data recorded on a grid system of 0.5 x 0.5 degree intervals and a near-complete species-level phylogenetic tree of Sinningieae inferred from a simultaneous analysis of seven DNA regions were used to address the role of geographical isolation in speciation. Geographical range overlaps between sister lineages were measured across all nodes in the phylogenetic tree and analyzed in relation to relative ages estimated from branch lengths. Although there are several cases of species sympatry in Sinningieae, patterns of sympatry between sister taxa support the predominance of allopatric speciation. The pattern of sympatry between sister taxa is consistent with range shifts following allopatric speciation, except in one clade, in which the overlapping distribution of recent sister species indicates speciation within a restricted geographical area and involving changes in pollinators and habitats. The relationship between floral divergence and regional sympatry was also examined by analyzing floral contrasts, phenological overlap, and the degree of sympatry between sister clades. Morphological contrast between flowers is not increased in sympatry and phenological divergence is more apparent between allopatric clades than between sympatric clades. Therefore, our results failed to indicate a tendency for sympatric taxa to minimize morphological and phenological overlap (geographic exclusion and/or character displacement hypotheses). Instead, they point toward adaptation in phenology to local conditions and buildup of sympatries at random with respect to flower morphology. Additional studies at a lower geographical scale are needed to identify truely coexisting species and the components of their reproductive isolation.

Continental-scale patterns of canopy tree composition and function across Amazonia.

The world's greatest terrestrial stores of biodiversity and carbon are found in the forests of northern South America, where large-scale biogeographic patterns and processes have recently begun to be described. Seven of the nine countries with territory in the Amazon basin and the Guiana shield have carried out large-scale forest inventories, but such massive data sets have been little exploited by tropical plant ecologists. Although forest inventories often lack the species-level identifications favoured by tropical plant ecologists, their consistency of measurement and vast spatial coverage make them ideally suited for numerical analyses at large scales, and a valuable resource to describe the still poorly understood spatial variation of biomass, diversity, community composition and forest functioning across the South American tropics. Here we show, by using the seven forest inventories complemented with trait and inventory data collected elsewhere, two dominant gradients in tree composition and function across the Amazon, one paralleling a major gradient in soil fertility and the other paralleling a gradient in dry season length. The data set also indicates that the dominance of Fabaceae in the Guiana shield is not necessarily the result of root adaptations to poor soils (nodulation or ectomycorrhizal associations) but perhaps also the result of their remarkably high seed mass there as a potential adaptation to low rates of disturbance.

Displacement of an herbaceous plant species community by mycorrhizal and non-mycorrhizal Gmelina arborea, an exotic tree, grown in a microcosm experiment.

Gmelina arborea Roxb. (Gmelina, Yemane) is a fast growing tree, native from India and considered as a potentially invasive woody plant in West Africa. Mycorrhizal inoculation of seedlings with Glomus intraradices was performed to study (1) the effect on the growth of G. arborea, (2) the impact on the catabolic diversity of soil microbial communities and (3) the influence on the structure of herbaceous plant species communities in microcosms. Treatments consisted of control plants, pre-planting fertilizer application and arbuscular mycorrhizal (AM) inoculation. After 4 months' culture in autoclaved soil, G. arborea seedlings were either harvested for growth measurement or transferred into containers filled with the same soil but not sterilized. Other containers were kept without G. arborea seedlings. After 12 months' further culture, effects of fertilizer amendment and AM inoculation on the growth of G. arborea seedlings were recorded. AM colonization was significantly and positively correlated with plant diversity. The substrate-induced respiration response to carboxylic acids was significantly higher in the absence of G. arborea and in the presence of G. intraradices as compared to the other treatments. The influence of AM symbiosis on plant coexistence and on allelopathic processes of invasive plants are discussed.

Photoperiodic induction of synchronous flowering near the Equator.

In tropical rainforests, 30-65% of tree species grow at densities of less than one individual per hectare. At these low population densities, successful cross-pollination relies on synchronous flowering. In rainforests with low climatic seasonality, photoperiodic control is the only reliable mechanism for inducing synchronous flowering. This poses a problem because there is no variation in day length at the Equator. Here we propose a new mechanism of photoperiodic timekeeping based on the perception of variation in sunrise or sunset time, which explains and predicts the annually repeated, staggered, synchronous and bimodal flowering of many tree species in Amazonian rainforests near the Equator.

Systematics and evolution of tribe Sinningieae (Gesneriaceae): evidence from phylogenetic analyses of six plastid DNA regions and nuclear ncpGS.

For nearly all species in the three genera of tribe Sinningieae (Gesneriaceae), Sinningia, Paliavana, and Vanhouttea (mostly in southeastern Brazil) plus 10 outgroups, we have sequenced six non-coding DNA regions (i.e., plastid intergenic spacers trnT-trnL, trnL-trnF, trnS-trnG, atpB-rbcL, and introns in the trnL and rpl16 genes) and four introns in nuclear plastid-expressed glutamine synthetase gene (ncpGS). Separate and combined analyses of these data sets using maximum parsimony supported the monophyly of Sinningieae, but the genera Paliavana and Vanhouttea were found embedded within Sinningia; therefore a new infrageneric classification is here proposed. Mapping of pollination syndromes on the DNA-based trees supported multiple origins of hummingbird and bee syndromes and derivation of moth and bat syndromes from hummingbird flowers. Perennial tubers were derived from perennial stems in non-tuberous plants.

Nectar Sugar Composition in Relation to Pollination Syndromes in Sinningieae (Gesneriaceae).

A putative correlation between nectar sugar composition and pollination syndrome was evaluated in the tribe Sinningieae (Neotropical Gesneriaceae). Sucrose, fructose and glucose were quantified in the nectar of 45 species using high performance anion-exchange chromatography. Representative species of the hummingbird, bee, bat and moth pollination syndromes were sampled in relation to their numeric importance in the tribe. In hummingbird and bee flowers, which represent 95% of the species in Sinningieae, nectar was sucrose-dominant (ratio [sucrose]/[hexose] > 1). Sugar ratios below one were only found in the nectar of three species with moth and bat syndromes. Sugar concentration averaged 23.9 ± 10.6% (wt/total wt) in hummingbird flowers and 28.7 ± 10.6% in bee flowers, whereas diluted nectar (7.1 ± 3.4%) was restricted to bat flowers. Similarities in the nectar of hummingbird and bee flowers contrast with the presence of specific morphological traits associated with these two syndromes, indicating that plant-pollinator relationships rely on flower display rather than on nectar characteristics. By contrast, distinct nectar chemistry is correlated with the bat syndrome in which a particularly low sucrose production is responsible for hexose dominance.