Henrik Balslev

High tree alpha-diversity in Amazonian Ecuador

In a 1 ha square plot of terra firme forest at 260 m elevation in Amazonian Ecuador, all trees with diameter at breast height (dbh) ≥5 cm were studied. There were 1561 individuals, 473 species, 187 genera and 54 families. Of these, 693 individuals, 307 species, 138 genera and 46 families had a dbh ≥10 cm. This is the highest number of tree species ever recorded for a tropical rain forest sample of this size. In both dbh classes, the most species-rich families were: Fabaceae sensu lato (including Mimosaceae and Caesalpiniaceae), Lauraceae and Sapotaceae; the most species-rich genera, were Pouteria, Inga and Protium. The vertical space was partitioned among species: 166 species were found only in the 5–10 dbh cm class and were mostly sub-canopy treelets, and 307 species with dbh ≥10 cm were mostly large canopy trees.

Medicinal plant knowledge and its erosion among the Mien (Yao) in northern Thailand.

ETHNOPHARMACOLOGICAL RELEVANCE We studied local knowledge and actual uses of medicinal plants among the Mien in northern Thailand, documenting traditional medical practices and its transfer between generations. AIM OF THE STUDY With the assumption that discrepancies between knowledge and actual use represent knowledge erosion, we studied whether actual use of medicinal plants corresponded to peoples knowledge of such uses. MATERIALS AND METHODS We used local knowledge from four specialist informants as the domain for semi-structured interviews with 34 randomly selected non-specialist informants. We calculated informant consensus, use value, and fidelity level for each species and use category and performed statistical analyses with Kolmogorov-Smirnov tests, Pearson correlation coefficient, Spearmans rank correlation coefficient, and paired-sample t-tests. RESULTS We found significant discrepancies between knowledge and actual use of medicinal plants. The number of known and actually used plants increased with increasing informant age and decreased with increasing years of formal education. CONCLUSIONS Medicinal plant knowledge and use in these Mien communities is undergoing inter-generational erosion because of acculturation and interrupted knowledge transmission. Preservation of Mien medicinal plant intellectual heritage requires continued documentation concerning use, conservation, and sustainable management of this resource, which should be publicized to younger Mien.

Geographical ecology of the palms (Arecaceae): determinants of diversity and distributions across spatial scales

BACKGROUND The palm family occurs in all tropical and sub-tropical regions of the world. Palms are of high ecological and economical importance, and display complex spatial patterns of species distributions and diversity. SCOPE This review summarizes empirical evidence for factors that determine palm species distributions, community composition and species richness such as the abiotic environment (climate, soil chemistry, hydrology and topography), the biotic environment (vegetation structure and species interactions) and dispersal. The importance of contemporary vs. historical impacts of these factors and the scale at which they function is discussed. Finally a hierarchical scale framework is developed to guide predictor selection for future studies. CONCLUSIONS Determinants of palm distributions, composition and richness vary with spatial scale. For species distributions, climate appears to be important at landscape and broader scales, soil, topography and vegetation at landscape and local scales, hydrology at local scales, and dispersal at all scales. For community composition, soil appears important at regional and finer scales, hydrology, topography and vegetation at landscape and local scales, and dispersal again at all scales. For species richness, climate and dispersal appear to be important at continental to global scales, soil at landscape and broader scales, and topography at landscape and finer scales. Some scale-predictor combinations have not been studied or deserve further attention, e.g. climate on regional to finer scales, and hydrology and topography on landscape and broader scales. The importance of biotic interactions - apart from general vegetation structure effects - for the geographic ecology of palms is generally underexplored. Future studies should target scale-predictor combinations and geographic domains not studied yet. To avoid biased inference, one should ideally include at least all predictors previously found important at the spatial scale of investigation.

Cenozoic imprints on the phylogenetic structure of palm species assemblages worldwide

Despite long-standing interest in the origin and maintenance of species diversity, little is known about historical drivers of species assemblage structure at large spatiotemporal scales. Here, we use global species distribution data, a dated genus-level phylogeny, and paleo-reconstructions of biomes and climate to examine Cenozoic imprints on the phylogenetic structure of regional species assemblages of palms (Arecaceae), a species-rich plant family characteristic of tropical ecosystems. We find a strong imprint on phylogenetic clustering due to geographic isolation and in situ diversification, especially in the Neotropics and on islands with spectacular palm radiations (e.g., Madagascar, Hawaii, and Cuba). Phylogenetic overdispersion on mainlands and islands corresponds to biotic interchange areas. Differences in the degree of phylogenetic clustering among biogeographic realms are related to differential losses of tropical rainforests during the Cenozoic, but not to the cumulative area of tropical rainforest over geological time. A largely random phylogenetic assemblage structure in Africa coincides with severe losses of rainforest area, especially after the Miocene. More recent events also appear to be influential: phylogenetic clustering increases with increasing intensity of Quaternary glacial-interglacial climatic oscillations in South America and, to a lesser extent, Africa, indicating that specific clades perform better in climatically unstable regions. Our results suggest that continental isolation (in combination with limited long-distance dispersal) and changing climate and habitat loss throughout the Cenozoic have had strong impacts on the phylogenetic structure of regional species assemblages in the tropics.

Perceptions, use and availability of woody plants among the Gourounsi in Burkina Faso.

The present study was conducted in five villages around the Nazinga Game Ranch, Burkina Faso. Fifty informants of the Gourounsi ethnic group were used. Eighty-one useful woody species were identified, out of a total of 110 woody species in the area. Woody plant use was quantified as: edible fruits (28 species), vegetable sauce (22 species), firewood (33 species), construction (29 species) and medicine (64 species and 167 remedies). Further, species accumulation curves were used to estimate that more than 650 remedies for medicine are used in the area. The communitys knowledge of plants was analysed in relation to age, gender, village of residence and amount of intercultural visits. The knowledge pattern was remarkably uniform, with only two variations: (1) men generally identified more edible fruit trees than women, and (2) one village reported more firewood species than the other four villages. The informants had a variety of opinions concerning the availability of useful plants, but the majority found the availability to be fine and 47% of the informants searched for useable products in the savanna on a daily basis. No correlation was found between an informants impression of useful products availability and his/her frequency of visits into the savanna. The results show that the Gourounsi people live in intimate relation with the savanna surrounding their villages. They are aware of the environment and are willing to learn and adopt new conservation practices.

Growth rates and mortality patterns of tropical lowland tree species and the relation to forest structure in Amazonian Ecuador

Growth in diameter and the relationship between age and size are analysed for 22 tree species in Amazonian Ecuador using growth simulation by a stochastic technique that projects the diameter-age relationships of a species. Maximum diameter growth rates varied from 1.2 mm y –1 ( Grias neuberthii ) to 20.0 mm y –1 ( Cecropia sciadophylla ). Minimum growth rates ranged from almost zero in Neea divaricata to 2.4 mm y –1 in Mollia lepidota . Median growth rates ranged between c. 0.5 mm y –1 ( Grias neuberthii, Neea divaricata ) and 11.6 mm y –1 ( Cecropia sciadophylla ). The maximum simulated life-span spent between a DBH of 10 cm and the largest DBH of a species varied from 54 y ( Cecropia sciadophylla ) to 529 y ( Neea divaricata ). Fast growing species and species that potentially can grow old showed a convex survivorship curve, whereas slower growing species and species that do not grow very old showed sigmoid, linear and convex survivorship curves. The species were grouped according to their DBH-height relationship and according to their maximum age, maximum growth rate, and maximum DBH. The groups probably reflect different light requirements. A negative correlation was found between maximum age and mortality rate. Growth rates vary within species, thus the largest tree is not necessarily the oldest.

Growth and mortality of trees in Amazonian tropical rain forest in Ecuador

Abstract. Structural changes are analysed in four samples representing 4 ha, two line transects and two hectare plots, of Amazonian tropical lowland rain forest in northern Ecuador. Only trees with a DBH ≥ 10 cm were included. A sample of floodplain forest in Anangu represents the largest turnover found in tropical forests (stand half-life = 23 yr). The line transect and hectare plot both of tierra firme forest in Anangu have the same turnover (37 yr) and were balanced for death and in-growth of both individuals and wood (basal area). The 1-ha tierra firme sample in Cuyabeno had a turnover of 67 yr and was in a growing phase. The floodplain line transect in Anangu was in a phase of structural breakdown. However, the floodplain line transect had the largest growth of basal area per tree (23.4 cm2/yr). The tierra firme samples had a growth of 9.6, 10.1, and 13.6 cm2/yr. Most of the dead trees fell with some uprooting in three of the four samples. However, no significant difference in the distribution of mode of death was found between the four samples. Death was independent of topography and the dead trees were randomly distributed. As the trees grow up they occupy more space and larger trees (DBH ≥ 15 cm) become more uniformly distributed, whereas smaller trees (DBH ≤ 15 cm) were randomly distributed. Our study confirms that plots of 1 ha are not sufficient to include representative samples of different stages of forest structure.

Abundance and cover of ground herbs in an Amazonian rain forest

In a 1-ha plot in an unflooded moist tropical forest in Reserva de Produccion Faunistica Cuy abeno in Amazonian Ecuador, 96 species of vascular herbaceous plants were found rooted in the ground; they were all perennials; 25 species were pteridophytes, representing 11 families, 71 species (14 families) were angiosperms. Araceae, Marantaceae, and Poaceae were the most important angiosperm families. The total abundance of the ground herbs was 10 960 individuals, the total cover was 250 m2, or 2.5% of the 1-ha plot. Species of ground herbs exhibit two major life-form strategies: the obligate terrestrial species (59%) are restricted to the ground; the facultative terrestrial species (41 %) have climbing and epiphytic individuals as well. Difference in life-form strategy as well as difference in edaphic specialization along a topographic gradient are two factors that may enhance the number of coexisting species within the 1-ha sample plot.

Light Converts Endosymbiotic Fungus to Pathogen, Influencing Seedling Survival and Niche-Space Filling of a Common Tropical Tree, Iriartea deltoidea

Pathogens are hypothesized to play an important role in the maintenance of tropical forest plant species richness. Notably, species richness may be promoted by incomplete filling of niche space due interactions of host populations with their pathogens. A potentially important group of pathogens are endophytic fungi, which asymptomatically colonize plants and are diverse and abundant in tropical ecosystems. Endophytes may alter competitive abilities of host individuals and improve host fitness under stress, but may also become pathogenic. Little is known of the impacts of endophytes on niche-space filling of their hosts. Here we evaluate how a widespread fungal endophyte infecting a common tropical palm influences its recruitment and survival in natural ecosystems, and whether this impact is modulated by the abiotic environment, potentially constraining host niche-space filling. Iriartea deltoidea dominates many wet lowland Neotropical forests. Diplodia mutila is a common asymptomatic endophyte in mature plants; however, it causes disease in some seedlings. We investigated the effects of light availability on D. mutila disease expression. We found I. deltoidea seedlings to preferentially occur under shady conditions. Correspondingly, we also found that high light triggers endophyte pathogenicity, while low light favors endosymbiotic development, constraining recruitment of endophyte-infested seedlings to shaded understory by reducing seedling survival in direct light. Pathogenicity of D. mutila under high light is proposed to result from light-induced production of H2O2 by the fungus, triggering hypersensitivity, cell death, and tissue necrosis in the palm. This is the first study to demonstrate that endophytes respond to abiotic factors to influence plant distributions in natural ecosystems; and the first to identify light as a factor influencing where an endophyte is placed on the endosymbiont–pathogen continuum. Our findings show that pathogens can indeed constrain niche-space filling of otherwise successful tropical plant species, providing unoccupied niche space for other species.

A comparative study on medicinal plants used in Akha's traditional medicine in China and Thailand, cultural coherence or ecological divergence?

AIM OF THE STUDY The survey aims to study the effect of geographic separation of ethnic groups on local knowledge of medicinal plants used by Akha people in Thailand and China, who were separated 100-120 years ago, to see how different the two geographically distinct but culturally similar groups were in this respect. MATERIALS AND METHODS Interviewing 10 villagers in each of five Akha villages, three in Thailand and two in China, about which plants they used and how they used them. RESULTS A total of 95 medicinal plants registered in the five villages only 16 were shared between China and Thailand. Otherwise the use patterns were quite similar with respect to which plant families and plant growth forms were used and also in terms of in which habitats the Akha found their medicinal plants. CONCLUSIONS The moving to a different site has forced the Akha to find a new set of species, but that when using these new species they have maintained other traditions relating to medicinal plants.