Both habitat filtering and dispersal limitation influence the compositional structure of forest communities, but previous studies examining the relative contributions of these processes with variation partitioning have primarily used topography to represent the influence of the environment. Here, we bring together data on both topography and soil resource variation within eight large (24–50 ha) tropical forest plots, and use variation partitioning to decompose community compositional variation into fractions explained by spatial, soil resource and topographic variables. Both soil resources and topography account for significant and approximately equal variation in tree community composition (9–34% and 5–29%, respectively), and all environmental variables together explain 13–39% of compositional variation within a plot. A large fraction of variation (19–37%) was spatially structured, yet unexplained by the environment, suggesting an important role for dispersal processes and unmeasured environmental variables. For the majority of sites, adding soil resource variables to topography nearly doubled the inferred role of habitat filtering, accounting for variation in compositional structure that would previously have been attributable to dispersal. Our results, illustrated using a new graphical depiction of community structure within these plots, demonstrate the importance of small-scale environmental variation in shaping local community structure in diverse tropical forests around the globe.
Wild mushrooms are a vital source of income and nutrition for many poor communities and of value to recreational foragers. Literature relating to the edibility of mushroom species continues to expand, driven by an increasing demand for wild mushrooms, a wider interest in foraging, and the study of traditional foods. Although numerous case reports have been published on edible mushrooms, doubt and confusion persist regarding which species are safe and suitable to consume. Case reports often differ, and the evidence supporting the stated properties of mushrooms can be incomplete or ambiguous. The need for greater clarity on edible species is further underlined by increases in mushroom‐related poisonings. We propose a system for categorizing mushroom species and assigning a final edibility status. Using this system, we reviewed 2,786 mushroom species from 99 countries, accessing 9,783 case reports, from over 1,100 sources. We identified 2,189 edible species, of which 2,006 can be consumed safely, and a further 183 species which required some form of pretreatment prior to safe consumption or were associated with allergic reactions by some. We identified 471 species of uncertain edibility because of missing or incomplete evidence of consumption, and 76 unconfirmed species because of unresolved, differing opinions on edibility and toxicity. This is the most comprehensive list of edible mushrooms available to date, demonstrating the huge number of mushrooms species consumed. Our review highlights the need for further information on uncertain and clash species, and the need to present evidence in a clear, unambiguous, and consistent manner.
There is a scarcity of published information on the abundance and richness of arbuscular mycorrhizal fungi (AMF) in natural and semi-natural landuse types in Sri Lanka. The Upper Hantana (UH) area, which comprises landuse types with different histories, was selected to fulfill this knowledge gap. A study was carried out to investigate the abundance and richness of AMF in selected landuse types, including restored pine stand (REP), degraded grassland (DEG), Paraserianthes stand (PST) and natural forest patch (NFP) at Upper Hantana in the Central Province of Sri Lanka. The highest AMF spore abundance was observed in the NFP. However, the AMF spore richness was higher in both NFP and REP than in DEG and PST. At NFP, the medium-sized spores dominate the AMF spore population. Furthermore, NFP showed the least evenness in AMF distribution compared to other landuse types. Glomus was the most abundant genus in all selected landuse types. Acaulospora was observed only in DEG and PST. The colonization potential of AMF varies highly between species and selected landuse types, with no clear relationship between AMF abundance and root colonization potential. The results speculate that AMF spore abundance is determined by the composition and diversity of the vegetation. The results also revealed that the AMF richness at REP was similar to that of NFP, indicating a positive impact on the below-ground biota within a relatively short period following restoration.
An interesting bioluminescent fungus growing on dead bamboo stems was collected from bamboo forests in the East Khasi and West Jayantia Hills Districts of Meghalaya, Northeast India. Both morphological characteristics and phylogenetic analyses of nrITS and nrLSU regions showed that the bioluminescent fungus belongs to the genus Roridomyces and is a new species to science, as well as the first report of the genus, Roridomyces, in India. Full descriptions, colour photographs, phylogenetic trees to show the position of the novel bioluminescent taxon, and comparisons with its morphologically and phylogenetically similar species are provided.
While the importance of local-scale habitat niches in shaping tree species turnover along environmental gradients in tropical forests is well appreciated, relatively little is known about the influence of phylogenetic signal in species' habitat niches in shaping local community structure. We used detailed maps of the soil resource and topographic variation within eight 24-50 ha tropical forest plots combined with species phylogenies created from the APG III phylogeny to examine how phylogenetic beta diversity (indicating the degree of phylogenetic similarity of two communities) was related to environmental gradients within tropical tree communities. Using distance-based redundancy analysis we found that phylogenetic beta diversity, expressed as either nearest neighbor distance or mean pairwise distance, was significantly related to both soil and topographic variation in all study sites. In general, more phylogenetic beta diversity within a forest plot was explained by environmental variables this was expressed as nearest neighbor distance versus mean pairwise distance (3.0-10.3 % and 0.4-8.8 % of variation explained among plots, respectively), and more variation was explained by soil resource variables than topographic variables using either phylogenetic beta diversity metric. We also found that patterns of phylogenetic beta diversity expressed as nearest neighbor distance were consistent with previously observed patterns of niche similarity among congeneric species pairs in these plots. These results indicate the importance of phylogenetic signal in local habitat niches in shaping the phylogenetic structure of tropical tree communities, especially at the level of close phylogenetic neighbors, where similarity in habitat niches is most strongly preserved.
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