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The ectomycorrhizal fungi associated with American chestnut (Castanea dentata) were characterized using DNA extracted from the root-tips of naturally occurring saplings from a forest in northeastern Tennessee. A total of 18 taxa were recorded, although one of these (Oidiodendron maius) was surprising because it has been reported previously to form what appear to be mycorrhizal associations only with members of the Ericaceae. One-third of the recorded taxa were representatives of the genera Russula or Lactarius (both members of the family Russulaceae), and three other genera (Cortinarius, Tomentella, and Tricholoma, each represented by two species). The data presented herein at least suggest that members of the Russulaceae are among the most common and widespread ectomycorrhizal fungi associated with naturally occurring individuals of American chestnut in the forests of eastern North America in which it was once dominant. However, it should be pointed out that our data are limited and thus are best considered as preliminary.
Opuntia cespitosa (until recent taxonomic splitting, identified as O. humifusa) is an endangered cactus in Canada, is found in only two populations nationwide after some local extirpations. The larger site is at Point Pelee National Park (PPNP-ON) at the northern edge of its range has little published data. Data were collected for plant size, overlying cover (the species is sensitive to high shade), reproductive variables, and various cladode (pad) characteristics to assess response to local conditions. The PPNP-ON population was considered conspecific to many populations throughout the eastern USA until recently. A southern Humifusa clade population in Florida was sampled to confirm the recent separation of these populations into distinct species. A variety of parametric (e.g., ANOVA) and nonparametric (chi-square, Spearman's correlation) tests were used to determine relationships across variables. This study contributes to our foundational knowledge of an endangered species. Results for this species in its last major Canadian population include that site conditions affect variables such as etiolation, in addition to shade. Plants are taller and have larger pads in Florida, supporting an upcoming taxonomic revision which would split the Floridian populations from the Ontario plants. Past work also suggests that Opuntia pads develop phototropically to maximize PAR (photosynthetically active radiation) receipt. Results show that while pads are statistically more parallel than perpendicular to the pad from which they grow, the offset is random. Thus physiological limitation of orientation is possible, or if there is a phototropic response, it occurs at the pad/areole scale.
Changes in landscape spatial structure—specifically, reductions in habitat area and connectivity—are thought to be a primary cause of pollinator declines across North America. However, the mechanisms by which landscape structure influences pollinator diversity are not well understood. Because flowering plants and pollinators are generally mutualistic, the impact of landscape structure on one can influence the diversity of the other directly or indirectly. Here, we examine the direct and indirect effects of landscape structure on plant and pollinator communities in the naturally patchy, dolomite glade grasslands of the Missouri Ozarks. We quantified landscape spatial structure and the richness of plants and flying invertebrate pollinators in 30 glades. Higher pollinator diversity was not directly related to greater landscape area and connectivity. However, we found evidence for an indirect relationship where better-connected landscapes support higher plant richness, which in turn supports greater pollinator diversity. Our findings highlight the importance of conserving extensive, well-connected natural habitat in order to maintain the plant diversity needed to support diverse pollinator communities.
The Deep Fork National Wildlife Refuge (3,925 ha) is located in east-central Oklahoma. We report 584 taxa of vascular plants (565 species and 19 infraspecific taxa), 349 genera, and 106 families. The largest families were the Poaceae (with 84 taxa), Asteraceae (73 taxa), and Fabaceae (45 taxa). Eighty introduced taxa and 13 taxa tracked by the Oklahoma Natural Heritage Inventory were encountered.