Fourteenth research symposium University of Durham 1974

Abstract

Background: Few studies analysing lichen diversity have simultaneously considered interactions among drivers that operate at different spatial and temporal scales.

Aims: The aims of this study were to evaluate the relative importance of host tree, and local, landscape and historical factors in explaining lichen diversity in managed temperate forests, and to test the potential interactions among factors acting at different spatial scales.

Methods: Thirty-five stands were selected in the ?rség region of western Hungary. Linear models and multi-model inference within an information-theory framework were used to evaluate the role of different variables on lichen species richness.

Results: Drivers at multiple spatial scales contributed to shaping lichen species richness both at the tree and plot levels. Tree-level species richness was related to both tree- and plot-level factors. With increasing relative diffuse light lichen species richness increased; this effect was stronger on the higher than on the lower part of the trunks. At the plot scale, species richness was affected by local drivers. Landscape and historical factors had no, or only a marginal, effect.

Conclusions: Lichen conservation in temperate managed forests could be improved if the complex interactions among host tree quality and availability, micro-climatic conditions, and management were taken into consideration.     

A phytosociological study of a mid-altitude heath in County Durham, Northern England

A phytosociological survey of Hedleyhope Fell, a mid-Durham heath, was carried out. Much of the Fell is rank Nardus grassland, with damper Juncus and Eriophorum patches. Disturbed areas to the west are covered by poor Agrostis/Trifolium/Festuca grasslands. The eastern end of the Fell forms a locally valuable area of heathland. 115 relevés were taken and 131 species of plant recorded. Classification by two-way indicator species analysis suggested the delimitation of 19 noda. The principal ordination axes, produced by detrended correspondence analysis, emphasised the importance of soil moisture gradients, organic/mineral soil gradients and levels of disturbance in determining the vegetation. The Fell, at 300 m, falls between the lowland heaths of southern England and the upland mires of the north. Indeed, its vegetation contains some assemblages and species characteristic of both habitats. The heaths of central, mid-altitude County Durham are found where the coal measures lie close to the surface and so this habitat type has suffered extensively from opencast mining activity in the recent past. Proposed opencast sites, if they go ahead, will destroy the Fell.     

Airborne Fungi Survey of Some Residences in Durham,North Carolina,USA

Gravity settling culture (GSC) plate collections of endogenous fungi were made at four homes in Durham, North Carolina. During frost-free periods (May-August), the most frequently isolated genera included Mucor, Cladosporium (Hormodendrum), Aspergillus, Penicillium, Rhizopus, Alternaria, Cunninghamella, Aureobasidium, Fusarium, Heterosporium, Amblyosporium, and other (unidentified) fungi. Higher numbers of mold isolates were associated with high shade and high levels of organic debris near the home and poor landscaping and landscape maintenance. Lower concentrations of mold isolates were associated with the presence of a central electrostatic filtration system and good compliance with dust controls. The viable mold spore levels were lower in homes where the electrostatic filtration unit was operated continuously rather than intermittently. These findings reflect the ease with which outdoor spore clouds may penetrate structures and obscure evidence of internal fungus source. The data also imply that because of size-related undersampling, open plates can exclude abundant types of recovery. No statistically significant correlations could be made between indoor mold isolates and any of the following: number and age of the occupants, age and size of home, month of survey or the presence of plants. Attempts have been made to facilitate the diagnosis of fungal allergy by gathering together examples of places and materials which are most likely to be a risk for mold sensitive patients.