Soredial dispersal from individual soralia in the lichen Hypogymnia physodes (L.) Nyl.

Soredial dispersal from individual soralia of Hypogymnia physodes (L.) Nyl. was studied in the field under natural conditions and by exposing the soralia to an electric fan. Individual soralia were placed on the adhesive surface of dust particle collectors which were pinned to vertical boards in the field. The majority of soredia that were deposited on the adhesive strips during the experiments were found within 1 cm of the source soralium. Deposition was studied over 6 successive days under natural conditions. Significantly fewer soredia were deposited from soralia after removal of mature accumulations and from soralia taken from moist thalli compared with soralia from air dry thalli. In addition, there was a decline in soredial deposition over the 6 days. The influence of wind speed and initial thallus moisture content on soredial deposition over short intervals of time was studied using an electric fan. More soredia and larger soredial clusters were deposited from air dry than moist soralia at all wind speeds. Variation in wind speed between 4 and 9 m/sec had little effect on soredial deposition. Deposition of soredia was also studied using the fan over successive 5-min intervals. Large numbers of soredia were deposited during the first 5-min period. Deposition then declined but recovered after about four 5-min periods. In all experiments there were differences between individual soralia in total numbers of soredia deposited and in the pattern of deposition over time. These results suggest (1) soredia accumulate on soralia and these deposits may be gradually or rapidly depleted in the field, (2) that after the release of soredial accumulations some newly exposed soredia may be rapidly dispersed, (3) a high initial thallus moisture content inhibits soredial release and (4) variation in wind speed is less important than moisture in influencing soredial deposition. The results may help to explain the intermittent pattern of soredial deposition and the poor correlations between deposition and climatic factors observed previously in the field. © 1992.

Individual differences in cognitive style and their effects on task and social orientations of self-managed work teams

When assembling self-managing work teams, the personalities of team members are often overlooked. One personality variable known to be critical for effective decision making in teams is cognitive style. This study sought to examine how differences and similarities in analytic/intuitive cognitive styles affected the behavior of team members on the task/emotionally expressive dimension identified by Bales. As hypothesized, intuitive individuals and homogeneous intuitive teams were found to initiate more social-emotional acts. Contrary to expectations, intuitive rather than analytic individuals and homogeneous intuitive rather than analytic teams engaged in more task-oriented behaviors. Teams also tended to select intuitive individuals as leaders. The possibility that different combinations of styles may be important for overall team effectiveness was subsequently discussed, and it was suggested that this may depend on whether the nature of the work environment is relatively well structured and mechanistic or relatively unstructured and organic.