Felling

Abstract: The principal source of energy for warming streams is the sun. The amount of sunlight reaching the stream may be increased after clear-cut logging. Average monthly maximum temperatures increased by 14°F and annual maximum temperatures increased from 57° to 85°F one year after clear-cut logging on a small watershed in Oregon's coast range. In a nearby watershed where strips of brush and trees separated logging units from the stream, no changes in temperature were observed that could be attributed to clear- cutting.

Abstract: The composition and structure of the bird com- munity were investigated in French Guiana (northeastern Amazonia) I year and 10 years after selective logging and compared with bird community composition and structure in undisturbed primary forest A point-count method was used in which 937 0.25-ha sample quadrats were censused for 20 minutes each. Whereas logging removed little more than 3 trees/ha, 38% of the forest undergrowth was destroyed and a higher proportion of the canopy was opened or dam- aged. An overall 27-33% decrease of species richness, fre- quency, and abundance occurred after logging with a less marked decline of diversity and evenness indices, a substan- tial increase in the proportion of dominant species, and a 45% difference in species composition, weighed by fre- quency, between logged and undisturbed forest communi- ties. Forty-two percent of the species from the primary forest decreased sharply or disappeared after logging and only 34% increased or remained unchanged. Microhabitat selection was the main correlate of sensitivity to disturbance. Most affected by logging were species associated with the under- story of tall mature stands especially terrestrial species, members of mixed flocks, and solitary sallying insectivores, all of which decreased by 70% to over 90%. Most birds as- sociated with canopy, small gaps, and vine tangles declined by only 10-30%. Small frugivores and species associated with clearings or edges increased. Among other factors, phys-