• Kimball, Alan J.
  College of Natural Resources, Forestry, and Agriculture, University of Maine, Orono, Maine.
  
• Witham, Jack W.
  College of Natural Resources, Forestry, and Agriculture, University of Maine, Orono, Maine.
  
• Rudnicky, James L.
  College of Natural Resources, Forestry, and Agriculture, University of Maine, Orono, Maine.
  
• White, Alan S.
  College of Natural Resources, Forestry, and Agriculture, University of Maine, Orono, Maine.
  
• Hunter Jr., Malcolm L.
  College of Natural Resources, Forestry, and Agriculture, University of Maine, Orono, Maine.
  

In relatively young, closed canopy, temperate forests, forest management may achieve important ecological goals by using modified silvicultural techniques that mimic natural patterns of disturbance, forest structure, and stand development. This paper reports the short-term effects on canopy closure and understory vegetation or a partial harvest that removed 42% of the basal area in a 10-ha portion of a 40-ha study area dominated by 60-80 year old, post-agricultural Quercus rubra L., Pinus strobus L., and Acer rubrum L. in mid-coast Maine. All harvest-created canopy gaps were inventoried and mapped fourteen months after the harvest. Naturally occurring ledge gaps (gaps caused by the absence of canopy trees due to extremely shallow soils or exposed bedrock) and tree gaps were mapped and measured on 30 adjacent, untreated, hectares. Tree gaps ranged from 10 sq. m to 184 sq. m; over 92% were less that 50 sq. m in size and the majority were less that 25 sq. m. Ledge gaps ranged from 10 sq. m to 906 sq. m. The harvest-created gaps ranged from 25 sq. m to 3000 sq. m. In the aggregate, tree gaps covered only 0.7% and ledge gaps only 3.2% of the uncut forest whereas the harvest-created gaps covered 26.5% of the partially cut forest. After four growing seasons, the forest floor vegetation of the three types of gaps differed significantly with junipers (Juniperus communis L.) dominating ledge gaps, ferns and tree seedlings dominating tree gaps, and tree seedlings forbs and slash (downed woody material left from timber harvest) dominating harvest created gaps.