Even and Uneven aged

• Even-aged


  • Canopy level-shallow with slender stems
  • Wind hazard careful management required to prevent wind throw especially for shallow rooted species
  • Small trees are suppressed, release is unlikely
  • Regeneration occurs over short period
  • Site is exposed to deterioration by wind, rain and erosion during period when next generation of trees are small
  • Control of site maybe lost to invading vegetations
  • Subject to serious fire, pest and diseases losses
  • Slash, a onetime heavy accumulation adds to fire and insect hazard
• Uneven-aged


  • Deep irregular can conopy with sturdy boles
  • Wind hazard very low
  • Small trees are future crop trees that will respond to release
  • Distributed over the whole rotation age of the crop trees
  • Site in opening is always protected by surrounding trees
  • Site conditions stable, existing undesirable vegetation difficult to control
  • Fire, disease and insect losses less likely to be serious
  • Continuing light slash and slow hazard
• Growth Stages


  • Seedling - from germination to 3 feet in height
  • Sapling from 3 feet to 10 feet tall
  • Large sapling - 10 feet tall and 4 inches in diameter
  • Small pole - from 4 to 8 inches in diameter
  • Large pole - from 8to 12 inches in diameter
  • Standard - from 12 to 24 inches in diameter & breast height
  • Veteran - over 24 inches in diameter at breast height
• Forest succession


  The gradual replacement of one community of plant by the other
• Sere


  The sequence of communities in a succession
• Seral stage


  Refers to each community produced in the succession
• Succession


  • Orderly, directional and therefore predictable
  • Can occur when the community itself modifies the physical environment so that other population can be established
  • Culminates in a relatively stable community
• Primary Succession


  Occurs on sites that have not previously borne vegetations
• Secondary Succession


  Induced by external forces that alter the community by removing past or all of the original vegetations
• Climax


  The culminating stage in plant succession, where the vegetation is self-perpetuating and in equilibrium with the environment
• Monoclimax theory


  • Implies that in any climatic region, there can be only one climax community, given unlimited time for development in the absence of disturbance, with climate as the controlling force
• Polyclimax theory


  • Implies that in any climatic region there can be several climax communities, recognizing that vegetation is constantly changing and that the communities are only relatively stable, with climate, soil, topography and biota influencing community dynamics and the likelihood of disturbances
• Types of climax


  • Climatic climax - stable vegetation of mesic sites, determined by climate
  • Edaphic climax - vegetation determined by soil factors
  • Physiographic climax - vegetation determined by topographic peculiarities
  • Pyric climax - vegetation maintained by the occurrence of fire at regular intervals
• Site


  An area considered for its ecological factors which influence the capacity to produce forest or other vegetations
• Site quality


  The potential capacity of the site to produce desired vegetation as indicated by a key
• Stocking density


  An indication of the number of trees in a stand as compared to the desired number for best growth
• Measures of stand density

  • Basal area
  • Volume
  • Number and distribution
  • Crown closure
  • Bole area
  • Crown competition factor
  • Tree-area ratio
  • Stand density index
• Measures of site quality


  • Direct measurement of factors affecting the productivity of the forest and integrating them into a single index
  • Indirect measurement through indicators like volume, soil, plant indicators, height growth
• Tolerance


  The ability of the plant to survive under deep shade and intense root competition
• Intolerance


  The opposite of tolerance, being light demanding
• Tolerant trees


  • Reproduce and form under stories beneath canopies of less tolerant trees
  • Are very persistent, living in spite of small growth for many years, and develop very well when released
  • Have heavy crowns of several layers
• Intolerant trees


  • Reproduce successfully only in the open or where the canopy is greatly broken
  • Die out rapidly and respond sluggishly if released before death
  • Have thin open crowns