Mechanical or Geometric: the thinning of trees in either even or uneven age stand involving removal of trees in rows, strips, or by using fixed spacing intervals Frequently, these are the first thinnings in young stands that are densely crowded andor relatively uniform with little differentiation into crown classes. Spacing criteria are only considerations No impact on DBH distributions
Methods of thinning Mechanical thinning Low thinning Crown thinning Selection thinning Free thinning … After thinning Mechanical thinning Mechanical or Geometric: the thinning of trees in either even- or uneven age stand involving removal of trees in rows, strips, or by using fixed spacing intervals Frequently, these are the first thinnings in young stands that are densely crowded and/or relatively uniform with little differentiation into crown classes Spacing criteria are only considerations No impact on DBH distributions Mechanical thinning There are two ways applying mechanical thinning: Row thinning Spacing thinning Mechanical thinning (row thinning) Cut all trees in rows or strips at fixed intervals throughout the stand They are often utilized for the first thinning(s) in plantations where the rows are readily apparent The removal of every third row is the most common practice A mechanical row thinning in a pine plantation stand (Adapted from Fact Sheet G3398, Wisconsin Woodlands: Intermediate Cuttings in Forest Management, University of Wisconsin-Extension) Row thinning Mechanical thinning (spacing thinning) Selecting trees at fixed intervals for retention and cutting the rest This strategy is most applicable as the first thinning in very overcrowded young stands developed from dense natural reproduction Mechanical thinning by spacing in lodgepole pine Arapaho National Forest, Co Spacing thinning Low thinning Thin from below, ordinary thinning, German thinning Low thinning or thinning from below is the removal of trees from the lower crown classes (the smallest trees) to favor those in the upper crown classes (the largest trees) In general there are Grade of low thinning: Grade A; B; C; D Grade is degree of thinning Grade of low thinning Low thinning 10 Selection thinning Thinning of dominants, diameter-limited thinning, Borggreve method • • • • Remove large trees to favor small trees Maximized current economic return Higher income earlier in stand Relies on smaller trees to respond to open growing conditions 16 Selection thinning 17 Selection thinning 18 Selection thinning 19 20 Free thinning The removal of trees to control stand spacing and favor desired trees, using a combination of thinning criteria without regard to crown position 21 Free When faced with a stand with a irregular structure, it may not make sense to any of the above thinnings Apply all other elements of thinning at once Thin to improve stand structure Application/rotation sets stage for other thinnings 22 Crop tree management Crown-touching release Trees which fit/will fit your needs Northern and eastern hardwoods Where no suitable crop trees are found, not cut any trees Space crop trees out; no more than two together 23 24 How to choose? Stand conditions/composition Goals? More flexibility early in rotation Generally harvest downward through canopy over time Start heavy, then get lighter Thinning should be applied in some times e.g Selection/liberation, then crown/free, then low 25 Management Concerns Immediate return the larger the trees that are thinned, the bigger the immediate return Future development of stand growth of large vs small trees improvement of value 26 Management Concerns Time - earlier in rotation, trees tend to be smaller Development - promote the growth of small trees vs big trees in current stand Markets - what are the critical sizes to profitably log? Economics - try to put off investments, schedule revenues sooner 27 Management Considerations • • • • Logging damage Equipment Labor Hauling costs 28 Management Concerns Conveys conception of how you want stand structure altered Trees to take Vs trees to leave Administration The goal or target of thinning can be in terms of Number of trees/acre BA/acre Relative density (SDI) 29 Considerations Spacing Species Tree size (dbh, height) Stem quality (knots, sweep, defects) Crown (vigor) Disease 30 ... are Grade of low thinning: Grade A; B; C; D Grade is degree of thinning Grade of low thinning Low thinning 10 Crown thinning Crown thinning, thinning from above, high thinning, thinning in the... reproduction Mechanical thinning by spacing in lodgepole pine Arapaho National Forest, Co Spacing thinning Low thinning Thin from below, ordinary thinning, German thinning Low thinning or thinning from... impact on DBH distributions Mechanical thinning There are two ways applying mechanical thinning: Row thinning Spacing thinning Mechanical thinning (row thinning) Cut all trees in rows or strips