Epsilon Archive for Student Projects

Abstract

Red pine (Pinus resinosa Ait.) plantations have been established in Michigan with
expectations of mixed final product goals: pulpwood, boltwood and possibly sawlogs.
The effects of alternative treatments on tree and stand attributes were examined in:
the Atlantic Mine trial, thinned in spring 2006 with three alternatives: (1) every fifth row
removal plus crown thinning, (2) every third row removal plus crown thinning and (3)
every third row removal plus thinning from below; the Crane Lake trial, thinned in fall
2004 with two alternatives: (1) every third row removal and (2) every third row
removal plus thinning from above; the Middle Branch East trial, thinned in fall 2004
with two alternatives: (1) every third row removal plus one in three remaining trees
and (2) every third row removal plus one in five remaining trees. All trials included
control plots where no thinning was applied. The trials were established in the field as
a randomized complete block experiments, in which individual trees were measured
in 3-4 fixed-area plots located within each treatment unit. Growth responses of
diameter at breast height, height, live crown length, stand basal area and stand
volume were examined along with their increments. The Tukey multiple comparison
test was used to detect significant differences between treatments in their effect on
tree growth response. The results showed that diameter increment increased with
increasing thinning intensity and was significantly larger in thinned plots compared to
unthinned. Treatments did not substantially affect average tree height increment.
Stand basal area increment was significantly larger in the control plot only the year
after the harvest. Volume increment was significantly larger in controls, but did not
differ considerably among remaining treatments. However, the ratio of volume
increment to standing volume was significantly smaller in unthinned plots compared
to thinned. Since thinning treatments in all trials hardly ever differed significantly in
their effect on stand growth response, mainly due to the relatively short time of the
evaluation, heavier thinnings should be favored due to higher volume increment rates
and shorter time needed to reach desirable diameters. Nevertheless, economic
evaluation based on obtained results will be conducted in the future in order to make
final decisions about the most profitable treatment.