The majority of variables we tested to characterize understory
light regimes following an intermediate-scale disturbance had
returned to pre-disturbance conditions after three growing seasons. However, there were significant differences in percent of fullsunlight between control and moderate damage plots and light and
moderate damage plots; based on measures of light at breast
height. We did not find significant differences in measures from
our hemispherical photographs. The difference between percent
of full sunlight on control v. light damage plots was not discernible,
which does not necessarily mean canopy gaps had been completely
filled, but rather that well-developed individuals in the midstory
increased sufficiently in height and crown volume to negate the
increases in light from canopy gaps. Although the canopy was still
open at our sampling, midstory stems restricted light to the
seedling and sapling layers. Consequently, even though the mean
percent of full sunlight in the moderate plots fell within the 20–
50% range required for understory Quercus stems (Dey, 2002), light
levels below breast height (i.e. light level in the regeneration layer)
were insufficient for Quercus recruitment.
Percent of full sunlight on control and light damage plots, which
best represented actual understory light levels at breast height,
were comparable to those from the region (Canham et al., 1990;
Schweitzer and Dey, 2011 ). Schweitzer and Dey (2011) quantified
forest response to different levels of regeneration harvests in north
Alabama and the levels of canopy openness and gap fraction they
documented after three growing seasons were comparable to those
found in this study after the same time since disturbance. The stage
of stand development is particularly important when evaluating
the effects of intermediate-scale disturbances on understory light
levels. The majority of stems disturbed by the wind event were
canopy trees, and during the understory reinitiation stage the midstory in these forest systems is well-developed. Thus, rather than
creating new opportunities for the establishment of new stems,
the disturbance served largely as a mechanism to release stems
already present in the midstory. Consequently, the resultant
changes in the light regime at breast height were ephemeral and
lasted only a few growing seasons.
The majority of variables we tested to characterize understorylight regimes following an intermediate-scale disturbance hadreturned to pre-disturbance conditions after three growing seasons. However, there were significant differences in percent of fullsunlight between control and moderate damage plots and light andmoderate damage plots; based on measures of light at breastheight. We did not find significant differences in measures fromour hemispherical photographs. The difference between percentof full sunlight on control v. light damage plots was not discernible,which does not necessarily mean canopy gaps had been completelyfilled, but rather that well-developed individuals in the midstoryincreased sufficiently in height and crown volume to negate theincreases in light from canopy gaps. Although the canopy was stillopen at our sampling, midstory stems restricted light to theseedling and sapling layers. Consequently, even though the meanpercent of full sunlight in the moderate plots fell within the 20–50% range required for understory Quercus stems (Dey, 2002), lightlevels below breast height (i.e. light level in the regeneration layer)were insufficient for Quercus recruitment.Percent of full sunlight on control and light damage plots, whichbest represented actual understory light levels at breast height,were comparable to those from the region (Canham et al., 1990;Schweitzer and Dey, 2011 ). Schweitzer and Dey (2011) quantifiedforest response to different levels of regeneration harvests in northAlabama and the levels of canopy openness and gap fraction theydocumented after three growing seasons were comparable to thosefound in this study after the same time since disturbance. The stageof stand development is particularly important when evaluatingthe effects of intermediate-scale disturbances on understory lightlevels. The majority of stems disturbed by the wind event werecanopy trees, and during the understory reinitiation stage the midstory in these forest systems is well-developed. Thus, rather thancreating new opportunities for the establishment of new stems,the disturbance served largely as a mechanism to release stemsalready present in the midstory. Consequently, the resultantchanges in the light regime at breast height were ephemeral andlasted only a few growing seasons.
การแปล กรุณารอสักครู่..
Majority of the variables we tested to characterize understory
Light regimes following an Intermediate-scale disturbance had
returned to pre-disturbance conditions after Three Growing Seasons. However, there were significant differences in PERCENT of Fullsunlight between plots and Light Control and moderate damage and
moderate damage plots; based on measures of Light at Breast
height. We did not Find significant differences in measures from
our hemispherical photographs. The difference between PERCENT
of full Sunlight on Control v. Light damage plots was not discernible,
which does not necessarily Mean canopy GAPS had been completely
Filled, but rather that well-developed individuals in the Midstory
Increased Sufficiently in height and Crown volume to Negate the.
increases in light from canopy gaps. Although the canopy was still
open at our sampling, Light Midstory stems restricted to the
Seedling and Sapling layers. Consequently, even though the Mean
PERCENT of full Sunlight fell in the moderate plots 20-Within the
50% required for Range understory stems Quercus (Dey, 2002), Light
levels Below Breast height (IE Light level in the regeneration layer)
were insufficient for. Quercus Recruitment.
Percent of full Sunlight on Control and Light damage plots, which
best represented Actual understory Light levels at Breast height,
were comparable to those from the Region (Canham et al., 1.99 thousand;
Schweitzer and Dey, 2011). Schweitzer and Dey (in 2011) quantified
Forest response to different levels of regeneration harvests in North
Alabama and the levels of canopy openness and Gap fraction they
documented after Three Growing Seasons were comparable to those
in this Study Found Same time since after the disturbance. The Stage
of Development stand is particularly important when evaluating
the effects of Intermediate-scale disturbances on understory Light
levels. Majority of the stems Wind Disturbed by the event were
Trees canopy, the understory and during the Midstory Reinitiation Stage Systems is well-developed in these Forest. Thus, rather than
creating opportunities for the New Establishment of New stems,
the disturbance served largely as a mechanism to release stems
already present in the Midstory. Consequently, the resultant
Changes in the Light regime at Breast height were ephemeral and
lasted only a few Growing Seasons.
การแปล กรุณารอสักครู่..