. Natural regeneration of Douglas-fir and associated species using modified clear-cutting systems in the Oregon Cascades. Forest regeneration Oregon; Douglas fir Oregon; Clearcutting Oregon; Forest regeneration Cascade Range; Douglas fir Cascade Range; Clearcutting Cascade Range. hours of shade and number of Douglas-fir seedlings per plot on 8 of 1 3 units. The pooled data from all three major types of cuttings showed a highly signifi- cant correlation between hours of shade and number of Douglas-fir seedlings per Figure between stocking and distance from the south edge of
. Natural regeneration of Douglas-fir and associated species using modified clear-cutting systems in the Oregon Cascades. Forest regeneration Oregon; Douglas fir Oregon; Clearcutting Oregon; Forest regeneration Cascade Range; Douglas fir Cascade Range; Clearcutting Cascade Range. hours of shade and number of Douglas-fir seedlings per plot on 8 of 1 3 units. The pooled data from all three major types of cuttings showed a highly signifi- cant correlation between hours of shade and number of Douglas-fir seedlings per Figure between stocking and distance from the south edge of timber on two east-west oriented strip clear cuts. Unit S5 is 100 feet wide and unit S6 is 200 feet wide. In general, the relation between hours of shade and regeneration was more marked on east-west strip clear cuts and patch clear cuts than on north- south strip clear cuts. A partial explanation of differences between units is provided by He found seedlings must be exposed to a high soil surface temperature for a continuous period of time before heat damage occurs to the seedling. Apparently, intermittent sunlight is less damaging than an equal duration of continuous sunlight. Only part of the variation between units can be explained in this way; other factors, such as time of day plot receives stand shade, pattern of ground shade, and microexposure, doubtless play a major rol How much shade can be expected from a particular stand edge? The theoretical relationship of tree height, percent slope, angle of sun, and stand shade is shown in figure 2. In practice, this relationship is modified by the continuity and crown condition of the stand providing shade. Plotted results from two units (fig. 1) indicate that a timber edge on the south affects a smalle — See footnote 3, p. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly r
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