In a straight hemlock proposition, the protection question may differ considerably from that involved by deciding between fir and hemlock. In the latter case, because of the assistance of fire to fir, the growth already on the ground must have considerable value to warrant foregoing the several advantages of slash burning. In the former, slash burning has no object except to reduce future risk. The inference is that a much less promising stock of young growth is worth protecting.
While this is true, there is danger of overestimating its value, especially if care is not taken in logging. It has been remarked that suppressed misshapen hemlock is not apt to make a healthy growth, that windfall is a peril, and that if the previous shade has been heavy, sudden opening to sunlight may be fatal. It should also be remembered that even slightly injured young hemlock is worthless, for it is almost certain to be attacked by borers. Anything which deadens a small portion of the bark like axe blazes, fire scorch, or scars from strap leads, is dangerous. Hemlock is more liable than fir to general defects like black streak, borers, fungous disease and mistletoe, therefore investment in reforestation needs the maximum safeguard against them. In many instances better results may be obtained from a new healthy seedling stand following a purifying fire, even at some loss of time, than from well started young growth which is unhealthy and likely not only to fail itself but also to infect any seedlings which may come in among it. Consequently if the slashing is not large, and reproduction from the sides may be counted on, the above considerations, coupled with the reduction of future fire risk, may suggest slash burning just as in the case of fir. The remarks apply particularly if it is considered necessary to log as clean as possible.
With a good, healthy start toward a new forest, however, it will usually be best to keep fire out, for the material saved will warrant greater expense in protection during the growing period. Representative tracts, both on the coast and in the Cascades, have been studied which showed that, with care in lumbering, enough good young hemlock too small for logs or skids could be saved after present-day logging of a heavy mixed fir and hemlock stand to produce in fifty years 11,000 or 12,000 feet of timber over 14 inches in diameter. This would not be wholly additional to the second crop of seedlings which might be produced if these trees were not preserved, for the ground and light they use would be denied to the seedlings, but undoubtedly the yield would be greater than could be secured if they were destroyed.
This means that under similar conditions we may go still further and actually apply the selection system, especially if the original stand is nearly pure hemlock. So far we have discussed areas left by present-day logging methods. Suppose, however, the owner of a good tract of hemlock, having decided that conditions do not warrant trying to get fir, is willing to modify his methods for the sake of better hemlock returns at some future cutting. He would probably do best to take out only the mature trees, leaving everything which is still growing with fair rapidity. Greater light will stimulate these immensely as well as encourage further seeding of the ground. The few merchantable trees he spares, together with those now unmerchantable, will, in perhaps twenty years, make another excellent crop. By leaving a fairly dense stand he prevents the windfall danger which threatens the survivors of too vigorous cutting, and also prevents them from assuming the branchy form of trees which receive too much side light. The fire danger is much reduced by resultant shading of the ground and slightly by the lesser cover of debris. In short, he makes the most economical use of the ground, and the capital represented by the trees he spares is well invested.
To sum up, hemlock lends itself to almost every form of management. Determination as to which is most advisable is governed by its extremely variable manner of occurrence and by the local promise offered by associate species. The foregoing discussion can only serve as suggestive when considering given conditions.
WESTERN CEDAR (Thuya plicata)
Except for small swamp and river bottom areas, where the land is likely to be more valuable for agriculture than for forest culture, pure cedar stands are not common. Therefore it is as a component of mixed stands that cedar is likely to become a problem in conservative management. To some extent it presents a peculiar question by being taken out alone for special purposes, such as poles and bolts, independent of ordinary logging of sawtimber.
Western cedar is a typically shade-bearing tree and also endures much ground moisture. Its occurrence as an under story and in swamps does not indicate that it always requires such conditions, however, but more often means merely that they protected it from competition or from destruction by fire. Charred remains of very large, fine cedar are often found on comparatively dry slopes where fire has resulted in complete occupation by fir at present. Cedar's failure to reappear there after removal is probably because its thin bark and shallow roots allowed its destruction by a fire which was survived by some better protected fir seed trees. Nevertheless, cedar must be classified as a moisture-loving species and occupies dry soils only in coast or mountain localities where there is a compensating heavy rainfall.
Reproduction and management of western cedar have not been sufficiently studied to warrant very positive conclusions. This neglect is probably due to a wide belief that in spite of its present commercial importance, its place in the future forest will be small. It most commonly occurs with other trees in heavy stands, which make the preservation of any young cedar difficult because of the destructiveness of logging. Being of comparatively slow growth, also persistent in retaining branches when grown in the light, it is not as promising for artificial reproduction as Douglas fir or white pine. To let it become old enough for good shingle material will be too expensive to pay, for roofing is one of the wood products easiest to substitute for. While cedar is adapted for poles, posts and other underground use, less decay-resisting species can be made equally durable by chemical treatment. In other words, as a second crop it is probably below other species in ease of establishment, rapidity and quantity, and will not have sufficient peculiar value to compensate for consequent less economical use of the ground.
There may be exceptions to this rule. Good young cedar in forests which are to be handled under the selection system should be carefully protected. It can always be utilized and may bring revenue before anything else can be cut. For the same reason it has been suggested for planting with fir and white pine, either simultaneously as a small proportion or later in blank spaces where the others fail. Under such conditions the main stand will not be modified and the cedar will afford a valuable adjunct.