Factors Important to Yellow Birch Establishment in Upper Michigan

Abstract

Increasing the proportion of yellow birch (Betula alleghaniensis Britton) in the northern hardwood type should also increase the economic return from management. Under current market prices the stumpage value of yellow birch is about double that of sugar maple (Acer saccharum Marsh.), the next most valuable species in the type. The use of yellow birch for veneer accounts for most of its high value. In upper Michigan about 30% of the net volume of this species is sold as veneer compared to only 7% of the volume of sugar maple. The proportion of yellow birch stems in the old-growth northern hardwood stands is seldom over 12% (Lake States 1935). In this type it is most commonly found as single trees on the edge of small openings or occasionally in small groups where the more tolerant species have died out or been destroyed by a catastrophic type of disturbance. Yellow birch seldom occurs as a pure stand except on relatively small areas that have been opened and mineral soil exposed, such as by windthrow, light burns, or abandoned clearings. However, in the hemlock-yellow birch sub-type (Soc. Amer. Foresters 1954), which occurs on mesophytic sites, yellow birch commonly makes up 25% or more of the stand basal area. In secondgrowth stands the percentage is usually less, the amount seeming to vary with the soil moisture conditions and species association. Some regeneration studies have been made in the north central and northeastern portions of the botanical range of yellow birch, but very little work has been reported in the Lake States, which are in the western portion. Although the general silvical requirements of this species are fairly well known, particularly as the tree reaches the larger size classes, little information is available on the early stages of establishment and growth in the Upper Peninsula of Michigan. The reasons for the lack of sufficient yellow birch reproduction after cutting in other regions are generally considered to be the relative intolerance of the species (Baker 1949, Graham 1941), browsing by animals, and more specific seedbed requirements than its competitors. A study was begun in the Upper Peninsula of Michigan in the fall of 1952 to determine (1) the influence of seedbed conditions on the regeneration of yellow birch, and (2) the relative importance of physical and biotic factors on the establishment and early growth of yellow birch seedlings. In the area selected for study, all seedbearing trees except yellow birch and a few white pine and hemlock were cut during the winter of 1952-53, and the area was disked in the fall of 1953. This paper summarizes the changes that occurred during four growing seasons after disking and discusses results of special studies on the factors affecting the early growth of yellow birch.