and public land. One variation is the Femelschlag, a German invention meaning "expanding group shelterwood with reserves." A patch of seedlings is located or established by cutting, and the mature trees surrounding this patch are cut, with the exception of several high-quality reserves. Regeneration then establishes around the edges of this new gap in response to the increased light. When this regeneration has established, the gap is expanded by cutting the trees around the edge of the gap, again leaving some reserves. The forest is regenerated in concentric circles that eventually meet, providing a diverse structure and steady income from repeated cuttings. Shelterwood and Seed-Tree Compared Shelterwood is very similar to seed-tree as a regeneration method. Both use natural regeneration to create an even aged stand. However, the seed-tree method is focused on very few trees that will be wind dispersed. So for example red pine 25/ha, 7/ha for larch, 15-20/ha for Douglas fir. Whereas the shelterwood method would typically have more trees as they provide a protective aspect and may well be trees with a hard mast that do not disperse so well such as oak or beech. So if shelterwood was used you might find 49/ha for Douglas fir, mixed conifers 86/ha. The amounts will vary according to species, site, age and health variables of the trees concerned. This means that in shelterwood the trees will be removed at some time as part of the method, but with seed-tree methods there are so few that it is not necessary to make a cut just to remove them, they are more likely to be taken when performing a tending or thinning operation or other cut than a removal cut. Potential problems Any silvicultural method is more prone to certain problems than another. Shelterwood has several particular problems. Windthrow from poor selection of trees in relation to the local wind patterns and direction on a site. Felling of trees may damage the regenerating level if not done carefully. Repeated cuts means repeated entry into the land with forest machinery, which can compact the soil and damage trees accidentally if not done carefully. With modern training this is substantially reduced from what was common in earlier times during the industry development. If variations such as strip shelterwood cutting is used a regeneration method the trees might not grow consistently after treatments creating an uneven aged stand more like a Plenterwald than