To the extent that all trees and other forest plants require the same resources for regeneration and growth (e.g., light, water, and nutrients), silvicultural treatments for increasing stocking and growth rates are fairly generalizable.  But there are many forests which require special attention due to extreme edaphic conditions, flooding frequencies, steep slopes, or high elevation.

Forests on extremely nutrient-poor soils

Harvesting timber entails removal of nutrients and physical disturbances that affect rates of nutrient mineralization, leaching, and erosion.  Where soils are extremely nutrient poor (=oligotrophic), special care must be taken to avoid further depleting nutrient reserves and thereby jeopardizing future site productivity and commercial yields.  On many oligotrophic sites, most of the nutrient reserves are in the living biomass and soil organic matter.  Whatever silviculture techniques are employed on such sites, they must protect these nutrient reserves.  The best general approach is to treat the forest very gently.  Open only small gaps, leave the relatively high nutrient content bark and branches on site, and restrict the harvest intensity so as to reduce the removal of nutrients from the forest.

Forests on steep or otherwise erosion-prone sites

Erosion is a problem on all but the flattest and best drained sites, but some forests are extremely prone to erosion by flowing water.  Erosion a particular concern in forests in critical watersheds, even if the site is not especially erosion-prone.  The likelihood and severity of erosion is a function of soil structure, vegetative cover, rainfall intensity, and slope steepness and length.  As natural forest management is relegated to poorer and poorer sites, foresters will increasingly have to contend with steep slopes and the suite of associated problems.  Also, with increasing scarcity of forest resources, forests in watersheds that should be completely protected will be under increasing pressure for harvesting.

The best way to avoid soil erosion is to prevent development of the conditions that favor it.  For example, forests on very steep slopes (>35^o) should not be harvested.  Forests on more modest slopes (20-35^o) might be harvestable using aerial extraction methods (e.g., helicopters on skyline systems), but not with ground based yarding.  Harvesting should be suspended during rainy periods and machines and methods designed to reduce soil compaction (e.g., wide-tracked skidders using well-planned skid trails) should be employed.

Forests on steep slopes differ from those on level ground in several ways.  Where soils are at all unstable, curved boles and other basal stem deformities tend to be more common on slopes.  Forests on slopes are also usually very dynamic due to frequent treefalls, soil slumping, and larger landslides.

The costs and difficulties of timber harvesting generally increase with increasing slope.  Because the crowns of trees on slopes tend to be better developed on the downhill side, directional felling is difficult unless the trees are climbed and winched uphill.  Such an effort might be cost effective considering the likelihoods of bole damage and excessive disruption of the residual forest when trees are felled downhill. If forests on steep slopes must be harvested, the role of trees in soil stabilization should be kept constantly in mind.  Removal of too many trees will destabilize slopes and increase the risk of landslides.  Road and skid trail construction on slopes also increases landslide risks by disrupting water infiltration into the soil, impounding water, and creating local slopes steeper than their angle of repose.  Machine traffic near the headwaters of small streams is of particular concern because these areas are naturally unstable and are the sources of much sediment in even undisturbed water catchments.