Relationship between Soil Productivity and Tree Volume in Primeval Forest Ecosystems in Northeastern China

Soil properties are well known to influence plant productivity. Site-specific studies were conducted in primeval forest ecosystems in northeastern China to determine a quantitative relationship between soil productivity and tree volume. Three species-dominant primeval forest ecosystems (subalpine, spruce and fir, and Korean pine and hardwood) within the Changbai Mountain Natural Reserve area were selected as study sites. Soil properties of three landscape positions (convex, linear, and concave) in each of the three ecosystems were characterized, and the productivity was quantified using a soil-based productivity index (PI) model. On-site measurements of tree volume were used to assess their correlation with the soil PI values. A range of soil PI values occurred in landscape positions because of differential soil properties in each forest ecosystem. The PI values generally increased along the convex to concave transect and decreased with elevation. Soil pH and depth were identified as primary factors that limited the soil productivity, accounting for 52-56% of the PI variance. Tree volumes of each of the three ecosystems were positively correlated with soil PI values, with R-2 of 0.82 to 0.87. The tree volume response to soil PI was dependent on the forest types. This field Study demonstrated that the soil-based PI model Would be a useful tool in identifying undesirable soil conditions of tree growth for site management and effectively predicting tree productivity based on soil properties within the site- and species-specific forest ecosystems. FOR. SCI. 55(4):335-342.