Tree influence on carbon stock and C:N ratio of soil organic layer in boreal Scots pine forests.

摘要

Observed small-scale spatial variation of forest soil is suggested to be produced by tree influence. We examined spatial variation of the tree influences by modelling tree influence potential that accounts for location and size of trees. Thereafter, we tested significance of the correlations between the tree influence potential and soil properties (carbon stock and C:N ratio of the organic layer) with Monte Carlo permutation tests. The methods were applied to five Scots pine stands located in the boreal vegetation zone in Finland. We found statistically significant tree influence on soil C:N ratio in all studied stands, but the tree influence on soil carbon stock was significant only in three of five stands. This indicates that location of trees has a relatively steady and remarkable influence on spatial variation of a soil parameter that reflects soil fertility and nutrient balance, but variation of soil carbon stock is not that clearly affected by current tree stand. The correlations between C:N ratios and tree influences were positive in four of the five stands, indicating that soil was less fertile near the trees. The methods described here produce statistically reliable information pertaining to the influence of trees on soil properties.