Spatial Variation of Organic Carbon Stocks in Peat Soils and Gleyzems in the Northeast of Sakhalin Island

Stocks of organic carbon in the northeast of Sakhalin Island average 109.8 kg/m(2) in medium-deep oligotrophic peat soils, 75.8 kg/m(2) in oligotrophic peat gley soils, 20.9-42.7 kg/m(2) in peat gleyzems, and 16.6 kg/m(2) in gleyzems. The vertical distribution of volumetric concentrations and the carbon stocks in different subtypes of peat soils and gleyzems have been studied. Linear regression equations have been developed to estimate carbon stocks in dependence on the depth of the peat layer. The coefficients of variation of the carbon stocks on test plots of 50 x 50 m in size increase in the following order: medium-deep oligotrophic peat soils (3.1-7.3%) < oligotrophic peat gley soils (3.3-12.9%) < peat gleyzems (9.2-21.7%) < gleyzems (22.9%). The proportion of the carbon stock variances has been estimated for three spatial scales (50 x 50 m, 5 x 5 km, and 10 x 10 km) with the use of the hierarchical analysis of variance. The required number of sampled profiles for reliable data on the mean carbon stocks in peat soils and gleyzems has been estimated. Nomograms for determining the least significant difference between the estimates of the mean soil carbon stocks have been proposed for studies with a small number of samples.