Chin J Plan Ecolo ›› 2006, Vol. 30 ›› Issue (5): 771-779.

• Research Articles •

### THE ESTIMATE OF FINE ROOT BIOMASS IN UPPER SOIL LAYER OF LARIX OLGENSIS PLANTATION BY GEOSTATISTICS METHOD

SUN Zhi_Hu; MU Chang_Cheng; SUN Long

1. Forestry College, Northeast Forestry University , Harbin 150040, China
• Online:2006-09-30 Published:2006-09-30
• Contact: MU Chang_Cheng

Abstract:

Background and Aims Drilling soil core, simply averaging the surveying values and ignoring the information of sampling point locations are in common use in estimating the fine root biomass of forest. Owing to the significant heterogeneity of fine root distribution, using the method above may be not proper. The Larix olgensis stand was chosen for a case study. Answer to the following question was sought: is the fine root biomass estimated by combining the coordinates of sampling points.
Methods Semivariance analysis of Geostatistics was used to quantify the spatial heterogeneity of fine root (<2 mm) biomass in upper layer of soil (0-10 cm) in Larix olgensis stand (14-40 year). Fine root biomass was estimated with kriging interpolation of Geostatistics and definite integral. 
Key Results The semivariograms of fine roots in all six Larix olgensis stands were best described by spherical model. The spatial variability of fine root in all six Larix olgensis stands was mainly caused by structural factors with spatial structural ratio >25 %. The scales of spatial heterogeneity of fine roots (1. 76-5.58 m) showed a positive linear correlation (p＝0.074 4) with stand age (14-40 year). The sign_test of nonparametric statistics of paired samples showed that the kriging interpolation, based on the results of semivariance analysis, could be used to estimate the fine root biomass in Larix olgensis stands. The relationship between the estimated fine root biomass and the values of its corresponding coordinates was best fitted by bivariate order 10 cosine series polynomial. Based on the result of definite integral to those polynomials (integral range was limited to plot size), total fine root biomass of the 14_year, 19_year, 22_year, 26_year, 32_year, 40_year_old stands was 1.097 3, 1.434 0, 1.185 4, 0.974 3 , 1. 682 6, 1.255 6 Mg•hm-2, respectively. No differences (α=0.037 3 ) were found in the fine root biomass in upper soil layer of Larix olgensis stands with difference stand ages. The estimated of fine root mass of individual stems increased exponentially with stand age (α=0.002).
Conclusions Kriging interpolation method of Geostatistics, combined with multiple regression and definite integral, provide a new optimal alternative for the estimation of fine root biomass in Larix olgensis stands.