Spatial Variation and Distribution Characteristics of Asymbiotic Nitrogen Fixation in Cunninghamia lanceolata, Eucalyptus and Pinus massoniana Plantation Forests - Taking Guangxi Gaofeng Forestry as an Example

Abstract

【Objective】The study was conducted to investigate the spatial distribution and content differences of asymbiotic nitrogen fixation (ANF) in different ecosystem components of Cunninghamia lanceolata, Eucalyptus, Pinus massoniana plantation forests in different growing seasons.【Method】By using ordinary kriging interpolation, analysis of variance and correlation analysis, we conducted a characterisation study of spatial variability and content differences in ANF of Cunninghamia lanceolata, Eucalyptus, Pinus massoniana plantation forests in Guangxi Gaofeng Forestry by determining the amount of ANF in soil, litter and canopy leaves in the growing season and non-growing season.【Result】In both growing and non-growing seasons, the trends of ANF in each component of plantation forests were different and significant, with strong spatial correlation and heterogeneity. In the growing season, the distribution of soil ANF was low in the northeast and high in the southwest, while the distributions of litter and canopy leaves were high in the northeast and low in the southwest; in the nongrowing season, the spatial distributions of soil and canopy leaves were generally similar to those in the growing season, and that of the litter showed the opposite result. Soil ANF was the highest in plantation forests, at 1.2834 and 0.5668 kg/hm2·y, and the lowest was in canopy leaves, at 0.0009 and 0.0028 kg/hm2·y. ANF in soil differed significantly from that in litter and canopy leaves. In the growing season, the amount of soil ANF was significantly negatively correlated with litter, and the correlation between the other components was not significant; in the non-growing season, the amount of ANF between the components did not have a significant correlation.【Conclusion】The spatial differentiation of ANF in various components of Cunninghamia lanceolata, Eucalyptus, Pinus massoniana plantation forests in different seasons was significant and strong, and ANF mainly existed in the soil fraction. Therefore, the application of a certain amount of nitrogen fertilizer to the soil during the planting of Cunninghamia lanceolata, Eucalyptus and Pinus massoniana can promote the growth of plantation forests.

Keywords

• asymbiotic nitrogen fixation
• spatial distribution
• kriging interpolation
• plantation forest
• guangxi gaofeng forestry