Spatial patterns of soil respiration in a spruce-fir valley forest, Northeast China

Purpose: The quantification of spatial patterns of soil respiration (RS) is an important step in modelling soil carbon budgets. This study aims to characterise the spatial variability of RS using traditional and geostatistical analyses in a mature temperate forest during the growing season, with emphases on temporal variation in the spatial patterns and soil properties and stand structural parameters driving the variability of RS.

Materials and methods: RS, soil temperature and soil water content were sampled at 780 positions in a 9.12-ha permanent plot in a spruce-fir valley forest in the spring, summer and autumn of 2015. Furthermore, edaphic properties were measured adjacent to each sampling point, and all trees with DBH (diameter at breast height of tree) greater than 1 cm were mapped in the plot.

Results and discussion: RS showed strong spatial variation across the three measurement campaigns, with the autocorrelation length ranging from 10 to 17 m. The spatial variability of RS in the spring period was relatively higher than that of summer and autumn. Soil water content was confirmed to be the primary factor driving spatial RS, followed by soil temperature, soil organic carbon, total nitrogen, C:N, pH and the maximum DBH within radius of 4 m of sampling points. The multiple regression model fitted by soil properties and stand structural parameters could account for 11–32% of the spatial variation of RS. However, the involved factors in the regression model varied with season, and soil temperature was more important in controlling the spatial variability of RS in the spring period.

Conclusions: The study highlights that soil water content and soil temperature play the most important role in determining the spatial patterns of RS across the growing season.