Spatial heterogeneity and influence mechanisms on soil respiration in an old-growth tropical montane rainforest with complex terrain

IntroductionAlthough numerous studies have investigated ecosystem-scale soil respiration (SR) at different ecosystem, our understanding of spatial heterogeneity of SR at plot scale is still incomplete, especially in tropical rainforests with complex topography. Further, the ecological factors that drive the variability of SR in tropical rainforests is also poorly understood. MethodsHere, we investigated the spatial variations and control mechanisms of SR in a 60-ha plot of old-growth tropical rainforest with complex topography. Specifically, we sampled a 60-ha plot in intervals of 20 m to measure SR with LI-8100, used semi-variogram of geostatistical tools to examine spatial heterogeneity of SR. ResultsThe mean SR rate in this plot was 4.312 +/- 0.0410 (SE) mu mol m(-2) s(-1). Geostatistical analysis indicated that the SR rate at this plot had a moderate spatial dependence, with a nugget-to-sill ratio of 68.1%. The coefficients variance of SR was 36.2% and the patch size was approximately 112 m. Stepwise linear regression analysis (involving a multiple regression tree) revealed that the independent factors regulated different types of SR's. Liner mix-effect models showed that SR was significantly positively related to soil phosphorus and negatively to the slope in the 60-ha plot. Spatial disturbance of SR along multidimensional habitats that an increase in elevation of the multidimensional habitat, which was accompanied by enhanced SOC and soil phosphorous, also increased its SR in the 60-ha plot. DiscussionThis study would be helpful in designing future field experiments for a better understanding of SR at plot scale.

Automated summary

This study investigated the spatial variations and control mechanisms of soil respiration in a 60-ha plot of old-growth tropical rainforest. The results showed that the average soil respiration rate in the plot was 4.312 +/- 0.0410 (SE) μmol m(-2) s(-1). Geostatistical analysis revealed a moderate spatial dependence of soil respiration in the plot. Regression analysis indicated significant positive correlation with soil phosphorus and negative correlation with slope.