Spatial variability of soil carbon across a hillslope restoration planting in New Zealand

Context

Forest restoration has been adopted by governments and local communities across the globe to restore ecological functions and as a measure to mitigate climate change.

Aims

This study investigated the spatial variation in landscape, vegetation, soil characteristics, and soil carbon storage under young restoration plantings across a hillslope in northern New Zealand.

Methods

Soil samples (0–10 cm, 10–20 cm, and 20–30 cm) were taken from 121 locations across 5–20-year-old restoration plantings, remnant and regenerating bush and pasture. Samples were analysed for bulk density, pH, and soil carbon concentration and soil carbon stocks were calculated. Ordinary kriging and multiscale geographically weighted regression (MGWR) were used to predict and explain soil carbon stocks across the landscape.

Key results

Soil carbon stocks (0–10 cm depth) across the study area ranged from 1.9 to 7.1 kg m⁻². Spatial analysis revealed that elevation, slope, stem density, bulk density, and pH had a significant effect on the magnitude and distribution of soil carbon stocks.

Conclusions and implications

This study has shown that topography had a strong effect on soil carbon stocks across the young restoration plantings. The outcome of this study highlights the importance of taking landscape and soil characteristics into account when planning a forest restoration project.