Landscape Determinants of Soil Carbon and Nitrogen Storage in Southern New England

Abstract

We present estimates of C and N storage from forest soils of northeastern Connecticut, USA. Fifty‐six plots were sampled from the forest floor (FF) to 15 cm, and 21 of these plots were sampled to 60 cm. Carbon storage varied more in the FF (2.32 ± 1.06 kg C m−2) than in the top 15 cm of mineral soil (3.43 ± 0.70 kg C m−2). Nitrogen storage, however, varied less in the FF (0.086 ± 0.037 kg m−2) than in the mineral soil (0.224 ± 0.068 kg m−2). Carbon and N storage from the FF to 60 cm averaged 7.91 ± 1.74 and 0.56 ± 0.13 kg m−2, respectively. Variations in nutrient storage were explained using one and two‐way ANOVAs, three‐way multivariate regression trees (MRTs) and three site factors: forest stand composition, soil series, and topography. Carbon and N storage in the FF were best explained by stand composition. Carbon storage in the mineral soil was best explained by topography and N storage in the mineral soil was best explained by both stand composition and soil series. In general, hemlock (Tsuga canadensis Carr) stands and hill bottoms were associated with the most C and the soil series in the poorest drainage class and hardwood stands were associated with the most N. When these results were compared with other estimates from the region we observed that nutrient storage varied widely in the FF at local scales (<10 km), but varied more widely in the mineral soil at regional scales (>100 km). These data suggest that soil series and stand composition will provide good local and regional estimates of N storage. Similarly, stand composition will provide good local estimates of C storage. However, variables that explain variation in the mineral soil, such as topography and management history, will be needed to provide regional estimates of C storage.