资源环境科技发展态势分析平台

Shallow water tables protect northern peatlands and their important carbon stocks from aerobic decomposition. Hydraulic conductivity, K, is a key control on water tables. The controls on K, particularly in degraded and restored peatlands, remain a subject of ongoing research. We took 29 shallow (50cm) peat cores from an estuarine raised bog in Wales, UK. Parts of the bog are in close-to-natural condition, while other areas have undergone shallow peat cutting for fuel and drainage, followed by restoration through ditch blocking. In the laboratory we measured horizontal (K-h) and vertical (K-v) hydraulic conductivity. We fitted linear multiple regression models to describe log(10)-transformed K-h and K-v on the basis of simple, easy-to-measure predictors. Dry bulk density and degree of decomposition were the strongest predictors of K-h and K-v. Perhaps surprisingly, the independent effect of hummocks was to produce higher-K-v peat than in lawns; while the independent effect of restored diggings was to produce higher-K peat than in uncut locations. Our models offer high explanatory power for K-h (adjusted r(2)=0.740) and K-v (adjusted r(2)=0.787). Our findings indicate that generalizable predictive models of peat K, similar to pedotransfer functions for mineral soils, may be attainable. K-h and K-v possess subtly different controls that are consistent with the contrasting roles of these two properties in peatland water budgets. Our near-surface samples show no evidence for the low-K marginal peat previously observed in deeper layers at the same site, indicating that such structures may be less important than previously believed.