Development and application of landform segmentation procedures

Landscape-scale approaches to research in soil science are explicitly focus ed on transfers of components within and between landscapes. Despite wide-s pread recognition of the importance of these transfers, the application of landscape-scale approaches has been hindered by the lack of clear, reproduc ible research designs. Landform segmentation is used to divide natural and human-influenced landscapes into functionally distinct units. A specific ty pe of landform segmentation, landform element classification, was used in a comparative mensurative design to compare the effects of cultivation on so il distribution and soil organic carbon (SOC) storage and in a manipulative design to determine the relationship between N2O emissions and fertilizer rate in a hummocky till geomorphic surface in southern Saskatchewan. Signif icant transfers of SOC and surface soil from convex shoulder units to lower slope positions occurred over the past 90 years, resulting in a change in the type of soils that occupy these positions at two research sites. The ob served pattern is consistent with a tillage translocation dominated surface . The dominant control on N2O emissions in the landscape are spatial differ ences in water-filled pore space (WFPS) that are strongly controlled by wat er redistribution. Emissions from drier, shoulder landform element complexe s are consistently low throughout the year, whereas a strong positive relat ionship between N fertilizer rate and N2O emissions occur in the wettest, l evel depressional elements. (C) 2001 Elsevier Science B.V. All rights reser ved.