Grassland ecosystems established under the conservation reserve program (CRP) in the Prairie Pothole Region (PPR) currently provide soil conservation and wildlife habitat services. We aimed to determine if these lands also sequester soil organic carbon (SOC), as compared with neighboring croplands across multiple farms in the North Dakota PPR. We sampled soil from small plots at 17 private farms in the central North Dakota PPR, where long-term (≥15 years) grasslands managed under the CRP were paired with neighboring annual croplands. Cores were collected to 100 cm and split into 0-10, 10-20, 20-30, 30-40, 40-70, and 70-100 cm soil depth layers. We hypothesized the effect of land use on soil organic carbon (SOC), root carbon (C), and bulk density would be greatest near the surface. For 0-10 and 10-20 cm layers, grasslands managed under the CRP were lower in bulk density and higher in SOC. From 0 to 70 cm, grasslands managed under the CRP were higher in root C. Average (±standard error) SOC for re-established grasslands and croplands was 25.39 (0.91) and 21.90 (1.02), respectively, for the 0-10 cm soil layer and 19.88 (0.86) and 18.31 (0.82), respectively, for the 10-20 soil layer. Compared to croplands, re-established grasslands sampled in the North Dakota PPR were 3-13 % lower in bulk density and 9-16 % higher in SOC from 0 to 20 cm, while root C was 2-6 times greater from 0 to 70 cm.

Wetland restoration in the Prairie Pothole Region (PPR) often involves soil removal to enhance water storage volume and/ or remove seedbanks of invasive species. Consequences of soil removal could include loss of soil organic carbon (SOC), which is important to ecosystem functions such as water-holding capacity and nutrient retention needed for plant re-establishment. We used watershed position and surface flow pathways to classify wetlands into headwater or network systems to address two questions relevant to carbon (C) cycling and wetland restoration practices: (i) Do SOC stocks and C mineralization rates vary with landscape position in the watershed (headwater vs. network systems) and land use (restored vs. native prairie grasslands)? (ii) How might soil removal affect plant emergence? We addressed these questions using wetlands at three large (?200 ha) study areas in the central North Dakota PPR. We found the cumulative amount of C mineralization over 90 d was 100% greater for network than headwater systems, but SOC stocks were similar, suggesting greater C inputs beneath wetlands connected by higher-order drainage lines are balanced by greater rates of C turnover. Land use significantly affected SOC, with greater stocks beneath native prairie than restored grasslands for both watershed positions. Removal of mineral soil negatively affected plant emergence. This watershed-based framework can be applied to guide restoration designs by (i) weighting wetlands based on surface flow connectivity and contributing area and (ii) mapping the effects of soil removal on plant and soil properties for network and headwater wetland systems in the PPR.

Livestock graze hill country regions worldwide where grassland biomass or structure is important both economically as forage and enviromentally as habitat for wildlife. Manual measurements of biomass in remote and expansive hill country landscapes are time consuming, expensive, and difficult to estimate due to spatiotemporal variability. Pasture areas where livestock utilisation or grassland biomass is exceptionally high or low could be mapped within a topographic framework. A model was developed that integrates several data sources (elevation, spectra and field data) to estimate hill-country biomass. Topographic data were modelled and used to classify biomass, which ranged from low at summits (1493 kg/ha) to high at toe-slopes (2876 kg/ha). These estimates were compared with the current plant height-based model, which ranged from low (2014 kg/ ha) to high (3032 kg/ha). This paper demonstrates how expansive, heterogeneous grassland landscapes can be assessed seasonally using topographic markers within an integrated spatial data framework. Keywords: Remote sensing, DEM, structure, Landsat 8, forage utilisation, graziers