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Submitted to: Soil Ecology Meeting Abstracts
Publication Type: Abstract Only Publication Acceptance Date: 6/8/2017 Publication Date: N/A Citation: N/A Interpretive Summary: Soil properties are thought to affect rangeland ecosystem functioning (e.g. primary productivity, hydrology), and thus soil variables that are consistently correlated with key ecosystem functions may be general indicators of rangeland health. We summarize results from several studies in mixed-grass prairie of the Northern Great Plains. We tested many would-be predictor variables of local variation in peak aboveground grassland biomass and water infiltration. Individual properties explained a moderate amount of variation in plant biomass (=18%) and infiltration (=15%). For example, plant biomass was positively correlated with field-saturated infiltration, subsurface microbial biomass, and some plant available nutrients (boron, manganese, and phosphorus). Plant biomass was negatively associated with two soil properties, subsurface soil carbonate concentration and the stability of soil macroaggregates near the soil surface. In calcareous grasslands, soil carbonate levels are important because they are likely inversely related to soil depth and availability of some limiting nutrients (e.g. plant available phosphorus). Many popular indicators of soil and rangeland health, such as soil organic carbon, organic matter, and water-stable aggregates, were found to be poor predictors. For example, water infiltration was unrelated to aggregate stability but was related to plant biomass. We hypothesize that other plant and soil properties (i.e. litter and bare ground cover) explain greater amounts of variation in infiltration. While protection of soil is critical to overall rangeland ecosystem functioning, our findings suggest that the relationship between soil properties and plant biomass (or infiltration) in natural grasslands is complex. A major challenge is to uncover indicator variables that consistently explain appreciable variation in peak grassland biomass, especially variation within an ecosystem independent of precipitation. Technical Abstract: Soil properties are thought to affect rangeland ecosystem functioning (e.g. primary productivity, hydrology), and thus soil variables that are consistently correlated with key ecosystem functions may be general indicators of rangeland health. We summarize results from several studies in mixed-grass prairie of the Northern Great Plains. We tested many would-be predictor variables of local variation in peak aboveground grassland biomass and water infiltration. Individual properties explained a moderate amount of variation in plant biomass (=18%) and infiltration (=15%). For example, plant biomass was positively correlated with field-saturated infiltration, subsurface microbial biomass, and some plant available nutrients (boron, manganese, and phosphorus). Plant biomass was negatively associated with two soil properties, subsurface soil carbonate concentration and the stability of soil macroaggregates near the soil surface. In calcareous grasslands, soil carbonate levels are important because they are likely inversely related to soil depth and availability of some limiting nutrients (e.g. plant available phosphorus). Many popular indicators of soil and rangeland health, such as soil organic carbon, organic matter, and water-stable aggregates, were found to be poor predictors. For example, water infiltration was unrelated to aggregate stability but was related to plant biomass. We hypothesize that other plant and soil properties (i.e. litter and bare ground cover) explain greater amounts of variation in infiltration. While protection of soil is critical to overall rangeland ecosystem functioning, our findings suggest that the relationship between soil properties and plant biomass (or infiltration) in natural grasslands is complex. A major challenge is to uncover indicator variables that consistently explain appreciable variation in peak grassland biomass, especially variation within an ecosystem independent of precipitation. |
