Fear and Leaching in Michigan or, Dude, where’s my nutrients?

Fear and Leaching in Michiganor,Dude, where’s my nutrients? Emily Farrer, Joshua Haag, Joel Perkovich , Katherine Windfeldt

Introduction • Properties of Soil • Physical • Chemical • Biological • Synthesis of Lab and Field Data • The Development of a Northern Oak Ecosystem

Physical Properties of Soil • Texture • Sand • H20 Holding Capacity • 0.12 cm3 H2O/cm3 Soil • Lowest of all sites • Bulk Density • 1.1 g/cm3 • 2nd Lowest behind NH

Chemical Analyses CEC -Lowest CEC of all sites at 2.2 cmolc/kg (other sites range 3.86-8.71 cmolc/kg) - Thus, smallest nutrient holding capacity of all soils Base Saturation - Lowest BS of all sites at just 13% (other sites range from 97-99%) pH - Most acidic of all sites at 4.21 (Mixed Oak highest pH at 5.97)

Soil Biological Properties

Ecosystem Biological Properties • Low ecosystem biomass and N compared to other forests • Aboveground and forest floor second lowest (OH lowest) • Soil biomass and N pools lowest

Northern Oak Physiography Structure / Texture - Well-sorted, sandy PM from former lake bed = larger particle size, weak structure and sandy texture Bulk Density (Db) - Well-sorted (homogenous), loosely packed soil results in second lowest Db ` at 1.1 gm/cm3(other sites range 1.02-1.34) CEC / Base Saturation - Lowest CEC at 2.2 cmolc/kg 90% sand and 3% clay = weak electronegative charge for CEC - Lowest BS at 13% Role of topography / fire and well-drained sandy PM = nutrient loss Available Water Content - Lowest AWC at 0.12 cm3 H20/cm3 soil (other sites range 0.14-0.44) - well-drained sandy PM, lower elevation and southern aspect = H20 loss pH - Most acidic at 4.21, Non-calcareous PM offers no buffer for soil acidification via weathering

Soil: Field and Lab Profile Sandy and acidic throughout Lab data supported Little structure Low OM Moderately shallow, weak profile Well-drained – weathering Low OM, no humus accum. O horizon thin A shallow Low biomass in forest floor and soil E weak Bs weak C sand

SOM rules! Structure Color SOM Water holding capacity CEC (& anion EC) Base Saturation pH Microbial biomass Microbial respiration N mineralization NPP

Vegetation History • 1880’s white pine logged, big burn • Natural fire regime until 1930 when human fire suppression began Composition • Overstory • black oak, white oak, red oak, red maple • Understory / Ground Cover • white pine, red maple, sassafras, blueberry, wintergreen, Pensylvania sedge

Vegetation Low Biomass - 224 Mg/ha • Lowest AWC 0.12 cm3 H2O/cm3 soil • Lowest Nutrient Availability • Nitrogen content of 1584 kg/ha • CEC of 2.2 cmol/kg • BS of 0.13 Species Composition – Dry/Acidic • Lowest AWC 0.12 cm3 H2O/cm3 soil • Lowest Nutrient Availability • Lowest pH of 4.21 • Fire regime Perpetuation of system • Fire regime/Dry site • Oak species

Nutrients CEC The Development of a Northern Oak Ecosystem • Young soil • Limited weathering • Low CEC (and non-calcareous parent material) • Well drained (low FC and AWC) -> Loss of nutrients by leaching

SOM Nutrients CEC Soil Development and Ecosystem Feedbacks • Few nutrients -> low biomass • Low biomass -> little SOM • Little SOM -> Low CEC • Loss of nutrients by leaching

Nutrients Nutrients CEC Soil Development and Ecosystem Feedbacks • Physiographic and topographic characteristics -> prone to fire • Loss of nutrients by burning and leaching

Summary: • Young, relatively unweathered soil • Susceptible to leaching • Loss of nutrients • Low productivity and biomass • Low SOM and CEC • Susceptible to fire • Loss of nutrients • Low productivity and biomass • Low SOM and CEC • Positive feedbacks maintain low biomass

Fear and Leaching in Michigan or, Dude, where’s my nutrients?