Cedar Afforestation of Prairie Alters Soil Properties On a Decadal Time Scale.

Eastern red cedar (Juniperus virginiana) encroachment on native grassland can rapidly transform the vegetation and ecosystem, but the resulting effect on soil properties including hydrology, mineralogy, microbiology and chemistry is not well understood.  This study examined soil properties at five sites in tallgrass prairie within the Bluestem Hills Major Land Resource Area.  Two trees were selected per site.  Soil sampling was done under the tree canopy, at the dripline, and in native grass along a transect at each tree.  Vertical profile descriptions of morphology, genesis, and taxonomy were documented, and bulk density values were determined for each pedon.  Laboratory characterization data was determined for each genetic horizon, along with wet aggregate stability.  Dendrochronological investigations yielded a tree age range of 17 to 56 years, with a mean of 35 years.  Analyses indicated an increase in base cations and pH in the surface horizon of soils under the Juniperus canopy relative to the dripline and prairie soils sampling positions.  Although not statistically significant, granular structure at the surface was thinner under the tree canopy and the argillic subsurface horizon was shallower.  These are important characteristics for soil formation and therefore, changes in these properties are rather significant because of their rapidity.  Field and laboratory characterization indicated that soils under eastern red cedar vegetation still retain many properties of the prairie derived soil, however some properties related to soil genesis may be more dynamic and can be influenced on a decadal time scale.