|Title||Manipulation of soil resource heterogeneity in a tallgrass prairie restoration|
|Publication Type||Conference Proceedings|
|Year of Publication||1999|
|Authors||Baer, SG, Blair, JM, Knapp, AK|
|Publisher||University of Nebraska at Kearney|
|Conference Location||Kearney, NE|
|Keywords||altered plant rooting depth, altered soil nutrient availability, Great Plains, limestone barriers, recalcitrant C, soil template, Species diversity|
Plant species diversity in native prairie ecosystems is influenced by heterogeneity of soil resources, which results from interactions among plant communities, soil properties, topography, and disturbance. Key factors which promote plant diversity in native prairie include soil moisture, rooting depth, and nutrient availability. Most prairie restorations in the Great Plains occur on former agricultural land and the soil template for these restorations has been physically homogenized through tillage practices. The reduction in soil resource heterogeneity in restored prairies may be causally related to low plant species diversity commonly encountered in these sites. To examine the role of soil heterogeneity in restoring prairie ecosystems, replicated blocks (n=4) of 4 plots consisting of different levels of soil heterogeneity were established in an agricultural field. The 4 plot types included: control (least heterogeneous with respect to soil resources), altered plant rooting depth, altered nutrient availability, and combined variation in plant rooting depth and nutrient availability (maximum heterogeneity). Plant rooting depth was varied by burying limestone barriers at 25 cm to create alternating strips of deep and shallow soil. Variation in soil nutrient (inorganic N) availability was established via increased N (+fertilizer), decreased N (+ recalcitrant C), and no change in N. All plots were seeded with the dominant native grasses and >30 forb species. Incorporation of recalcitrant C reduced total inorganic N availability 90% as a result of 98% reduction in available nitrate. Plots containing strips of low N availability exhibited significantly (p < 0.05) greater spatial variability than plots without this manipulation. Thus, the experimental design and methods implemented have increased heterogeneity of soil nutrients, and this will enable us to address the role of variation in soil resources on restoring tallgrass prairie.