Monday, August 2, 2010 - 4:20 PM

COS 2-9: Long-term effects of climate change on grassland soil systems: A reciprocal transplant approach

Steven C. Rostkowski Jr., J.M. Blair, C.W. Rice, and T.M. Todd. Kansas State University


Altered precipitation patterns are predicted to accompany climate change and are likely to impact grassland soil communities and nutrient cycling processes, which are dependant to a large extent soil water content. While short-term responses of soil communities and nutrient cycling to changes in precipitation amounts and soil water availability have been documented, very few studies have examined the long-term effects of these changes.  A long-term reciprocal transplant experiment, initiated in 1993, provides a unique opportunity to address the long term response of soil communities (e.g. microbes, macroinvertebrates, and microarthropods) and nutrient cycling due to altered precipitation amounts. In 1993, large (25cm x 70cm), intact soil cores and associated plants were reciprocally transplanted between a mesic tallgrass site (Konza Prairie Biological Station) and a more arid mixed-grass site (Kansas State University Agricultural Research Center at Hays) in a randomized block design. For the present analyses, both “native” and “transplanted” cores incubated at each site for 16 years were extracted in May 2009, along with additional cores from the surrounding areas for comparison.


After analyzing nutrient pools and soil communities, we found soil cores being more affected by incubation site rather than soil type.  Results on root biomass, microbial biomass, nematode densities, and macroinvertebrate densities showed significantly higher values in soil incubated at the more mesic Konza site, relative to the Hays site.  More specifically, we noticed the transplantation of Konza soil to the more arid Hays site resulted in a reduction of microbial biomass by ~30%, root biomass by ~30%, and  nematode densities by ~75%.  In addition, preliminary analyses on soil microarthropod densities indicate a similar trend.  These results confirm the importance of long-term effects of altered soil water content on soil communities and nutrient pools, and suggest complex, potential responses to Global Climate Change.