|Schuler, T - USDA FOREST SERVICE|
|Harmon, P - DIV NATURAL RESOURCES|
Submitted to: Journal of Plant Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: May 15, 2001
Publication Date: March 4, 2002
Citation: Morris, D.R., Baligar, V.C., Schuler, T.M., Harmon, P.J. 2002. Biological nitrogen fixation and habitat of running buffalo clover. Journal of Plant Nutrition. 25:735-746. Interpretive Summary: Running buffalo clover is a protected and endangered leguminous plant species native to the eastern U.S. Part of the U.S. Fish and Wildlife recovery plan for running buffalo clover calls for locating Rhizobium bacteria (if any) that are capable of fixing nitrogen in the plant, determining competitive interactions between running buffalo clover and weedy associations, and determining nutrient limitations to running buffalo clover growth. An experiment was set up to address these three issues. Plants were labelled with isotopic N-15, harvested, and tissues were analyzed to try to detect N fixation in the plant. Soil samples were taken to assess nutrient status. Plant roots infected with Rhizobium could not be identified because there appeared to be a lack of biological N fixation in this species. Plant most closely associated with running buffalo clover were nettle and deer tongue. Nutrient limitation under mountainous settings appear to be P and Mg and possibly lime.
Technical Abstract: Running buffalo clover (RBC) (Trifolium stoloniferum (Muhl. ex Eat.)) is an endangered species whose survival is uncertain. An experiment was conducted on extant RBC sites to investigate biological N2 fixation, associated plant species, and soil conditions under natural mountain settings. Isotope (N15) dilution technique was used to calculate quantities of N fixation. Associated plant species were identified, and their dry matter contributions to the total system were assessed. Nitrogen fixation did not appear to contribute a significant portion of the plant N demand. Close cutting (3-cm height) did not seriously damage RBC stands, and RBC constituted between 11 and 44 % of the stand throughout the sampling period. Clover forage quality was adequate for grazing animals with around 15 % protein. Of the 37 different plant species identified in experimental plots, nettle (Urtica dioica L.) and deer tongue (Panicum clandestinum L.) were most closely associated with RBC based on significant correlation coefficients (r=0.90 and 0.83, respectively). Native RBC was growing in relatively fertile soil. However, P and Mg may be limiting growth. It appears that RBC is a non-N fixing legume whose cutting management may be similar to other forage clovers.