Sweet clover aids native species in a stressful environment
Melilotus officinalis, a nitrogen-fixing legume, widely planted by livestock producers and bee keepers has been shown to form both positive and negative relationships with native plant species depending on the surrounding environmental conditions. A consistently strong and positive relationship exists between Melilotus cover and native species cover in a semi-arid habitat (Badlands sparse vegetation) while in a less ‘stressed’ mesic environment (western wheatgrass prairie) Melilotus competes weakly with native species.
These results are consistent with the predictions of the stress-gradient hypothesis (Bertness and Callaway, 1994). The mechanism through which positive relationships form in Badlands sparse vegetation is likely to be habitat amelioration, possibly nitrogen enrichment of soil or protection from dessication, wind or erosion. More studies will need to be done in order to confirm this.
This economically valuable plant also forms positive relationships with other non-native species in Badlands sparse vegetation posing a potential conservation dilemma. The authors suggest that management should focus on control of the non-native species positively affected by Melilotus.
References: Van Riper, L., & Larson, D. (2008). Role of invasive Melilotus officinalis in two native plant communities Plant Ecology, 200 (1), 129-139 DOI: 10.1007/s11258-008-9438-6
Bertness, M., & Callaway, R. (1994). Positive interactions in communities Trends in Ecology & Evolution, 9 (5), 191-193 DOI: 10.1016/0169-5347(94)90088-4




