Survival of bristly locust (Robinia hispida L.) in an emulated organic silvopasture

Authors: Burner, David; Burke, Joan

Submitted to: Native Plants Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/24/2012
Publication Date: 10/1/2012
Citation: Burner, D.M., Burke, J.M. 2012. Survival of bristly locust (Robinia hispida L.) in an emulated organic silvopasture. Native Plant Journal. 13(3):195-200.

Interpretive Summary: Very little agricultural research has been conducted on bristly locust, a widely adapted, short-statured, native tree species that lacks the offensive thorns of some related species. As a first step in assessing its grazing potential, researchers at ARS-Booneville conducted a study to determine if bristly locust trees could be successfully transplanted in a pasture with only minimal weed suppression. Results showed that bristly locust established well despite considerable competition from bermudagrass and sericea lespedeza. Planting up to three trees/plot improved survival, but not shoot production or spread at 2 years post-planting. Goats at a low stocking rate were introduced to the bristly locust stand 2 years after planting, and were observed to browse the trees. Since organic practices usually require that tree seedlings are established without herbicides to control weeds, results will benefit small-scale, organic livestock producers who cannot absorb either the costs of chemical weed control or temporary loss of the land base for pasture renovation. More research is needed on the feed value, grazing management, and animal weight gains for pastures with bristly locust.

Technical Abstract: Bristly locust (Robinia hispida L.), a native tree legume which has received relatively little scientific attention from an agronomic perspective, could have value as livestock browse. The objective of this research was to assess transplant survival of bristly locust in an experimental silvopasture. Trees were mechanically transplanted from a natural, putatively clonal stand into a warm season grass-legume sward, emulating methods that might be used by a small-scale organic livestock producer. Budburst occurred during a short time interval, and was complete for nearly all trees by early April. Most trees had either flower buds or emerged flowers by the end of April, but seeds were not observed on any of the trees. Number of live shoots plot-1 at 5 months and 1 year post-planting was about half that at 0 months. Extensive shoot proliferation occurred at 2 years, when trees had more than twice the live shoots as at 0 months (mean of 5.3 shoots plot-1, range 0 to 26 shoots plot-1). Mean radial spread of rhizomes at 2 years was 1.4 m (range 0.5 to 2.4 m). Bristly locust was well suited for organic livestock browse because of good survival and shoot proliferation in competition with existing herbaceous vegetation. Further research is needed, however, on its nutritive value, presence/absence of anti-nutritional factors, anthelmintic properties, and grazing management.