Establishing Bristly Locust (Robinia hispida) in an Emulated Organic Silvopasture.

Bristly locust is a native tree legume with an extensive range throughout much of the eastern US and Canada. Bristly locust is < 3 m tall, produces pink flowers, and the branches, petioles, flower stalks, and fruits are covered by soft, inoffensive bristles. Little agronomic research has been conducted on the species, but it might have value as livestock browse. Our objective was to assess its transplant survival in an emulated organic goat silvopasture. The shallow rooted trees were mechanically transplanted from a putatively clonal, natural source area into a warm season grass-legume bermudagrass-sericea lespedeza sward. Due to varying stocking rate in the source area stand and mechanical planting, each of the 237 plots contained a varying number of trees (1 to 4 trees plot^-1, mean = 1.9 + 0.06 trees plot^-1). Planting stock had mean topped height of 0.77 + 0.26 m, and mean basal stem diameter of 22.8 + 16.1 mm. Number of live trees plot^-1 at 5 months and 1 year post-planting (1.3 trees plot^-1 on each date) was about half that at planting (2.5 trees plot^-1). However, extensive shoot proliferation occurred at 2 years, when there was more than twice the live shoots as at planting (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 herbage. Mature Spanish meat goats readily browsed bristly locust during a brief, 7 d, grazing period. Goats on such silvopastures would likely control spread and risk of accidental escape by browsing the tender, recently emerged shoots. Further research is needed on nutritive value, presence/absence of anti-nutritional factors, anthelmintic properties, and grazing management.