Spatial legume composition and diversity across seeded landscapes

Pastures typically have diverse landscapes, and resulting soil conditions a nd plant composition can vary within small area units. This study was perfo rmed to quantify the spatial variation in legume contribution to the plant community when seeded into established perennial cool-season grass pastures . Pastures were interseeded with an 11-legume mixture and divided into thre e stocking methods (continuous, rotational, and nongrazed), with each stock ing method containing five landscape positions (summit, backslope, toeslope , opposite backslope, and opposite summit). Grass and legume components wer e sampled three times annually between 1996 and 1998. Backslopes had greate r legume dry matter (DM) composition (161 g kg(-1)) than either summit (62 g kg(-1)) or toeslope positions (7 g kg(-1)), and total legume concentratio ns increased over years. Legume composition consisted mostly of red clover (Trifolium pratense L.), birdsfoot trefoil (Lotus corniculatus L.), and whi te clover (T. repens L.). Species richness and Shannon-Weiner diversity ind ex (H'(dm)) for the legume functional group were also greatest on backslope landscape positions, especially in continuously and rotationally stocked p astures. Legume DM composition showed a positive linear relationship with l egume species richness in continuous, rotational, and nongrazed pastures (r (2) = 0.76). The H'(dm) showed a positive linear relationship with legume D M composition in only rotationally stocked paddocks (r(2) = 0.88). The legu me component at grazed backslope sites filled a niche left unoccupied by th e grass component. Species and site recommendations for pasture improvement and management should be made based on landscape position and stocking met hod.