SIMULATION OF SALMONBERRY AND THIMBLEBERRY POPULATION ESTABLISHMENT AND GROWTH

A salmonberry (Rubus spectabilis Pursh) and thimbleberry (Rubus parvif lorus Nutt.) population simulation model was developed and compared wi th field observations for verification and validation. The species-spe cific influence of different phenological stages (early spring bud bre ak, early summer fruit set, and fall senescence), different environmen ts (at different sites), and intraspecific density on demographic proc esses was incorporated into the model. The model predicts the number o f individuals in different life-history stages at three phenological s tages during a growing season. Simulations were most accurate when com pared with low genet density planted populations. Salmonberry populati ons on a moist site were most accurately simulated. Thimbleberry simul ation accuracy was reduced by poor prediction of sprout densities. Sal monberry and thimbleberry population response to an application of gly phosate was simulated and compared with observed canopy cover for 3 ye ars following application. The simulated response was accurate for the 1st year following application, but did not account for continued can opy cover in the observed populations. Salmonberry canopy cover and me an ramet height in response to manual cutting at three phenological st ages was also simulated. The model simulations indicated that the most prolonged reduction in salmonberry cover followed cutting at the repr oductive stage of growth.