Seed Study - Challenges
Some of the factors that make revegetation in the northern Great Plains and in national parks challenging include persistent drought and wildlife. Rainfall measured at the study plots during the 2005 growing season (May-September) was 33.6 cm (13.2 inches), which was a large improvement over 2004, when the seed was being collected. Dry conditions in 2004 (10.9 cm, or 4.3 inches below normal for the whole year) made plants unreliable about producing seed or caused them to set seed later than they normally would. The 2005 moisture tended to come in large amounts all at once with long periods in between of hot, dry, windy weather. During the dry periods, the plots were hand-watered in an effort to avoid desiccation of the seedlings. This effort added an additional 6.4 cm (2.5 inches) of water. The 2006 growing season precipitation of 17.6 cm (6.9 inches) was well below the normal of 29.2 cm (11.5 inches), making life hard for new seedlings and those that had sprouted the previous year.
Wildlife species that affect seeded areas include deer, elk, bison, and rabbits. The bison are particularly troublesome because they not only eat the vegetation, but their footprints and wallows wipe out many seedlings. Browse use on shrub species in fall/winter of 2005 was moderate to heavy, particularly on prairie rose (Rosa arkansana). The local rabbits in the plot area were so used to people that they contentedly grazed on the vegetation under the benches we used while collecting data.