Influence of nitrogen on antelope bitterbrush seedling establishment.

Abstract

Nitrogen enrichment, immobilization, or inhibition of nitrification were used to investigate the influence of available nitrogen on the seedling recruitment of antelope bitterbrush (Purshia tridentata [Pursh] DC) and annual grass competition. The influence of nitrogen enrichment on antelope bitterbrush seedling recruitment depended on the form of nitrogen applied. Ammonium sulfate applications markedly enhanced growth of herbaceous annuals resulting in the loss of all antelope bitterbrush seedlings the first growing season. Enrichment with calcium nitrate marginally enhanced growth of herbaceous annuals and enhanced the growth of antelope bitterbrush seedlings. Immobilization of nitrogen with carbon (sucrose) applications suppressed the growth of herbaceous annuals and produced large, vigorous antelope bitterbrush seedlings. Similar results were obtained by inhibiting nitrification with applications of nitrapyrin or combining nitrapyrin and carbon applications.