Effect of Fire and Grazing on Invasive Species in Northern Mixed Grass Prairie. Final Report

摘要

Invasive plants pose a threat to pristine and natural mixed grass prairie so managers seek to control them. On the basis of experience in the tall grass prairie, some hypothesize that they may be controlled with fire and grazing. The fact that the invaders are cool season species in a cool season prairie, rather than cool season species in a warm season matrix, reduces the possibility of selectively treating them- - and casts doubt on the applicability of these tools in mixed grass prairie. Long-term management experiments at Lostwood and Des Lacs National Wildlife Refuges (NWR) provide a near ideal opportunity to test these hypotheses. The replicated factorial experiment includes six burning treatments (0-6 burns) crossed with two grazing (grazed and ungrazed) treatments. By subsampling each unit, one can estimate the local (bottom, N-slope, S-slope, and hilltop) and regional (North Dakota vs. Montana) effects of water availability. We field-sampled units to compare the spread of nine species - - i.e., the long distance dispersal (frequency) and clonal spread (cover) - - among these treatments. Responses to various aspects of fire and grazing were measured with multiple regression.