ENVS469 Lecture Notes - Lecture 6: Nitrogen Cycle, Nitrification, Dundas Valley Conservation Area
25 Feb 2020
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Week 5 part ii_grassland ecology and restoration (herbivores and fire disturbance in restoration) Increases biomass and diversity of forbs; decreases biomass of grass: bison deposition of feces & urine. Initially, toxic waste of carcass kills vegetation, but after, highly fertile early successional species re-establish: *difference w/ cattle because cattle don"t wallow and no carcasses remain on the landscape, and diet is higher in forbs. Burns patches of high biomass: decreasing effect cool-season grass (spring) Creates spatial variation in biomass & species distribution. Dynamic mosaic of high/low biomass, grass/forb dominance: high species diversity. ^ red = high biomass; blue = low biomass. Burn area: often only 70-90% under natural conditions. In some areas, 50% alternating to ensure continuous habitat. Survival: plants: growth points underground, animals: flight or seek shelter on-site. Optimal burn conditions: low humidity, proper winds (enough to carry the wind but not so much that it"s uncontrolled), and enough biomass to sustain the fire.
