Succession and Wildfires
Describe what ecological succession means in your own words
Change in species composition in an area over time.
What is a trophic level?
The feeding position of an organism within a food chain.
Herbivores don't overgraze vegetation because predators keep their populations in check.
What was the importance of the book Silent Spring?
Increased awareness of DDT, helped launch environmental movement that led to created of EPA and regulation on pesticides.
What is the difference between primary and secondary succession
Primary starts with no soil, secondary already has soil at earliest stage
What does the 10% rule says about how energy and biomass move through a food chain?
90% of energy/biomass is used by organisms at each trophic level and lost as heat. Only 10% moves on to next level.
Where on a food web might you find a keystone species? Why?
On the top (apex predators). Due to 10% rule, there is much less abundance and diversity of top predators relative to vegetation.
What is one benefit of wildfire on an ecosystem?
What are some of the environmental impacts of animal agriculture?
Methane emissions (enteric fermentation), land use for pasture and growing feed, eutrophication and pesticides from feed production, deforestation
The elk started brazenly grazing willows and aspen faster than they could regenerate. Led to loss of beavers and change in river's flow.
Give 1 example of a human health effect of pesticides and 1 examples of an environmental harm.
eg. Non-hodgkin lymphoma and damages gut microbiome / colony collapse disorder in bees.
In what way does succession help us understand the environmental impact of industrialized monoculture?
It tries to force land to remail in early stages, requires large work/fuel input
How could silvopasture help reduce the environmental impact of raising livestock?
Turns pasture into semi-forested area --> carbon retention and habitat, reduces need for supplemental feeding
What is rotational grazing and why is it beneficial?
Moving grazing livestock between paddocks frequently. Allows the vegetations a chance to regenerate between grazings. Also manages parasite loads.
What kinds of toxins tend to be bioaccumulated most easily?
Fat soluble
What are the four stages of the Milpa Cycle?
1. Burn forest to grow annuals (corn, beans, etc..)
2. Young orchard with annuals growing under small trees.
3. Mature orchard
4. Forest regeneration
If I eat 3kg of potatoes and 2kg of pork and my friend eats 1kg of potatoes and 4kg of pork, how much land does it take to produce each of our meals?
Mine- 23ft2
Friend's- 41ft2
How does rotational grazing mimic the role of a keystone species like wolves in nature?
Because you are keeping the herbivores moving so they don't overgraze the vegetation.
What types of organisms tend to have the highest levels of bioaccumulated toxins and WHY?
Top trophic levels because of the 10% rule. Most of the biomass/energy they consume passes through their bodies, but the toxins stay behind and build up.