7. Populations can be Harvested Sustainably Flashcards
Can we harvest populations without negatively affecting their population size?
Yes, it is done often and has been forever - gardening and hunting require harvest
Why do we harvest from nature?
our wealth comes from nature, we use it to make:
- food
- shelter
- clothing
- drugs
Explain an example that rationalizes sustainable harvest
the exponential growth model and its bank account analogy
the more money in an account the more you’ll make from interest (because it is dependent on the money in the account) - sustainable harvest is when the ‘interest’ is harvested, but not the capital (initial investment into the account)
What is sustainable harvest?
taking the ‘interest’ and not the ‘capital’
How to sustainably harvest an exponentially growing population (J-curve)
harvest the ‘interest’ (or anything less than it) alone
Explain the population growth of an S-curve graph
the more slope the more growth, it typically occurs in the middle of the “s”
the growth rate slows as it approaches K (carrying capacity), at carrying capacity there is no growth
How can a logistically growing population (S-curve) be harvested without an effect to its population size?
there is no harvest without effect at carrying capacity (births already equal deaths), so harvest would lower the ‘capital’
What happens to a population if you harvest it at carrying capacity?
the population responds to less competition = more offspring per female, lower mortality rate, faster individual growth rate
through the necessitated population growth, it creates a sustainable harvest (kinda)
SO! What is the best way to harvest a logistically growing population?
take anything less than or equal to the maximum sustainable yield (MSY = half of K)
to generate ‘interest’ you have to decrease the capital, and then don’t touch it (aka creating a DIY exponential growth model)
What is population sustainability?
applicable to the logistic growth model, the idea of creating a DIY exponential growth model harvest, never allowing a population to dip under its maximum sustainable yield
(decreasing the ‘capital’ to generate ‘interest’, and then only harvesting the DIY interest and never touching the capital)
for the exponential growth model, it’s only taking the ‘interest’
What isn’t always accounted for in population sustainability / harvesting logistically growing populations?
the environment also affects the growth of populations and thus the MSY, it won’t be the same no matter what and should be accounted for if taking exactly or close to the NOT-nuanced MSY
How do Indigenous peoples determine sustainable harvest?
traditional, ecological knowledge that includes the fluctuations that occur in populations
called “honourable harvest”, never taking more than half, leaving some for others, generally harvesting in a way that minimizes harm
What type of definition of sustainability is this lecture?
the first ecological definition of sustainability
