Historically resource managers focused on individual species, with three goals:

1. recover species that were over-exploited
2. control/eradicate "over abundant" and economically-harmful species;
3. manage species for a sustainable harvest.

Modern management still includes some focus on individual species, but also on communities and habitat/landscapes. We’ll examine these three approaches this week.

Mostly focused on declining species

Proximate factors: the immediate, direct cause: e.g., low birthrate

Ultimate factor: the fundamental cause: e.g., pollution that caused lower birth rates.

It is the ultimate factor that you need to fix, or in most cases you’re just delaying the inevitable decline.

Extinctions:

Deterministic forces: ultimate factors that are generally predictable and the result for species inevitable.

Stochastic forces: random events, catastrophes and rare phenomena that finish off the population.

Ways of analyzing populations to assess the minimum needed to avoid stochastic extinction.

PVA: Modeling to estimate extinction risk and indicator parameters like Ne.

MVP: the smallest spatially discrete population having a certain probability (e.g., 99%) of not going extinct ("remaining extant") over as period of time (100 or 1000 years).

Age at breeding

Life span

Genetic diversity

Probability, type, and intensity and extent of catastrophic events

Experimental: isolate populations and analyze them thru time.

e.g., Amazon forest patches

Observational Approach: monitor spatially discrete populations of different sizes over time.

e.g., Bighorn sheep populations in the American West.