D
discount rate the annual rate at which future benefits or costs are discounted relative to current benefits or costs.

dynamic equilibrium a market equilibrium that results when present and future costs and benefits are considered.

H
Hotelling's rule a theory stating that in equilibrium the net price (price minus production costs) of a resource must rise at a rate equal to the rate of interest.

M
marginal net benefit the net benefit of the consumption or production of an additional unit of a resource; equal to marginal benefit minus marginal cost.

N
net price (of a resource) the price of a resource minus production costs.

nonrenewable resources resources available in fixed supply, such as metal ores and oil.

O
optimal depletion rate the depletion rate for a natural resource that maximizes the resource’s net present value.

P
present value the current value of a stream of future costs and/or benefits, calculated through the use of a discount rate.

R
renewable resource(s) resources supplied on a continuing basis by ecosystems; renewable resources such as forests and fisheries can be depleted through exploitation.

resource depletion tax a tax imposed on the extraction or sale of a natural resource.

S
social cost the market and nonmarket costs associated with a good or service.

static equilibrium a market equilibrium that results when only present costs and benefits are considered.

supply constraint an upper limit on supply of, for example, a nonrenewable resource.

T
total net benefit total benefit minus total cost.

U
user cost(s) opportunity costs associated with the loss of future potential uses of a resource, resulting from consumption of the resource in the present.