Only with long-term data sets will the parks be able to determine changes in amphibian numbers that are caused by either natural factors or human-related stresses, such as climate change, habitat alteration, exotic species, UV radiation, and contaminants.
(the parks; to determine; changes in amphibian numbers) (amphibian numbers; are caused; by either natural factors or human-related stresses, such as climate change, habitat alteration, exotic species, UV radiation, and contaminants)
the parks amphibian numbers
to determine are caused
changes in amphibian numbers
by either natural factors or human-related stresses, such as climate change, habitat alteration, exotic species, UV radiation, and contaminants