premise: cutting down trees has a negative impact on an ecosystem / organisms living in an ecosystem sent2: an animal is a kind of organism sent3: organisms are a part of an environment sent4: surface mining has a negative impact on the lithosphere / the biosphere / the ecosystem sent5: national parks limit mining / logging / hunting sent6: killing means harming something causing death sent7: logging is when humans cut down trees / forests for wood sent8: harming an animal species has a negative impact on the population size of that species sent9: ecosystem can mean environment.
hypothesis: scientists have to meausre the amount of precipitation