Conserve means to prevent lost of something.
Natural Resources are raw materials such as coals, oil, fossil fuels, rock and mineral resources,etc.
So they want you to prevent lost of coals, fossil fuels, oil, rock and mineral resources,etc. In other words, is to save the world...
depends on what you mean by "back then".
conserve
Many governments around the world conserve their natural resources by
one way is to conserve resources is to reduce the amounts that are used
because misuse fof natural resources as well as its important to conserve water , forest etc for our next generation.
deforestation
water,paper,plant
Recycle.
the imperialism and anti imperialsim.
To keep your inviorment safe.
recycling cardboard boxes
Many natural resources are finite or limited. If they are not conserved and continue to be wasted as they are now, they will eventually run out.