It is quite unfortunate the meaning of the word "conservation" gets lost in the politics surrounding it.
Conservation, from a physics and engineering standpoint is best understood in terms of the physical laws you likely don’t remember learning about in high-school. Specifically, I am referring to the law of conservation of mass-energy, which states (somewhat simplified) that for a closed system the amount of mass and energy remains constant.
In other words, if I had a completely sealed, perfectly insulated box full of 5 pounds of Hydrogen and Oxygen, and then combined them to form water, I would have exactly 5 pounds of water. No additional mass would be created (The fellow in the image on the left is Antoine Lavoisier. He performed essentially that experiment) .
Or let’s say the sealed, insulated box contains nothing other than a hamster wheel, spinning a certain number of revolutions per second. Now, if there is no friction, then the hamster wheel will spin indefinitely (another conservation law – conservation of momentum is at play). The hamster wheel in this case has mass, and kinetic (or motion) energy. If there is friction, then it will slow down, as the kinetic energy from the spinning wheel is converted to heat energy. The temperature in the box will rise, and when the wheel stops, there will be an amount of heat energy equal to the amount of kinetic energy the wheel had at the beginning. Motion energy was converted to heat energy - Conservation.
Consider the earth then. Where mass is concerned, Earth is very nearly a closed system. Sure, we get the occasional bit of mass added in the form of a meteor, or similar space object, and we shoot small amounts of mass from earth to space in the form of rockets and satellites. But relative to the size of the earth, those little bits in and out are miniscule.
Earth is not a closed system with respect to energy. We absorb energy from the Sun. We release heat into space. The gravitational pull of the sun and the moon on the ocean (tides) also adds energy.
Are you glazed over and drooling in your lap yet? The worst is over (maybe). Here on earth, everything else that happens is within that context. We humans don’t really create stuff, (or destroy stuff). We simply convert stuff. Take a tree. Add a little labor to chop it up, and you get lumber. Grind it to itty-bitty pieces, and it is sawdust. Grind it up further, mix with water, flatten and dry and the tree becomes a piece of paper. That is all we do really; utilize stuff and energy to make different stuff.
So real conservation is at its root, about maintaining a… a balanced budget, if you will. It is about making sure we aren’t using more energy than we can practically create, and that we aren’t converting the mass from something useful to something useless faster than we can convert the useless mass back to useful mass.
A true conservationist is concerned about the use of fossil fuel, because it took an incredibly long time to make that fuel, we simply cannot create it as fast as we can consume it. Nuclear power carries a similar concern. There is a limited amount of radioactive material on the planet, and the energy creation process converts it to a material we don’t have a practical use for, which will remain potentially un-useful for thousands or even tens of thousands of years. It would probably be a good idea to get away from using such things as consumables, and focus their use on longer term outputs (for example, oil can be used for manufacturing plastics. Not the disposable stuff - trash bag and such - but things with longevity, like fencing, or siding for houses). And when it comes to energy, we should probably focus our attention on sources which are rapidly renewable (solar, wind, wave, geothermal, hydrogen...).
Of course, there are more complicated considerations. Consider coffee, as an example. In the past 20 years, coffee growers have selectively bred coffee plants which can grow well in full sun. This has allowed them to remove the forestation which used to provide protection for the coffee plants (which naturally preferred shade), allowing them to increase production levels. This is an economically desirable move, as it allows for an increase in supply to meet the ever growing demand.
This has however required them to use chemical fertilizers, pesticides, herbicides, etc… which were not needed before. The Tall forest and the ecosystem associated with it provided the protection from pests and nutrients to the soil. With this ecosystem gone, it is necessary to provide that protection and nutrition via artificial means. (As a side note: Many of these consumables contain components derived from fossil fuels, I have already suggested that is probably not a good idea.).
This production method is also eliminating habitat for migratory birds (and other critters) that inhabit the forest canopy. Now, I suppose you could argue that this is simply survival of the fittest. Adapt and evolve or die. But adaptation, evolution requires biodiversity. Eliminating entire species reduces the available diversity. This is probably not a good idea (Think “inbreeding”).
Additionally, if an entire species is wiped out, we may lose access to potential benefits as yet undiscovered. Who knows what plant or critter might be the source of new knowledge, or life-saving medicine? (For an example, see Curing Lessons Learned from Plants. )
Conservation shouldn’t get lost in political maneuvering, or extremist positions. It should really be a very scientific, measured process. How much do we consume? How quickly can we recycle the exhaust products? Are the required inputs (both mass and energy) created at a greater rate than we are consuming them? This generally gets ignored by business plans, which are generally not concerned with long term viability, compared to short term margin growth. And the nuts on the other side of the fence, romanticizing about wolves, blowing up fur factories, vandalizing mink farms and the like certainly aren’t helping the cause.
But somewhere in the middle of all the business, politics, and red-necked rebelliousness and bunny-hugging nuttiness, is a rational point of conservation common sense. It would sure be nice to get there.