In the book Environmental Values I picked up from the AU library a few months back, there was an article entitled "Non-Anthropocentric Value Theory and Environmental Ethics" by J. Baird Callicott. The article was on the dry side, so unless it's something that really interests you, I wouldn't recommend trying to muddle your way through it. Instead, I'll sum it up as best I can here:
The author begins by discussing that the definition on environmental ethics is one that isn't completely agreed upon. Some view environmental ethics as an application of established philosophical ideas with respect to the environment, yet others see environmental ethics as it's own unique ethics - something that may perhaps require its own moral and even metaphysical principles. The author argues that if environmental ethics is in fact a theoretical, as opposed to applied discipline, that the "most important philosophical task for environmental ethics is the development of non-anthropocentric value theory" (Callicott 67).
Anthropocentric value theory, as I've already discussed, is defined as any theory that assigns intrinsic value to human beings and regards all other things (other life forms included) as being valuable only to the extent that they are means to some human end (instrumentally valuable). The use of a utilitarian calculus to decide the moral rightness/wrongness of any action with environmental consequences would be inherently anthropocentric.
Callicott then goes on to discuss a number of non-anthropocentric theories; theories that challenge the idea that human beings are the only species with intrinsic value.
He begins with what he describes as the most conservative theory: 'animal liberation' theory. This theory is the most conservative because it requires the least change from our prevailing anthropocentric, utilitarian ethical paradigm. Animal liberation, or ethical hedonism, only requires that classical utilitarianism be implemented consistently. Proponents of this theory argue that the idea that only human experiences of pleasure and pain was never within the original principles of utilitarianism. Problems we incur with this theory are similar to the problems we incur with utilitarianism as more commonly interpreted. That is to say, ethical hedonism would allow the destruction of forest for pasture for cattle, since plants are not sentient beings. Also, this theory doesn't take into account the delicate balance of species necessary for a healthy ecosystem.
The next theory Calicott explains is ethical conativism. Ethical conativism is born out of the Schweizerian reverence for life. This theory defines interest in terms of conatations (will-to-live) and intrinsic value in terms of interest. That is, things have intrinsic value if interests may intelligibly be assigned to them. Ethical conitavism opens up the realm of ethics to plants as well as humans and other animals because it argues that plants have interests even if they are not conscious of them. However, it still is an inadequate theory because, like ethical hedonism, it doesn't acknowledge the difference between wild vs. domestic species, and the role of super organismic entities (i.e. biomes, the biosphere). Also, if ethical conativism were to be strictly followed, its proponents would have to be fruititarians (only eating already dead fruits and vegetables).
Calicott identifies better alternatives such as 'theistic axiology' (all things in the world are good and have intrinsic value because they are created by God, the 'stewardship view' (in which humans are obligated to protect and take care of nature), and 'holistic rationalism' (all good things are inherently good/valuable to the degree of their 'goodness'). However, he finds these theories inadequate as well.
Though Calicott does not propose a theory for environmental ethics, he identifies four characteristics that any appropriate value theory for environmental ethics must have.
1.Both individual organisms and 'super organismic entities' (such as food webs) must be seen as possessing intrinsic value,
2. Should distinguish between wild and domesticated animals and plants,
3. Must be consistent with current evolutionary and ecological biology,
4. Must give intrinsic value to all the parts and species of our present ecosystem.