The primary consideration in the ethics of conservation is the concept of ownership. This question rests on the distinction of property rights and ethical rights.
Strictly speaking, a country has land ownership of its resources as designated by laws. This (in itself) is not an issue unless the resources are depletable. There is no reason that a country "owning" a piece of land also "owns" the ability to drain its resources for perpetuity. Their ownership exists because it is recognized that they occupy it presently, however that recognition came to be. Therefore, considering future populations will also "own" it in their present, ownership does not extend to the ability to strip the resources to the point that it negatively impacts future generations.
This consideration is fairly literal and assumes property rights. Ethically, that any resource or piece of the earth is able to be owned is fundamentally up for debate. In the ethics of conservation, it must be considered that all people have the same rights to the earth and that potentially this is none at all. Additionally, there are considerations to be made for other species and habitat conservation.
Furthermore, an ethical approach in any arena would be to conserve and share rather than to destroy. Altruism, doing things for the overall good, is a possible rule set for the ethics of conservation, given that the earth is our one planet. Ethically, it makes sense to follow altruistic principles for such a commonality. If the earth is itself a resource, then it is the ultimate shared right. Damaging it by using up its energy sources and furthering climate change infringes on the rights of other countries and future generations. In environmentalism, this is the theory of intergenerational justice.
That being said, altruism is a high demand for an ethical rule set in conservation. Given the baseline of not depleting the earth of resources, sustainability might be considered a better policy. Sustainability is a binary: either a practice/policy can be kept up (will not reach its limit) or it will not. In the case of depletable resources, this means eradication, or dangerously low levels. While an extreme consideration, the ethics of conservation must account for that possibility in the future.