Peaceful coexistence, in nature and sometimes mankind, is a survival mechanism in itself when populations of diversity are thrust together within an Edge Ecology. An Edge Ecology is an ecology where two 'edges' of a population, culture, class, methodology, background, phyla, etc that are different meet. One of the best examples of an edge ecology is human activities and systems and Natural activities and systems. (The systems that would be in place even if humans did not occupy that space for generations.)
Transportation corridors are a good example of edge ecologies and even within the human experience, people easily see that there is a difference between the 'driving experience' the walking experience, and the in adjacent homes, shops, etc., on any given corridor. Coexistence can occur if there is a benefit that each niche (patch or side) of the ecology can provide to the other and still be free to retain it's own structure and process or be allowed to easily adapt.
However, when this option is not available for whatever reasons, redundant niches, in highly stressful situations or areas, are pared down to the least number possible. This happens naturally or anthropogenically when a habitat's carrying capacity (Water, energy, food, shelter, protection from predation, consumers, health, social opportunities etc) dwindles. If we are speaking of strictly the human view, this can be seen as blight, disrepair, and a decrease in safety.
When the stress is high enough and ecologies shrink to nearly unsustainable levels, we refer to the habitat and more specifically to the species dwelling therein as 'endangered.' If enough niches are affected, so that some become missing in places they would ordinarily be, this is known as, "extinction." Many scientists are concerned because society depends on diversities of natural cultures from food, building materials, water, and air, much of which is dependent on mans activities. This is why we hear the word "sustainable" so often. Sustainability requires that not only that mankind's infrastructure works under a variety of conditions economically, socially, and from a human perspective what humans consider a good environment, but natural systems must also be allowed to flourish that support human activities.
Nature is for life and living. So the process of survival will continue to pair down the tree, knocking down entire branches to match the carrying capacity of the overall system if humans continue to consume more than they were ever supposed to be allotted and faster than what can be replaced. The natural systems will continue to attempt to find balance and sustainability on its own if there was a large reduction of water, nutrients, sunshine, etc until it can get the tree of life to make it until the good times when it can once again flourish, or if there is total extinction. Lots of people consider the forces of nature bad. But forces of nature made mankind and all the animals in it, the water, the oceans, all the food producing fruits in it. Natural systems on which humankind depends have been working for a long time. Now its time for man to decide if the investment that nature has given is worth it. In other words, if mankind itself is worth finding a better balance to allow for natural systems to work more easily.
Some species can respond to an overpopulation or under population circumstance relatively quickly and in a way that ensures future generations can survive. However, these species usually have shorter life spans and are more prolific. They also tend to be a food base for the larger and more complex animal species. The higher up the ladder one goes in either size, energy needs, longevity, and/or intelligence, the less ability the animal has to respond to lack of capacity in the short term.
Human beings are unique in there ability to understand patterns and what that means in the near future, mid range future and long term future. However, social systems which can last decades if not hundreds of thousands of years are much slower to change. Capital Markets are still based off of ideas that are already old and outdated. It is vital for corporations, computer programs as well as populations of people to understand how to bring into the models real sustainability which takes into account impacts on water recharging needs, weather events, pollution potential, etc.
Despite first world nations and new first world nations being told they have to be on a resource diet, this is less true as what is needed is more of an 'off grid' capacity that draws less on grid energy from obtaining materials to building, living, and working. an opportunity exists for ingenuity, creativity, and action, to add capacity back into the system. The good news is, humans can pare down, densify up, and live more economically before nature is pushed towards catastrophic events to the global society.
My specialty are edge ecologiies as they apply to transportation corridors because really, transportation corridors are one long edge ecology. What is an edge ecology? An edge in the landscaping world is anything that impedes passage or is a barrier that can be represented on a map with a line. Thus, sound walls, pavements, medians, building walls, construction barriers, are edges. But it is more than that. Ecologies refer to a population of plants and animals in an environment. So an Edge Ecology as it applies to a Transportation corridor is the study of people, animals and plants as they interact and react in a transportation corridor based on the infrastructure provided and the needs of the capacity (think level of service) in that corridor. Good infrastructure invites people to be multi-modal, which results in more capacity with safety. Bad infrastructure takes away capacity even from the surrounding neighborhoods, retail and industrial zones and can make or break a region's economic base. In the slides below, which depicts good infrastructure and bad infrastructure design?