What environmental concern is associated with habitat loss?

Here's a simple answer to your very broad question: Plants and animals depend on one or more habitat types to survive. In general, the viability of a particular population of an organism is diminished with habitat loss. Depending on the amount of habitat lost, the species may go extinct. Whereas extinction is a natural phenomenon, human-induced changes to habitat have accelerated the loss of species. We know there are extensive connections among biological organisms. Sometimes species loss has significant consequences on other organisms (including humans), both good and bad. Organisms also provide environmental services that benefit a healthy ecosystem. Even if habitat loss does not result in extinction, there would likely be less of the organisms that rely on that habitat. Consequently, they cannot conduct the same level of environmental services. For example, a particular tree species may buffer the coast from hurricane-force winds. If habitat for that tree species is lost, the trees will die off and leave the coast susceptible to hurricane damage. Many believe the consequences of Hurricane Katrina were much worse because of extensive wetland losses in the area.