As you probably know, environmental problems are quite diverse. Likewise, the solutions to those problems.
An ecosystem approach typically involves understanding the interrelationship between different aspects of an ecosystem, and how what may seem like a solution to one problem could likely be detrimental to other aspects. In short, it involves taking into account all affected aspects of the ecosystem, and hopefully finding a solution that does not negatively impact any individual aspect, or at least has as little a negative effect as possible.