Plants and animals interact with each other to stay alive, which in turn forms complex systems. I think the Lion King covers the system simplistically in song-form at the beginning of the movie, but that doesn't cut it when trying to predict the effects of things like climate. Jianxi Gao, Baruch Barzel, and Albert-László Barabási study the complexities of nature's network in greater detail.
Mauro Martino helps explain the work in this video for Nature. [Thanks, Mauro]