Friday, January 21, 2011
The Wolf's Tooth: Keystone Predators, Trophic Cascades, and Biodiversity by Cristina Eisenberg--Book Review
This is a useful and interesting overview of the state of ecosystem management science, its history, complexities, and uncertainties. Eisenberg interlaces accounts of her own research on wolves, elks, aspens, and songbirds in Colorado, Wyoming, and elsewhere, with accounts of what others are doing or have done in similar settings and in very different ones. These include the Theodore Roosevelt Memorial Ranch in Montana, a working ranch that operates as a demonstration of how conservation and ranching can work in harmony, making a productive ranch in a wild landscape that includes bears, wolves, cougars, elk, mule deer, and other wildlife normal absent or barely hanging on in ranching territory.
The main point here is to explain the current state and history of ecological science. Eisenberg lays out the evidence of the importance of keystone predators, such as wolves in North America and sharks in the oceans, in maintaining a healthy level of biodiversity. One example: In the absence of wolves, elk overbrowse aspen saplings, leading to a lack of aspen in the middle age ranges, leading to a lack of the songbirds for whom a healthy density of mature and near-mature aspens are the preferred habitat. Over the last couple of decades, field research has strongly reinforced the importance of these keystone predators in maintaining the diversity that we need in order to continue to live comfortably on this planet.
But the top-down effects of keystone predators aren't the whole story. Food supply, disease, climate change, and other "bottom up" effects are also important, and interact with the top-down effects of keystone predators. In some circumstances one is more important, in other circumstances the other is more important--and the same ecosystem can flip from one to the other as its major force due to disruptions such as fires, volcanic eruptions, or human habitat destruction.
At times this is a bit dry, but other parts are lively and interesting, and overall this is very useful background for understanding environmental issues that make the news and affect our daily lives.
I received a free electronic galley of this book from the publisher via NetGalley.