Habitat destruction: death by a thousand cuts

Humankind has dramatically transformed much of the Earth’s surface and its natural ecosystems. This process is not new—it has been ongoing for millennia—but it has accelerated sharply over the last two centuries, and especially in the last several decades. Today, the loss and degradation of natural habitats can be likened to a war of attrition. Many natural ecosystems are being progressively razed, bulldozed, and felled by axes or chainsaws, until only small scraps of their original extent survive. Forests have been hit especially hard: the global area of forests has been reduced by roughly half over the past three centuries. Twenty-five nations have lost virtually all of their forest cover, and another 29 more than nine-tenths of their forest (MEA 2005). Tropical forests are disappearing at up to 130 000 km a year (Figure 4.1)—roughly 50 football fields a minute. Other ecosystems are less imperiled, and a few are even recovering somewhat following past centuries of overexploitation. Here I provide an overview of contemporary habitat loss. Other chapters in this book describe the many additional ways that ecosystems are being threatened—by overhunting (Chapter 6), habitat fragmentation (Chapter 5), and climate change (Chapter 8), among other causes—but my emphasis here is on habitat destruction per se. I evaluate patterns of habitat destruction geographically and draw comparisons among different biomes and ecosystems. I then consider some of the ultimate and proximate factors that drive habitat loss, and how they are changing today. 4.1 Habitat loss and fragmentation