Assess the connection between the well-being of people and the well-being of nature.

Human modification of the environment is one of the prevailing themes in our tour of biomes. All biomes have been modified by people, some more than others. The concept of natural biomes, as described in this chapter, provides a background for the current mosaic of human land uses, as shown in Figure 8.28.

Habitat fragmentation is the division and reduction of natural habitat into smaller pieces by human activity. In his book Song of the Dodo, David Quammen compares the process of habitat fragmentation to cutting up a Persian rug: A whole Persian rug functions exquisitely, but if the rug is cut into pieces, it becomes worthless. Our tour of biomes has revealed that habitat fragmentation is reducing Earth’s natural biomes and ecosystems into ever-smaller pieces that are surrounded by anthropogenic landscapes.

286

India, Java, and much of eastern China are bright blue and purple in Figure 8.28, indicating villages with large human populations engaged in irrigated and rain-fed agriculture. The seasonal tropical forest and tropical savanna biomes that would occur naturally in India are completely gone, as are China’s temperate deciduous forests. The slopes of the Himalayas, once montane forest, are now mainly rice-growing agricultural settlements and dense mixed settlements.

Food production accounts for a large proportion of human land use. The most widespread human land use is rangelands, where domesticated livestock graze. Rangelands are followed by croplands, the second most widespread human land use.

Over the last 500 years, hunting pressure was responsible for over 90% of the extinctions of mammals and birds. Today, habitat fragmentation, climate change, and competition from non-native species are the most significant factors causing species endangerment and extinction. Figure 8.29 discusses examples of other factors that are or have been important in threatening species.

Most of us do not hunt rhinos for their horns or orchids for our collections. But we all contribute to species loss through habitat fragmentation. The materials people use and the foods people eat come to us through a global network of trade. International trade, driven by consumer demand, accounts for 30% of the threats to species worldwide. Research published in the journal Nature in June 2012 details the relationships between international demand for goods and threats to species resulting from those demands. Many of the goods and materials North Americans and Europeans enjoy originate overseas, where their extraction or production takes an environmental toll. Coffee, for example, comes from Brazil, beef from Argentina, cacao (chocolate) from Central America, and palm oil from Indonesia. Figure 8.30 links these goods to the ecosystems from which they come.

Why should anyone care about the loss of a rare orchid, or a spider monkey in Central America? It is unfortunate that 21,000 km² (8,100 mi²) of Amazon rainforest are lost each year, and with it, probably several thousand species never before seen by people. But does it matter in a practical sense? Most people will never see a tropical rainforest. Fewer still will ever see a spider monkey outside a zoo.

287

Trade in coffee and chocolate is thriving. Is that not good? People matter, too. Why should we value orchids and spider monkeys? In a strictly self-serving sense, we should care about other species and their natural environments because they support people in many ways:

Humans are connected to and supported by the biosphere. Saving species and their habitats maintains natural resources, preserves ecosystem services, generates revenue through ecotourism, and preserves a richer and more interesting world. Saving species also addresses the problem of climate change. So the answer to the question, “Do people matter?” is resoundingly yes. The health and well-being of people are inextricably connected to the health and well-being of the biosphere.

288