International housing boom hurting nature

A study co-authored by Stanford (Calif.) University associate professor of biological sciences Gretchen Daily concludes that the average household is shrinking--a global trend that is fueling an international housing boom which threatens the survival of plants and animals in dozens of countries, including the U.S. According to her research, housing units throughout the world are being built at a rate that outpaces population growth, resulting in a loss of habitat, natural resources, and biodiversity.

"We had hoped to find that, where human population growth was slowing, biodiversity might be given some breathing room," says Daily. "But instead, we've found that urban and suburban sprawl are accelerating faster than population growth is decelerating."

Throughout the world, the average number of people living together in a household is shrinking, primarily because of lower fertility rates, an increasing number of divorces, higher per capita income, aging populations, and a decline in multigenerational family units, the study notes. "Reduction in average household size takes a double toll on resource use and biodiversity. First, more households means mote housing units, thus generally increasing the amount of land and materials (for example, wood, concrete, and steel) needed for housing construction." Second, fewer people per household leads to higher per-capita consumption of water, fuel, land, and other natural resources, even when the size of the population declines. "This easily overlooked trend presents a particularly serious threat to biodiversity--the plants, animals, and microbes underpinning our life-support systems," Daily emphasizes. "The threat is particularly acute in so-called biodiversity `hotspot' countries, where extraordinarily rich stocks of native species are threatened by human activities."

The researchers analyzed demographic data compiled by the United Nations from 141 countries, 76 of which have been identified as biodiversity hotspots, including Australia, India, Kenya, Brazil, China, Italy, and the U.S. "Ignoring population growth, reduction in household size alone is projected to add 233,000,000 households to hotspot countries between 2000 and 2015," Daily stresses. This trend could have a particularly damaging effect in biologically sensitive areas such as the Wolong Nature Reserve in China, where the growth in new homes has led to deforestation and the loss and fragmentation of habitat for giant pandas.

The threat to global biodiversity is likely to escalate, the report maintains, because current household trends, such as higher divorce rates and increased affluence, are expected to continue. For example, in Florida's Indian River County north of Miami, the number of residents per household has declined by 22% in the last 30 years, while the floor area in a single-story one-family house has increased by one-third.

COPYRIGHT 2003 Society for the Advancement of Education
COPYRIGHT 2003 Gale Group