urban sprawl / living together

Les Schaffer schaffer at optonline.net
Mon Jan 13 22:02:57 MST 2003


Nature AOP, published online 12 January 2003


Effects of household dynamics on resource consumption and biodiversity

JIANGUO LIU*, GRETCHEN C. DAILY+, PAUL R. EHRLICH+ & GARY W. LUCK+

* Department of Fisheries and Wildlife, Michigan State University,
E. Lansing, Michigan 48824, USA

+ Center for Conservation Biology, Stanford University, Stanford,
California 94305, USA

Human population size and growth rate are often considered important
drivers of biodiversity loss[1-6], whereas household dynamics are
usually neglected. Aggregate demographic statistics may mask
substantial changes in the size and number of households, and their
effects on biodiversity. Household dynamics influence per capita
consumption[7, 8] and thus biodiversity through, for example,
consumption of wood for fuel[9], habitat alteration for home building
and associated activities[10-12], and greenhouse gas
emissions[13]. Here we report that growth in household numbers
globally, and particularly in countries with biodiversity hotspots
(areas rich in endemic species and threatened by human
activities[14]), was more rapid than aggregate population growth
between 1985 and 2000. Even when population size declined, the number
of households increased substantially. Had the average household size
(that is, the number of occupants) remained static, there would have
been 155 million fewer households in hotspot countries in
2000. Reduction in average household size alone will add a projected
233 million additional households to hotspot countries during the
period 2000-15. Rapid increase in household numbers, often manifested
as urban sprawl, and resultant higher per capita resource consumption
in smaller households[15-19] pose serious challenges to biodiversity
conservation.


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