The question of which forces control terrestrial ecosystems lies at the heart of a long-standing debate among ecologists. One theory, the so-called bottom-up theory, suggests that plant defense mechanisms exert control by limiting food availability for herbivores. Top-down theorists, however, suggest that predators limit the numbers of herbivores and hence their impact on the vegetation. Now new findings in the current issue of the journal Science that describe animal communities isolated for 15 year
New catalyst means greener paper is not pulp fiction.
Pollution from paper production could be cut, say US chemists, with a new way of refining wood pulp 1 . But the process must go through the mill before it can convert industry.
During paper production, gluey wood component lignin is stripped out to leave stringy cellulose. The harsh chemicals used create environmental pollutants, such as toxic and long-lasting chlorinated compounds.
A new chemical
Mosquitoes’ evolve rapidly in response to global warming.
Mosquitoes are holing up later as winters get warmer, US ecologists have shown. This is the first genetic adaptation to global warming to be identified. Less flexible animals could face extinction, they warn.
The North American mosquito Wyeomyia smithii uses shortening day length to judge when to bed down for the winter. Modern mozzies wait nine days more than their ancestors did in 1972, William Bradshaw and Christin
Deforestation is drying out cloud forests.
“It drips,” says ecologist Robert Lawton, describing the Costa Rican cloud forest, “and it’s plastered with plants of all sizes climbing over each other. Stand still for long and they’re growing on you.”
Now the lush life he describes may be threatened. Satellite pictures show that deforestation at the foot of western Costa Rican mountains is drying out swirling summit mists.
When warm, wet tradewinds blowing off the Caribb
European subsidies to enhance farmland wildlife may not be working.
The effectiveness of schemes that seek to promote biodiversity by paying farmers to cut back on intensive agriculture could be called into question by some research findings from Holland.
The incentive programmes, which already cost the European Union 1.7 billion euros (US$1.5 billion) each year and are rapidly expanding in scope, are partly motivated by the desire of European governments to subsidize farmin
Air pollution used to be something you could see and smell. But as air quality standards have tightened, the air over most industrial sites, airports and cities has gradually cleared. Nevertheless, invisible toxic agents such as ethyl benzene, butadiene and styrene continue to pose risks to public health. With a view to detecting and quantifying these agents, Siemens Environmental Systems Limited in Poole, England has introduced UV Falcon. The system consists of a transmitter that projects a UV (ult