MOSAIC: Global warming on wild flowers
ONE in every five species of wild flower could die out over the next century if levels of carbon dioxide in the atmosphere double, in line with predictions, scientists said recently.
A study of the impact of global warming on plants has found that most of the environmental changes are likely to result in a substantial loss of plant life. Even though plants need carbon dioxide to survive, the research found that higher levels of the gas reduced numbers of wild flowers by 20 per cent, and cut overall plant diversity by eight per cent.
Scientists from Stanford University in California altered the environment of 36 open-air plots of land — on which between five and 20 wild plants had been growing — over a period of three years. They doubled carbon dioxide, increased “rainfall” by 50 per cent, caused average temperatures to rise by 1.7 C and added nitrogen pollutants to the soil — all of which are likely to happen because of global warming. The researchers, who published their study in the Proceedings of the National Academy of Sciences, described the findings as “dramatic”.
Plots that received all four treatments — which emulated the environmental conditions likely to exist 100 years from now — suffered a decline of 25 per cent in wild flowers and even those given extra nitrogen or carbon dioxide suffered a 10 or 20 per cent decline.
Only increased watering resulted in a rise in diversity. Scientists suggested that increased carbon dioxide, temperature and nitrogen allowed some plants to grow faster for longer, making it difficult for other plants to survive.
Professor Christopher Field, who led the study, said the team was surprised to find that increased carbon dioxide and watering caused such opposite effects given that they were both essential for plants to grow.
“One hypothesis is that elevated carbon dioxide added moisture to the soil, which tended to extend the growing season of the dominant plants, leaving less room for other species to grow,” Professor Field said.
The study demonstrated how some wild plants would suffer while others benefited from the effects of climate change. “Certain kinds of species are much more sensitive to climate and atmospheric changes than others. It turned out that wild flowers were much more sensitive to the treatments than grasses were, no matter what combination of treatments we tried.”— Samina Iqbal
A difficult climb
ALTITUDE illness is common in people ascending to more than 2500 meters, especially if the ascent is rapid, states a recent issue of the British Medical Journal.
Acute mountain sickness presents as headache, loss of appetite, nausea, vomiting, fatigue, dizziness, lightheadedness and difficulty in sleeping. Symptoms occur six to twelve hours after arrival at a new altitude and resolve in one to three days, provided no further ascent is made. The exact changes causing mountain sickness are not known, but it is attributed to swelling in the brain or lack of oxygen treatment comprises of rest, pain killers, and anti-vomiting agents. Acetazolamide and dexamethasone may be required in some cases.
Preventive measures against mountain sickness consist of a slow ascent to provide time to the body for acclimatisation for increased delivery of oxygen. Above 3000 meters, the sleeping time should be increased. Some subjects may need Acetazolamide or dexamethasone. Other substances as Ginko biloba and aspirin have been suggested by some scientists, as preventive measures for altitude illness.
Pre-existing medical conditions can be a high risk for mountain sickness. These include, Angina Pectoris, which can worsen and Chronic obstructive airway disease and cystic fibrosis of the lungs can deteriorate fast at high altitudes.
Diabetics are not affected by altitudes as such, but symptoms of hypoglycemia can be confused with those of mountain sickness. Some glucometers may not work accurately at heights and checking of blood glucose may not give correct results.
Planning a trip for high altitude ascents should be done carefully, and after a detail physical check up. Adequate drug supplies should be carried and itineraries should be flexible to allow intermittent rest.— Dr Fatema Jawad
|
