Over the past year, 410,000 acres have been fallowed in this vast agricultural region that provides 30 percent of all the produce grown in the United States and virtually all of the worldвЂ™s almonds, walnuts, and pistachios. The amount of water transported through irrigation systems to CaliforniaвЂ™s Central Valley-the most productive agricultural region in the world-has been reduced to only 20 percent of customary quantities, forcing farmers to deepen groundwater wells and drill new ones. Elsewhere in the Southwest, Lake Powell, the largest reservoir on the Colorado River, is at 44 percent of capacity. In California, reservoirs are currently at only 38 percent of capacity, and the snowpack is only 25 percent of normal for late January. Lake Powell, in 2009, showing a white calcium carbonate вЂњbathtub ringвЂќ exposed after a decade of drought lowered the level of the reservoir to 60 percent of its capacity. Drought can lead to failed crops, desiccated landscapes, wildfires, dehydrated livestock, and in severe cases, water wars, famine, and mass migration.ДЄlthough the situation in the West has not yet reached such epic proportions, the fear is that if it continues much longer, it could. But this bland definition belies the devastation wrought by these natural disasters. Meteorologists define drought as an abnormally long period of insufficient rainfall adversely affecting growing or living conditions.

This long drought has crept up on the region, partly because droughts encroach slowly and they lack the visual and visceral effects of other, more immediate natural disasters such as earthquakes, floods, or tsunamis. The southwestern states are also experiencing moderate to severe drought, and this comes on the heels of a very dry decade. A relatively wet December has given way to the driest January on record, and currently over 90 percent of California is in severe to exceptional drought. The majority of water in the western United States is delivered by winter storms from the Pacific, and over the past year, those storms were largely blocked by an enormous ridge of high pressure. Increased transpiration under long-term high evaporation demands may cause occasional local drying of soil around roots, associated with soil shrinking in clay, which can be followed by serious damage to buildings.The state of California is beginning its fourth year of a serious drought, with no end in sight. These figures represented about 50% of potential evapotranspiration when considering projected crown areas. 1 dmВі mвЃ»ВІ dвЃ»В№ or almost 100 dmВі mвЃ»ВІ per growing season. However, transpiration expressed per root surface area (and/or whole root system enveloping area) was practically the same in both trees, i.e. 65-140 1 per fine summer day and in average 10 mВі per growing season. The trees utilized relatively large amounts of water for transpiration, i.e. Maximum rooting depth of shaded and exposed trees, as determined by GPR, was approximately 1.4 and 1.7 m, respectively. However, no garden was present near the shaded tree, therefore roots remaining under the asphalt surface did not increase in area in any particular direction. However, a small piece of garden existed near the non-shaded tree, and root area of roots growing in this direction increased significantly, due to a presumed increase in available water and nutrients. The ground surface above the root systems was covered by asphalt. Root systems of two mature Field maple trees (Acer campestre L.) growing in both shaded and non-shaded sites, on clay soil in an urban environment, were analyzed by ground penetrating radar (GPR), light microscope and sap flow techniques.

Eco global survival tree stump?