Redwood Reader

'Myth' that forests improve water flows – studyhttp://news.yahoo.com/s/nm/environment_trees_dc;_ylt=ApNj8sqff1zf.IfcRX.RwMsPLBIF;_ylu=X3oDMTBiMW04NW9mBHNlYwMlJVRPUCUlSouth Africa Puts the Unemployed to Work, Restoring Land and Water
http://www.nytimes.com/2005/07/26/science/earth/26afri.html Amanda Hawn, July 26, 2005
With a Push From the U.N., Water Reveals Its Secretshttp://www.nytimes.com/2005/07/26/science/26wate.html?th&emc=thWilliam J. Broad July 26, 2005
This article from Reuters via Yahoo today is a good example of mixed signals and incomplete understanding of the nature of forest systems as precipitation interface and storage areas. The accompanying article from South Africa shows what happens when these kinds of programs are correctly envisaged and operated. The thought that trees should supply water in dry areas has never been true, since lowered rainfall will lead to a grass economy and a higher bacteria to fungi ratio in the soil. Trees that evolved to live on less water exist but high water trees in a low water environment will eventually dry out the landscape. Native vegetation has evolved its own methods for water storage locality by locality over eons.
Native systems, whether grass, forbs shrubs or trees, use fungi species that create soil water storage in these moisture regimes. Tree ranges often coincide with moisture bands as here on the North Coast where we have Douglas fir, redwood and pine belts, and plenty of examples of preferences such as live oak preferring drier sites and so forth
The authors say deep roots hurt in dry times but we see they have missed the entire precipitation interface concept when they say flows are not increased in dry seasons. Maybe compared to direct runoff, which here DOES mean erosion. Again they are afraid water soaking into the biological zone is lost as evapo-transpiration. While this is true much more water is lost from direct evaporation from lakes and rivers. A recent article stated that the five largest lakes in California evaporate more water than the two largest reservoirs hold when full, every year.
We see all kinds of challengeable statements in this article. The amount of particulate matter produced by forests has been shown to be far greater than previously thought. We get all kinds of headlines from these articles about forests creating air pollution and so forth. We point out the deuterium study showing how much Amazon rainfall is from transpired water rather than ocean evaporation. Hydroxyl radicals emitted by trees tear smog molecules like ozone and carbon monoxide apart and create friendlier atmospheric conditions. Emitted molecules are shown to cause water vapor to condense into drops.
Finally, in most of the cases shown the study is for perceived optimum species grown for wood or pulp or some other third purpose, rather than natives grown for water production. We can be sure species decide where who lives the best. Our perceptions are often clouded by good performance under good conditions. A landscape won’t be tested until extreme conditions occur, whether rainfall, drought or disease. We also note that if the landscape has been disturbed by clearing it will take fifty years for the maximum storage area to re-grow back to the starting point. So just planting trees won’t assist the water situation for some time. We also see no stepwise approach, planting one species to hold down the landscape while another species tries to reestablish itself. Here non natives are often useful, as using ponderosa pine to create shade for Douglas fir, with the pine scheduled for harvest as poles in thirty or thirty five years because it doesn’t do well over time in a wet landscape. In short, snapshot views are not very helpful in deciding a course stable for the landscape and profitable for men.
Meanwhile in South Africa a deep knowledge of water and wild land issues has found its way into practices we should look at collectively known as conservation farming. At the very top of the list is the removal of successful non-native vegetation, which is successful because it taps the regions water supply, often draining it. This causes farm and wildlife feed plants to suffer and the people and wildlife with them. The understanding has become that native plants work in the landscape because they store water in the ground for the dry season, keeping springs and streams wet in dry season. Many natives go dormant in the dry season, extending the time water is in the root zone. We see the nonnative vegetation often has successful strategies that outperform natives in the short run but often fail under duress. If enough of the landscape has converted before duress, the results can be devastating to local wildlife populations and habitat. The Africans are also very aware of carbon sequestration and should be players in the carbon market, since this is the likeliest way of deriving income from theses activities in the short term. The program can be a model for the rest of Africa and even natural lands anywhere. But in the current atmosphere of aid to Africa, paying them for resource protection and improvement surely is preferable to welfare handouts and business as usual.
This program has come to cover the same ground we are looking at. Starting with a program to reduce alien plants that were drying rivers up called Working for Water in 1995, and as much a program to put the “poorest of the poor” and especially single parents, the program has expanded to all South Africa and grown into several sister programs-first Working for Wetlands, to restore marshes and other riparian places: then Working on Fire, for suppression and control of wild fires: and Working for Woodlands, which is replanting regions with native vegetation.
It is noteworthy the program seeks to jumpstart natural cycles rather than planning on fixing everything. That is to say we too often count on our ingenuity to fix unexpected consequences when a return to a less intrusive method may be far more beneficial. The program is also creating a labor pool of skilled workers.
We applaud the concept of restoring the natural flow regimes with an eye to providing for human use through Conservation Farming. The activities of the modern land manager have cost the local people and landscape. Finally the government understands and finds itself restoring lands damaged by previous government programs, like restoring the farmland the government paid farmers to drain decades ago. We see eucalyptus detested for using a hundred gallons a day, and note it is or was one of the four primary invasive species in Northern California, along with pampas grass and Scotch broom, and we can relate to the Afrikaans name of ‘mother of millions” and what they mean by “aliens are going ballistic”.
Finally, I watched a report on conditions in Zimbabwe, just to the north and inhabiting a latitude that once made it the breadbasket of Africa. Today the government has forces white farmers off the land without compensation. The natives are not able to operate the farms and Zimbabwe is sliding toward collapse under its ruler Robert Mugabe. Large numbers of black Zimbabweans are illegally crossing the border into Botswanaland, where the government is trying to sort the economic and political refugees from agent provocateurs. The despair and desperation of those in custody shows the crux of the problem in a way words can’t, even over television.
The last article tells of the UN’s water assessment tool known as isotope hydrology. Isotopes allow for chemical fingerprinting of water molecules by the isotopic, or number of neutrons, in a given molecule. Water samples are based on various isotopes of oxygen and hydrogen such that each drop of water has a signature. This way flow, origins, age, source flow and fate of a water source can be determined and management decisions made in light of knowledge. An example shown in the article is if a water source is very young it is probably easily replenished by rain and can continue as is. But if the water is “old”, or fossil water stored in the ground millennia ago, there is a real danger of emptying the reserve.
This is the basis of the deuterium study mentioned earlier in this blog that allowed recognition of transpired water from terrestrial vegetation as opposed to ocean evaporation is repeated here except with O18 to O 16 ratios rather than hydrogen isotopes. Carbon 14 dating is used to determine the age of aquifer waters. This helps establish whether recharge is occurring. Many of the areas worked by the International Atomic Energy Commission projects are in arid developing nations, where the need may be the greatest.
In any case, a lot of recognition of the need to capture precipitation is becoming evident in a variety of ways. The disappointed scientists in the first article should go to a conservation farm. We have seen the effect of wolves on vegetation cause major improvements in just a couple of years; here it is the invasive thirsty plants removal that restores the stream. None of these can cause precipitation patterns to shift, but we can manage what we get much more efficiently.