Todd Dawson's Lab
When I think of Todd Dawson's work, I think of my own obsession of wondering what is going on under the ground as opposed to walking through the woods and looking at all the beautiful scenery. Yes of course the scenery is beautiful and exciting. However, my metamorphosis and obsession with underground biological life networking came about over a long period of time. While I always had interest in 'Botany' & 'Plants', I gradually came to realize through my own study and research that a healthy above ground paradisaic scenario is made only possible and a success by a properly installed under ground networked system.
Nature, when not interfered with, takes care of itself. However, human's on the other hand are wowed by the Ooooooo-facter of various Large Corporate Marketing Schemes when it comes gardening and landscaping. Billions of Dollars in advertising over almost a century has indoctrinated people on Earth that Chemicals are the answer for your every need in the garden and landscape and without them you are bound to fail. Careful consideration should always be given to just exactly how things work in nature and then simply replicate these processes by developing practical application concepts into your own project. The mistake comes when mankind believes they can out perform and improve upon nature. No need to list the failures of this thinking. Anyone can read and listen to the News today and see that human's are rapidly destroying our planet.
That aside, let's get back to what work Todd Dawson and his team have pioneered. There are terms and phrases they research called 'Hydraulic Lift' - 'Hydraulic Redistribution' - 'Hydraulic Descent' and all of this has to do with a root phenomena where by roots of key species of any type of ecosystem facilitate the redistribution of water and nutrients through yet another complex and sophisticated piece of "Earth Internet" hardware called a mycorrhizal network or grid. These mycorrhizal organisms are nothing more than beneficial fungus which uses mycelial network fibers to inter-connect with various species of plants in an underground mutualistic association. In a nut shell the fungi provide an increased rate of absorbtion by 200% of water and nutrients and gives these to the trees or shrubs and in turn, the fungi who can't manufacture their own food through photosynthesis are rewarded from the plant carbons and other sugars by which the fungi survives.
Below is an animated illustration off Todd Dawson's Lab site which beautifully illustrates just what happens during daylight hours, nighttime and even during the rainy season when trees and shrubs are in dormancy state.
|Animated imgage - Dawson's Lab|
Sap velocity in the taproot and lateral root of P. robustum during the transition from the dry to wet season in the Floresta Nacional do Tapajós.(a–c) Schematics for water movement at nighttime before the rain (a), daytime before and after the rain (b), and nighttime after the rain (c). Arrows shown the dominant flow direction determined by sapflow. (d) Graph showing sap velocity. Positive values mean that water flows to the plant, and negative values means away from the plant into the surrounding soil. The dashed line represents a rain event (36 mm). See the text for a complete explanation.
|(Photo courtesy of NetPS Plant Finder)|
"Mother Nature's Irrigators" by Todd Dawson
"Mother Nature's Irrigators"
"By comparing variations in isotopic concentrations taken from different sources, they were able to show that mature streamside trees do not use stream water but used deep groundwater. When Dawson came to Cornell in 1990, he looked for ways to combine his research in water use with his interest in woody plants and their distribution and physiology. During the summers of 1991and 1992, Dawson observed the water use of Maples."Todd Dawson made a further research work of this streamside (Riparian Habitat) water use by Trees. These trees amazingly prefer the deep groundwater to the surface water abundant in what appears to be a healthy surface water situation. Take the time to read the paper they did on this in the link title:
"Streamside Trees That Do Not Use Steam Water"
|Image - semanticscholar.org|
"A LONG-STANDING axiom is that plant distribution is strongly influenced by soil moisture content1,2. While it has been shown that plant taxa inhabiting streamside communities receive or use more water3, it is assumed that this water is obtained from the stream adjacent to where they are found growing. Here we show, using hydrogen isotope ratio analyses at natural abundance levels, that mature streamside trees growing in or directly next to a perennial stream used little or none of the surface stream water. The deuterium to hydrogen content of both source and xylem waters indicated that mature trees were using waters from deeper strata. Although adult trees may have roots distributed continuously throughout a soil profile, it seemed that the most active sites of water absorbtion were limited to deeper soil layers. In contrast, small streamside individuals appeared to use stream water, whereas small non-streamside individuals used recent precipitation as their primary water source. Our analyses provide both a relatively non-destructive method for assessing water sources of plants and a means of assessing potential competitive interactions among cooccurring taxa. In addition, the method may aid in resolving the role of water in determining plant distributions in areas characterized by sharp soil moisture gradients."
"Because the wood is unadulterated, the tissues hold a chemical record of weather patterns during the period the tree lived. Jahren studies carbon, hydrogen, oxygen, and nitrogen because these elements are taken from the soil, water, and air and incorporated into the tissue of plants and animals.
Jahren and her colleague Leonel Silveira Lobo Sternberg of the University of Miami in Coral Gables, Florida, are examining chemically different forms, or isotopes, of oxygen in these ancient redwoods to reveal weather patterns during the Eocene period.
Oxygen that a plant uses, said Jahren, comes primarily from water. Determining the chemistry of that water could reveal exactly where it came from. Rain that arrives after traveling long distances over land has a very different chemical signature than rain that travels over the ocean or just very short distances, she explained.
The researchers' analysis of the oxygen content of the wood revealed "a bizarre absence of oxygen-18, the heavy isotope," said Jahren. Water contains both oxygen 16—the more common and lighter isotope—and the more rare oxygen 18. The analysis suggests that the water contained almost exclusively oxygen 16."
|Images from Wikipedia Content|
"Scientists at UC Berkley are embarking on a new project to understand how global warming is effecting our fresh water supply. And they are doing it by tracking individual raindrops Mendicino and north of Lake Tahoe."
Here is the video link which is only about ten minutes long. Enjoy!
"QUEST: Life of a Raindrop"
The animated illustration at the top of this page which shows the various functions of the phenomena called Hydraulic Lift & Redistribution comes from a paper Dawson and other researchers did called,
"Root Functioning Modifies Seasonal Climate"
Abtract: Hydraulic redistribution (HR), the nocturnal vertical transfer of soil water from moister to drier regions in the soil profile by roots, has now been observed in Amazonian trees. We have incorporated HR into an atmospheric general circulation model (the National Center for Atmospheric Research Community Atmospheric Model Version 2) to estimate its impact on climate over the Amazon and other parts of the globe where plants displaying HR occur. Model results show that photosynthesis and evapotranspiration increase significantly in the Amazon during the dry season when plants are allowed to redistribute soil water. Plants draw water up and deposit it into the surface layers, and this water subsidy sustains transpiration at rates that deep roots alone cannot accomplish. The water used for dry season transpiration is from the deep storage layers in the soil, recharged during the previous wet season. We estimate that HR increases dry season (July to November) transpiration by ≈40% over the Amazon. Our model also indicates that such an increase in transpiration over the Amazon and other drought-stressed regions affects the seasonal cycles of temperature through changes in latent heat, thereby establishing a direct link between plant root functioning and climate.