Tall tree water problem solved, according to articles in ScienceShots 21 May 2014 and Functional Ecology doi: 10.1111/1365-2435.12284. The height of trees has been thought to be limited by how far water can be transported upwards from the trees’ roots. Leaves need water to keep their cells alive, maintain the structure of the leaf, and as a raw material for photosynthesis. This problem is reinforced by the fact air is drier, and sunlight more intense, at great heights, and therefore more water is lost by evaporation. However, giant California redwoods seem to be able to defy both gravity and evaporation as they keep their leaves well hydrated. It has been known that redwood leaves can absorb water from fogs, but how do they cope when the fog has cleared?
It turns out that leaves can store water. Researchers from Japan and USA collected redwood leaves from different heights, and studied them for their water absorbing and storing properties. They found the higher the leaves were on the tree, the more water they could store. Leaves from the crown of the tree had a different structure than those lower down. Leaves from the highest part of the trees had much more “transfusion tissue” – water storing tissue, than the leaves from lower parts of the trees.
The researchers tested how much water could be stored in leaves from different heights and found the topmost leaves could store up to five times the amount of water needed to keep the leaf functioning. They also found the topmost leaves have a smaller amount of xylem tissue – the water conduit tissue that transports water from the roots. This means the topmost leaves are more reliant on stored water than transported water.
The researchers wrote: “In coast redwoods, water storage in foliage, near the site of photosynthesis, may be an important physiological adaptation that maintains water status and helps overcome constraints on water supply. This may explain how the world’s tallest species solves the dilemma that water stress is highest near the treetop, where light availability for photosynthesis is highest, and continues to push the limits of tree height”. According to ScienceShots it may also explain “why redwoods surveyed in foggier northern California grow up to 30m taller than those in the drier south”.
Editorial Comment: Notice how the evolutionary biologists use the word “adaptation” for what really are design features. If redwood trees did not already have the ability to produce leaves that could absorb and store water from fog they wouldn’t be able to grow tall, because they would have nothing to adapt with. Adaptation is a real process that enables living things to cope with changes in their environment, but it works by modifying or turning on already built-in features, and this only happens because the organism can also sense the need for change in its structure and function, and activate the relevant cellular processes. Growing in a place that has fog is not going to produce any genes for transfusion tissue, or genes that regulate the relative amounts of xylem and water absorbing tissue.
This method of providing water for the topmost leaves would also help explain why many trees in the fossil record were so enormous. Such water storing leaves would work well in God’s original very good world described in Genesis 1 and 2, where the earth was watered each day by a rising mist, and enable trees to grow very tall indeed (Genesis 2:1-6). (Ref. forestry, arboreal, conifers, design)
Evidence News vol. 14 No. 14
20 August 2014
Creation Research Australia