Drought, Plants, and the Height of Trees

April 9, 2012 0 Comments

It is known that plants can communicate through chemical signals and now it has been found that they have memory. Here is some interesting recent research indicating that plants can remember drought conditions thus making them more prepared for when it happens in the future. This has apparently been known to green thumbs and gardeners for years, but I had never heard of it and now scientists have figured out how they do it. The plant’s genes are affected during a drought-like period and these protective genetic factors activiate faster the next time dry weather comes around. The common terminology is “hardening”. With-holding water from seedlings for a couple of days before transplanting them in the ground and then watering the day of transplant is a good practice to help the plants survive during periods of warm dry weather in the Summer. I knew that using a fan or exposing seedlings to wind will help them be more sturdy as they grow. Also, putting them outside or exposing them to cooler outdoor air before transplanting them will improve success. Now I can add drought hardening to my repertoire.

I am not sure to what extent trees can become hardened against drought, but dryness and cold are two of the factors that affects various species of trees from colonizing news areas. Places in the western U.S. do not support natural forests because of the long periods of dry weather. Trees do not move into the arctic where the weather is too cold. One of the predictions following the theory of AGW is that trees will move farther north and populate the formerly barren freezing tundra. Even though there has been some significant warming in arctic areas in recent decades, scientists have not seen as many trees move farther north as predicted. One of the reasons – dryness. Many of the arctic areas that have seen warming have also been fairly dry. Also, precipitation in the arctic is traditionally lower than most other places on the planet.

If more trees do in fact end up colonizing the arctic it will be important to estimate how much biomass they represent, because trees take carbon dioxide out of the air. Knowing how much “biomass” is there or might develop in the future will give us better information for climate models. But how might one measure the biomass of trees accurately. Satellite images let us know where tress are but not how “big” they are. In this measurement, perhaps LIDAR can come to the rescue. Take a look at this cool map showing the height of trees around the world. The LIDAR (think of it as a “laser-radar”) instrument on NASA’s Cloud and Land Elevation Satellite was the one that compiled the image. It will be interesting if the trees in the arctic continue to grow taller in coming years.

Have a good Monday! Meteorologist Justin Loew

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