Arctic Ecology - Adaptations To Conditions - Plants


One of the most serious problems that plants face is ice crystal formation in the cells, which results in tissue death. Plants have two ways to resist freezing: avoid it or tolerate it. If a plant has taken the avoidance route, it has several different ways to evade freezing. It can build up insulation, have its stem close to the ground, use the insulation from snow cover, and supercool. When supercooling, water is able to remain in its liquid state down to −38 °C or −36 °F (compared to its usual 0 °C or 32 °F freezing point). After water reaches −38 °C (−36 °F), it spontaneously freezes and plant tissue is destroyed. This is called the nucleation point. The nucleation point can be lowered if dissolved solutes are present.

If a plant has taken the tolerance route, it has several different ways to tolerate freezing. Some plants allow freezing by allowing extracellular, but not intracellular freezing. Plants let water freeze in extracellular spaces, which creates a high vapor deficit that pulls water vapor out of the cell. This process dehydrates the cell and allows it to survive temperatures well below −38 °C (−36 °F).

Another problem associated with extreme cold is cavitation. Ring-porous wood is susceptible to cavitation because the large pores that are used for water transport easily freeze. Cavitation is much less of problem in trees with ring-diffuse wood. In ring-diffuse wood, there is a reduced risk of cavitation, as transport pores are smaller. The trade-off is that these species are not able to transport water as efficiently.

Read more about this topic:  Arctic Ecology, Adaptations To Conditions

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Famous quotes containing the word plants:

    Luxurious Man, to bring his Vice in use,
    Did after him the World seduce:
    And from the fields the Flow’rs and Plants allure,
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    Brute force crushes many plants. Yet the plants rise again. The Pyramids will not last a moment compared with the daisy. And before Buddha or Jesus spoke the nightingale sang, and long after the words of Jesus and Buddha are gone into oblivion the nightingale still will sing. Because it is neither preaching nor commanding nor urging. It is just singing. And in the beginning was not a Word, but a chirrup.
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