GEOG 2500 Lecture : Soils and Vegetation.docx
Document Summary
Plant species need an adequate amount of moisture. They don"t want too much moisture, and they also don"t want too little moisture. xerophytes=species in dry environments. There are three strategies: escapees, avoiders, and tolerators. Escapees are seeds that escape from low-moisture conditions in their environment. Tolerators can become completely dry, and if you throw water on them, can come back to life. These things occur in the sonoma desert, and they can withstand extreme drying. A lot of energy is needed to suck moisture out of the soil. They are a new world family whose leaves are quite small and are restricted to subtropics. They have a root system, needles and stem tissues, and cam photosynthesis. Cam photosynthesis allows us to store co2 as a malic acid. Stomata opens at night, gas exchange, take in co2, and cam pathway can convert it to something that can be stored. Roots need oxygen because they have to do cell functions.
