Did you know that not all deserts are hot? Some deserts are extremely cold and they are called tundra deserts. Here is a video that shows how plants in different conditions adapt to the environment. Enjoy :)
Wednesday, August 25, 2010
More about plant adaptations in deserts
Desert Plant Adaptations
Habitats in Central Washington range from alpine and rainforest in the west, to dry ponderosa forests and shrub steppe to the east. A few plants can live in variety of conditions, and some are restricted to specific habitats.
The plants that grow in the arid eastern region near the Columbia River and the Columbia Basin have a number of traits which help them to be successful in the desert. In the photo to the left is Salvia dorrii and Artemisia tridentata in the Columbia Basin near Moses Coulee, Washington State. Two of the main adaptations of plants in arid environments is having an economical water management system, and maximizing the energy gain from the process of photosynthesis. Some plants, called xerophytes, have adapted their physical structure to suit the rigors such a harsh environment as the desert. 1/3 of the earth's land surface is desert, or about 10% of the total earth surface. Xero- means dry and -phyte means plant. These plants have adapted by having smaller leaves, grow compactly and close to the ground, and a non-porous covering on their leaves such as wax. Hair on the leaves of plants helps to reduce the evaporation of moisture from the surface of leaves by reflecting sunlight and inhibiting air movement. The process of photosynthesis requires both carbon dioxide and water to create energy for the plant. Water is usually absorbed through the roots, and carbon dioxide is absorbed through tiny pores in the plant called stomata. Through the stomata the plant is able to obtain carbon dioxide, but it also loses water by evaporation when the pores are open. Some plants cope with the water loss problem by having fewer stomata, or by having the stomata only open at night when it is cooler. All of these adaptations help to reduce evaporation and transpiration of water. Differences in cellular structure and function, as well as in the basic process of creating carbohydrates from water and carbon dioxide also help plants to survive in arid conditions. The common process of photosynthesis is called the C3 cycle because carbon is fixed by the plant into a three carbon compound (phosphoglyceric acid) in order to make carbohydrates. Another process of photosynthesis used by desert plants such as bunchgrass fixes the carbon into a four carbon compound (malate or aspartate acid). This C4 process, although not used by many plants, is more efficient in maximizing energy gain than normal photosynthesis.
Pseudoroegneria spicata- bluebunch wheatgrass.
Succulent plants such as stonecrop (Sedum spp.) and cactus can store water in the specialized tissues of plant cells called vacuoles. In some desert plants the cells, unlike in the ordinary varieties of cultivated plants, can also survive extreme dehydration then rehydrate when water is available with little or no damage to the cells. It also helps desert plants to have spines or prickles to deter animals from eating the photosynthetic material it worked so hard to produce. Succulents especially need this protection because their cells are full of water that thirsty animals would love to eat. There also many chemicals that are produced by plants that deter herbivores. Other plants, called phreatophytes, have adapted root systems that are long enough to reach underground water sources. Phreato- means well and -phyte is plants. Tamarisk or salt-cedar is example of a phreatophyte. It is an invasive non-native plant, which can cause severe problems because it robs rivers and aquifers of water particularly in the Southwest US. Native examples of phreatophytes an extensive root system is the big sagebrush (Artemisia tridentata) and Ericamerica nauseosa, whose roots can grow up to 25 meters deep. Because big sagebrush is able to utilize underground water sources it can remain photosynthetic throughout the summer, and is one of the latest blooming of all plants in the Columbia Basin. Other plants cope with the extremes in temperature and rainfall by becoming dormant during the winter or droughts, and escaping difficult times all together. Annual plants, also called ephemerals, only grow for one growing season- from seed to flower to seed and grow only when conditions are at optimum. Some seeds can remain dormant for years and even decades, waiting to germinate when the conditions are favorable. Members of the Liliaceae- Lily family and others such as the genus Lomatium (Apiaceae family), store energy within their roots when they bloom in spring and set seed. The Lomatium macrocarpum or bigseed biscuitroot has 80% or more of the plants tissues are below the soil surface in the roots. This stored energy is enough to survive for most of the year in a dormant state. By late summer the upper parts of the plant and leaves dry out above the ground and the have already matured and blown away, leaving none of the plant's soft tissues exposed to heat and dryness of summer. By the middle of summer many plants in a desert environment are dormant, and show few signs of life. Another strategy of drought avoidance can be seen near any stream or wet area. Some plants only germinate and grow in riparian areas, forming the stark contrast in vegetation seen near any water source in arid regions.
Source: http://www.cwnp.org/adaptations.html
Habitats in Central Washington range from alpine and rainforest in the west, to dry ponderosa forests and shrub steppe to the east. A few plants can live in variety of conditions, and some are restricted to specific habitats.
The plants that grow in the arid eastern region near the Columbia River and the Columbia Basin have a number of traits which help them to be successful in the desert. In the photo to the left is Salvia dorrii and Artemisia tridentata in the Columbia Basin near Moses Coulee, Washington State. Two of the main adaptations of plants in arid environments is having an economical water management system, and maximizing the energy gain from the process of photosynthesis. Some plants, called xerophytes, have adapted their physical structure to suit the rigors such a harsh environment as the desert. 1/3 of the earth's land surface is desert, or about 10% of the total earth surface. Xero- means dry and -phyte means plant. These plants have adapted by having smaller leaves, grow compactly and close to the ground, and a non-porous covering on their leaves such as wax. Hair on the leaves of plants helps to reduce the evaporation of moisture from the surface of leaves by reflecting sunlight and inhibiting air movement. The process of photosynthesis requires both carbon dioxide and water to create energy for the plant. Water is usually absorbed through the roots, and carbon dioxide is absorbed through tiny pores in the plant called stomata. Through the stomata the plant is able to obtain carbon dioxide, but it also loses water by evaporation when the pores are open. Some plants cope with the water loss problem by having fewer stomata, or by having the stomata only open at night when it is cooler. All of these adaptations help to reduce evaporation and transpiration of water. Differences in cellular structure and function, as well as in the basic process of creating carbohydrates from water and carbon dioxide also help plants to survive in arid conditions. The common process of photosynthesis is called the C3 cycle because carbon is fixed by the plant into a three carbon compound (phosphoglyceric acid) in order to make carbohydrates. Another process of photosynthesis used by desert plants such as bunchgrass fixes the carbon into a four carbon compound (malate or aspartate acid). This C4 process, although not used by many plants, is more efficient in maximizing energy gain than normal photosynthesis.
Pseudoroegneria spicata- bluebunch wheatgrass.
Succulent plants such as stonecrop (Sedum spp.) and cactus can store water in the specialized tissues of plant cells called vacuoles. In some desert plants the cells, unlike in the ordinary varieties of cultivated plants, can also survive extreme dehydration then rehydrate when water is available with little or no damage to the cells. It also helps desert plants to have spines or prickles to deter animals from eating the photosynthetic material it worked so hard to produce. Succulents especially need this protection because their cells are full of water that thirsty animals would love to eat. There also many chemicals that are produced by plants that deter herbivores. Other plants, called phreatophytes, have adapted root systems that are long enough to reach underground water sources. Phreato- means well and -phyte is plants. Tamarisk or salt-cedar is example of a phreatophyte. It is an invasive non-native plant, which can cause severe problems because it robs rivers and aquifers of water particularly in the Southwest US. Native examples of phreatophytes an extensive root system is the big sagebrush (Artemisia tridentata) and Ericamerica nauseosa, whose roots can grow up to 25 meters deep. Because big sagebrush is able to utilize underground water sources it can remain photosynthetic throughout the summer, and is one of the latest blooming of all plants in the Columbia Basin. Other plants cope with the extremes in temperature and rainfall by becoming dormant during the winter or droughts, and escaping difficult times all together. Annual plants, also called ephemerals, only grow for one growing season- from seed to flower to seed and grow only when conditions are at optimum. Some seeds can remain dormant for years and even decades, waiting to germinate when the conditions are favorable. Members of the Liliaceae- Lily family and others such as the genus Lomatium (Apiaceae family), store energy within their roots when they bloom in spring and set seed. The Lomatium macrocarpum or bigseed biscuitroot has 80% or more of the plants tissues are below the soil surface in the roots. This stored energy is enough to survive for most of the year in a dormant state. By late summer the upper parts of the plant and leaves dry out above the ground and the have already matured and blown away, leaving none of the plant's soft tissues exposed to heat and dryness of summer. By the middle of summer many plants in a desert environment are dormant, and show few signs of life. Another strategy of drought avoidance can be seen near any stream or wet area. Some plants only germinate and grow in riparian areas, forming the stark contrast in vegetation seen near any water source in arid regions.
Source: http://www.cwnp.org/adaptations.html
Monday, August 23, 2010
Adaptation to dry conditions
This is a plant which is able to survive in very dry conditions. Its sahpe is very different from that of plants found in wet places. Therefore, it is said to be adapted to suit its environment. Environment means surroundings. Adapt means to change so as to fit in with the surroundings.
Plants which are able to survive in dry conditions are called xerophytic. These usually undergo four main types of adaptation, all of them to help conserve water. Conserve means to use up as little as possible.
Take a look at the xerophytic plant. In this case, it is the famous cactus known for its spiky leaves. Did you know that the leaves are one of the most important adaptations of the cactus?
- These leaves are thin, like spines, and curled round so that water losing pores (stomata) are on the inside, away from the sun and wind.
- The roots spread out just under the surface of the soil. This is so that when the rain falls, it rarely soaks more than one metre deep. The roots spread out widely in this shallow layer to take in soil water quickly after a shower
- Desert plants store water to conserve water. Roots and stems are some parts of the desert plants which are able to do so. A round shape can hold more than a long, thin shape so most desert stems have riunded, swollen shapes
- Stems and leaves are designed to reduce water loss by evaporation. They have a waxy coating which keeps water in . The rounded shapes give desert plants snall surface area for their size compared with plants in wet areas. This means thet have less surface to lose water from, so they keep more water witthin them than plants in wetter lands.
Steps in science by R Bateman and P Lidstone Book 3
Chapter 2 page 14
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