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Balogun Opeyemi
Balogun Opeyemi

Aridity is the major and almost the only environmental factor that defines a desert, Desert is a temperate environment with low water supply for plant growth, this functional water deficit that serves as the primary limitation to which desert organisms must adapt. Adaptations of desert plants are the morphological and behavioral responses of flora to maximize their chances of survival in arid regions. The impression that the desert environment is hostile is strictly an outside viewpoint. Adaptation enables indigenous organisms not merely to survive here, but to thrive. Furthermore, specialized adaptations often result in a requirement for the seasonal drought and heat. Desert plants survive the long rainless periods with three main adaptive strategies: succulence, drought tolerance, and drought evasion. Each of these is a different but effective suite of adaptations for prospering under conditions that would kill plants from other regions. Plants evincing adaptation to arid conditions are termed xerophytes.

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SEMINAR PRESENTATION ON PLANT ADAPTABILITY TO ARID ENVIRONMENTS PRESENTED BY SUPERVISOR: DR. (MRS.) A.A.J. MOFUNANYA CO-ORDINATOR: DR. A.A MARKSON DEPARTMENT OF BOTANY, UNIVERSITY OF CALABAR AUGUST, 2015 UKPONG BLESSING ANIEFIOK MATRIC NO.11/091144032 Design and Implemented by Bhalodew Contact Global Limited www.balodew.com.ng
INTRODUCTION Adaptations are special features that allow a plant to live in a particular place or habitat. These features might make it very difficult for the plant to survive in a different place (Braus 2005). Aridity is the sole factor that defines a desert and is the primary limitation to which desert organisms must adapt (Silverstein et al, 2008). Aridity is region characterized by a severe lack of available water, to the extent of hindering or preventing the growth and development of plant and animal life (Helena and Billings 2011). Aridity results from the presence of dry, descending air.
FIG 1: A NATURAL DESERT PLANTS Desert plants tend to look very different from plants native to other regions. They are often swollen, spiny and have tiny leaves that are rarely bright green. SOURCE: Cornell (1979).
STRATEGIES OF ADAPTATION Life forms may be classified into 4 major categories that represent strategies of adaptation, according to Solbrig and Orians, (1977). Drought-escaping plants: annuals which germinate and grow only when there is sufficient moisture available to complete their life cycle. Only their seeds persist during times of drought. Drought-evading plants: non-succulent perennials which restrict their growth activity to periods when moisture is available. Typically, they are drought-deciduous shrubs which go dormant or die back during dry periods. Drought-enduring plants: evergreen shrubs. Extensive root systems coupled with various morphological and physiological adaptations of their aerial parts enable these hardy xerophytes to maintain growth even in times of extreme water stress. Creosote bush (Larrea tridentata) Drought-resisting plants: succulent perennials. The water stored in their swollen leaves and stems is usually used very sparingly.
ADAPTIVE FEATURES OF ARID PLANTS Desert plants have developed three main adaptive strategies: Succulence: Succulent plants store water in fleshy leaves, stems or roots. Desert rains are often light and brief, and the soil dries rapidly under an intense sun. To cope with these conditions, nearly all succulents have extensive, shallow root systems. The roots of a saguaro extend horizontally about as far as the plant is tall but are rarely more than four inches (10 cm) deep. The water-absorbing roots are mostly within the upper half inch (1.3 cm) (Dimmitt (2009). . Many succulents, possess a water-efficient variant of photosynthesis called Crassulacean Acid Metabolism (CAM). CAM plants open their stomates for gas exchange at night and store carbon dioxide. By day, while the stomates are closed, photosynthesis is conducted using the stored carbon dioxide. Because of the lower temperatures and higher humidity at night, CAM plants lose one-tenth as much water per unit of carbohydrate synthesized as standard C3 plants (Delfine et al, 2001). Drought tolerance: Drought tolerance (or drought dormancy) refers to a plant's ability to withstand desiccation without dying. Plants in this category often shed leaves during dry periods and enter a deep dormancy. Most water loss is from transpiration through leaf surfaces, so dropping leaves conserves water in the stems Dimmitt, (1997). (Figure 1 and 2). Drought avoidance: Annual plants escape unfavorable conditions by not existing. They mature in a single season, then die after channeling all of their life energy into producing seeds instead of reserving some for continued survival.
b.) Just after a rain, this fern is partly hydrated, partly dormant a.) The vegetation here is dried out, but still quite alive Fig. 1 Adaptive strategies of arid plants Source: Dimmitt, (1997).
ADAPTATION MECHANISM OF ARID PLANTS The following are the mechanism responsible for survival of plant in desert environments: Seed Adaptations Growth Response Adaptations Leaves Adaptations Root System Adaptation Stem Modifications Leaves Adaptations: typical leaves of warm desert plants are small and narrow (Dimmitt, 1997 )(Figure 2a), a design that enables leaf temperature to be near ambient temperature even when stomata are closed, so leaves can avoid lethal summertime temperatures during summer drought (Bashan, et al, 2012). Root System Adaptation: the root extremely elongated, e.g. Tall sagebrush has an extensive root system of 25meters from the plant (Laity, 2009) (Figure 3) Stem Modifications: arid plants tend to alter their physical structure. Some of this plant do not have leaves but instead depend on chlorophyll in the outer tissue of their skin to conduct photosynthesis (Nelson, 1976).
FIG 2: FEATURES OF DESERT PLANTS Source: Phillips and Comus (2000); Laity (2009). a.) Schott's Acacia with very small leaves c.) Honey Mesquite remaining green during a dry period b.) Velvet mesquite DEEP roots (to 160 ft!) Microphyllous leaves
FIG. 3: ROOT SYSTEM CACTUS AND ACACIA TREE IN ARID ENVIRONMENT Source: Marasco, et al, (2012)
CONCLUSION The desert environment may seem hostile, but this is purely an outsider's viewpoint that life rarely exist in arid environment. Adaptations enable indigenous plants and animals not merely to survive here, but to thrive most of the time. This work has justify the wrong belief that life in the desert is impossible.
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  • 1. SEMINAR PRESENTATION ON PLANT ADAPTABILITY TO ARID ENVIRONMENTS PRESENTED BY SUPERVISOR: DR. (MRS.) A.A.J. MOFUNANYA CO-ORDINATOR: DR. A.A MARKSON DEPARTMENT OF BOTANY, UNIVERSITY OF CALABAR AUGUST, 2015 UKPONG BLESSING ANIEFIOK MATRIC NO.11/091144032 Design and Implemented by Bhalodew Contact Global Limited www.balodew.com.ng
  • 2. INTRODUCTION Adaptations are special features that allow a plant to live in a particular place or habitat. These features might make it very difficult for the plant to survive in a different place (Braus 2005). Aridity is the sole factor that defines a desert and is the primary limitation to which desert organisms must adapt (Silverstein et al, 2008). Aridity is region characterized by a severe lack of available water, to the extent of hindering or preventing the growth and development of plant and animal life (Helena and Billings 2011). Aridity results from the presence of dry, descending air.
  • 3. FIG 1: A NATURAL DESERT PLANTS Desert plants tend to look very different from plants native to other regions. They are often swollen, spiny and have tiny leaves that are rarely bright green. SOURCE: Cornell (1979).
  • 4. STRATEGIES OF ADAPTATION Life forms may be classified into 4 major categories that represent strategies of adaptation, according to Solbrig and Orians, (1977). Drought-escaping plants: annuals which germinate and grow only when there is sufficient moisture available to complete their life cycle. Only their seeds persist during times of drought. Drought-evading plants: non-succulent perennials which restrict their growth activity to periods when moisture is available. Typically, they are drought-deciduous shrubs which go dormant or die back during dry periods. Drought-enduring plants: evergreen shrubs. Extensive root systems coupled with various morphological and physiological adaptations of their aerial parts enable these hardy xerophytes to maintain growth even in times of extreme water stress. Creosote bush (Larrea tridentata) Drought-resisting plants: succulent perennials. The water stored in their swollen leaves and stems is usually used very sparingly.
  • 5. ADAPTIVE FEATURES OF ARID PLANTS Desert plants have developed three main adaptive strategies: Succulence: Succulent plants store water in fleshy leaves, stems or roots. Desert rains are often light and brief, and the soil dries rapidly under an intense sun. To cope with these conditions, nearly all succulents have extensive, shallow root systems. The roots of a saguaro extend horizontally about as far as the plant is tall but are rarely more than four inches (10 cm) deep. The water-absorbing roots are mostly within the upper half inch (1.3 cm) (Dimmitt (2009). . Many succulents, possess a water-efficient variant of photosynthesis called Crassulacean Acid Metabolism (CAM). CAM plants open their stomates for gas exchange at night and store carbon dioxide. By day, while the stomates are closed, photosynthesis is conducted using the stored carbon dioxide. Because of the lower temperatures and higher humidity at night, CAM plants lose one-tenth as much water per unit of carbohydrate synthesized as standard C3 plants (Delfine et al, 2001). Drought tolerance: Drought tolerance (or drought dormancy) refers to a plant's ability to withstand desiccation without dying. Plants in this category often shed leaves during dry periods and enter a deep dormancy. Most water loss is from transpiration through leaf surfaces, so dropping leaves conserves water in the stems Dimmitt, (1997). (Figure 1 and 2). Drought avoidance: Annual plants escape unfavorable conditions by not existing. They mature in a single season, then die after channeling all of their life energy into producing seeds instead of reserving some for continued survival.
  • 6. b.) Just after a rain, this fern is partly hydrated, partly dormant a.) The vegetation here is dried out, but still quite alive Fig. 1 Adaptive strategies of arid plants Source: Dimmitt, (1997).
  • 7. ADAPTATION MECHANISM OF ARID PLANTS The following are the mechanism responsible for survival of plant in desert environments: Seed Adaptations Growth Response Adaptations Leaves Adaptations Root System Adaptation Stem Modifications Leaves Adaptations: typical leaves of warm desert plants are small and narrow (Dimmitt, 1997 )(Figure 2a), a design that enables leaf temperature to be near ambient temperature even when stomata are closed, so leaves can avoid lethal summertime temperatures during summer drought (Bashan, et al, 2012). Root System Adaptation: the root extremely elongated, e.g. Tall sagebrush has an extensive root system of 25meters from the plant (Laity, 2009) (Figure 3) Stem Modifications: arid plants tend to alter their physical structure. Some of this plant do not have leaves but instead depend on chlorophyll in the outer tissue of their skin to conduct photosynthesis (Nelson, 1976).
  • 8. FIG 2: FEATURES OF DESERT PLANTS Source: Phillips and Comus (2000); Laity (2009). a.) Schott's Acacia with very small leaves c.) Honey Mesquite remaining green during a dry period b.) Velvet mesquite DEEP roots (to 160 ft!) Microphyllous leaves
  • 9. FIG. 3: ROOT SYSTEM CACTUS AND ACACIA TREE IN ARID ENVIRONMENT Source: Marasco, et al, (2012)
  • 10. CONCLUSION The desert environment may seem hostile, but this is purely an outsider's viewpoint that life rarely exist in arid environment. Adaptations enable indigenous plants and animals not merely to survive here, but to thrive most of the time. This work has justify the wrong belief that life in the desert is impossible.