Home  EnviroNews  International Conferences  Picture Gallery  Sponsor  Contact  Search  Site Map



ICPEP-5 (2015) Souvenir

Plants Adaptations in Different Habitats

By: Shivani Srivastava* and Nandita Singh*

 

Adaptations build up in due course and production as a comeback to the ever changing environment. They allow an organism to reduce competition for space and nutrients, reduce predation and increase reproduction. There are however, several factors that can limit these adaptations: availability of water, light, predation and temperature (fig 1) (UNM Department of Biology). Desert plants look very different from plants that live near the ocean or in the mountains. Each type of plant thrives in a different type of environment.

Figure1. The characteristics of the environment that influence a plant success to grow healthy

 

There are five main types of nutrients that plants use are: Nitrogen, Phosphorous, Potassium, Calcium, and Magnesium. Nutrients are substances that provide energy and materials for plants to grow. There are five main types of nutrients that plants use, but not all plants use them equally. For example:

  • A pine tree might use a lot of nitrogen but not very much phosphorous, but

  • A cactus might use a lot of phosphorous and not much nitrogen.

Plants have adaptations to help them survive (live and grow) in different areas. These adaptations might make it very difficult for the plant to survive in a different place. This explains why certain plants are found in one area, but not in another. For example: Desert plants grow far apart so that they can get water and nutrients from a larger area. The sharp spines of a cactus keep animals from eating it. Plants in the high mountains grow close to the ground as protection from the wind. The leaves, stems, roots, and reproductive parts of plants can be very different depending on where the plant lives. In the same way Mosses are soft cushiony plants that live in damp places. Mosses have few or no stems. They are non-vascular plants. They grow close to the ground. They hold soil in a forest and prevent it from being washed away by heavy rains. These plants have no roots so most of them grow close to the ground to keep from drying up. Some mosses, known as sphagnum peat mosses, absorb water like sponges and hold the water in their stems. The mosses often form wet, spongy quilts between the trees in damp forests. Some of the adaptations plants in different environments are following:

 

The Tropical Rainforest:


Global distribution of tropical rain forest in the world
Source: http://www.blueplanetbiomes.org/rainforest.htm

 

The rainforests are forests with tall trees, warm climates, and lots of rain. In some rainforests it rains more than one inch nearly every day of the year. The rainforest are the Earth's oldest living ecosystems. These forests are found in Africa, Asia, Australia, and Central and South America, Mexico and on many of the Pacific, Caribbean, and Indian Ocean Islands. The largest rainforest in the world is the Amazon rainforest in South America.

 

Plants adaptation to rain forest:

For better survive in the hot, wet tropics, plants of the tropical rainforest have had to develop special features called adaptation. Some adaptations of plants are following:

  1. The weather of tropical rainforest is hot and wet; so that trees generally have a thin, smooth bark because they don’t need thick bark to prevent moisture like plants in temperate deciduous forests. The smoothness of the bark makes it difficult for other plants to grow on their surface.

  2. The leaves of rainforest trees have adapted to survive with the large amount of rain. The leaves are big, thick and waxy, and have 'drip tips' to let the rain drain off quickly. Plants need to shed water to avoid growth of fungus and bacteria in the warm, wet tropical rainforest.

  3. The cover of rainforest is connected by creepers and ferns, and mosses grow on the trees. Lianas are climbing woody creeper that wraps rainforest tree. They have their roots in the ground and climbing high into the tree canopy to reach available sunlight.

  4. Many large trees have huge ridges called buttresses near the base that can rise 30 feet high before blending into the trunk. Buttress roots provide extra stability and increase the surface area of a tree so that it can 'breathe in' more carbon dioxide and 'breathe out' more oxygen.

  5. Some trees have above-ground roots called prop or stilt roots which give extra support to the trees. These roots can grow about 85 cm in a month.

  6. Epiphytes are the plants that grow mainly on the twigs, trunks, and even the leaves of rainforest trees so that they can get sunshine. The roots of these plants are not in soil, because of this get their food from air and water. For example: orchids, philodendrons, ferns and bromeliads.

  7. In the rainforests competition for light is intense so that plants arranged their leaves at different angles so that a plant avoids shading its own leaves.

  8. Most stranglers (killer tree) are found in rain forest. The seed of the strangler starts their life as an epiphyte high in the trees. After some time they sends their seedling and long roots down to the ground from where it begins to surround the host tree. It grows quickly and finally suffocates the host: when the host tree dies it leaves a huge upright strangler with a hollow core.
    Source:
    http://www2.montes.upm.es/Dptos/DptoLinguistica/inglesI/RFalltasks07-08.pdf

  9. Young rainforest plant may have red leaves to give them protection from the sunlight whilst their internal organs for photosynthesis are still developing. They act as a sunscreen by reflecting red light whilst the leaf is still young.

The Tropical Savannah:


Global distribution of tropical Savannah in the world
Source: http://www.blueplanetbiomes.org/savanna.htm

 

Savannas are habitually a transitional zone between forest and desert or grassland. Savanna occupies half the global tropical zone (Lehmann et al., 2014). In Savannas summer season is wet for about 6 to 8 month while winter season is dry. The dry season is marked by months of drought and fire but these conditions are essential for the maintenance of savannas. Savannas also maintain an open canopy despite a high tree density. The open canopy allows sufficient light to reach the ground to support an unbroken herbaceous layer consisting primarily of grasses.

Plants adaptation to Tropical Savannah:

Tropical savannas plants survive with dry soil, periodic fires and threats from herbivores. They are very well adapted for these extreme conditions. Some of these adaptations of plants are following:

  1. During the time of sufficient water grasses in tropical savannas grow very quickly and when water becomes insufficient, they turn brown to minimize water loss. They store nutrients and moisture in their roots while waiting for rain. With food and water reserves stored below ground, the grasses are able to survive the effects of fire. This fire stimulates new growth and refills the soil with nutrients.

  2. During the wet season the Baobab tree produce leaves in the form of tiny finger-like clusters. This small size of leaf helps to decrease water loss. The baobab tree can store up to 120,000 litres of water in its trunk and this stored water helps Baobab tree to survive in the long months of drought. It also has thick bark which can protect it against fire and helps it to retain more of its moisture.

  3. The acacia tree can survive drought conditions because it has developed long tap roots that can reach deep, ground water sources. It is also fire resistant. Some varieties re-sprout from the root crown when the above ground portion of the tree is damaged by fire.

  4. The Kangaroo Paw has adapted to dry conditions so it requires less water than most other plants and it can also tolerate high temperatures. These perennial plants are noted for their unique bird attracting flowers.

  5. The Kangaroo Paw has tiny woolly hairs also which hold onto water droplets.

  6. Most of the trees of Savannah have the ability to drop its leaves during dry periods so it can conserve energy and water.

  7. Savannah’s trees have Hydrophilic root system which can extract water from deeper into the ground.

The Taiga:


Global distribution of Taiga in the world
Source: http://www.blueplanetbiomes.org/taiga.htm

 

The taiga is the world's largest terrestrial biome. The main seasons in the taiga are winter and summer. The spring and autumn are so short. There are some lichens and mosses are found in this area, but most plants are coniferous trees. There are not a lot of species of plants in the taiga because of the harsh conditions because not many plants can survive the extreme cold of the taiga winter.

Plants adaptation to Taiga:

The plants that live in the Taiga are better adapted to life in a land of limited sunlight and poor soil nutrition.

  1. Evergreens trees are conical in shape, allowing them to shed heavy snows with minimal damage to the trees' branches. The evergreens also tend to grow tall and close together, which helps protect them from cold and wind.

  2. Lots of trees have very dark green needles which stimulate photosynthesis when temperatures rise.

  3. The trees of Taiga have relatively small surface area of evergreen needles which helps to decrease water lose by evaporation, especially in winter when water is frozen and unavailable to plants.

  4. Evergreen needles have a waxy coating that serves as a protectant against wind and drought.

The Mangroves:


Global distribution of Mangrove forest in the world
Source: commons.wikimedia.org

 

Mangroves are a crossroad where oceans, freshwater, and land area meet. They are among the most productive and complex ecosystems on the planet, growing under environmental conditions that would kill ordinary plants very quickly. Mangroves are important wetlands that are found around the world but whose continued existence is under threat (Wang et al. 2014). They occur in tropical and subtropical intertidal estuarine zones and feature various salt-tolerant plants that fulfil a range of essential ecological functions and provide numerous valuable natural resources (Nagelkerken et al. 2008).

 

Plants adaptation to Mangroves:

Mangrove trees can survive very well in the extreme conditions of estuaries with two key adaptations like the ability to survive in waterlogged and anoxic (no oxygen) soil, and the ability to tolerate brackish waters. Some more adaptations of plants are following:

  1. Mangrove soils are regularly water-logged and loaded with salt. High tides bring marine aquatic and estuarine conditions, while low tides expose mud and roots to aridity, heat and desiccation. To cope with these conditions plants have special vertical roots, called pneumatophores. The pneumatophores form from lateral roots in the mud, often projecting above soil. These roots permit some oxygen to reach the oxygen-starved submerged roots and also can exhibit development of air cavities in root tissues, designs that aid oxygenation of the tissues. The density, size and number of pneumatophores vary per tree. They are green and contain chlorophyll for example e.g. Avicennia, Sonneratia.
    Source: http://www.mangrovewatch.org

  2. The major plant species forming the mangrove ecosystem have aerial roots, commonly prop roots or even stilt roots. Stilt roots are important in aeration and help to attach the plants for e.g. Rhizhophora spp.

  3. Production of viviparous propagule is a reproductive strategy in mangroves that contributes to salt tolerance (Zheng et al. 1999).

  4. The accumulation of low-molecular-weight organic solutes such as sugars, some amino acids, and quaternary ammonium compounds involved in the adaptation to abiotic stress (Hibino et al. 2001).

  5. Many mangrove species, such as the Grey Mangrove and the River Mangrove (common species along the Redlands coast), have leaves with glands that excrete salt.

  6. Some species such as the Grey Mangrove can also tolerate the storage of large amounts of salt in their leaves – which are discarded when the salt load is too high.

  7. Under salinity stress, accumulation of osmoprotectants, especially in the cytosol, chloroplasts and mitochondria minimizes water loss from the leaf cells (Heldt 1999).

  8. Mangroves are able to turn their leaves to reduce the surface area of the leaf exposed to the hot sun. This enables them to reduce water loss through evaporation.

  9. Mangroves with high levels of antioxidants are reported to have greater resistance to this oxidative damage (Jithesh et al. 2006).

  10. Other mangrove species are viviparous. They retain their seeds until after it has germinated and a long, cylindrical propagule has formed. When it has matured to this stage, the parent tree drops it into the water, where it remains dormant until it finds the soil and is able to put out roots.
    Source: http://www.mangroves.godrej.com

The Tundra:

Global distribution of Tundra

Source: http://www.blueplanetbiomes.org/tundra.htm

 

Arctic tundra is a huge and wide ranging biome characterized by short-statured plant population embedded in a thin layer of seasonally thawed soil underlain by permafrost (Walker et al., 2005). Soils in the permafrost region, including tundra contain almost one-half of worldwide soil organic carbon (C), and the maximum percentage of this organic carbon seized in soils that have been perennially frozen since the last glaciations (Tarnocai et al., 2009); Hugelius et al., 2013). There are two different types of tundras, the "Arctic" and the "Alpine tundra." The Arctic tundra is located around the North Pole and the alpine tundra exists in mountains all over the world. They both have extremely cold climates as well as very low diversity of life, as not a lot of animals and plants are suited to survive in such severe conditions.

Plants adaptation to Tundra:

Tundra is a type of biome distinguished by its very cold temperatures, lack of precipitation, and absence of trees. Despite these harsh conditions, several plants have adapted to the tundra's climate. Some adaptations of plants are following:

  1. Tundra also contains permafrost, or permanently frozen soil. The thicker active layer allows roots to penetrate deeper into the soil substrate and thus increases nutrient uptake (Schimel et al. 2004).

  2. The tundra features strong wind (Wielgolaski et al., 1981), generally blowing 30 to 60 miles per hour, making it difficult for many plants to survive.

  3. Plants adapt to the tundra by growing close to the ground, becoming dormant through the winter, reproducing through division, and growing protective coverings. For example Cotton grass, sedge, mosses, lichens, arctic dryads, arctic birches, and arctic poppies all thrive in the tundra

  4. Plants are dark in color---some are even red---this helps them absorb solar heat like Arctic willow. Source: http://tundrabiome5.weebly.com

  5. Some plants are covered with hair which helps keep them warm.

  6. Some plants grow in clumps to protect one another from the wind and cold.

  7. Some plants have dish-like flowers that follow the sun, focusing more solar heat on the center of the flower, helping the plant stay warm for example Arctic poppy.

  8. Small leaves help the plants retain moisture.

  9. Because of the short growing season, most tundra plants are perennials. Perennials do not die in the winter.

  10. Some plants, like lichens, can survive on bare rock because they don't need soil to grow.

  11. Moss can grow in wet places or on bare rock.

  12. Mosses are flowerless plants with very tiny leaves and no roots. Each plant has tiny threadlike rootlets (called rhizoids) that absorb moisture and minerals from the soil. On moist ground hundreds of tiny moss plants form spongy cushions or mats.

  13. Some birds and small mammals use moss to line their nests.

Conclusion:

Plants have several basic needs for better survival. They need solar light, water, air and minerals or nutrients for good growth. They also need to be able to reproduce in order to ensure that their species survives. Some of the main threats to the survival of plants include a lack of sunlight, a lack of water, a lack of good soil and a proper space. In the same way an abundance of water, air, solar radiation (UV rays) and the activities of animals are also harmful for plants. There are many challenges that plants face in order to survive. How well plants adapt to their changing environments will determine their future. It is important to remember, that almost all other living things believe on plants in some way and we all believe on plants being able to adapt to their environments as well.

 

*CSIR-National Botanical Research Institute, Lucknow, India


This article has been reproduced from the Souvenir released during the Fifth International Conference

on Plants & Environmental Pollution (ICPEP-5) held at Lucknow from 24-27 February, 2015.


Home | EnviroNews | International Conferences | Picture Gallery | Sponsor | Join/Contact | What others say | Search | Site Map

Please report broken links and errors on page/website to webmaster@isebindia.com