FOREST ECOSYSTEMS A forest is best defined as an ecosystem or assemblage of ecosystems dominated by trees and other woody vegetation. These are ecosystems where flora and fauna are seen in abundance. It is a natural ecosystem consisting of dense growth of trees and wild animals They have a large number of living organisms in small area. i.e. density of life in forest ecosystem is high.
The forest ecosystem has two parts: The non-living or abiotic aspects of the forest The living or the biotic aspects of the forest The type of forest depends upon the abiotic conditions at the site. For Example, Forests on mountains and hills differ from those along river valleys. The plants and animals form communities that are specific to each forest type. For instance coniferous trees occur in the Himalayas and Thorn trees grow in arid areas. The snow leopard lives in the Himalayas while the leopard and tiger live in the forests of the rest of India. FOREST ECOSYSTEMS
Structure of forests
The forest floor – D- is where recycling occurs, fungi, insects, bacteria, and earthworms are among the many organisms that break down waste materials and ready them for reuse and recycling throughout the forest system. These are comprised of decomposing leaves, animal droppings, and dead trees and animals. Understory layer- C- of a forest consists of immature trees and small trees that are shorter than the main canopy level of the tree. Understory trees provide shelter for a wide range of animals. The understory is made up of bushes, shrubs, and young trees that have adapted to living in the shade of the canopy. The canopy – B - is the layer where the crowns of most of the forest's trees meet and form shady, protective “umbrella” over the rest of the forest. This is where most of the tree's food is produced as they receive most of the sunlight. Emergents –A- are trees whose crowns emerge above the rest of the canopy. Structure of forests
Evergreen forests grow in the high rainfall areas or in areas where monsoons last for several months. Evergreen plants shed a few of their leaves throughout the year. There is no dry leafless phase as in a deciduous forest. An evergreen forest thus looks green throughout the year. A very little light penetrates down to the forest floor due to the canopy formed by overlapping of trees The forest abounds in animal life and is most rich in insect life. The forest is rich in orchids and ferns. Types of forests
Coniferous Forests grow in places with very cold winters and cool summers. Found in the cold, windy regions around the poles These forests have tall stately conifer trees with needle like leaves and downward sloping branches so that the snow can slip off the branches. They have cones instead of seeds and are called gymnosperms. They get less rain than all the other forests.
Types of forests Tropical Rain Forest: Year-round high temperatures and abundant rainfall makes this a dense, lush forest. Found near the equator. Trees are very tall and the leaves are always green. The hot and humid conditions make tropical rainforests an ideal environment for bacteria and other microorganisms.
Types of forests Deciduous Forests are found in regions with a moderate amount of seasonal rainfall that lasts for only a few month The deciduous trees have large, flat leaves which are shed during the winter and hot summer months.They regain their fresh leaves just before the monsoon, when they grow vigorously in response to the rains.
Functions Forest Ecosyste m Functions prevent the storms by minimizin g the wind speed Maintains local and regional climatic conditions Facilitates eco tourism Reduces surface run off of water and thus prevents floods, soil erosion and soil quality degradation Lowers Carbon Dioxide level and temperature and purifies air Provide habitat to diverse animal species Major source of Timber
DESERT ECOSYSTEMS Deserts, like forests and grasslands, occur all around the world. Desert ecosystems are found in regions receiving an annual rainfall of less than 25cm. They occupy around 17 percent of all land on the planet. Due to very high temperature, intense sunlight and low water availability, flora and fauna are very poorly developed and scarce. Deserts are formed in the driest of environment. The temperature of deserts may vary from very hot as in hot deserts, to a very cold as in cold deserts.
Vegetation is mainly bushes, shrubs, few grasses and rare trees. Leaves and stems of these plants are modified to conserve water. The best known desert plants are the succulents like spiny leaved cacti. Animal life includes insects, reptiles, birds, camels all of whom are adapted to the desert conditions. DESERT ECOSYSTEMS
Features of Desert Ecosystem Deserts receive less than 25 cm of rainfall each year and rainfall is very irregular. Parts of the Sahara can go years without any rain at all. Deserts experience a wide range of temperature from day to night. There is little to absorb the sun's radiation, so it all goes to the soil or sand. Similarly, there is nothing -- cloud cover, vegetation, water -- to hold the warmth, so it quickly goes away. The soil is very dry (sand) and is low in organic nutrients, as few plants live, die and decay there. Desert animals and plants are adapted to reproduce quickly during the brief moist period.
ADAPTATIONS Annual plants have seeds that are able to stay dormant until there is sufficient rainfall to support the young plant. Desert plants which are adapted to drought conditions through reduced leaf size and the dropping of leaves in any conditions both reducing loss via transpiration. In most of the desert plants, there are spines instead of leaves. The roots of most desert plants remain well developed and occur in the top of the soil in order to take maximum possible advantage of any rainfall. Many animals live in burrows, only go out at night, and generally try to avoid the heat. Even lizards, which hunt in the day, avoid the heat of noon. Some desert animals have large ears (desert fox, jack rabbit, hedgehog, and bandicoot) to radiate heat away from their body. The desert squirrel holds its tail over its head like an umbrella to stay cool.
TYPES OF DESERTS TYPESDESCRIPTIO N TEMPERATURESOILLIFE Hot And Dry Desert present around the equator remains hot through out the year summers are extremely hot. no or very little rainfall nights in these deserts are cooler than the day temperature may reach around o C. soil of these deserts is shallow, coarse, rocky and gravely. highly specialized plants have reduced leaves known as spines and thick cuticles to prevent water loss. Common plant species of these deserts are: cacti, prickly pears, The animals found here are mostly nocturnal and get out at night when the desert is cooler. There is a majority of reptiles and insects while animals such as kangaroo rats are also found in majority. These animals tend to remain buried under the ground during the hot days Semiari d Desert moderate versions of hot and dry deserts. Summers similar to that of hot and dry deserts, but temperature does not exceed beyond 38 o C. much cooler at night as compared to the hot and dry deserts. rain is of low concentration but enough to give slight moisture in the air. varies from sandy, to coarse, to shallow and gravely. soil has a very low salt concentration. highly specialized plants both nocturnal and day time animals. Non mammals are reptiles and insects while mammals include: kangaroo rats, rabbits and skunks. Some birds such as borrowing owls are also found here. Coastal Desert moderate deserts where the temperature is normal throughout the year Cool winters and warm summers The average temperature during summers is o C and is around 5 o C during the winters. The rainfall is not very abundant, but on an average 8-13 cm rain falls every year. fine textured, porous and has a moderate salt content. Plants have an extensive root system which draws maximum water when ever there is a rainfall. A part from reptiles amphibians like toads and mammals like coyote are also found here. Insects and birds like golden eagle are also present. Cold Deserts exceptional deserts where the temperature is extremely cold. extremely cold and very long winters The summers are relatively warmer and moist with abundant rainfall. The temperature may reach up to 26 o C during the summers. silty, having a high salt content and is heavy. The soil is also porous at places. There is a large population of plants found here. Most plants are deciduous, tall and have spikes instead of leaves. Animals include: kangaroo rats, pocket mice, jack rabbits, kit fox, deer and coyote. Because of extreme cold there are very few reptiles and amphibians.
GRASSLAND ECOSYSTEMS Grasslands are characterized as lands dominated by grasses rather than large shrubs and trees. Grasslands are found in both temperate and tropical regions of the world but the ecosystems are slightly varying. This area mainly comprises of grasses with very little amount of shrubs and trees. Main vegetation is grasses, legumes and plants belonging to composite family. Many grazing animals, herbivores and insectivores are found in grasslands.
Grasslands cover nearly one third of the earth’s land surface and supply three quarters of the energy that the world needs. grasslands are open and continuous areas made up of many different kinds of grasses, like, Cocksfoot, Upright Brome, Tor Grass GRASSLAND ECOSYSTEMS
Grasslands cover areas where rainfall is usually low and/or the soil depth and quality is poor. The low rainfall prevents the growth of a large number of trees and shrubs, but is sufficient to support the growth of grass cover during the monsoon GRASSLAND ECOSYSTEMS
A variety of grasses, herbs, and several species of insects, birds and mammals are found in grassland ecosystems where food is plentiful after the rains, so that they can store this as fat that they use during the dry period when there is very little to eat. GRASSLAND ECOSYSTEMS
Types Tropical Grasslands Located near the Equator, between tropic of cancer and tropic of Capricorn Also known as Savannahs remain warm year round with marked dry and wet seasons that discourage the creation of forests. Rainfall of 30 to 50 inches a year is concentrated in six to eight months with drought the rest of the year typically have well-drained soils with only a thin layer of humus, often located in the transitional region between rainforest and desert. Temperate Grasslands Located in the mid-latitudes, north of Tropic of cancer and south of tropic of Capricorn. undergo hot summers and cold winters with moderate rainfall distinguished by deep-rooting, perennial tall grasses, flowers and herbs with very few shrubs and trees. Trees are rare as there is not enough moisture for them to grow. Rainfall of 10 to 20 inches a year rich, fertile soils and favorable climate
FUNCTIONS Grasslands function as a habitat for biotic components or living organisms. Grasslands Provide Food Crops can be grown on them to provide the food that people. Grasslands serve as pastures to the livestock.
Features Domination of short plants as a result of dry climate, poor soil, fire and grazing of animals. Growing conditions are favorable only for short season. Fast growth of grass as their growing points are located low down near the soil enabling them to grow back in spite of grazing or overgrazing. Most grasslands are hot and dry. Grasslands change their appearance throughout the year. For Eg: they look lifeless in winters and bloom in spring. Plants and animals are well adapted to the prevalent conditions of grasslands.
AQUATIC ECOSYSTEMS An aquatic ecosystem is an ecosystem located in a body of water. It comprises aquatic fauna, flora and the properties of water too. An aquatic ecosystem is an ecosystem in a body of water. Aquatic ecosystems include oceans, lakes, rivers, streams, estuaries, and wetlands.
Within these aquatic ecosystems are living things that depend on the water for survival, such as fish, plants, and microorganisms. These ecosystems are very fragile and can be easily disturbed by pollution. Aquatic Ecosystem Marine Ecosystem Freshwater Ecosystem AQUATIC ECOSYSTEMS
Marine Ecosystem They cover approximately 71 percent of the earth’s surface. Oceans are the main body of salty water that is further divided into important oceans and smaller seas. Major oceans include the Pacific Ocean, Indian Ocean, Arctic Ocean, Atlantic Ocean and Southern Ocean. Estuaries are places where rivers meet the sea and may be defined as areas where salt water is diluted with fresh water. Due to this dilution, estuaries have high levels of nutrients. The water is neither truly fresh water, since it has salt content, but it is also not consider salt water because it has a lower level of salt than the ocean.
FRESHWATER ECOSYSTEM Very small proportion of earth’s area that is only 0.8 percent of the earth’s surface is covered by them. The water in freshwater ecosystems is non-saline. Approximately 41 percent of the earth’s fishes are found in freshwater ecosystems. Fresh water can be defined as the water that contains a relatively small amount of dissolved chemical compounds. Fresh Water Ecosystems Standing Water (Lentic Envt.) Moving Water (Lotic Envt.)
FRESHWATER ECOSYSTEM Standing Water: Standing water ecosystems are known as Lentic ecosystems such as lakes and ponds. The organisms in lentic ecosystem includes algae, rooted and floating-leaved plants, invertebrates such as crabs, shrimps, crayfish, clams etc, amphibians such as frogs and salamanders; and reptiles like alligators and water snakes. Moving Water: flowing-water ecosystems are known as Lotic ecosystems with water flowing in a unidirectional way. Examples are rivers and streams, which harbor several species of insects and fishes.
Structure of Aquatic Ecosystems
FUNCTIONS they recycle nutrients, purify water, Attenuate/ calm floods, recharge ground water, provide habitats for wildlife, human recreation, important to the tourism industry, especially in coastal regions.