Forest Ecosystem

FOREST ECOSYSTEM

A fore forest st is more more than than just just the tree trees. s.

A sing single le fores forestt is a

complete, functioning ecosystem that supports innumerable plant and animal animal specie speciess as well as earth, earth, water, water, and air subsys subsystems tems..

The

subs subsys yste tems ms prov provid idee the the esse essenc ncee of life life of the the fore forest st and and are are in themselves themselves a byproduct byproduct of forest forest systems, systems, all of which are reciprocal reciprocal and interdependent.

A fore forest st ecos ecosys yste tem m is a comp comple lex x of livi living ng and and nonnon-li livi ving ng elemen elements ts which interre interrelat late. e. An ecosyste ecosystem m can be small small (like your  your   backyard)  backyard) or large (like (like the planet planet earth). It depends depends on the range of  individual species or group of species being discussed (e.g.: a salmon stock or a forest type), geology (e.g.: a mountain range or watershed), and other issues.

3.13.1.Types of Characteristic Features

a) Temperatu Temperature re Fores Forestt Ec Ecosys osystem tem

The The temp temper erat atur uree fore forest st ecos ecosys yste tem m is very very impo import rtan antt on Earth Earth.. Temperate forests are in regions where the climate changes a lot from summer summer to winter. winter. Tropical Tropical rain rain forests forests are in regions regions where the climate climate stays constan constantt all year long. long. Temperate Temperate forests forests are almost almost alwa always ys made made of two two type typess of tree trees, s, deci decidu duou ouss and and ever evergr gree een. n.

Deci Decidu duou ouss tree treess are are tree treess tht tht lose lose thei theirr leav leaves es in the the wint winter er.. Evergreens are trees that keep them all year long, like pine trees. Forests Forests can either either be one or the other, other, or a combinat combination ion of both. both. A fourth fourth kind of forest forest is a temperate temperate rain rain forest. forest. These are found found in Califo Californi rnia, a, Oregon Oregon and Washingt Washington on in the United United States. States.

These These

forests are made of redwoods and sequoias, the tallest trees in the world. The amount of rainfall in an area determines if a forest is   present. present. If there is enough enough rain to support support trees, trees, then a forest will will usually develop. develop. Otherwise, the region region will become become grasslands.

b) The Tropical Tropical Rain Rain Forest Forest Ecosy Ecosystem stem

Tropical rain forests are one of the most important areas on Earth. These special ecosystems are homes to thousands of species animals and plants plants..

Contra Contrary ry to popula popularr belief belief,, rain forests forests are not only

densel densely y packed packed plants plants,, but are also full full of

tall tall trees that that form a

ceilin ceiling g from the Sun above. above. This This ceilin ceiling g keeps small small plants plants from growin growing. g.

Areas Areas where where sunligh sunlightt can reach the surfac surfacee are full of 

interesting plants.

Structure of Forest Ecosystems

Diffe Differen rentt orga organi nism smss exis existt with within in the the fores forestt laye layers rs..

Thes Thesee

organ organis isms ms inte interac ractt with with each each othe otherr and and thei theirr surr surrou ound nds. s.

Each Each

organi organism sm has a role role or niche niche in sustain sustaining ing the ecosy ecosyste stem. m.

Some Some

  provide food for other organisms, other provide shelter or control  populations trough predation.

Producers

All living living organi organisms sms intake intake energy energy in order to survive survive.. In a fore forest st ecos ecosys yste tem, m, thre threes es and and othe otherr plan plants ts get get thei theirr ener energy gy from from sunlight. Plants produce their their own food, in in the form of carbohydrates. carbohydrates. Plants are, therefore, called the primary producers, since they produce the basic foodstuffs for other organisms within food chains and food webs. Photosynth Photosynthesis esis is the chemical chemical reaction reaction that allows allows plants to  produce their own food.

Consumers

Animals Animals cannot cannot produce their their own food. food. They must must consume food food sour source cess for for the the ener energy gy they they need need to surv surviv ive. e.

All All anim animas as,,

incl includ udin ing g mamm mammal als, s, inse insect cts, s, and and bird birdss are are call called ed cons consum umer ers. s. Consumers rely on plants and other other animals as a food source. source. Details of these animals in a forest ecosystem have been given earlier.

Prim Primar ary y cons consum umes es only only eat eat plan plants ts and and are are refe referr rred ed to as herbivores. herbivores. Second Second consumers consumers are referred to as carnivores carnivores and feed on herbivores. herbivores. Tertiary Tertiary consumers consumers are carnivores carnivores that feed on other  other  carnivores. Omnivores eat both plant and animal matter.

Decomposers

Leaves, needless, and old branches fall to the forest floor as trees grow. grow. Eventualit Eventuality y all plants plants and animals animals die. die. These materia materials ls are decomposed by worms, microbes, fungi, ants, and other bugs. Decomp Decompose osers rs break break these these items items down down into into their their smalle smallest st primary primary elements to be used again. Decomposers are important in they sustain the nutrient cycle of ecosystems.

Humans are part of Forest ecosystem

Humans are consumers We get food and materials from forests. Beca Becaus usee of this this,, we are are a part part of the the fore forest st ecos ecosys yste tem. m.Hu Huma man n consumption alters forest ecosystems. Human intervention may be necessary to sustain forest communities under the increased pressure of human use.

3.13.3

The components of an ecosystem are connected in a complex web.How does the forest web sustain itself ?

What What star starts ts the the food food cucl cuclee in the the fore forest sts. s.?? We will will exam examin inee a vari variet ety y of cycle ycless that hat exist xistss in fore forest st ecosystems,and their functions.

(a)

Energy cycle

The sun starts rts the foo food pyramid by fue fueling the   photosynthesis process. The sun’s energy constantly changes form as plants convert light into plant biomass ,which is then consum consumed ed by other other organi organisms sms.. Plants Plants perform perform an import important ant action of energy fixation, which is the basis of all life.

(b)

Water Cycle

Water is constan constantly tly cycling. cycling. The water water cycle collects collects,,  purifies,  purifies, and distribut distributes es the world’s water. water. Without Without the water  cycle, cycle, life on earth would would be impossibl impossible. e. Trees and plants plants are   part part of this this water water cycl cycle. e.

Tran Transp spir irat atio ion n is the cont contro roll lled ed

evaporation progress by which plants lose H2Q through the   pores pores in their leaf structures structures.. A full-grown full-grown tree can transpire transpire hundreds of gallons of water a day during growing season. (c)

Nutrient Cycle

We already know trees rely on nutrients like phosphorous and nitrogen nitrogen for healthy healthy growth growth and reproduc reproduction. tion. Throughou Throughoutt a tree’s life stages, they constantly use and return nutrients to the soil. soil.

Nutrie Nutrient nt cycles cycles regula regularly rly transfo transform rm nutrie nutrients nts from the

non-living environment.

3.13.2.Change in Forest Composition and Structure

Forest Forest compos compositi ition on and struct structure ure consta constantl ntly y change change due to natural processes and disturbances.

(i)

Natural Succession

Succ Succes essi sion on is a natu natural ral proc proces esss that that alte alters rs a fores forest‘ t‘ss compos compositi ition on and structu structure re over over time. time.

Throug Through h succes successio sion, n,

ecosystems constanly constanly undergo undergo change. change. One plant plant community replaced another plant community as species present decline and die. die. This This progressi progressive ve replace replacemen mentt of one type type of plant plant commun community ity with with anothe anotherr is called called succes successio sion. n. Distur Disturban bance ce  plays a role in driving succession.

Succession goes through a series of stages. stages. Early success ional ional stages stages usuall usually y consis consistt of faster faster-gro -growin wing, g, shorte shorter-li r-lived ved trees like like aspen. Later stages stages are made up of slower slower growing growing trees that live longer lifespans, such as oak, sugar maple, or  hemlock.

(ii)

Natural Disturbance

Disturbance is considered anything that alters the current composition of of the forest. Wind throw, wildfire, frost, insects, herbiv herbivore ores, s, and diseas diseasee are consid considere ered d natura naturall distur disturban bances ces..

Disturba rbances can be small to large rge scale events. The composition of the the forest is altered by disturbance. Wind throw may remove remove severa severall trees from the forest forest..

Some speci species es of 

trees are more susceptible to wind throw, like aspen.

Intense wildfires are a disturbance that can eliminate all trees trees in an area. Dry, Dry, hot weather weather,, a buildu buildup p of dead dead plant plant material and lightning start many natural wildfires. Wildfires are part of the natural success ional process of forests.

Other climate disturbances also change forests. A winter  with with temper temperatu atures res below below zero zero for severa severall consec consecuti utive ve days days weakens some trees, making them more susceptible to diseases. At the same time, a hot dry summer in Wisconsin causes water  stress in some some trees. While While this may not kill kill plants plants and trees right a way it will will weaken weaken them. This makes makes it harder to store food for the winter, or to fight off disease and pests.

Insects can alter the composition and structure of forests   by removing removing entire entire species species from an area. area. Herbivores Herbivores such such as deer deer browse browse tree tree bark, bark, branch branches, es, and young young seedli seedlings ngs.. This This  browsing severely affects the tree’s growth potential and limits the ability ability of the next generat generation ion to regenerate regenerate.. Browsing Browsing by insects and herbivores weakens and exposes trees to natural and exotic diseases.

Although natural disturbance causes dramatic changes in forest forests, s, these these events events are are impor importan tantt for fore forest st healt health. h. These These changes changes provide provide opportuniti opportunities es for the species species to change over  time.

(iii)

Human Disturbance

Huma Human n are are chan change ged d by huma human n dist distur urba banc nce. e. For For over  over  10,0 10,000 00 year years, s, huma humans ns have have influ influen ence ced d the the comp compos osit itio ion n of  forests by both both the introduction and removal of species. When humans remove trees, this opens the overstory to suppressed trees, leading to quick changes in structure and function.

Human change often mimics natural forest changes but at a much faster faster pace. The use of many managemen managementt techniques techniques are often meant to speed along the natural succession proceed of forests and alter the composition and structure. Examples of  human disturbances are forest logging and thinning, fires, and the introduction of exotic species.

3.14. GRASSLAND

ECOSYSTEM:

CHARACTERISTIC FEATURES

TYPES

AND

Over one quarter of the Earth’s surface is covered by grasslands grasslands..

Grasslands Grasslands are found found on every every continen continentt except except

Antarctica, and they make up most ofAfrica and Asia. There are several types of grassland. They are distinguished distinguished by different names like plains, prairies, savannas and pampas.

Grassl Grassland andss develo develop p where where there there isn’t isn’t enough enough rain rain for  forests but too much rain for deserts. Grasslands are filled with grass. There are many types of grass, grass, though. though. Fields of wheat wheat are considered grasslands, even though they are ar e often cultivated   by people. people. Grass is special special because because it grows grows underneat underneath h the ground. During cold periods periods the grass can stay stay dormant until it warms up.

The annual rainfall ranges between 25 to 75 cm and is usually usually seasonal seasonal;; while temperat temperatures ures are moderate moderate.. Summer  Summer  drought and winter blizzards can be severe, with periodic fire devastati devastation on in these biomes. biomes. The dominant dominant plant plant species species are short and tall grasses and other flowering plants, many of which are perennials perennials with extensiv extensively ely developed developed roots. roots. The soils soils of  these grasslands often have a deep organic layer.

Structure and Function

The different components of a grassland ecosystem are:

Abiotic Component

These are the nutrients present in the soil and other components  present in the air. The basic elements are supplied by carbon dioxide, dioxide, water, nitrogen, sulphates sulphates etc. All these are present present in atmosphere and soil of that location.

Biotic components

In gras grassl slan ands ds the the produ produce cers rs are are main mainly ly gras grasse ses, s, herb herbss and and shrubs. All these contribute to production of biomass. Common species of grass are sp. Cynodon etc. As regards the consumers the basic basic three three types types are Primary Primary,, Second Secondary ary and Tertia Tertiary. ry. Prima Primary ry cons consum umer erss feed feed dire direct ctly ly on gras grass. s. All All the the graz grazin ing g animals as well as the termites and insects come under this catego category. ry. The second secondary ary consum consumers ers feed feed on these these primary primary cons consum umer erss and and incl includ udee snak snakes es,, liza lizard rdss etc. etc. The The tert tertia iary ry consumers feed on secondary consumers. Examples are eagles and vultures. Fungi, bacteria etc are the decomposers. These micr micro o orga organi nism smss cons consum umee the the dead dead bodi bodies es and and brin bring g the the nutrients back to the soil.

DESERT ECOSYSTEM Types and Characteristic Characteristic Features

One can find at least one desert on every continent except Europe and Antarctica. Each desert is different in some way,  but they all have one thing in common. In order for and area of  land to be considered a desert, it must receive less than 10 inches of water a year. How come deserts get such little water? Clouds are scarce in these regions and we all know that without clouds, there can’t  be rain, snow or any other precipitation. But clouds also serve another purpose – they block out some of the Sun. The desert gets mighty hot during the day because the Sun beats down on the sand. At night, the deserts gets very cold, because there aren’t clouds around to keep the heat from escaping to the atmosphere. Ther Theree are plen plenty ty of diffe differen rence cess betw betwee een n the the dese deserts rts of the the world. Some deserts are made of very fine, red sand, others consist consist of sand mixed with pebbles and rocks. The desert sand started started out as rock, but years of weathering weathering by wind and water  has has crea create ted d dune duness in the the dese desert rts. s. Thes Thesee sand sandss are are most mostly ly minerals, and sometimes oil can be found hidden deep within the rocks.

Structure and Function

The different components of a desert ecosystem are:

(A)Abiotic Component

The abiotic component includes the nutrients present in the soil and the aerial environment. The characteristic feature f eature of the abiotic component is lack of organic matter in the soil and scarcity of water.

(B)Biotic Component

The various biotic components representing three functional groups are :

(a) Producer organisms

The producers are mainly shrubs or bushes, some grasses and a few trees. The most famous desert plant is the cactus. There are many species of cacti. The saguaro cactus is the tall, pole shaped cactus. The saguaro can grow up to 40 feet tall. It can hold several tons of water inside its soft tissue. Like all cacti, the saguaro has a thick, waxy layer that protects it from the Sun. Other succulents include the desert rose and the living rock. This strange plant looks like a spiny rock. It’s disguise protects it from predators. The welwitschia is a weird looking plant. It has two long leaves and a big root. This plant is actually a type of tree and it can live for thousands of years.

There are many other kinds of desert plants. Some of them have thorns, others have beautiful flowers and deadly poisons. Even in the worst conditions, these plants continue to thrive. (b)Consumers

These include animals such as insects and reptiles. Besides them, some rodents, birds and some mammalian vertebrates are also found.



Desert Insects and Arachnids :

There are plenty of insects in the desert. One of the most common and destructive pests is the locust. A locust is a special type of grasshopper. They travel from place to place, eating all the vegetation they find. Locusts can destroy many crops in a single day.  Not all desert insects are bad, though. The yucca moth is very important to the yucca plant, because it carries pollen from the flower to the stigma. The darkling beetle has a hard, white, wing case that reflects the Sun’s energy. This allows the bug to look for food during the day. Ther Theree are are also also seve severa rall spec specie iess of ants ants in the the dese desert rt.. The The harvester ants gather seeds and store them for use during the dry season. And the honeypot ants have a very weird habit. Some members of the colony eat large amounts of sugar, so

much that their abdomens get too large for them to move. The rest of the colony feeds off this sugar. There are also arachnids in the desert. Spiders are the most notabl notablee arachn arachnids ids,, but scorpi scorpions ons also also belong belong in this this group. group. Some species of scorpions have poison in their sharp tails. They sting heir predators and their prey with the piercing tip.

Desert Reptiles

Reptiles are some of the most interesting creatures of the desert. Reptiles can withstand the extreme temperatures because they can control their body temperatures very easily. You can put most of the desert reptiles into one of two categories; snakes and lizards. Many Many spec specie iess of ratt rattle lesn snak akes es can can be foun found d in the the dese desert rt.. Rattlesnakes have a noisy rattle they use to warn enemies to stay stay away. away. If the predat predator or ins’t ins’t carefu careful, l, the rattle rattlesna snake ke will will strike, injecting venom with its sharp fangs. Other desert snakes include the cobra, kingsnake and the hognose. Lizards make up the second category of desert reptiles. They are probably the most bizarre looking animals in the desert. While some change colors and have sharp scales for defense, others change their appearance to look more threatening.

One such creature is the frilled lizard. When enemies are near, the lizard opens its mouth, unveiling a wide frill. This makes the lizard lizard look bigger bigger and scarier. scarier. The shingleb shingleback ack has a tail with the same shape as its head. When a predator bites at the tail, the shingleback turns around and bites back. There are only two venomous lizards in the world, and one of  them is the gila monster. It has a very painful bite.



Desert Mammals

Like the other inhabitants of the desert, birds come up with inte intere rest stin ing g ways ways to surv surviv ivee in the the harsh harsh clima climate te.. The The sand sand grouse has special feathers that soak up water. It can then carry the water to its young trapped in the nest. Other Other birds, birds, like like the gila gila woodpe woodpecke cker, r, depend depend on the giant giant saguaro s its home. This woodpecker hollows out a hole in the cactus for a nest. The cool, damp inside is safe for the babies. The roadrunner is probably the most well known desert bird. Galahs are interesting birds, in that the number of eggs they lay depends on the climate. If the desert is in a drought, they don’t lay any. However, during more tolerable years, the galah may lay as many as five eggs.



Desert Mammals

Many desert desert mammals mammals are burrowers burrowers.. They dig dig holes in in the ground ground and stay there there during the the hot days. days. They return return to the surface surface at night to feed. feed. Hamsters, Hamsters, rats and their their relatives relatives are all burrowers. Not only do the burrows keep the animals cool, cool, they are also a great place to store food.

Of course, course, not not all animals animals live live in holes holes in the ground. ground. The kangaroo and spicy anteater both live in the Augralian desert region. Spiny anteaters anteaters are unusual unusual mammals because because they lay eggs.

The desert is also full of wild horses, foxes and jackals, which are part part of the canine canine family family.. And we can’t can’t forget forget the cats. cats. Lions are are found all over over the deserts deserts of southern southern Africa. Africa. They get their water from the blood of their prey. 

Camels – The Cars of the Desert

Camels Camels could be included included in the mammal mammal section. section. Camels Camels are the cars of the the desert. Without them, people would would have great diffic difficult ulty y crossing crossing the hot terrai terrain. n.

There There are two types types of 

camels: Bactrian and dromedary. The main difference between between the two is the number number of humps. humps. Dromedarie Dromedariess have one hump and bactrian have have two. Both kinds are are used by people, people, but only  bactrians are found in the wild.

Camels Camels are great great transp transport ortati ation on becaus becausee they they use very very little little water. Camels can withstand very high temperatures without sweati sweating. ng. They They also also store store fat fat in their their humps humps for for food. food. If a Bactrian camel travels a long distance without eating, its hump will actually get smaller.

(c) Decomposers

Due to poor vegetation the amount of dead organic matter is very very less. less. As a resu result lt the the deco decompo mposer serss are very very few. few.

The

common decomposers are some bacteria and fungi, most of  which are thermophillic.

3.16 AQUATIC ECOSYSTEM: TYPES,

CHARACTERISTIC FEATURES, STRUCTURE AND FUNCTION

3.16.2.Lakes

A lake lake is a body body of wate waterr comp comple lete tely ly surro surroun unde ded d by land land.. Lakes Lakes can either either be salty salty or fresh water water.. Most Most lakes are in   place placess where where glaciers glaciers used used to exist. exist. When When a glacie glacierr moves forward, it carves away a deep valley and when the ice melts it forms a lake in the valley. Other lakes are are formed in craters or  or  when a river changes its course.

Lakes are short-lived surface features because the water can sink into into the ground ground or evaporate evaporate into the the sky. In order for a like to remain, it must be constantly fed by a river or rainfall.

3.16.3.Rivers and Streams

Rive Rivers rs are are very very impo import rtan antt to Earth Earth beca becaus usee they they are majo major  r  force rces

that

shaps

the

landscape.

Also,

hey

provide

transp transport ortati ation on and water water for drinki drinking ng washin washing g and farming farming.. Rivers can flow on land or underground in deserts and seas.

Rivers may come from mountain springs, melting glaciers or  lakes.

A river’s contribution to the cycle is that it collects water from the ground and returns it to the ocean. The water w drink is  bout 3 billion years old because it has been recycled over and over since the first rainfall.

A delta is where where a river meets meets the sea. Usually Usually the river river flows more slowly at the delta than at its start because it deposits sediment. Sediment can be anything from mud, sand and and every rock rock fragments fragments..

A special special environ environmen mentt is created created when the

fresh water from the river mixes with the salty ocean water. This environment is called estuary.

The longest river is the Nile River in Africa, and the Amazon River River in South America America carries the most most water. The muddiest muddiest river is the Yellow River in China.

3.16.4Estuaries

An estuary is an unique environment where fresh water and salt water come together. Estuaries are found on the coast coast where a river or bay or other sources of fresh water has access to the open sea. A good example of an estuary is a salt marsh that can

 be found found close to the coast. coast. Another Another example example is when a river  feeds directly into the ocean. ocean. The largest estuary estuary in the United States is the Chesapeake bay estuary on the east coast of the U.S.

Estuaries are affected by the tides. tides. So, there can be be changes of  sali salini nity ty,, temp tempera eratu ture re and and othe otherr phys physic ical al prop proper erti ties es in an estuarial system which means the organisms there must be very tolerant tolerant to change. change. Even with that that consideration consideration,, estuaries estuaries are among the most fertile places in the world. All kinds of plants and animals animals live there. there. When looking looking at estuarie estuaries, s, scientists scientists quickly realized that these areas were extremely nutrient-rich  because of sediment deposit of rivers, creeks or streams feeding into into the salt salt water water environ environmen ment. t.

Unfort Unfortuna unatel tely, y, estuari estuaries es

haven’t haven’t always always been seen as valuabl valuable. e. In the past, past, they were were seen as worthless and were used as dumps, or places for new land develo development pment (by fillin filling g in the marshy marshy area). However, However, now the systems are being set up to establish, manage and maintain estuary reserves, and to provide for their long-term stewardship.

3.16.5Pond Ecosystem

The definition of a pond is any body of water over 1m square that is inundated, “wet” for more than8 months of the year.

That definition tells us quite a lot about a ponds ecosystem. The first is obvious, it doesn’t have to be large to be useful, in fact even a bird bath will be visited by the water boatman if he is in need of a place to rest and eat.

If a pond does dry out it isn’t a disaster, both plants and animals have adapted to this eventuality.

The pond is the most valuable as far as wildlife is concerned, if  the pond is reasonably shallow (no more than 90 cm) and very well planted it will support a vast array of animals and plants.

Some potential inhabitants and visitors are frogs, Newts, Toads, Foxes, Foxes, Hedgeh Hedgehogs ogs,, Badger Badgerss birds birds,, Bats, Bats, Grass Grass snakes snakes,, Slow Slow worms, Water Voles, Birds of all sizes, Great diving beetles, Water boatman, Dragon fly Larvae and adults, Damsel flys, Daphnia, Daphnia, Cyclops, Cyclops, Spiders, Spiders, Water scorpion (not dangerous), dangerous), zoo plankton, Wirlygig beetle, Pond skaters, Lace wings. The  potential list of insects and other small things is huge.