ECOSYSTEMS 10 SEPTEMBER 2014

Transcription

1 EOSYSTEMS 10 SEPTEMER 2014 Lessn Descriptin In this lessn we: The cncept f ecsystem, structure and ecsystem functining: bitic factrs itic factrs Energy flw Ecturism Summary n ecsystem is a particular area in which living (bitic) and nn-living (abitic) cmpnents INTERT with each ther n ecsystem cnsists f tw main cmpnents: IOTI cmpnent and the IOTI cmpnent IOTI FTOR Physigraphic factrs Slpe spect (slpe directin) Height abve sea level What cncepts yu need t knw. Edaphic factrs (sil) Types f sil lam clay and sand (ph, humus cntent, texture, water retentin capacity and air cntent) Light day length and seasnal changes - phtperidism Temperature effect f day/night and seasns hibernatin, migratin, annuals, deciduus endthermic vs. ectthermic Water hydrphytes, Mesphytes, xerphytes water cycle imprtance f wetland s tmspheric gases Wind IOTI FTOR What cncepts yu need t knw. uttrphic cmpnents prducers Hetertrphic Primary cnsumers - herbivres Secndary cnsumers carnivres, scavenger, mnivre Tertiary cnsumers Decmpsers saprphytes, bacteria

2 Energy Flw Sunlight is the ultimate surce f energy in an ecsystem - phtsynthesis There is a flw f energy thrugh ecsystems starting with the energy f fd in the plants. The cnsumers eat the plants and each ther. ll living rganisms die and they are fd fr the decmpsers. The decmpsers return the nutrients t the sil r water t be used by the prducers. t each trphic level energy is lst. The transfer f energy frm ne rganism t anther is called a fd chain. The psitin an rganism ccupies in a fd chain is called a trphic level. fd chain never ccurs in islatin, but is usually linked t ther fd chains t frm a fd web.

3 Eclgical Pyramids The different trphic levels are ften represented as eclgical pyramids Prducers always make up the base f an eclgical pyramid, and the cnsumers fllw. Three types f eclgical pyramids can be distinguished: Pyramid f numbers Pyramid f bimass Pyramid f energy Pyramid f Numbers pyramid f numbers illustrates: The number f individuals at each trphic level Pyramid f imass Pyramids f bimass shw the ttal mass f the rganisms at each trphic level. Pyramid f Energy Pyramids f energy shw the amunt f energy at each trphic level

4 Nutrient ycles Nutrients are essential fr the grwth and develpment f living rganisms. Nutrients that are needed in fd chains cme frm the atmsphere the hydrsphere and the lithsphere. The cycles include The xygen cycle The carbn cycle The nitrgen cycle The water cycle The Oxygen ycle There is a fixed amunt f xygen. Oxygen needs t circulate thrugh the bisphere. Oxygen is needed fr the prcess f cellular respiratin t release energy Decmpsers need xygen t decmpse rganic matter Large amunt f xygen is disslved in the water f ceans, lakes and rivers Large part f the earth s xygen is fund in rcks Plants use carbn dixide fr phtsynthesis and release xygen

5 The arbn ycle The Nitrgen ycle

6 The Water ycle Ecturism Ecturism can be defined as Respnsible travel t natural areas where the envirnment is cnserved and where the well-being f the lcal peple is imprved Suth frica is a cuntry that is rich in bidiversity, and this is the greatest mtivatin fr turists t visit S With ecturism, certain principles are fllwed: Thrugh planning and impact studies can minimise the negative ecnmic, envirnmental and scial impact Generates greater ecnmic benefits fr lcal peple and enhances their well-being Emplyment pprtunities will reduce pverty fr lcal peple Invlves lcal peple in decisin-making that will affect them Helps prtect bidiversity Prvides the turists with enjyable and meaningful experiences. The lcal culture is then better understd The aim is fr all invlved t benefit. Questin 1 Test Yurself The effect f the length f day n plants is called:. Phttrpism. Phtperidism. estivatin D. Migratin

7 Questin 2 The diagram belw represents a water cycle: Which f the fllwing is true:. 1 = evapuratin ND 4 = transpiratin. 2 = transpiratin ND 3 = cndensatin. 4 = cndensatin ND 1= evapuratin D. 5 = precipitatin ND 2 = cndensatin Questin 3 The histgram alngside represents the number f rganisms in the varius trphic levels f a fd chain. If D represents the prducers, which clumn represents herbivres? D E Questin 4 Why is it difficult t incrprate nitrgen gas frm the atmsphere int the nitrgen cycle f the bisphere? D E Nitrgen is nt very abundant in the atmsphere. Few rganisms can directly utilise atmspheric nitrgen gas. Mst plants d nt require rganic nitrgen cmpunds fr survival. Oceans quickly absrb nitrgen gas. Living rganisms quickly absrb nitrgen gas

8 Questin 5 Organisms that use inrganic nutrients and an utside energy surce t prduce sugars and ther rganic nutrients fr themselves and ther members f the cmmunity are D Questin 6 auttrphs saprphytes hetertrphs herbivres Which f the fllwing fd chains is crrect?. Prducers carnivres herbivres. Plants secndary cnsumers tertiary cnsumers. Prducers herbivres secndary cnsumers D. Plants herbivres primary cnsumers. Questin 7 The greatest rle f plants in the water cycle invlves D Transpiratin Run-ff Questin 8 Precipitatin Perclatin The crrect sequence f eclgical terms frm the simplest t the mst cmplex is D rganism, ppulatin, ecsystem, cmmunity. ppulatin, rganism, ecsystem, cmmunity. rganism, ppulatin, cmmunity, ecsystem. ppulatin, cmmunity, rganism, ecsystem.

9 Questin 1 Imprve yur Skills Use the diagram f the aquatic ecsystem belw and answer the questins that fllw. 1.1 What term can be used t describe the diagram illustrated abve? (1) 1.2 Identify the fllwing: a) The auttrphic rganism b) The secndary cnsumer c) The herbivrus rganism (3) 1.3 Explain why the amunt f available energy decreases at each trphic level. (2) 1.4 Identify 2 abitic factrs frm the diagram (2) In the early 1900 s there were recrds that large grups f crcdiles culd be seen basking in the sun alng the banks f rivers banks in Suth frica. In the 1920 s crcdile leather became very ppular fr making shes, belts and handbags etc and crcdiles were hunted illegaly. The results f the gradual exterminatin f crcdiles had a dramatic effect n the ecsystem because crcdiles have a very varied diet. They have been knwn t eat fish, crabs, and a variety f mammals including small buck and tters. The table belw indicates the change in numbers f crcdiles and tters ver a perid f time.

10 Number f crcdiles and tters frm Year Number f crcdiles Number f tters Draw ne graph t shw bth the crcdile and tter ppulatin frm (9) 1.6 What cnclusin can yu draw frm yur graph? (1) Questin 2 Read the fllwing infrmatin frm an experiment assessing the water quality f the Klip River in Jhannesburg, and answer the questins which fllw. The cllapse f Jhannesburg's Klip River wetland Mcarthy, T, V. rnld, J. Venter, & W.N. Ellery (Suth frican Jurnal f Science 103(9)) The Klip River wetland suth f Jhannesburg has lng been ecnmically imprtant t the regin, initially as a surce f water, and as a purifier f plluted water frm the western sectin f the Witwatersrand industries and mining. The river becmes plluted and the wetland becmes degraded. The prblem is likely t have been wrsened by a falling water table in the area due t excessive grundwater extractin. The wetland has almst lst its ability t remve phsphates and nitrates frm the water, and eutrphicatin prblems can cnsequently be expected t arise in the Vaal River. In additin, it is anticipated that the reeds alng the river will degrade ver the cming years, releasing metals, rganic waste and phsphates int the Vaal River. 2.1 What is a wetland? (1) 2.2 Hw wuld the Klip River wetland purify water? (2) 2.3 What is the link between eutrphicatin and nitrates? (3) 2.4 part frm industries and mining what culd cntribute t a high phsphate and nitrate pllutin prblem in the Klip River? (2) 2.5 What advice wuld yu give t the inhabitants f these areas t minimise the ptential prblems that have been frecast? (2x2) (4) Links