SNAB A2 Ecology Coursework

8/16/2019 SNAB A2 Ecology Coursework

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SNAB A2 EcologyCoursework


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Abstract This study was designed to explore the efect o soil depth on the growth o dandelion

Taraxacu! o"cinale# lea width in a grassland habitat$ To co!pare the efect o soildepth two diferent sa!ple areas were chosen% tra!pled grass & near the !ain pathwalk or pedestrians and non& tra!pled& near trees where tra!pling is less re'uent$ A

2(c! 'uadrat was used to collect data on the a)erage dandelion lea width within thesa!pled areas using the !ethod o rando! sa!pling$ *or each 'uadrat within thesa!pled area readings o the soil depth and the soil te!perature were taken$ A tergathering all !y results + carried out a ,ann -hitney . test which showed a strongnegati)e correlation between the two )ariables suggesting that% as the soil depthincreases the a)erage width o dandelion lea)es increases$ ,y !ethod had a ewli!itations such as the irregularity o soil te!perature% howe)er this could bei!pro)ed by taking regular readings o the soil te!perature e$g$ once e)ery 2/ hours$

0esearch and rationale-hile taking a 1og one !orning through reenwich 3ark + realised that the si4es o thedandelion lea)es )aried ro! one area to another$ +t appeared to be that the widths othe dandelion lea)es were noticeably larger in the parts o the 5eld where tra!plingwas less re'uent in contrast to the dandelion lea)es that were located near the !ainpathway pro)ided or the pedestrians$ A ter obser)ing + noticed that it was )eryco!!on or the pedestrians to wander away ro! the path% whether or a 'uickerroute or !erely or walking their dogs$ + also realised that children pre erred to run of

the pathway to play on the nearby grass6 this tra!pling would result in theco!pression o the soil causing the soil depth to decrease$ Another dile!!a thatcould result ro! treading on the grass would be an interruption in the processes oecological succession$

Ecological successionSuccession is the process o change in the structure o species in an ecologicalco!!unity where ani!als and plants colonise a speci5c area and o)er ti!e theseplants and ani!als are replaced by !ore )aried co!!unities 789$ Succession takesplace due to a particular change o en)iron!ental actors in a speci5c place% thisen)iron!ental change could be either physical or che!ical$ A change in surroundingso a habitat causes all the diferent species to adapt to a high le)el o co!petition inorder to thri)e under a certain set o conditions & which i are changed & are replacedby a set o better adapted species$ As the process o succession continues the plantsgrowing within the co!!unity not only beco!e larger in si4e6 but their structures alsochange to beco!e !ore co!plex$ This en)iron!ental change is afected by two !ain

actors$

The 5rst is biotic actors li)ing# which include disease6 predation6 territoryco!petition and a)ailability o !ates$ There are )ery ew biotic actors that couldha)e an efect on the growth o dandelions such as co!petition or e)en disease$:owe)er this is )ery unlikely because reenwich 3ark has )arious pro essionals whose


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roles include looking a ter the well being o all organis!s in the park$ + an outburst odisease so!ehow afected the plants the representati)es responsible or the parkwould !ake sure to re!o)e the species afecting the well being o the co!!unity$

The second is abiotic non&li)ing# actors which include soil te!perature6 soil structureand !ineral content6 light intensity6 water a)ailability and oxygen a)ailability$ Abiotic

actors are !ore likely to afect the !a1ority o plants including the growth o

dandelions rather than biotic actors$ This is because abiotic actors6 such as watera)ailability and soil structure will ha)e a direct afect on the growth o plants such asdandelions$

Since so!e land which is not yet colonised has )ery ew nutrients due to the poor'uality o the lands; soil6 pioneer species such as dandelions; o ten ha)e adaptationssuch as long roots or long nodes which help the! to take ad)antage o their habitatby !axi!ising their abilities to absorb the highest le)el o !inerals; or their bestgrowth$ -hile dandelions ha)e the adaptations o a pioneer species on bear land6 theyalso ha)e the ability to re!ain as a species in the long&ter! o )egetation$ Thedandelions ability to grow in a healthy habitat is afected by the 'uality o the abiotic

actors which are pro)ided or the!$ This !eans that abiotic actors such as the soildepth# ha)e signi5cant i!pact on the extent to which dandelion lea)es are able togrow$

As ti!e progresses the species colonising an area are replaced by species that are!ore co!plex with new adaptations$ Towards the late stages o succession when!ore species colonise an area6 the colonised co!!unity will ha)e high le)els obiodi)ersity because o all the diferent species that )ary$

The process o succession !ay afect a certain type o species in a negati)e way$ + acertain plant begins to grow in a new area6 this !ay attract a higher population opredators that are co!peting or this particular prey which !ay afect the growth othat species$ *or instance6 i the growth o dandelion lea)es is in act afected by thesoil depth6 then the presence o a new species that attracts !any ani!als could cause!ore tra!pling in the area$ The ani!als treading on the grass could cause a decreasein the soil depth in places where the dandelions are growing$ :owe)er this actor isless likely to ha)e an i!pact in reenwich 3ark because the co!!unity is well!anaged by the stafs that !ake sure the ani!als are only allowed to roa! withincertain areas which should contain the ood and !inerals needed or their sur)i)al$

Because o how old reenwich 3ark ages back too6 + expected to 5nd theco!!unity in the late stages o succession but was surprised by the earlystages it was still in$ + think that this !ay ha)e been caused by theinter)ention o the staf looking a ter the park in order to pre)ent thespecies in the co!!unity ro! o)er growing$ This gi)es an opportunity

or all the species in the habitat to thri)e !ore e"ciently without the

li!itations o ood and territory afecting their growth$ The i!portance o dandelions


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3reli!inary study+n order or !y in)estigation to be !ore accurate + decided to conduct a preli!inarystudy$ This would gi)e !e an opportunity to practice using all o the e'uip!ent andalso allow !e to re5ne !y !ethod$ oing through with a trial study allowed !e togather use ul data on the how long each repeat would take% this then helped !e to

decide on using one sa!ple area ro! each tra!pled and non&tra!pled rather thantwo ro! each6 which + would not ha)e enough ti!e or$ +n !y preli!inary study +collected data ro! 5)e coordinates using a 'uadrat# rather than ten in !y sa!plearea% this is because the purpose o this trial study is to test the !ethod rather than tocollect a ull set o reliable results$

Because + carried out a pilot study + was also able to choose !ore suitably locatedplaces in both the tra!pled and non&tra!pled or !y !ain in)estigation$ Thisconsisted o both the sa!ple areas ha)ing a si!ilar soil te!perature to ensure thatthis )ariable would not ha)e the !ost afect on the change o the independent)ariable dandelion lea width#$ A proble! + aced during !y trial !ethod was causedby a lack o dandelion lea)es in !y sa!ple areas% so!e o the coordinated where +placed !y 'uadrat had no lea)es or !e to !easure$ +n !y !ain in)estigation + ha)echosen areas with a higher abundance o dandelion lea)es to a)oid this issue$

The table below shows the calculations or 5nding the running !ean or soil depth$ +ound that there were 8D repeats in !y calculations because at this point the readingsor !y soil depth beca!e constant$

Table 1 – Soil depth running mean

Soil depthreadings (cm)

Running mean for

soil depth

$( F$? F$@

$( $( $( $(


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"raph 1 – Soil depth running mean scatter graph

8 2 ? / ( @ F@$

F

F$2

F$/

F$@

F$

$2

$/

$@

A ter 5nding the running !ean o soil depth + decided to then 5nd the running !eanor soil te!perature because this !ay also be a )ariable which afects the growth o

the dandelion lea)es$ Calculating the running !ean would help !e to deter!ine thenu!ber o readings r ro! each 'uadrat re'uired to help !e control this )ariable soil

te!perature# within !y experi!ent$

Table ! – Soil temperature running mean

Time (seconds) Temperature (degree#elsius)

8 /$? 2 /$2 ? /$? / ($/ ( ($/ @ ($/ F ($/ ($/ G ($/ 8D ($/ 88 ($2 82 ($2 8? ($2

$umber of soil depth

Soildepthrunning


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8/ ($2 8( ($2 8@ ($2 8F ($2 8 ($2 8G ($2 2D ($2

The table abo)e displays !y results o running the !ean or the soil te!perature$ Therunning !ean was shown to be 2D seconds because a ter 8D seconds o the sa!ereading this is when the te!perature o the soil beca!e constant$

"raph ! – Running mean for soil temperature

scatter graph

8 2 ? / ( @ F G 8D 88 82 8? 8/ 8( 8@ 8F 8 8G 2DD

8

2

?

/

(

@

3lanning*or this study + ha)e decided to use rando! sa!pling because this !ethod is the best

or ensuring that all bias is eli!inated% all areas within the sa!ple area ha)e an e'ualchance o being selected as the coordinated that are to be in)estigated$ .sing twotransects or!ed by two tape !easures each one !easuring 8D! + will or! !y

sa!ple areas in two diferent areas$ The 5rst sa!ple area will be set up near thepedestrian;s pathway in order or !e to in)estigate the soil depth which is shallowerdue to co!!on tra!pling$ The second sa!ple area + plan to in)estigate will be placed

Temperature of soil(degrees

Time


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in an area o land ar ro! the pathway6 closer to a set o oak trees where pedestrians;are less likely to tread non& tra!pled area#$

+ ha)e chosen these two areas because o the distinct pattern )isible with regards tothe si4e o dandelion lea)es% the lea)es see!ed to be larger nearer to the oak treeswhere less pedestrians are likely to tread on the soil$ :owe)er the si4es o the lea)esnearer to the pathway appear to be s!aller where the soil is shallower$ Collecting data

ro! both the tra!pled and non&tra!pled areas will pro)ide !e with su"cient dataor !easuring !y independent )ariable soil depth# and its afect on the width o

dandelion lea)es$

%!& 'iagram 1 This diagram displa s a clear image of ho* togather data from a speci+c sample area using random sampling

0ando! sa!pling is typically used or habitats which are consistent which is suitablein !y in)estigation or collecting data ro! two diferent areas within the sa!ehabitat 6 tra!pled and non&tra!pled $ .sing data ro! rando! sa!pling is a betterre ection o the dandelion lea width on both the sites + ha)e chosen because thesa!ples potentially co)er the whole area o each section and not 1ust a narrow bandacross the !iddle6 as in the belt transect %!&$ .sing rando! sa!pling will pro)ide !ewith )alid 'uantitati)e data or calculating the standard de)iation6 and taking 8Dreading ro! each sa!ple area within the habitat ensures the reliability o !y results$

To !easure the soil depth in !y non& tra!pled and tra!pled sa!ple areas + will use asoil pin6 roughly ?Dc! in length6 and as or !easuring the width o the dandelionlea)es + will be using a regular ruler no longer than ?Dc!$ + will use a scienti5ccalculator or generating a set o rando! nu!bers that will be used as !ycoordinates% these coordinates will indicate the location or placing the D$2(!H s'uare'uadrat$

,-uipment listI 2x 8D !eter tape !easure

I 8x 8D$2(!H s'uare 'uadrat

I 8x ?Dc! soil pin

I 8x ?Dc! ruler


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I 8x digital soil ther!o!eter

I 8x calculator

ethod8$ Jocate a suitable place or conducting the experi!ent$ To !easure the suitability o

the sites !ake sure that the place being in)estigated as trampled has the tape!easures e!anating ro! the !ain pathway6 and that the area being in)estigatedunder non-trampled is a reasonably good distance away ro! the pathway about?(!# K ha)e the transects e!anating ro! the set o oak trees where tra!pling is less

re'uent$ Also ensure that both the sites being in)estigated contain a su"cientabundance o dandelion lea)es or !easuring to ha)e enough data collected$

2$ 3lace both the 8D !eter tape !easures6 one hori4ontally and one )ertically6 eache!anating ro! suitable points pre)iously !entioned the pedestrian pathway ortrampled and the oak trees ro! non-trampled #$

?$ .sing the scienti5c calculator begin by generating the rando! nu!bers & shi t6 0anLbutton6 M# K that will be used as coordinates then place the D$2(!Hs'uare 'uadratwhere the coordinates show$

/$ 3ick the dandelion lea with the largest width !easure!ent and record this data downin c!#$ The !easure!ent o this dandelion lea should be a representati)e o the

dandelion lea width in the entire 'uadrat$

($ At each coordinate where the 'uadrat is placed i will take eight readings o the soildepth by penetrating the sur ace o the soil with the tip o the soil pin until it;s nolonger possible or the pin to !o)e any deeper$ The readings !ust all be in diferent

s'uares o the 2( s'uares within the 'uadrat ra!e$ A ter collecting eight diferent soildepths + will calculate the !ean a)erage using the readings o soil depth or each'uadrat% this a)erage should represent the entire 'uadrat$

@$ At each o the coordinates where !y 'uadrat will be placed + will take readings o thesoil te!perature using a ther!o!eter$ Because o the results ro! !y preli!inarystudy + will keep the ther!o!eter in the soil or 2D seconds% + a! using the soilte!perature as a control in !y in)estigation so using !y running !ean ensures !yresults are !ore reliable$ +n order or !y results to be )alid it is i!portant that the soil

te!perature !easure!ents are taken the sa!e way in each 'uadrat% because o this +will place !y ther!o!eter in the centre s'uare o each 'uadrat$ To i!pro)e !y!ethod + will use a stopwatch or counting the 2D seconds rather than counting in !yhead% the ti!e ra!e o !y counting !ay difer each ti!e so!eti!es !ay be slowerthan other ti!es#$

F$ A ter co!pleting all o !y !ethod and collecting all o the in or!ation ro! !yin)estigation + will use this data to conduct a ,ann -hitney . test$ This will show !ethe correlation6 i any6 between the efects o soil depth on the width o dandelionlea)es$ -ith the correlation + will be able to see whether to accept the null oralternati)e hypothesis$


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/ariablesAlthough soil depth is the !ain )ariable being in)estigated there are se)eral other)ariables which should also be taken in to consideration because o the in uencesthey could ha)e on the width o dandelion lea)es$ +n order or the in)estigation to be)alid it;s i!portant to ensure that the independent )ariable tra!pled )s$ non&tra!pled# is the )ariable with the !ost i!pact on the change in the dependant)ariable dandelion lea width#$

reenwich 3ark6 where + plan to carry out !y in)estigation6 is a natural en)iron!entwhich !akes it !ore di"cult or !e to control these other )ariables$ :owe)er6 boththe areas + a! in)estigating are in the sa!e 5eld which !eans it is easy or !e to!onitor the consistency o the )ariables within the sa!ple areas$ An exa!ple o thiswould be the consistency o the soil type6 as well as the stability o te!perature$

Temperature

ne o the )ariables which could ha)e the greatest signi5cance on the growth odandelion lea width could be caused by the inconsistent change in te!perature$ Thete!perature o the en)iron!ent in which plants grow afects the rate o so!e o the!ost i!portant reactions including that plants such as dandelions undergo or basicsur)i)al$ These reactions are all controlled by biological en4y!es$ As the te!peratureincreases the rate o reactions also increases% i the te!perature continues to increaseabo)e the opti!u! point the rate o reaction begins to decrease because theen4y!es denature & !eaning the en4y!es can no longer properly unction$ *or thesereasons + will !easure the te!perature o the soil to ensure that it;s not the )ariableresponsible or li!iting the growth o dandelion lea)es$

Soil p0

p: has a si!ilar afect as te!perature on en4y!e controlled reactions$ This isbecause a change in p: can change the shape o en4y!es6 thus changing itse"ciency at unctioning properly$ This !eans that the rate o photosynthesis wouldalso be afected% i the p: le)els increase abo)e the opti!u! p: range the acti)e siteo the en4y!e will change so photosynthesis will no longer be able to take place$ +ncontrast to the soil te!perature6 the p: o the soil is less likely to uctuateconsiderably so it will not greatly afect the dependant )ariable$ Because + cannot take

sa!ples o the soil to exa!ine the p: le)els in a lab the only way to !onitor thiswould be to ask the park representati)es owners or the p: o the soil$

Soil depth

Soil depth is the )ariable which + a! using in !y study as an independent )ariable$Soil has !ost o the nutrients needed or growth and plant sur)i)al such as waterwhich is needed or growth but !ost i!portantly plays a great role in the process inphotosynthesis$ ther nutrients that are ound in the soil include Nitrate ions6 needed

or protein synthesis6 ,agnesiu! ions K needed or the production o chlorophyll andCalciu! ions K which help cell elongation in plants such as dandelions$ + will be!easuring the soil depth using a soil pin which + will use to take readings ro! each'uadrat6 a ter that + will use these readings to calculate an a)erage$ T o ensure the


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)alidity o this process + will take the !easure!ents !ysel because the strength eachperson uses to push the pin into the soil !ay )ary$

0isk assess!ente

Score li2elihood Se3erit8 ery rare ery !ild2 0are ,ild? ccasional ,oderate/ *re'uent Se)ere( ery re'uent ery se)ere

,3ent i2elihood Seriousness

Total ris2 (li2elihood seriousness)

6recautions to beta2en tominimise ris2

+nsectbites stings

? 2 @ • -ear clothingwith long slee)es

• Carry insectrepellent spray

• A)oid irritatinginsects ho!es

Cutting handwith soil pin 2 ? @

• :old the pin ro!the top end

• +nsert gently inthe soil

• 3ull soil pin out osoil slowly

Jow branches 2 2 / • Jook ahead whenwalking

Tripping or

slipping

/ ? 82 • A)oid walking on

sloped land bytaking the !ainpathway

• A)oid walking inwet areas

puddles in rainywhether

etting lostwithin thepark

2 2 / • Oeep a phone athand thatcontains the!obile nu!berso leaders andgroup !e!bers


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• Bring along a !apo the park tona)igate around!ore easily

• Stick to the !ainpaths% a)oid usingside paths or'uicker routes

• 3ick a location ora group !eetingpoint i + lose !yway around

Abducted bystrangers

8 / / • A)oid con)ersingwith anystrangers

• Oeep within closerange o group!e!bers

• Oeep e!ergencycontact on speeddial

3lantsnettles#

/ 2 • -ear clothing thatco)ers areas othe body that are!ost likely to

co!e in contactwith plants e$g$glo)es 6 longtrousers and longslee)ed top

3oisonous3lants ungi#

2 2 / • -ash handsthoroughly a tercontact with plant

•


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The tables below are all the data gathered ro! !y real in)estigation$ Tables ? and /show all o the readings o the soil depth and dandelion lea width a)erages6 theadditional )ariable that + !onitored which was soil te!perature6 is also recorded in thetables$

Trampled

Table 8 – This table sho*s all of the data gathered from the trampled areain m in3estigation this *as the area ne t to the path*a . The sample area*as 1:m b 1:m emanating from the edge of the path*a .

#oordinates insample area (m)

easurement of

leaf *idth(cm)

ean soildepth (cm)

Soiltemperat

ure('egrees#elsius #

26? 8$2 ($G F$8 86@ 8$F $ 26/ 8$/ ($/ (6 2$/ ($ F62 2$8 ($? $8 6? 2$? @$G $? @68 8$G ?$G F$G @6? 2$/ ?$G F$ 26( ?$2 /$G $( 68 2$G @$G $/

$on ; trampledTable 4 – This table sho*s the data gathered from the non;trampled area<this *as the area near the oa2 trees (about 85m a*a from the path*a )*here trampling on the grass *as less fre-uent. The data includes thereadings of m independent and dependant 3ariables (soil depth a3eragesand dandelion leaf *idth) as *ell as m control 3ariable (soil temperature).

#oordinates insample area (m)

easurement of

leaf *idth(cm)

ean soildepth (cm)

Soiltemperat

ure('egrees#elsius #

86 ?$( F$/ $2 8D6F ?$ F$2 G$/ F6@ /$2 8/$G 88$? @6/ ?$8 8D$F 8D$2 @62 2$( 82$F 8D$ 86D /$@ ($F G$G ?6( /$? 8D$8 /6 ($2 G$/ G$( F6? ?$@ 8/ G$


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26@ ($2 F$? G$?

The tables below show all the soil depth readings within the 'uadrates o !yrando!ly generated coordinates in both the tra!pled and non&tra!pled sa!pleareas$ These results are ro! !y real in)estigation$

Table 5; Readings of soil depth in non trampled area

Table =; Readings of soil depth in trampled area

>nterpretation and e3aluation

Statistical anal sis

$ull h pothesis (0 : ) – Soil depth does not a?ect the *idth of

@lternati3e h pothesis (0 1 ) – Soil depth has an e?ect on the *idth of


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The scatter graphs below illustrate the correlation between soil depth and lea widthin both the tra!pled and non& tra!pled sa!ple areas$ )erall6 a positi)e correlation ise)ident6 as increasing the soil depth increased the width o each dandelion lea %howe)er there are !any uctuations along the graph$ This is !ainly due to the act

that it is i!possible to !easure how Ptra!pledQ a sa!ple area is% as !ost !yreadings were along the oot path6 so!e parts in !y tra!pled sa!ple area could ha)ebeen treaded on !ore o ten than others$

+n contrast6 when looking at the non&tra!pled sa!ple6 ewer uctuations are seen asthe areas had not been stepped on$ Again6 ro! this graph6 a positi)e correlation canbe seen between the soil depth and dandelion lea width$ This correlation !eans thatas the soil depth increases the width o dandelion lea)es also increases$ +n contrast tothe non&tra!pled area the tra!pled area shows that the lea width o dandelionsstays relati)ely the sa!e due to the si!ilarity o soil depth within the sa!ple area$

)er all there is a positi)e correlation between soil depth and dandelion lea width$ *orthis reason it is now i!portant to re1ect the null hypothesis and adopt the alternati)ehypothesis$


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"raph 5 – Sho*s e?ect of soil depth on the leaf *idth of dandelions onnon;trampled areas.

/ @ E 8D 82 8/ 8@D

8

2

?

/

(

@

Soil depth against leaf *idth ($on;trampled)

Soil;depth (cm)

4ea f;*idth (cm)

"raph = – Sho*s e?ect of soil depth on the leaf *idth of dandelionsin trampled areas.

?$( / /$( ( ($( @ @$( F F$( $(D

D$(

8

8$(

2

2$(

?

?$(

Soil depth against leaf *idth (Trampled)

Soil;depth (cm)

eaf;*idth (cm)


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To calculate the signi5cance o !y both !y sets o data ro! the tra!pled and non&tra!pledareas + will use the ,ann whiteys . test$ This test will allow !e see i there is a signi5cantcorrelation between the soil depth and lea width ro! both o !y sa!ple areas$ This willpro)ide !e with e)idence to support the signi5cant correlation6 i any$ This test is the !ostsuitable because + will be co!paring 2 diferent sets o data ro! both the tra!pled and non&tra!pled areas$

+n order to carry out a ,ann&-hitney . test + !ust rank all the data in ascending order i twoor !ore )alues ha)e the sa!e + would need to add the ranks as though the ranks werediferent and then di)ide that )alue by the nu!ber o )alues that are the sa!e$

$o. Trampled Ran2 $on;trampled Ran2!8 8$2 8 ?$( 82

2 8$F ? ?$ 8/? 8$/ 2 /$2 8(/ 2$/ F$( ?$8 8D( 2$8 ( /$@ 8@ 2$? @ /$( 8FF 8$G / /$? 8@

2$/ F$( ($2 8G$(G ?$2 88 ?$@ 8?

8D 2$G G ($2 8G$( (@ 8(/

+ ha)e ranked all the data abo)e in ascending order and in the case that two or !ore )aluesare the sa!e i ha)e added the total rank6 had they been diferent6 and di)ided by the nu!bero )alues with the sa!e rank$

The total nu!ber o the ranks or the *irst data set6 R0 8 M (@ and the total )alue or the rankso the second data set6 R0 2 M 8(/$

.sing these )alues and the or!ula . 8 M n8 x n 2# D$(n 2# n2 8# & R0 2 and si!ilarly . 2M n8 x n 2# D$(n 8# n8 8# & R0 8 + ha)e obtained

.8 M 8 and .2 M GG$

e

AB ann;Chitne Atest$ 1 B sample siDeone


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*or the ,ann -hitney test6 using 2 data sets with 8D ite!s each n 8 and n 2 M 8D# the critical)alue is 2? at p M D$D(

There ore6 as !y lowest )alue o . is less than the critical )alue 2?# + will re1ect the nullhypothesis : D6 and accept the alternate hypothesis at the (U signi5cance le)el$

Because + ha)e used a (U signi5cance le)el6 the critical )alue is 2?6 this !eans that orresults where . M 2? or lower there is a (U chance the results arose by chance and a G(Uchance that the results are in act correct$

:owe)er the )alue o the ,ann&-hitney . test that + calculated was 8% this is ar ro! thecritical )alue o 2?$ + the . )alue was below (U this !eans that the null hypothesis isaccepted because o the act that the results occurred by rando! chance$ :owe)er6 as !y,ann&-hitney . test )alue was lower than !y critical )alue this !eans that + a! able toadopt !y alternati)e hypothesis and re1ect the null hypothesis$ *ro! !y calculations and +a! able to state that !y results were not due to chance% this !eans that soil depth does in

act the lea width o a dandelion$

+n general !y results showed a positi)e correlation between soil depth and lea width$ +t isclear that the width o the dandelion lea)es was signi5cantly higher in the non&tra!pled areathan the tra!pled area$ This is because in the area where treading is !ore co!!on near thepathway#6 the soil is likely to be !ore co!pact in contrast to the area with less treading where

soil depth is higher$ + the soil beco!es !ore co!pact6 this pre)ents the roots o thedandelion lea)es ro! thri)ing to the ull length to which it could possibly grow$ This !eansthat the dandelion lea)es will not be pro)ided with all the !inerals that are only ound in thedeep layers o the soil$ + the soil is co!pact than e)en the >tap root; o the dandelion wouldnot be o !uch use or absorbing certain !inerals to aid the growth and reproduction odandelion plants$ ,ost o the i!portant processes such as photosynthesis and proteinsynthesis that aid in the growth o plants are uelled by the !inerals which are onlyaccessible ro! deeper soil le)els which !eans shallow soil li!its the extent to which thedandelion lea)es are able to grow$ The relationship between !y independent and dependant)ariable is shown clearly in !y set o data% the lea width was shorter in the tra!pled area

where the depth o the soil was !ore constant$ n the other hand6 the width o the dandelionlea see!ed to be at an increase in the non&tra!pled area where the soil was !uch lessco!pact$


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)erall6 the dandelions lea width is expected to be higher in the areas with deeper soil le)elsnon&tra!pled#% this is because an increase in the soil depth !eans that the dandelions are at

a better ad)antage or allowing their uni'ue roots to grow taller !aking it easier or !any!inerals to reach the dandelion plant6 hence reaching the lea)es e)entually$

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8$ Eoo2 Third edition Biological Science 8 K organis!s6 energy and en)iron!ent K

SNAB A2 Ecology Coursework

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