Environmental systems and1. Students investigated a societies PSL, Assignment II, Max. Marks: 20 community of trees by sampling a total area of 20 2 000 m . Species Douglas fir (Pseudostuga menziesii) Big Leaf aple (Acer macrophyllum) "rand #ir (Abies grandis) $a% !m"er o# plants 30 !0 2$0 &alc!late t'e plant density #or t'e (rand )ir. 2$0%20000 & 0.012 (1) $"% *escri"e t'e met'od !sed to collect t'is data. '(e met(od used is estimating density. )stimating density is t(e mean of t(e number of organisms present per s*uare area. '(e process to calculate t(is is by calculating t(e number of t(e re*uired organisms in every *uadrant and t(en find t(e mean of all t(e calculated *uadrants. (3) $c% Explain +'y pop!lations s'o+ a sigmoidal gro+t' c!rve. +n a population, t(e organisms gro- *uic.ly. '(is mar.s t(e up-ard curve of t(e sigmoidal curve. '(en t(e organisms mature and t(e curve flattens out a bit. '(e ne/t process is t(e declination stage -(ere t(e organisms become old and -ea.. '(ese become easy prey to ot(er predators. '(us t(is becomes t(e do-n-ard curve in t(e sigmoidal curve. 0s a result population displays an S1s(aped curve. (3) $,otal - marks% 2. $a% *e#ine t'e term species. Species are a group of organisms are a group of similar individuals t(at are capable of interbreeding -it( eac( ot(er. '(ey are t(e basic ta/onomic unit. (1) '(e figure belo- s(o-s t(e vegetation c(ange over time. 1 or &% contains climax vegetation. Succession. 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 & d e c id u o u s . La"el eac' grap' and t'e axes. (1) $ii% /!tline +'at is meant "y t'e term climax vegetation and identi#y +'ic' part o# t'e diagram a"ove $A. (2) $c% $i% *ra+ 0S1 and 021 pop!lation gro+t' c!rves on t'e axes "elo+. 4ollutants emitted by factories. (2) $iii% S!ggest t+o +ays in +'ic' '!man activity co!ld a##ect climax vegetation.1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 A . . a n d b irc ( sc ru b g ra sse s m o s s e s a n d lic ( e n s d ic o ty le d o n s d ic o ty le d o n s . Deforestation. 2lima/ vegetation is t(e type of vegetation t(at can establis( itself on any given environmental condition and in t(e absence of any ma3or disturbances. Population Time Population Time 2 . 2 s(o-s t(e clima/ vegetation.o o d la n d o a .it( ro o t n o d u le s ' im e $"% $i% State t'e name o# t'e process s'o+n in t'e diagram a"ove. '(is is because t(e ecosystem (as reac(ed its ma/imum carrying capacity. '(e carrying capacity of an environment is t(e ma/imum number of organisms it can sustainably (old.eeps increasing as t(e rate of reproduction is *uite (ig( and t(e deat( rate less. '(us t(e amount of organic matter . Succession is t(e process of c(ange in t(e species structure of an ecological community over time. t(e amount of organic matter increases. (2) $e% Explain +'y t'e amo!nt o# organic matter increases as s!ccession occ!rs.$2% $ii% Identi#y in +'ic' part o# t'e diagram a"ove $A. or &% yo! +o!ld expect to #ind species +it' S population gro-t( curves. 0 and B $2% $d% Explain +'y ecosystems in later stages o# s!ccession are likely to "e more sta"le. Succession is a naturally recurring process in t(e ecosystem. . 2 and B 5 population gro-t( curves. 0s a result t(ere are more organisms and as t(ey die. (1) 3 .