Ecosystem: Class 12 Biology Chapter 12 Hinglish mein

Monsoon mein school ground ke kisi dhoop wale kone mein baarish ke paani se bhari ek bucket chhod do. Do hafte ke andar paani hara ho jaata hai, usmein mosquito larvae kulbulaate hain aur neeche ek chipchipi film jam jaati hai. Yeh sab kisi ne jaan-boojhkar nahi daala, phir bhi bucket ab ek chhota system ban gayi hai: algae sunlight trap karti hain, chhote-chhote animals algae ko charte hain, aur microbes jo bhi marta hai use tod dete hain. Ecologists aise system ko ecosystem (पारितंत्र) kehte hain: living organisms ek doosre ke saath aur apne non-living surroundings ke saath itna kareeb se interact karte hain ki poora system ek functional unit ki tarah kaam karta hai.

Ecosystems har size ke hote hain, ek bucket ya gaon ke pond se lekar Sundarbans ke mangroves ya Arabian Sea tak. Suvidha ke liye hum unhe kuch broad kinds mein group karte hain (comparison dekho). Doosre extreme par, sab ko milakar, yaani poore biosphere ko, ek single global ecosystem maana ja sakta hai.

Is chapter ko ek energy budget ki tarah bhi padh sakte ho. Producers income kamaate hain (productivity), food chains use aage badhati hain, har organism uska kuch hissa heat ke roop mein kharch karta hai, aur decomposers peeche chhoote materials ko recycle karte hain. Pehle hum dekhenge ki ecosystem bana kaise hai, phir budget ko step by step follow karenge, aur aakhir mein use pyramids ke roop mein banayenge.

12.1 Ecosystem – Structure aur Function

Poocho ki mangrove grassland se alag kyun hai, to do tarah ke jawab milte hain: living organisms (biotic components) aur physical conditions (abiotic components: light, temperature, water, air, soil aur minerals). Akele koi bhi farq ko explain nahi karta. Khaara paani aur tides tay karte hain ki mangrove mein kaun se trees ug sakte hain, aur badle mein trees mud ko rokte hain aur paani par chhaaya karte hain. Isi two-way interaction se har ecosystem ka apna khaas layout, yaani uska structure, banta hai.

Structure: species composition aur stratification

Do features is structure ko describe karte hain. Pehla hai species composition: kaun-kaun si species maujood hain aur har ek kitni common hai, jise ecologists sample plots mein organisms ko pehchan kar aur gin kar banate hain. Doosra hai ki yeh species vertically kaise arranged hain, jise ecologists stratification (स्तरविन्यास) kehte hain.

Aise forest mein jao to layers aasaani se dikh jaati hain (Fig. 12.1). Har layer ko light ka alag hissa milta hai, isliye har layer alag plants ke liye theek hai, aur alag-alag animals unke beech khaana khaate ya chhupte hain. Water bodies mein bhi layers hoti hain: floating plants, open water ki algae aur tal mein jade weeds alag-alag depths par hote hain.

Function: chaar processes

Structure batata hai ki ecosystem mein kya hai; function batata hai ki woh kya karta hai. Chaar processes uske parts ko ek working unit mein jodte hain, aur baaki chapter unhe ek-ek karke dekhta hai:

• Productivity: producers sunlight se organic matter banate hain (Section 12.2).
• Decomposition: decomposers dead matter ko wapas simple substances mein tod dete hain (Section 12.3).
• Energy flow: energy producers se consumers tak jaati hai aur heat ban kar nikal jaati hai (Section 12.4).
• Nutrient cycling: carbon, nitrogen aur phosphorus jaise elements baar-baar use hote hain (neeche wala box).

Model ecosystem ke roop mein pond

Working model ke liye ecologists ko pond pasand hai: tum uske paar dekh sakte ho, phir bhi koi zaroori cheez missing nahi hai. Fig. 12.2 ko step by step dekho aur uske parts ko unke kaam ke hisaab se sort karo.

Abiotic parts. Usi pond ko kohre wali January aur chamakdaar April mein compare karo: April mein sab kuch tezi se ugta, khaata aur sadta hai. Light, temperature aur day length poore pond ke liye accelerator ki tarah kaam karte hain. Non-living part ka baaki hissa material hai: paani jismein minerals, gases aur organic compounds ghule hain, aur nutrients se bhare mud ka tal.

Producers. Kinare se andar ki taraf dekho: kinare par jade reeds aur sedges (marginal plants), surface par lilies aur duckweed (floating plants), uske neeche lehraati hydrilla (submerged plants), aur microscope ke bina na dikhne wale phytoplankton aur doosri algae jo dhoop wale paani mein behti rehti hain.

Decomposers aur consumers. Tal ka mud decomposers ke liye sabse vyast jagah hai: bacteria, fungi aur flagellate protists neeche doobne wali har cheez par kaam karte hain. Unke upar consumers rehte hain: tal par rengte snails aur worms, khule paani mein tairti fish, frogs aur insect larvae, aur phytoplankton ko charne wale zooplankton jaise water fleas aur rotifers.

Poore pond ko dekho to woh matter aur energy ke saath alag-alag bartaav karta hai. Matter recycle hota hai: phosphorus ka ek atom mud se hydrilla, hydrilla se snail aur wapas mud tak kai baar ja sakta hai. Energy ke saath aisa nahi hota. Woh sunlight ban kar aati hai, producers use fix karte hain, woh ek hi taraf consumers tak jaati hai aur aakhir mein heat ban kar nikal jaati hai. Matter cycle hota hai, energy flow karti hai: yeh contrast is chapter ka sabse kaam ka idea hai.

12.2 Productivity

Koi animal kuch bhi khaaye, uska khaana shuru mein sunlight ki energy se bana plant matter hi tha. Isliye kisi bhi ecosystem se pehla sawaal yeh hai ki woh kitna naya plant matter banata hai, aur kitni tezi se: yahi usmein rehne wale har doosre organism ka budget tay karta hai.

Maan lo tum ek paddy field ko coral reef se compare karna chahte ho. Kisi period mein har square metre par photosynthesis se bana plant matter ek shuruaat hai: yeh amount, $\mathrm{g}{\mathrm{m}}^{-2}$ mein mass ki tarah ya $\mathrm{k}\mathrm{J}{\mathrm{m}}^{-2}$ mein usmein rakhi energy ki tarah (purani books kcal use karti hain), primary production kehlata hai. Lekin reef saal bhar badhta hai jabki paddy ki fasal kuch mahine hi badhti hai, isliye sahi comparison ke liye rate chahiye. Primary productivity per unit time production hai, $\mathrm{g}{\mathrm{m}}^{-2}\mathrm{y}{\mathrm{r}}^{-1}$ ya $\mathrm{k}\mathrm{J}{\mathrm{m}}^{-2}\mathrm{y}{\mathrm{r}}^{-1}$ mein.

Gross aur net primary productivity

Plants jo kuch banate hain, sab apne paas nahi rakhte. Sabhi living things ki tarah woh respire karte hain, apni sugar ka kuch hissa jala kar growth, repair aur transport ke liye energy lete hain. Isliye hum total ko bache hue hisse se alag karte hain.

Respiration aam taur par GPP ka bada hissa le leta hai, plants aur climate ke hisaab se aksar ek-tihaai se do-tihaai tak. Fig. 12.3 mein ek saal ke production ko follow karo.

Baaki ecosystem NPP par hi jeeta hai. Uska kuch hissa herbivores kha lete hain, zameen par uska bada hissa bina khaaye mar jaata hai aur decomposers ka khaana banta hai, aur kuch extra plant body ke roop mein reh jaata hai. Jab consumers apna assimilate kiya hua khaana apne naye tissue mein badalte hain, to use secondary productivity (द्वितीयक उत्पादकता) kehte hain.

Productivity alag kyun hoti hai

Productivity har jagah ek jaisi bilkul nahi hoti. Yeh ek saath kai cheezon par depend karti hai:

• Khud producers. Species leaf area, growth rate aur photosynthetic capacity mein alag hoti hain; sugarcane aur maize jaise C${}_4$ plants garam, tez dhoop wale mausam mein carbon khaas taur par tezi se fix karte hain.
• Light aur temperature. Lambe, garam growing seasons chhote, thande seasons se zyaada photosynthesis hone dete hain.
• Paani. Thar isliye unproductive hai kyunki woh sookha hai, isliye nahi ki wahan sunlight kam hai.
• Nutrients. Nitrogen aur phosphorus, aur sea ke kuch hisson mein iron, aksar kam padte hain.

Numbers lagao to oceans hairaani se gareeb dikhte hain. Ek bahut quote kiye jaane wale estimate ke hisaab se, zameen ke plants saal mein lagbhag 115 billion tonnes dry organic matter banate hain aur oceans lagbhag 55 billion: duniya ke 170 billion ke total ka lagbhag ek-tihaai, aur woh bhi us sea se jo Earth ka lagbhag 70% dhakta hai (Fig. 12.4).

Itna saara paani itna unproductive kyun hai? Gehraai ke saath light jaldi kam ho jaati hai, isliye producers sirf upar ki patli layer mein photosynthesis kar paate hain. Udhar nutrients dead plankton aur droppings ke saath neeche andhere paani mein doob jaate hain, jahan koi producer unhe use nahi kar sakta. Zyaadatar open ocean mein light aur nutrients alag-alag jagah pahunch jaate hain. Sirf wahan sea bahut productive banta hai jahan currents gehre paani ko wapas upar laate hain, jaise kuch coasts ke paas, ya jahan rivers nutrients daalti hain.

12.3 Decomposition

Har spring mein school ground ke aas-paas ke peepal aur neem ke trees apne purane patte gira dete hain, aur kuch hafton tak zameen pairon ke neeche charmaraati hai. Monsoon khatam hote-hote zyaadatar litter gayab ho jaata hai, bina kisi ke jhaadu lagaye. Woh decompose ho gaya: living organisms ne use tod kar carbon dioxide, paani aur mineral nutrients bana diya.

Zyaadatar credit earthworms ko milta hai, aur farmers unki chhodi hui bhurbhuri, naram mitti ki kadar karte hain. Lekin zyaadatar chemistry aise bacteria aur fungi karte hain jo itne chhote hain ki dikhte nahi. Unke bina dead leaves, branches aur bodies ke dher lag jaate, aur unke andar band nutrients kabhi mitti mein wapas nahi aate.

Decomposition ke processes

Decomposition ek reaction nahi, balki kai processes hain jo ek hi detritus par ek saath kaam karte hain. Unhe alag-alag naam dena madad karta hai (Fig. 12.5), bas yaad rakho ki asli mitti mein yeh ek doosre mein mile hote hain.

• Fragmentation. Earthworms, millipedes aur woodlice jaise detritivores (अपरदाहारी) detritus ko chaba kar chhote tukdon mein tod dete hain, jisse woh surface bahut badh jaati hai jis par microbes attack kar sakte hain.
• Leaching. Baarish detritus se soluble minerals ko dho kar mitti ki layers mein neeche le jaati hai. Kuch mitti mein gehraai par insoluble salts ban jaate hain jinhe roots le nahi sakti.
• Catabolism. Bacteria aur fungi enzymes chhodte hain jo detritus ke bade organic molecules ko step by step chhote inorganic molecules mein tod dete hain.
• Humification. Aadha pacha hua kuch matter humus ban jaata hai, ek dark colloidal material jismein koi plant structure nahi bachta, aur jo sponge ki tarah paani aur nutrients sokh leta hai. Bahut kam microbes ise digest kar paate hain, isliye yeh mitti mein saalon tak tik sakta hai.
• Mineralisation. Dheere-dheere kuch microbes humus ko tod hi dete hain, aur aisa karte hue ammonium aur phosphate jaise inorganic nutrients free hote hain jinhe roots absorb kar sakti hain.

Rate ko kaun control karta hai?

Geeli mitti par chhoda gaya kele ka chhilka kuch hafton mein gayab ho jaata hai; gira hua sal ka lattha dashakon le sakta hai. Do tarah ke factors raftaar tay karte hain.

Detritus kis cheez ka bana hai. Microbes sugars, starch aur nitrogen se bhare proteins jaldi digest karte hain. Lignin, woh polymer jo wood ko sakht banata hai, aur chitin, jo insect exoskeletons aur fungal walls mein milta hai, sakht aur dheere sadne wale hain. Isliye same conditions mein naram, nitrogen se bhare patte lakdi wali tehniyon se jaldi sadte hain.

Mitti ka climate. Kerala ke forest floor ko Himalaya mein oonchaai par ek bog se compare karo. Kerala ki garam, nam mitti apne microbes ko saal bhar busy rakhti hai, aur gire patte kuch mahinon mein gayab ho jaate hain. Bog thanda aur waterlogged hai; bheegi mitti mein oxygen kam hone se (anaerobiosis) zyaadatar aerobic decomposers mushkil se kaam karte hain, aur bina decompose hua plant matter peat ke roop mein jama hota rehta hai. Climatic factors mein soil temperature aur moisture sabse zyaada maayne rakhte hain, kyunki yahi tay karte hain ki microbes kitne active hain.

12.4 Energy Flow

Yeh number sochne par majboor karta hai: kisi field par girne wali saari sunlight ka sirf lagbhag sauvaan hissa hi naye plant matter mein store hota hai. Fig. 12.7 dikhata hai ki baaki kahan jaata hai. Sunlight ka aadhe se kam hissa un wavelengths ki band mein hota hai jinhe chlorophyll use kar sakta hai, ise photosynthetically active radiation (PAR) kehte hain. Plants us PAR ka lagbhag 2–10% trap karte hain; baaki reflect ho jaata hai, patton ke aar-paar nikal jaata hai ya heat ban jaata hai. Earth par har animal ka har meal isi patli si slice tak wapas jaata hai.

Producers, consumers aur food chains

Har food chain aise organism se shuru hoti hai jo apna khaana khud banata hai. Pahaadi dhalaan par yeh producers herbs, shrubs aur trees hain; lake mein yeh phytoplankton, doosri algae aur jade hue water plants hain. Baaki sab, grasshopper se tiger aur tum tak, ko energy ke liye khaana padta hai aur woh consumer (heterotroph) hai; kuch plants khaate hain, kuch un animals ko khaate hain jinhone kabhi plants khaaye the.

Har consumer ko do tarah se naam diya ja sakta hai, uske feeding step se aur uske diet se, aur naamon ke yeh do sets ek step se khiske hue hain. Plants se ek step door primary consumer hai, yaani herbivore: grasshopper, parakeet ya chital, ya paani mein snail ya zooplankton. Do step door secondary consumer hai, ek carnivore jo herbivores ko khaata hai aur isliye primary carnivore kehlata hai. Teen step door tertiary consumer hai, yaani secondary carnivore.

Kaun kise khaata hai, iska sequence food chain hai. Haryana ke ek field mein ek grazing food chain (GFC) aise chalti hai: grass → grasshopper → frog → snake. Energy living plants se andar aati hai aur har baar jab ek organism doosre ko khaata hai, to chain mein upar jaati hai.

Sab kuch khaya nahi jaata. Tree apne patte gira deta hai, deer gobar chhod jaata hai, aur der-saber har plant aur animal marta hai. Yeh saara dead matter ek doosri tarah ki chain ko khaana deta hai, detritus food chain (DFC). Ismein bacteria aur fungi chhaaye rehte hain, aur woh anokhe tareeke se khaate hain: khaana nigalne ke bajaye woh dead matter par digestive enzymes chhodte hain, digestion ko apni body ke bahar hone dete hain, aur bane chhote molecules ko absorb kar lete hain. Is tarah khaane wale organisms saprotrophs hain (Greek sapros, sada hua). Earthworms jaise detritivores bhi isi chain mein khaate hain.

Food webs aur trophic levels

Asli feeding links kabhi ek chain jitne saaf-suthre nahi hote. Myna grazing chain se grasshoppers ke saath-saath detritus chain se earthworms bhi khaati hai, isliye dono chains jud jaati hain. Rats, jackals aur wild boar jaise omnivores plant food, animal food aur bacha-khucha, sab khaate hain. Is tarah judkar chains ek food web (खाद्य जाल) banati hain, jaise Fig. 12.8 mein.

Chain ya web mein har organism ki position, jo is baat se tay hoti hai ki woh khaana kaise paata hai, uska trophic level (पोषण स्तर) hai. Producers pehla trophic level (T1) banate hain, herbivores doosra (T2), herbivores ko khaane wale carnivores teesra (T3) aur unke predators chautha (T4). Tum khud ko kahan rakhoge? Is sawaal par hum Section 12.5 mein wapas aayenge.

Kaun si chain zyaada energy le jaati hai, yeh ecosystem par depend karta hai. Paani mein zyaadatar phytoplankton zinda hi kha liye jaate hain, isliye grazing chain energy ka main raasta hai. Zameen par herbivores plants ka sirf chhota hissa khaate hain; zyaadatar patte, lakdi aur roots bina khaaye mar jaate hain, isliye zyaadatar energy grazing chain ke bajaye detritus chain mein pahunchti hai.

Standing crop

Ek pal ke liye ecosystem ko rok do aur ek trophic level par har zinda cheez ko gino, ya taulo. Jo milta hai woh us level ka standing crop (खड़ी फसल) hai: ek snapshot, rate nahi. Ecologists ise ya to per unit area count ke roop mein batate hain ya biomass ke roop mein, yaani per unit area living matter ka mass, aur biomass ko lagbhag hamesha dry taulte hain. Neeche ki activity dikhati hai kyun.

10 per cent law

Jab chital charta hai, to ghaas ki zyaadatar energy kabhi deer nahi banti. Roots aur sakht stems bina khaaye chhoot jaate hain. Jo khaya jaata hai uska kuch hissa bina pache gobar mein nikal jaata hai. Jo pachta hai uska zyaadatar hissa deer ko zinda, chalta-phirta aur garam rakhne ke liye respiration mein jalta hai, aur heat ban kar nikal jaata hai. Sirf ek chhota bacha hissa naya deer tissue banta hai jise tiger kha sake. Fig. 12.9 in losses ko chain mein upar tak follow karta hai.

Har step par ek-dasvein se guna karo aur energy tezi se ghatti hai: producers ki 20 000 kJ NPP mein se lagbhag 2 000 kJ herbivores tak, 200 kJ carnivores tak aur sirf 20 kJ top carnivores tak pahunchta hai. Paanchve level ko 2 kJ milega. Is giraavat mein kahin na kahin itni kam energy bachti hai ki aisi population support nahi ho paati jo kaafi khaana dhoondh sake, isliye grazing food chains mein shayad hi kabhi chaar ya paanch se zyaada links hote hain.

12.5 Ecological Pyramids

Trophic levels ko ek ke upar ek stack karo, producers neeche aur top consumers sabse upar, aur har ek ko ek bar ki tarah banao jiski chaudaai dikhaye ki us level mein kitna hai. Aam taur par stack upar ki taraf pyramid ki tarah patla hota jaata hai. Aise diagram ko ecological pyramid (पारिस्थितिक पिरामिड) kehte hain. Yeh idea ecologist Charles Elton se aata hai, jinhone 1920s mein bataya ki chhote animals sankhya mein unhe khaane wale bade animals se kahin zyaada hote hain.

Teen alag quantities stack ki ja sakti hain:

• Pyramid of numbers: kisi diye gaye area mein har level par kitne individuals rehte hain.
• Pyramid of biomass: ek pal mein har level par living organisms ka dry mass (standing crop).
• Pyramid of energy: ek fixed time, aam taur par ek saal, mein per unit area har level se flow hone wali energy.

Inhe compare karne ke liye Fig. 12.11 ko step by step dekho. Tum jo bhi pyramid banao, use poore level ki census se banao: teen grasshoppers taul kar use herbivore level kehna ek bekaar bar dega, kyunki plot ki har herbivore species gini jaati hai.

Upright aur inverted pyramids

Grassland textbook wala shape deta hai. Grasses sankhya mein grasshoppers se zyaada hain aur weight mein kai guna bhaari; grasshoppers bhi sankhya aur weight mein frogs aur snakes se zyaada hain; aur har level apni energy ka sirf ek hissa aage bhejta hai. Teeno pyramids upright aate hain, jaise zyaadatar ecosystems mein hota hai.

Pyramids of numbers aasaani se ulat jaate hain, kyunki individuals ke size mein bahut farq hota hai. Ek bada peepal tree hazaaron caterpillars, aphids aur beetles ko khila sakta hai, jo darjan bhar insect khaane wali birds ko khilate hain, jinka shikaar ek akela hawk kar sakta hai. Us pyramid ka base ek individual hai, isliye woh base par inverted hai: neeche patla aur herbivores par sabse chauda. Birds par rehne wale lice jaise parasites jodo, to top ke paas woh phir chauda ho jaata hai.

Biomass pyramids bhi ulat sakte hain. Kisi bhi pal open sea ka sample lo to animals, yaani zooplankton aur fish milakar, un microscopic phytoplankton se bhaari hote hain jin par woh jeete hain: ek inverted pyramid of biomass.

Energy alag tarah se bartaav karti hai. Koi bhi level use khilane wale level se zyaada energy nahi pa sakta, kyunki har transfer kuch energy heat ke roop mein gawa deta hai, isliye pyramid of energy hamesha upright hi ho sakta hai. Uske bars ek fixed period, aam taur par ek saal, mein kisi diye gaye area par har level se guzarne wali energy dikhate hain. Neeche har tarah ke pyramids banane ki koshish karo.

Trophic level ek role hai, species nahi

Trophic levels batate hain ki organism kya kar raha hai, yeh nahi ki woh kis species ka hai. Pake anjeer khaati myna doosre trophic level par khaa rahi hai; wahi bird grasshopper pakadte waqt teesre level par khaa rahi hai. Tum sabse saaf example ho: ek hi meal tumhe ek saath kai levels par rakh sakta hai (Fig. 12.13).

Ecological pyramids ki limitations

Pyramids kaam ke isliye hain kyunki woh simple hain, aur is simplicity ki ek keemat hai:

• Mixed feeders. Do levels par khaane wali myna, bear ya insaan ko ya to baantna padta hai ya zabardasti ek bar mein daalna padta hai.
• Webs. Pyramid single links ka stack hai, lekin asli ecosystems uljhe hue webs hain jinhe bars ka koi stack nahi bana sakta.
• Decomposers. Bacteria aur fungi (saprophytes), jo zyaadatar dead matter ko process karte hain, stack mein kahin nahi dikhte.