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Mount Usu / Sarobetsu post-mined peatland
From left: Crater basin in 1986 and 2006. Cottongrass / Daylily
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[ trophic level | food web ]
Fig. Food web and trophic levels in the Arctic. Consider why the arctic ecosystem is fragile. |
Producer, P (= Autotroph)organisms that produce their own energy, i.e., peforming photosynthesis (or chemosynthesis)→ productivity (生産力) Consumer, C (≈ Heterotroph)organisms that gets their food from other living organisms to obtain energyMacroconsumer organisms (herbivores, carnivores, detritivore) Decomposer, D (≈ Saprotroph)organisms that obtain energy through the decomposition of dead or decaying organismsbacteria, fungi, worms, etc. |
= Food chain (食物連鎖) P → C1 → C2 → C3 → C4 → C5 ↑__↘ ↓____↓____↓____↓____↓ D ← ← ← ← ← ← ← ← ← ← ______________food chain Ex. Mount Usu (有珠山)┏━ Sparrow hawk (ハイタカ)┃____┃eats small birds, ratsd, squirrels, snakes, etc. ┃__Japanese rat snake (アオダイショウ) ┃____┃eats rats, birds, lizards, frogs, and others, including eggs ┗━ Great tit (シジュウカラ) ______┃ ┃eats insects (polyhagous) ______┃ ┗━━━━━━━━━━━┓ _Gypsy moss larva____________Nut weevils _(マイマイガ幼虫)______________(シギゾウムシ) ______┃eats leaves of deciduous tree__ ┃eats acorns and chestnuts (perforator) _Oak leaf (ミズナラ葉)__________Acorn (堅果) |
The optimal length of food chain probably exists
Food size → determined by the oral organs of animals Trophic cascade (栄養カスケード)indirect interactions that control entire ecosystems, occurring when a trophic level is suppressedEx. top-down cascade, bottom-up cascade, subsidy cascade top-down bottom-up subsidy Second consumer × ⇓ ⇓ First consumer ⇑ ⇓ × Producer ⇓ × ⇑ |
The structure of ecosystems is visualized by ecological pyramids that were proposed by Elton. Ecological pyramids show the amounts of various parameters across trophic levels. The major three parameters are: number (1), biomass (2) and energy (3).
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Fig. A. Ecological pyramids depict the (a) biomass, (b) number of organisms, and (c) energy in each trophic level. |