Primary And Secondary Productivity Ecosystem Pdf

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It also depends on a variety of environmental factors, availability of nutrients and photosynthetic capacity of plants. Click here to buy this book in print or download it as a free PDF, if available. Primary productivity depends on the plant species inhabiting a particular area. PDF

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Primary productivity , in ecology , the rate at which energy is converted to organic substances by photosynthetic producers photoautotrophs , which obtain energy and nutrients by harnessing sunlight , and chemosynthetic producers chemoautotrophs , which obtain chemical energy through oxidation. The total amount of biological productivity in a region or ecosystem is called the gross primary productivity. A certain amount of organic material is used to sustain the life of producers or autotrophs in a food chain , and what remains is the net primary productivity, which can be used by consumers or heterotrophs , which are made up of herbivores and carnivores in each environment. Primary productivity is usually determined by measuring the uptake of carbon dioxide or the output of oxygen. Production rates are usually expressed as grams of organic carbon per unit area per unit time. In terrestrial environments , primary productivity is generated by trees and other land plants including planted crops. Most primary producers require nitrogen and phosphorus —which are available as dissolved nutrients in the soil , lakes , and rivers and in the oceans as nitrate , nitrite , ammonia , and phosphorus.

Energy flow & primary productivity

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Comparative Analyses of Ecosystems pp Cite as. Ecosystem-level values of net primary productivity and herbivore biomass, consumption, and secondary productivity in terrestrial ecosystems were assembled from the literature. Data on belowground processes and trophic levels higher than herbivores were too rare in the literature to warrant a comparative analysis. All herbivore trophic-level properties were positively correlated with net primary productivity. Different ecosystem types were located at different positions on a common line. However, rather than regarding herbivore-level properties as simple consequences of producer properties, we believe it is more appropriate to regard primary production as an integrative variable indicative of processes throughout the ecosystem. Unable to display preview.

The unit of mass can relate to dry matter or to the mass of generated carbon. The productivity of autotrophs , such as plants , is called primary productivity , while the productivity of heterotrophs , such as animals , is called secondary productivity. Primary production is the synthesis of new organic material from inorganic molecules such as H 2 O and CO 2. It is dominated by the process of photosynthesis which uses sunlight to synthesise organic molecules such as sugar. Secondary production is the generation of biomass of heterotrophic consumer organisms in a system. This is driven by the transfer of organic material between trophic levels , and represents the quantity of new tissue created through the use of assimilated food. Secondary production is sometimes defined to only include consumption of primary producers by herbivorous consumers [2] with tertiary production referring to carnivorous consumers , [3] but is more commonly defined to include all biomass generation by heterotrophs.

Ecosystem-level values of net primary productivity and herbivore biomass, consumption, and secondary productivity in terrestrial ecosystems were as- sembled.

Productivity (ecology)

The rate of biomass production or the amount of food energy produced or obtained or stored by a particular trophic level per unit area in a unit time is called productivity. It can also be defined as the energy accumulated in plants by photosynthesis. According to Odum there are three types of productivities — primary productivity, secondary productivity and community productivity.

Внутри клубились тучи черного дыма. Все трое как завороженные смотрели на это зрелище, не лишенное какой-то потусторонней величественности. Фонтейн словно окаменел.

По иронии судьбы в Третьем узле секреты не очень-то любили. Нареченный Детским манежем, Третий узел ничем не напоминал стерильную атмосферу остальной части шифровалки. Его обстановка напоминала домашнюю - мягкий ковер, высокотехнологичная звуковая система, холодильник, полный напитков и всяческой еды, маленькая кухня и даже баскетбольное кольцо. В отношении шифровалки в АНБ сложилась своеобразная философия. Нет смысла вбухивать миллиарды долларов в дешифровальный компьютер и одновременно экономить на тех, кто работает на этой превосходной технике.