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Ecosystem - Biodiversity - Lecture Slides, Slides of Biology

English and Foreign Languages UniversityBiology

These are the lecture slides of Biodiversity. Key important points are: Ecosystem, Community, Dynamics, Chemical Cycling, Energy Machines, Matter Processors, Trophic Levels, Feeding Relationships, Laws of Physics, Law of Conservation

Typology: Slides

2012/2013

Uploaded on 01/22/2013

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•An ecosystem consists of all the organisms
living in a community as well as all the abiotic
factors with which they interact.
•The dynamics of an ecosystem involve two
processes: energy flow and chemical cycling.
•Ecosystem ecologists view ecosystems as
energy machines and matter processors.
•We can follow the transformation of energy by
grouping the species in a community into
trophic levels of feeding relationships.
Introduction
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Download Ecosystem - Biodiversity - Lecture Slides and more Slides Biology in PDF only on Docsity!

  • An ecosystem consists of all the organisms living in a community as well as all the abiotic factors with which they interact.
  • The dynamics of an ecosystem involve two processes: energy flow and chemical cycling.
  • Ecosystem ecologists view ecosystems as energy machines and matter processors.
  • We can follow the transformation of energy by grouping the species in a community into trophic levels of feeding relationships.

Introduction

  • The law of conservation of energy applies to ecosystems. - We can potentially trace all the energy from its solar input to its release as heat by organisms.
  • The second law of thermodynamics allows us to measure the efficiency of the energy conversions.

The laws of physics and chemistry

apply to ecosystems

  • Most primary producers use light energy to synthesize organic molecules, which can be broken down to produce ATP; there is an energy budget in an ecosystem.

An ecosystem’s energy budget depends on primary production

  • Gross and Net Primary Production.
    • Total primary production is known as gross primary production (GPP). - This is the amount of light energy that is converted into chemical energy.
    • The net primary production (NPP) is equal to gross primary production minus the energy used by the primary producers for respiration (R): - NPP = GPP – R
  • Primary production can be expressed in terms of energy per unit area per unit time, or as biomass of vegetation added to the ecosystem per unit area per unit time. - This should not be confused with the total biomass of photosynthetic autotrophs present in a given time, called the standing crop.
  • Production in Marine ecosystems.
    • Light is the first variable to control primary production in oceans, since solar radiation can only penetrate to a certain depth (photic zone).

We would expect production to increase along a gradient from the poles to the equator; but that is not the case. There are parts of the ocean in the tropics and subtropics that exhibit low primary production.

  • Nitrogen is the one nutrient that limits phytoplankton growth in many parts of the ocean.
  • Nutrient enrichment experiments showed that iron availability limited primary production.
  • Obviously, water availability varies among terrestrial ecosystems more than aquatic ones. - On a large geographic scale, temperature and moisture are the key factors controlling primary production in ecosystems.

In terrestrial ecosystems, temperature, moisture, and nutrients limit primary production

  • On a more local scale, mineral nutrients in the soil can play key roles in limiting primary production. - Scientific studies relating nutrients to production have practical applications in agriculture.
  • Pyramids of biomass represent the ecological consequence of low trophic efficiencies. - Most biomass pyramids narrow sharply from primary producers to top-level carnivores because energy transfers are inefficient.