Lecture 1 Flashcards
Ecosystem
all the organisms in a given area, along with the nonliving (abiotic) factors with which they interact; a biological community and its physical environment.
Ecosystems exist at many spatial scales (e.g., from ponds to the entire biosphere)
what does Ecosystem ecology examines?
Ecosystem ecology examines the flow of energy and chemical cycling in habitats, as well as, the effects of
natural and human-induced disturbances on ecosystems (e.g., air/water pollution, tree harvesting, land-use changes….)
Energy Flow
the passage of energy through the components of an ecosystem
Chemical Cycling
unlike energy flow, chemical cycling involves the circular (recycling) movement of materials within the ecosystem
For example, a terrarium as an ecosystem
Ecosystems consist of ____ & ___ components
Ecosystems consist of biotic & abiotic components
Biotic
all living organisms in an area (community)
Abiotic
physical environment with which the organisms interact
Abiotic & biotic components exchange _____ & _____ (e.g., nutrients)
Abiotic & biotic components exchange energy & materials (e.g., nutrients)
Abiotic Inputs into the ecosystem include:
- Energy (radiant)
- Inorganic substances (CO2, N, O2, minerals)
- Organic substances (e.g., proteins, carbohydrates, humic acids)
- Water
Energy (radiant)
Energy (radiant) is an overriding factor that affects temperature, moisture, seasons, and photosynthetic energy
temperature and moisture
temperature and moisture strongly influence the type of organisms present and the productivity of a given system
Biotic inputs into the ecosystem
- Organisms that move into an ecosystem (e.g., animal migrations)
- Influences from adjacent ecosystems
For example, upstream ecosystems or downwind ecosystems; ocean currents, ……..
Radiant Energy
•Majority of radiant energy reaching the planet is converted to heat Warms Earth & the Atmosphere, and in turn:
- Drives the hydrologic (water) cycle
- Generates air currents (winds) and ocean currents
•A small amount of radiant energy reaches photosynthetic organisms where it may be converted to photochemical energy
This photochemical energy is stored in ~170 billion metric tons of organic material produced globally per year
What is energy?
The capacity to do work
- Energy can only be described and measured by how it affects matter
- Energy is required to move matter in a direction it would not move if left alone
- All organisms require energy from their surroundings in order to stay alive
Familiar Forms of Energy
Thermal energy (heat) Radiant energy (e.g., light) Kinetic energy (motion) Chemical energy
photosynthesis:
radiant energy chemical energy (e.g., sugars)
Energy Conversions Laws
1) Universal laws govern how one form of energy can be converted to another
2) These laws apply equally to living and non-living things
3) The laws governing energy conversion are called
the laws of thermodynamics
Thermodynamics:
the study of energy transformations (conversions) that occur in a collection of matter
Energy Conversions Follow Two Laws
First Law: energy is neither created nor destroyed.
Second Law: conversion of energy from one form or another is always accompanied by a reduction in the order of the universe
OR
When energy is converted from one form to another, some of the energy becomes unavailable to do work
With each conversion of energy, the energy available to Do Work ____
Declines
The amount of disorder in a system =
Entropy
Heat can be considered a form of ______ because it represents RANDOM motion of molecules
Heat can be considered a form of entropy because it represents RANDOM motion of molecules
Autotrophs (self-feeders):
an organism that makes its own food , thereby sustaining itself without eating other organisms or their molecules
•Plants, algae and photosynthetic bacteria are autotrophs
Photosynthesis:
process by which photosynthetic organisms synthesize food molecules from carbon dioxide and water
by using light energy.
Note, only ~1% of the PAR that reaches the autotrophs is actually converted to chemical energy (e.g. sugars)
