community effect
Ex. Sea otters affect the abundance of kelp, but their influence is indirect--they dont feed on the kelp nor do they protect individual kelp plants from attach by sea urchins. But sea otters reduce the number of sea urchin. With fewer sea urchins, less ke
How is life sustained?
By the interactions of many organisms functioning together, interacting through their physical and chemical environments. This is called an ecosystem.
What are the two major parts in an ecosystem and define both?
Nonliving is the physical-chemical environment, including local atmosphere, water, mineral soil and living, called the ecological community, is the set of species interacting with the ecosystem.
In an ecosystem there are two basic kinds of processes that must occur, what are they?
1) a cycling of chemical elements and 2) a flow of energy.
-these processes are necessary for all life, but no single species can carry out all necessary chemical cycling and energy flow alone.
At its most basic, an ecosystem consists of...?
several species and a fluid medium (air, water, both).
Info about the chemical cycling
About 21 chemical elements are required by at least some form of life, and each chemical element required for growth and reproduction must be available to each organism at the right time, in the right amount, and in the right ration relative to other elem
Info about an ecosystem
an ecosystem consists of at least one species that produces its own food from inorganic compounds in its environment and another species that decomposes the wastes of the first species, plus a fluid medium-air, water, both.
One way that individuals in a community interact is by feeding one another.
Enerfy, chemical elements, and some compounds are transferred from creature to creature along FOOD CHAINS.
what are food chains?
the linkage of who feeds on whom.
what are food webs?
the more complex linkages.
How do ecologists group the organisms in a food web?
into trophic levels
what is a trophic level?
consists of all organisms in a food web that are the same number of feeding levels away from te original energy source.
what is the original source of energy in most ecosystems?
the sun
Green plants, algae, and certain bacteria produce sugars through the process of...?
photosynthesis, using only energy from the sun and carbon dioxide from the air.
-thus they are called AUTOTROPHS, "self-nourish", and are grouped into the first trophic level.
what are heterotrophs?
organisms which feed on others (animals)
herbivores
organisms that feed on plants, algae, or bacteria.
-members of the second trophic level
carnivores
meat eaters, feed directly on herbivores make up the third trophic level
decomposers
those that feed on dead organic material.
classifies in the highest trophic level in an ecosystem.
could be bacteria or fungi
what is a pelagic ecosystem?
ocean ecosystem
omnivores
eaters of both plants and animals-feed on several trophic levels
are ecosystem open or closed systems? why?
open: energy and matter flow into and out of them
what is a commonly used practical delineation of the boundary of an ecosystem on land?
the watershed
what happens within a watershed?
all the rain that reaches the ground from any source flows out in one stream
what determines the watershed?
topography
what is topography
they lay of the land
when a watershed is used to define the boundaries of an ecosystem, what happens to the ecosystem?
it is unified in terms of chemical cycling.
What do all ecosystems have in common?
not a physical size or shape but the flow of energy and the cycling of chemical elements--which give ecosystems the ability to sustain life.
All life requires energy. what is energy?
it is the ability to do work, to move matter
what is ecosystem energy flow?
it is the movement of energy through an ecosystem from the external environment through a series of organisms and back to the external environment.
Energy enters an ecosystem by two ways, what are they?
1)energy fixed by organisms and moving through food webs within an ecosystem
2)heat energy that is transferred by air or water currents or by convection through soils and sediments and warms living things.
Info about ecosystems
when we discuss ecosystems, we are talking about some of the fundamental properties of life and of the ecological systems that keep life going
what is the first law of thermodynamics? (known as the law of conversation of energy)
it states that in any physical or chemical change, energy is neither created nor destroyed but merely changed from one form to another
what is the second law of thermodynamics?
it addresses how energy changes in form.
-in other words, no use of energy in the real world can never be 100 % efficient. whenever useful work is done, some energy is inevitably converted to heat. collecting all the energy dispersed in this closed system
what is a closed system?
a system that receives no input after the initial input.
what is entropy?
it is the measure of the decrease in order (the disorganization of energy)
how does the second law of thermodynamics give us a new understanding of a basic quality of life?
it is the ability to create order on a local scale that distinguishes life from its nonliving environment.
this ability requires obtaining energy in a usable form, and that is why we eat
energy must be continually added to an ecological system in a usable form.
energy is inevitably degraded into heat, and this heat must be released from the system. If it is not released, the temperature of the system will increase indefinitely.
(the net flow of energy through an ecosystem, then, is a one-way flow)
an ecosystem must lie between a source of usable energy and a sing for degraded (heat) energy.
the ecosystem is said to be an intermediate system between the energy source and they energy sink. the energy source, ecosystem , and the energy sink together form a thermodynamic system.
what is a local increase?
when the ecosystem undergo's an increase in order, as long as the entire system undergoes a decrease in order which is called a GLOBAL DECREASE
Info
creating local order involves the production of organic matter. producing organic matter requires energy; organic matter stores energy
what is biomass?
the total amount of organic mater in an ecosystem
how is biomass increased?
through biological production (growth)
what is change in biomass over a given period called?
production
what is biological production?
it is the capture of usable energy from the environment to produce organic matter (or organic compounds)
-this capture is often referred to as energy "fixation", and it is often said that the organism has "fixed energy
how many kinds of production are there and what are they called?
2, gross and net
what is gross production?
the increase in stored energy before any is used
what is net production?
the amount of newly acquired energy stored after some energy has been used
what is the difference between growth and net production?
it is like the difference between gross and net production. your gross income is the amount you are paid and your net income is what you have left after taxes and other fixed costs
what are three measures used for biomass and biological production?
the quantity of organic material (biomass), energy stored, and carbon stored
how is biomass usually measured?
as the amount per unit surface area- for ex, as grams per square meter or metric tons per hectare
production, a rate, is the change per unit area in a unit of time
...
what is the production carried out by autotrophs called?
primary production
that of heterotrophs is called?
secondary production
how do most autotrophs make their sugar?
from sunlight, carbon dioxide, and water in a process called photosynthesis, which releases free oxygen
some autotrophic bacteria can derive energy from inorganic sulfur compounds, and theses bacteria are referred to as what?
chemoautotrophs
-such bacteria live in deep ocean vents, also in muds of marshes where there is no free oxygen
what happens once an organism has obtained new organic matter?
it can use the energy in that organic matter to do things: to move, make new compounds, to grow, reproduce, or store it for future uses
how is the use of energy from organic matter by most heterotrophic and autotrophic organisms accomplished?
through respiration
what happens in respiration?
an organic compound combines with oxygen to release energy and produce carbon dioxide and water
respiration is the use of biomass to do what?
release energy that can be used to do work
what does respiration do with the carbon dioxide that had been removed by photosynthesis?
returns it to the environment
what happens as energy flows through a food web?
it is degraded, and less and less is usable
what is energy efficiency?
it is defined as the ration of output to input, and it is usually further defined as the amount of useful work obtained from some amount of available energy
when we view organisms as food, we define efficiency as the farmer does, in terms of energy storage (net production from available energy)
when we are energy users, we define efficiency as the truck driver does, in terms of how much useful work we can accomplish with the available energy
what is a common measure of energy efficiency?
food chain efficiency or trophic level efficiency, which is the ratio of production of one trophic level to the production of the next lower trophic level. this efficiency is never very high.
are ecosystems dynamic,and what does that mean?
yes, and that means they change over time both from external (environmental) forces and from their internal processes
the classic interpretation of populations, species, and ecosystems and Earth's entire biosphere has been to assume that each is a stable, static system.
but the more we study these ecological systems, the clearer it becomes that these are dynamic systems, always changing and always requiring change.
_____ not only change but also then recover and overcome theses changes and life continues on.
ecosystems
what is ecological succession?
when disturbed, ecosystems can recover through this if the damage is not to great
-we can classify ecological succession as primary or secondary
primary succession
is the establishment and development of an ecosystem where one did not exist previously.
-coral reefs that form on lava emitted from a volcano and cooled in shallow ocean waters is an example
secondary succession
is reestablishment of an ecosystem after disturbances. in secondary succession, there are remnants of a previous biological community, including such things as organic matter and seeds.
-a coral reef that has been killed by poor fishing practices, polluti
succession
is one of the most important ecological processes, and the patterns of succession have many management implications
-ex of succession: when a house lot is abandoned in a city, weeds begin to grow. after a few years, shrubs and trees can be found; secondar
what is a bog?
an open body of water with surface inlets-usually small streams- but no surface outlet
species characteristic of the early stages of succession are called pioneers or _____
early successional species
-they have evolved and are adapted to the environmental conditions in early stages of succession.
in terrestrial ecosystems, vegetation that dominates late stages of succession is called LATE SUCCESSIONAL SPECIES, tends to be slower-growing and longer-lived, and can persist under intense competition with other species
For ex, in terrestrial ecosystems, late successional vegetation tends to grow well in shade and have seeds that, though not as widely dispersing, can persist a rather long time.
-middle successional species have characteristics in between the other two ty
what is one of the imp effects of succession ?
a change in storage of chemical elements necessary for life
on land the storage of chemical elements is essential for plant growth function generally increases during the progression from the earliest stages of succession to middle succession. there are three reasons for this:
1) INCREASED STORAGE-organic matter, living or dead, stores chemical elements. as long as there is an increase in organic matter within the ecosystem, there will be an increase in the storage of chemical elements.
2) INCREASED RATE OF UPTAKE-for ex, in te
how can early successional species affect what happens later in successional in three ways?
1)facilitation
2)interference
3)life history difference
in facilitation
in facilitation, an earlier successional species changes the local environment in ways that make it suitable for another species that is characteristic of a later successional stage.
-dune and bog succession illustrate facilitation. the first plant specie
in interference
in contrast to facilitation, interference refers to situations where an earlier-successional species changes the local environment so it is unsuitable to another species characteristics of a later successional stage. interference is common, for ex, in ame
changes in the time it takes different species to establish themselves give the appearance of a succession caused by species interactions but it is not.
...
in cases where no species interact through succession, the result is termed ________
chronic patchiness
chronic patchiness
is a characteristic of highly disturbed environments and highly stressful ones in terms of temp, precipitation, or chemical availability. for ex, in the warm deserts of CA, Arizona, and Mexico the major shrub species grow in patches, often consisting of m