FNR 331 exam 1

Although it wasn't formally recognized a field of science until the ________, understanding the basic tenants of Ecology was critical to early humans.

20th century

Okios means

house

logos means

study of

most major advances of ecology have happened in the last ______

70 yrs (recognized for 60)

ecology is often used as a synonym for

Environmentalism

ecology came of age in the

1960's

ecology

The branch of biological science concerned with the distribution, abundance, and productivity of living organisms and their interactions with each other and with their physical environment

Level 1

cell

level 2

tissue

level 3

organ

level 4

organ system

level 5

organism

level 6

population

level 7

community

level 8

ecosystem

level 9

biosphere

what is an ecosystem?

a functional system that includes an assemblage of interacting organisms and their environment which acts upon them and on which they act

what are the 5 major attributes of an ecosystem?

Structure, function, complexity, interactions and interdependence, temporal change.

Structure:

an ecosystem is composed of biotic and abiotic subsomponents

Function (processes):

within ecosystems there is a constant exchange of matter and energy between the physical environment and the biotic community and within the biotic community

Complexity:

high degree of integration; events and conditions are multiply determined; prediction of change or events difficult

there are only ___ true levels of biological integration:

3; cells, individuals and ecosystems

interactions and interdependence:

large changes in one component may have cascading effects on other components
led to early view of ecosystems/communities as a 'super organism'

temporal change:

ecosystems are not static
the structure and function of ecosystems change through time

Ecosystem change:

ecological succession: process of change after disturbance
mechanisms of successional change
autogenic
allogenic
biogenic

autogenic mechanisms

changes that are caused by the plants that participate in succession. (light, water, nutrients)

allogenic mechanisms

initiated from outside systems; do not initiate from within and are not related to the plant community (fire, wind, climate change)

biogenic mechanisms

biotic organism; include insect epidemics, diseases and the invasion of nonnative (exotic) species.

trophic:

who is eating who, levels

food chains or trophic chains:

who eats who, energy transfer

trophic webs:

chains together to for a web

what are the two type of trophic chains:

grazing and detrital

Grazing:

autotrophs->herbivores->carnivores

detrital:

commences with dead organic matter and involves saprotrophs

who came up with the term food web?

charles elton

ecological pyramids were developed to

provide a simple representation of trophic function and structure

biomass:

total weight of organic material in a population or other given unit

productivity:

production of biomass per unit area per unit time

Alfred J. Lotka

first to consider populations, communities and ecosystems as energy-transforming systems
suggested that an ecological system can be describes by a set of equations that represent exchanges of matter and energy among its components

Eugene P. Odum

strong proponent of ecosystem ecology where the cycling of matter and associated passage of energy through an ecosystem provides a basis for characterizing the systems structure and function

ecosystems can be described based on _______

Energetics

energy is lost with

each transfer from one trophic level to the next

energy is lost as heat

infrared radiation

second law of thermodynamics:

energy systems have a tendency to increase their entropy rather than decrease it through time

trophic efficiency definition:

the ratio of net productivity in one trophic level to the nest production in the previous trophic level

primary production:

organisms that produce their own energy

Net Primary Productivity (NPP):

amount of energy minus the loss in respiration

primary production varies with _____ ______

available nutrients

Aboveground Primary Productivity

increases to a peak at intermediate stand ages, then declines

aboveground biomass

in many forests, constitutes the largest reservoir of biomass

belowground biomass

in many forests, constitutes a much greater annual turnover of organic matter and energy

many species of plants will allocate more primary production to roots on more ______

xeric and nutrient poor sites.

assimilation efficiency

the ratio of assimilation (energy intake) to ingestion

eventually all biomass from other trophic levels ends up in the _____ _____

detritus chain

fungi dominate decomposition in _____ forests

coniferous

bacteria dominate decomposition ______ forests

deciduous

geochemical cycle

chemical cycling between systems

Biogeochemical cycle:

cycling chemicals within the ecosystem

biochemical cycle:

cycling of chemicals within individual organisms

in the geochemical cycle, chemicals move via ___

two pathways the gaseous and sedimentary cycle. (nutrients removed from ecosystem typically do not return)

the gaseous cycle:

predominate form of entry into an ecosystem for N, C, and O. sulfur also cycle as a gas

what causes acid rain?

nitrogen and sulfur oxides

tempurature inversion

a deviation from the normal temperature distribution in the atmosphere, resulting in a layer of cold air temporarily trapped near the ground in a warmer, upper layer

where does air pollution come from?

Nitrogen oxide and sulfur dioxide emissions

Natural Factors that Predispose Forests to Pollution Effects

•High pressure and frequent air stagnation events;

•Sunlight and heat that increases chemical reactivity;

•Elevation and topography, higher winds, more clouds;

•Rainfall and humidity which enhances deposition & haze;

•Organic emissions from trees (isoprene);

•Low buffering capacity in streams & acid soils

all chemicals are part of _____ cycles

sedimentary

There are three basic mechanisms involved in the movement of material in the sedimentary cycle:

meteorological, biological, geological/hydrological

Meteorological mechanism

inputs from dust and precipitation and outputs result of wind erosion and transportation

Biological mechanisms

Redistribution of nutrients via animal movement or migration

Geological/hydrological mechanisms

•Inputs via chemical weathering of rock and soil or dissolved nutrients moving into the ecosystem in soil water or stream water

The major input of nutrients in many systems is the ____ ____ of weathering erosion and soil solution movement

geological process

hydrologic studies:

•Measure or estimate quantity of nutrients entering the system by meteorological and biological process
•Measure the quantity of nutrients leaving the system in stream water
•The difference is an estimate of weathering input.

biogeochemical cycle

•Continuous exchange of chemicals between the biota and physical environment within an ecosystem.
•Uptake of nutrients by plants is a major component of this cycle.

most forest plants are highly (or completely) dependent upon mutualistic relationship between their ____ & _____

roots and mycorrhiza

what do mycorrhiza do?

•Increase the uptake of nutrients, N, P, K in particular
-increases the volume of soil occupied by the root system thus increasing absorbing surface
-increases the uptake of water
-organic acids secreted by hyphae accelerate decomposition

losses from litter fall and fine roots:

turnover accounts for most of N, Ca, and Mg loss from vegetation

rate of decomposition is influenced by

biota, temperature, chemical composition of leaves, moisture

ex of arthropod herbivore

cicada nymph

ex of arthropod predator

mite

ex of arthropod fungal feeder

springtail

ex of arthropod shredder

millipede

what do soil arthropods and other invertebrates do?

shred organic matter, stimulate microbial activity, mix microbes with their food, mineralize plant nutrients, enhance soil aggregation, burrow, stimulate the diversity of species

how many soil arthropods are there in a square meter of soil?

745k

Understories of most forests are low in biomass compared to the over-story

-Forests with pronounced shrub layer
-Forests with large biomass of bryophytes

Following a major canopy disturbance,

there is a flush of nutrients that become available as plant material on site begins to decompose

Microbial activity increases due to

reduced competition from tree roots and decreased transportation (more soil water available). This may delay nutrient availability to plants but it also reduces loss of nutrients prior to plant uptake.

Nutrients resulting from the assert effect are typically

•taken up rapidly by early successional species, drastically reducing nutrient loss through leaching and runoff.

The Hubbard Brook experiment arrested secondary succession and

prevented vegetation from sequestering nutrients

Because of the strong relationship between _______ ______ and __________, understanding how forest management affects nutrient cycling is critical to sustainable forest management

nutrient cycling (fertility), productivity

maintaining the nutrient capital of a managed forest ecosystem depends upon:

the inherent nutrient capital of the site
how often harvest occur
how much material is harvested
how the substrate is affected
what grows on the site after harvest

fire returns a flush of nutrients to the soil through ____

ash

in nutrient cycling, carbon is lost from the site through _____

combustion

nitrogen may be lost in severe fire through _______

Volatilization

fire is often referred to as a ______ ______

rapid decomposer

geochemical cycle-

Exchanges of chemicals between ecosystems

biogeochemical cycle-

exchanges of chemicals within an ecosystem

biochemical cycle-

redistribution of chemicals within individual organisms

what is retranslocation in the biochemical cycle?

helps to conserve nutrients, but not all nutrients can be reabsorbed equally.
N and S move in the form of amino acids when proteins break down. Mg, K and P also move easily. Ca is incorporated into the cell walls and is highly immobile

the rate of retranslocation is generally greater at _____ ____ sites

nutrient poor

not all nutrients are _____ _____

equally mobile