Bio Midterm 2
MAJESTIC PINE WOODS
- Small pond/lake
- 3 different types of trees dispersed throughout the property
(About 30 white pine, 10 sugar maple & 22 honeysuckle)
- Rich organic layer & mineral soil/sandy loam, lots of water
OLD FIELD WOODS
- River crossing diagonally across forest, 2 ponds
- Ground is green
- Giant hogweeds around ponds
- 3 Trembling aspens: more saplings
- Also black walnut, black locust, honeysuckle, pin cherry & white birch
- Large clay layer and medium amount of organic soil.
MAPLE RIDGE WOODS
- MANY sugar maples
- Dense amount of trees
- 3 white pines, 5 white ashes
- No bodies of water
- Alternate leaved dogwood
- Large mineral soil & sand/gravel layer
- Little water
- Small organic layer
- Very dry ground
Biodiversity: Biodiversity or Biological diversity is often used as a non-technical catch-all term for
nature. No definition is perfect or accepted by all biologists. However, we provide two of the more
commonly quoted definitions here defined by 1) the “Convention on Biological Diversity”, also
known as the Rio Summit, which defines biodiversity as “the variability among living organisms
from all sources including, terrestrial, marine and other aquatic ecosystems and the ecological
complexes of which they are part; this includes diversity within species, between species and of
ecosystems.”, and 2) The Canadian Biodiversity Strategy, which defines biodiversity as “the
variety of species and ecosystems on Earth and the ecological processes of which they are a
part”. In general, there are three levels of biodiversity: genetic, species, and ecosystem.
Background material on biodiversity theory can be found at the Canadian Biodiversity Web Site.
Species Richness: Species richness is simply the number of species present in an ecosystem.
Species richness is measured within an ecosystem by sampling the community, or taxonomic
group. The sampling intensity is achieved by plotting the number of new species with each sample
unit , such as a plot. Sampling species richness is complete when the species area curves is
saturated (levels off at ~7 plots in the figure below). Species richness is one component of the
concept of species diversity, which also incorporates evenness, that is, the relative abundance of
species. A good source of background information can be found on Wikipedia. A species area curve, showing the number of species found (Y-axis) based on how much area has
been sampled (X-axis).Click for larger image.
Abundance: Species abundance refers to the percent cover, biomass or frequency of individuals
per species. Relative abundance relates to the “evenness” of distribution of individuals among
species in a community. Two communities may be equally rich in species but differ in relative
abundance. For example, each community may contain 7 species and 210 individuals, but in one
community all species are equally common (e.g., 30 individuals of each species) and in the other
some species are common and others rarer.
Abiotic: Non-living or abiotic factors are non-living chemical and physical factors in the
environment. Includes light, radiation, temperature, water, the chemical surrounding composed of
the terrestrial atmospheric gases (including pollution), & soil factors such as nutrients and porosity.
These underlying factors affect different plants, animals and fungi to different extents. EX., some
plants are mostly water stressed, so the availability of water plays a larger role in their success.
Some archaebacteria require very high temperatures, or unusual concentrations of chemical
substances such as sulfur, because of their adaptation to extreme conditions.
Biotic: Living or biotic factors are all the living things that live within and shape an ecosystem. This
usually includes producers (plants that convert the sun’s energy into chemical food), consumers
and decomposers. The interactions (e.g., competition) among individuals or species plays an
important role in determining species survival and range limits.
Population: The number of individuals of a species within some area at some point in
time. Population ecology studies organisms from the point of view of the size and structure of their
populations. This includes the interaction of organisms with their environments by measuring
properties of populations such as: population size, population density, patterns of dispersion,
demographics, and population growth. Studies of individuals are concerned mostly about
physiology, reproduction, development or behavior. Population studies usually focus on the habitat
and resource needs of individual species, their group behaviors, population growth, and what limits
their abundance or causes extinction.
Community: The various species living in a given area at a particular point in time.Community
ecology studies the structure and dynamics of animal and plant communities. Studies of
communities examine how populations of many species interact with one another, such as predators and their prey, or competitors that share common needs or resources and often
compete for these resources.
Ecosystem: A system formed by the interaction of a community of organisms with their physical
environment. The study of ecosystems mainly consists of the study of certain processes that link
the living, or biotic, factors to the non-living, or abiotic, factors. Energy transformations and
biogeochemical cycling are the main processes that comprise the field of ecosystem ecology
Ms. Fields — Environmental Consultant
“The cold stream water from the Old Field Woodlot is the purest stream water in southern
Ontario and home to many species of fish. The bird diversity is highest in the Old Field Woodlot,
followed by Majestic Pine woods and the lowest in the Maple Ridge Woods.”
Ms. Flowerpot — Environmentalist
“The beauty and serenity of Majestic Pine Woods has intrinsic value to the people in this city.
Maple Ridge Woods is home to many birds and we have established many bird feeders that are
cared for by the local community neighbourhoods. The Old Field Woods is home to many pesky
skunks and racoons that get into our composters and garbage boxes!”
Mr. Stumpage — Forester
“The basal area is low in the Old Field Woodlot, and it is dominated by a diverse shrub
physiognomy. The basal area is high in both the Majestic Pine woods and the Maple Ridge
Woods, which have dominant tree physiognomies. We aged the woodlots using increment bores
and counted the tree rings: Old Field Woodlot is 20 years old, Majestic Pine woods is only 80
years old (rich soils make big happy trees) and the Maple Ridge Woods is 250 years old.”
Mr. Woods — Conservation Officer
“Alpha diversity is highest in the Old Field Woodlot, followed by the Majestic Pine woods and
least in the Maple Ridge Woods. Beta diversity is low between Majestic Pine woods and Maple
Ridge Woods. Beta diversity is high when comparing the Old Field Woodlot to either Majestic
Pine woods or Maple Ridge Woods.”
Mr. Burnz — Developer
“We support sustainable management of biodiversity and will support woodlot management
plans that enhance woodlot biodiversity. This will include a restoration plan that will plant key species in each of the woodlots in collaboration with community groups. We would also like to
support and enhance community bird feeder programs in each of the woodlots.”
Population Growth: Population growth is the change in the number of individuals during some
period of time. This is often calculated using demographic data; population growth rate = birth
rate – death rate + immigration – emigration. The calculation of population size is
expressed as Pt2 = Pt1 + (B) – (D) + (I) – (E), where Pt2 is the final population at the final time,
Pt1 is the original or starting population size.
Carrying capacity: This refers to the number of individuals who can be supported in a given area
within natural resource limits, and without degrading the natural social, cultural and economic
environment for present and future generations. The carrying capacity for any given area is not
fixed. It can be altered by disturbances that deplete resources, which often are accompanied by a
population decrease. As the environment is degraded, carrying capacity actually shrinks, leaving
the environment no longer able to support even the number of individuals who could formerly have
lived in the area on a sustainable basis. No population can live beyond the environment’s carrying
capacity for very long.
Carrying capacity. Click for larger image.
Species Interactions: Species that live in the same ecosystem interact in many different
ways:competition, predation, parasitism, mutualism, amensalism, neutralism, antagonism,
commensalism, etc. Note that some mutualisms may be either obligate (must live with it’s partner
species) or facultative (can live without its partner species). The organization of a community in an
ecosystem with respect to ecological interactions is referred to as community structure.
Ecosystem Processes: Ecosystem processes include energy flows and the cycling of materials.
These two processes are linked, but they are not the same. Energy enters the biological system as
light energy, or photons, which is transformed into chemical energy in organic molecules by
cellular processes including photosynthesis and respiration, and ultimately is converted to heat
energy. This energy is dissipated, meaning it is lost to the system as heat; once it is lost it cannot
be recycled. Without the continued input of solar energy, biological systems would quickly shut
down. Thus the earth is an open system with respect to energy. Many elements such as carbon,
nitrogen, or phosphorus enter living organisms in a variety of ways. Plants obtain elements from
the surrounding atmosphere, water, or soils. Animals may also obtain elements directly from the
physical environment, but usually they obtain these mainly as a consequence of consuming other
organisms. These materials are transformed biochemically within the bodies of organisms, but
sooner or later, due to excretion or decomposition, they are returned to an inorganic state. Often bacteria complete this process, through the process called decomposition or mineralization. During
decomposition these materials are not destroyed or lost, so the earth is a closed system with
respect to elements (with the exception of a meteorite entering the system now and then). The
elements are cycled endlessly between their biotic and abiotic states within ecosystems. Those
elements whose supply tends to limit biological activity are called nutrients. Grasslands are often
used as a model for ecosystem process.
Energy enters an ecosystem in the form of heat from the sun. This energy is absorbed by
organisms such as plants, and is then converted to other forms of energy and stored. Plants,
animals and microorgnaisms release energy in the form of heat, for example through breathing
and sweating. Energy is also released from an ecosystem during a fire. Plants only capture about
one percent of the energy that reaches the earth from the sun.
This movement of energy from producers to consumers is called a Food Chain.
Food Chains are found in two parts of an ecosystem. The "grazing" food chain includes the
producers and consumers that cycle energy from living plants. The "detritus" food chain cycles
energy from non-living remains of both plants and animals.
The "grazing" food chain has a number of steps. At each step only about 10% of the energy is
passed up through the chain. The rest is passed back into the atmosphere as heat through
breathing and decomposition. The first step is photosynthesis.
The "detritus" food chain is a system where the energy produced by the breakdown of dead plant
and animal matter is cycled into the "grazing" food chain. Detritus is organic matter formed by
decaying animal or plant tissue, or fecal matter. Detritus eaters (or detritivores) such as insects,
worms and other small organisms feed on dead plants, waste products from animals and dead
animals. Decomposers are fungal or bacterial organisms that work within the dead material to
help break it down, activating decay and decomposition. This important part of the ecosystem
takes the last of the energy that was originally absorbed by the plants and returns it to the soil.
Carbon can be traced through the ecosystem in a cycle that is similar to the water cycle. Plants
take in carbon in the form of carbon dioxide from the atmosphere through respiration. When
plants are eaten the carbon is transferred to the consumers. As plant material is broken down in
the digestive system of an animal, carbon is absorbed as a nutrient for use by that animal. It is
released back into the atmosphere as carbon dioxide through respiration and through the
decomposition of dead animals and fecal matter. Grassland fires also release carbon dioxide into
Some water is absorbed into the soil. The rest runs over the surface of the ground and collects in
low areas to form into wetlands, lakes and rivers. Finally, some water that reachs the ground is
evaporated back into the atmosphere. (Same with snow)
Plants take up some of the water contained in the soil through their roots. Other water that
permeates (soaks through) the soil flows into wetlands, lakes, and rivers. The rest becomes part
of the water table. The water table is water that remains in the soil, filling the pores between rocks
and soil particles. Water is returned to the atmosphere as water vapour through evaporation and
transpiration. Transpiration is a process in which water molecules leave the plant's surface
through evaporation. The water that reaches wetlands, lakes and rivers flows eventually to the ocean, with some of it
evaporating along the way. Evaporation provides the moisture in clouds that condenses to form
droplets of rain or snow. These droplets of water return to the earth as precipitation, and the cycle
The portions of grassland ecosystems that occur in low elevations and especially on south-facing
slopes suffer from a water deficit during the hottest and driest months of the year. The amount of
water that is released into the atmosphere through transpiration and evaporation is larger than
the amount that falls as rain at this time of year. Grassland plants have adopted a variety of ways
to survive under these difficult growing conditions.
Bright yellow sagebrush buttercups are some of the earliest flowers to be seen in the grasslands
early spring. They start to grow before all the snow has left the grasslands, their shallow roots
take advantage of all the water stored in the thawed upper layers of the soil. By the end of May
the available moisture is well below the reach of the roots of the plants, and little remainsof the
sagebrush buttercup but some dried out leaves.
Plants such as low pussytoes and silky lupine start growing a little later in the spring and bloom
before the summer drought begins. They may grow again as soil moisture increases after fall
showers. Some of the bunchgrasses have a similar early growth habit but become semi-dormant
during the summer drought. They put on a significant amount of growth when fall rains arrive.
Deeply-rooted shrubs such as big sagebrush and rabbitbrush start growing later in the year and
are covered with yellow flowers in the fall.
All organisms need many nutrients. Nutrients are found in the soil. Nutrients combine with water
in the soil and are transported through the roots of the plant to those parts that need them. They
are then passed through the food chain as the consumers eat the plants and each other. The final
decomposition of both producers and consumers returns the nutrients back to the soil.
Neutralism describes the relationship between two species which interact but do not affect each
Amensalism is a relationship in which a product of one organism has a negative effect on another
organism. It is specifically a population interaction in which one organism is harmed, while the
other is neither affected nor benefited.
Competition is a mutually detrimental interaction between individuals, populations or species, but
rarely between clades.
Synnecrosis is a particular case in which the interaction is so mutually detrimental that it
results in death.
In antagonistic interactions one species benefits at the expense of another.
Facilitation describes species interactions that benefit at least one of the participants and cause
no harm to either.
Commensalism benefits one organism and the other organism is neither benefited nor harmed. Mutualism
Mutualism is an interaction between two or more species, where species derive a mutual benefit,
for example an increased carrying capacity. Similar interactions within a species are known
OBLIGATE: cannot survive in short or long term without the other species.
Ms. Fields — Environmental Consultant
“We used stratified random sampling protocols for streams to gather water samples and fish. Our
bird data came from breeding bird surveys conducted by our staff within random sample points on
transects within each woodlot.”
Ms. Flowerpot — Environmentalist
“We do not need to have a reason for enjoying nature’s splendour and the intrinsic value of
biodiversity. The community has made a list of birds seen at the bird feeders and along the trails
in Maple Ridge Woods and Majestic Pine Woods. We stay away from Old Field Woods because it
has dangerous Giant Hog weed that caused serious injury to some of our neighbourhood
Mr. Stumpage — Forester
“We estimated basal area per hectare using both diameter at breast height and wedge prisms at
random points along a grid of transects in each woodlot. The number of random point samples
was determined using a sample area curve where the variation in basal area levelled off when we
measured enough random points. At each point we estimated the abundance of vegetation in the
tree, shrub or herb layers, which was used to assess forest physiognomy.”
Mr. Woods — Conservation Officer
“We have data from current and past surveys of vegetation, mammals and birds for each of
these woodlots. This is augmented by additional records from the North American Breeding Bird
Survey (BBS) and records from Area of Natural & Scientific Interest (ANSI), including COSEWIC
(Committee on the Status of Endangered Wildlife in Canada).”
Mr. Burnz — Developer
“We will develop the appropriate sustainable management and restoration plans in coordination
with the city and local citizens. This will begin with a survey of the local communities that will
provide a list of concerns and suggestions for the sustainable forest ecosystem management of
Abiotic variables: Abiotic factors are those non-living physical and chemical factors that affect the
ability of organisms to survive and reproduce. This includes those inert factors of the ecosystem
such as light, temperature (heat), chemical products, water and atmosphere.
Why is light an important factor in forest ecosystems? Light is an essential abiotic factor in forest
ecosystems because it constitutes the main supply of energy for organisms. Plants with chlorophyll can change the light energy into chemical energy via the process known as photosynthesis. This
chemical energy is stored in complex organic substances that are used for growth and the
production of seeds. Large amounts of biomass are stored in the forests using energy harnessed
from the sun. Many plants have adapted to high or low light conditions; shade tolerant plants can
dominate the understory of dense forest canopies. Light is also regulates many biological rhythms
of a large amount of species of both plants and animals. Many flowering plants use a
photoreceptor protein, such as phytochrome or cryptochrome, to sense seasonal changes in night
length, or photoperiod, which they take as signals to flower. Animals use light in various ways. For
example, insects use ultraviolet light to differentiate flowers from another when harvesting nectar
or pollen; this interaction contributes to pollination in plants, which is the subject of many co-
evolutionary studies. Birds orient themselves by means of the perception of small differences in
the reflection of light UV by the objects on land such as different types for forests, water, rocks, etc.
(Question on importance of light? ^)
Niche: To understand species’ distribution models it is important to also think about species
occurring in environmental space, which is a conceptual space defined by the environmental
variables to which the species responds. The concept of environmental space has its foundations
in ecological niche theory. Hutchinson: