BIOL Midterm 2
Majestic Pine Woods
Maple Ridge Woods Old Field Woods The Old Field Woodlot is at the sensitive headwaters of the local watershed that provides water and
is very weedy.
Biodiversity: Biodiversity is often used as a nontechnical term, which refers to the different scales of biological
variation. 1) the Convention on Biological Diversity, also known as the Rio Summit, 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.”
2) The Canadian Biodiversity Strategy, defines biodiversity as “the variety of species and ecosystems on Earth and the
ecological processes of which they are a part”. In general, biodiversity comprises three scales of variation: genetic,
species, and ecosystem.
Species Richness: Species richness is defined as the number of species present in a defined area such as a
community or ecosystem.
Sampling species richness is complete when the species area curve is saturated
Abundance: Species abundance refers to how common a species is in a defined area and can be measured as
percent cover, biomass or frequency of individuals per species
Relative abundance: is a term that refers to the comparison of the species abundance within a defined area
and relates to the “evenness” of distribution of individuals among species in a community.
Abiotic: Abiotic factors are the physical and chemical features of an environment. Abiotic factors include light
(radiation), temperature, water (availabilty, composition, flow), atmospheric gases (including pollution), and soil
factors such as nutrients and porosity.
Biotic: Biotic factors refer to 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 (organims that eat other plants and/or animals) and decomposers (organisms such as bacteria or fungi that feed off dead biota, decomposing large organic
molecules into smaller units).
Population: A populations refers to the collection of individuals of a single species within a defined area at a specified
point in time.
Community: A community refers to the collection of species (each with its own population) living in a given area at a
particular point in time.
• Maple Ridge Woods contains several very rare species – FALSE
• Old Field Woods is the headwaters of a local watershed. TRUE
• Majestic Pine Woods has large pine trees TRUE
• Maple Ridge Woods has a deep layer of mineral soil. TRUE
• Majestic Pine Woods has a highly variable water table. – TRUE
• The three levels of biodiversity are: Genetic Diversity, Species Diversity, and Ecosystem Diversity. – TRUE
• The Canadian Biodiversity Strategy defines biodiversity as “the variety of species and ecosystems on Earth and
the ecological processes of which they are a part”. – TRUE
• The number of individuals of a species within some area at some point in time. – POPULATION
• Number of species in an ecosystem or sample. SPECIES RICHNESS
• A group of species in an ecosystem at some point in time. – COMMUNITY
• Distribution of individuals among species in a community. – SPECIES EVENNESS
• The percent cover, biomass or frequency of individuals per species. – SPECIES ABUNDANCE
The cold stream from the Old Field Woods is the purest stream water in southern Ontario and home to many species
The bird diversity is highest in the Old Field Woodlot, followed by Majestic Pine woods and the lowest in the Maple
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
The Old Field Woods is home to many pesky skunks and raccoons that get into our composters and garbage boxes!
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
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.
Alpha diversity is highest in the Old Field Woodlot, followed by the Majestic Pine woods and least in the Maple Ridge
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.
Key Concepts and Terms
A forest is composed of a canopy, sub canopy, shrub layer, organic matter and species diversity.
Population Growth: The change in the number of individuals during some period of time.
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, B is the number of births, D is the number of deaths, I is the number of immigrants, and E is the
number of emigrants.
Carrying capacity (K) : The number of individuals that can survive on the available resources within a given
As the environment is degraded, carrying capacity actually shrinks, leaving the environment no longer able to support
the original number of individuals in the population that may have been sustained for many years. No population can
live beyond the environment’s carrying capacity for very long
Species Interactions: Different species that live in the same ecosystem/community interact in many different ways.
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: Include both the flow of energy and the cycling of materials. Energy enters the biological system as light energy, or photons, which is transformed into chemical energy in organic
molecules (e.g., carbohydrates) by the cellular process known as photosynthesis. Respiration is another cellular
process that results in the conversion of organic molecules into heat energy; this energy is lost to the system as heat
and cannot be recycled.
During decomposition these materials are not destroyed or lost, so the earth is a closed system with respect to
elements; a minor source of elements comes from meteorites. The elements are cycled endlessly between their biotic
and abiotic states within ecosystems.
The total species diversity in a landscape (gamma diversity) is determined by two different things, the mean species
diversity in sites or habitats at a more local scale (alpha diversity) and the differentiation among those habitats (beta
• The carrying capacity for any given area is fixed. – FALSE
• Carrying capacity 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. – TRUE
• Obligate mutualists must live with a partner species. – TRUE
• Population growth is the change in the number of species during some period of time. – FALSE
• Ecosystem processes include energy cycling and interaction among species for nutrients. – FALSE
• An interaction between two organisms or species, in which the fitness of both species is lowered by the presence
of the other. – COMPETITION
• An interaction between organisms or species, in which one organism or species benefits at the expense of
another. – PREDATION
• An interaction between two or more species, where both species derive a mutual benefit, for example an
increased carrying capacity. – MUTUALISM
• An interaction that benefits one organism and the other organism is neither benefited nor harmed –
• The relationship between two species which interact but do not affect each other. – NEUTRALISM
• The physical traits of shade tolerant plants may include broad, thin leaves and high levels of foliar nutrients. –
• Spatial scale can be decreased to microhabitats (point diversity) or increased to include multiple woodlots in a
township at a broader landscape scale (gamma diversity). – TRUE
• Communities in early succession will be dominated by slowgrowing, welldispersed species. – FALSE
• Physiognomy refers to the most dominant vegetation in a forest. – TRUE
• The number of species within local woodlot local scale is called alpha diversity. – TRUE
Abiotic factors: are nonliving. They include the physical and chemical factors that affect the ability of organisms
to survive and reproduce; some examples of abiotic factors are light, temperature (heat), chemical products, water
Light 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, development of flowers and the production of fruit/seeds. Many plants have
adapted to high or low light conditions; shade tolerant plants can dominate the understory of dense forest canopies.
Light also regulates many biological rhythms of a large amount of species of both plants and animals. Plants use a photoreceptor protein (e.g., phytochrome or cryptochrome) to sense seasonal changes in photoperiod. This signals
anthesis, which is the development of flowers.
Niche: species occurring in “environmental space”; the space that an organism occupies, which is confined by
environmental variables to which the species responds.
Hutchinson (1957) provides a basic definition: “niche is the set of biotic and abiotic conditions in which a species is
able to persist and maintain stable population sizes.”
The fundamental niche is defined by the environmental
conditions in which a species can survive and persist; however
the species may not be present within all of this space. The
realized niche includes the environmental and ecological
conditions under which a species actually exists and persists.
Habitat: the environment in which a species is known to
occur. Which is influenced by biotic and/or abiotic environmental
variables. Higher habitat diversity is often correlated with higher
species richness in ecosystems.
Functional traits: define species in terms of their ecological
roles within an ecosystem. These traits determine how a species will interact with other species and the environment.
Functional diversity: it accounts for the diversity of functional traits of all the the species in a
Trait: is a measurable property of an organism that influences its performance and species have functional traits
that are uniquely adapted to the ecological niche.
Competitive exclusion principle: EX The shade tolerant species are at an advantage in the woodlot
understory because they are able to competitively exclude other species of tree seedlings from establishing that are
not shade tolerant.
Ecosystem engineering: Some organisms can control the availability of res