Intro to forest ecosystems Flashcards
How much of the earth’s land mass is forests?
~1/3
How much of the earth’s plant leaf area do forests make up?
~2/3
How much of the earth’s biomass do forests contain?
80-90%
how much of the carbon stored in living organisms is contained in forests?
~70%
how much of the earth’s terrestrial biodiversity do forests contain?
> 80%
What are 5 important things that forests do for the planet and us?
protect soil
filter water
affect weather
provide food or fuel
provide wood and fibre
How much of Canada’s water originates in forests?
~80%
Give an example of how forests affect weather
the Amazon rainforest affects weather in other regions
How many people globally rely on forests for food and fuel?
more than 1.6 billion
How many hectares of forest have been lost from 1990-2020?
~420 million ha
What is an example of how an area can be rapidly regaining forest coverage?
through forest plantations
ex. China has a reforestation program
What continents of the world have seen net gains in forest area (hectares/year) in the last 3 decades?
Asia
Oceania (in the last 10 years)
Europe
Minimally in N and Central America from 2000-2010
What continents of the world have seen net losses in forest area (hectares/year) in the last 3 decades?
South America + Africa have experienced major net losses
Oceania and N and C America some
What are 3 things that define a forest?
administrative purposes (legal designations)
land use (purpose of land)
land cover (density of trees)
What 2 features do land cover definitions of forests depend on?
tree height (ex. trees are over 5m)
tree cover (ex. forests have over 10%)
What height defines a tree according to the land cover definition?
> 5m are trees
< 5m are shrubs
What % of tree cover defines a forest according to the land cover definition?
> 10% tree cover over the area
How much of BC is designated as forest? How accurate is this?
85% is designated as forest, but not all of that area is actually forested (ex. mountains, water)
How does the % tree cover definition change the distribution of forested areas globally as it increases?
10% of tree cover includes a lot of the planet (4 billion ha)
vs
50% tree cover includes a more accurate area (2.5 billion ha)
vs.
75% tree cover includes a lot less of the planet
Which % tree cover is probably most accurate definition of the planet’s forested areas?
50% = 2.5 billion ha
A forest includes trees of what minimum height?
min 5m
How can the degree of human disturbance affect the description of forests?
primary forests
vs
secondary forests
vs.
plantations
these classifiers change the definition of a forest
What 10 countries have the largest forest area (when considering all forest definitions)?
Russia
Brazil
Canada
US
China
Australia
DR of Congo
Indonesia
India
Peru
How does changing the definition of forests to primary forests change the countries with largest area?
Some new countries on the list and some of the countries with large forested areas removed from list
Brazil
Russia
Canada
US
Peru
Indonesia
Colombia
Mexico
Bolivia
Papua New Guinea
Note that China, India, Australia and Congo not on this list
What does ecology mean? What are the word origins? and what is the most encompassing and accurate definition?
Oikos (Greek) = home/house
logia (Greek) = study
Ecology = ‘the scientific study of the abundance, dynamics, and distribution of organisms and their interactions with their biotic and abiotic environment’
What are the major elements of the definition of ecology?
abundance
dynamics
distribution
interactions of organisms with both living and non-living components of their environment
How does the definition change for forest ecology?
it specifies that the organisms are forest organisms
otherwise the same
What is the objective goal of forest ecology?
‘to study what controls the patterns of distribution and abundance of different organisms in forests of the world’
What is the ecological hierarchy from least to most complex (top to bottom)?
individual
population
community
ecosystem
landscape
biome
biosphere
What makes it challenging to define each structure in the ecological hierarchy?
the increasing complexity with each level makes the lines/boundaries blurry
Define an ecological population
a group of individuals from the same species that interact with the same environment
What is a metapopulation?
2+ populations of the same species that experience gene flow
What is an ecological community?
a group of interacting species (ex. a forest has trees, shrubs, annals, soil organisms)
What is an ecological metacommunity?
a group of local communities connected by the dispersal of multiple potentially interacting species (ex. gene flow, organisms, resources)
what is the difference between a population and a metapopulation?
a population is one group of a single species that interact with each other and the same environment
vs.
a metapopulation is 2+ populations (of the same species) that exchange genes
what is the difference between a metapopulation and a metacommunity?
a metapopulation is 2+ populations that interact via gene exchange
whereas,
a metacommunity is a group of communities (populations of different species) that are linked by multiple interacting species
Define an ecosystem
a community + the environmental and physical (ie., abiotic) factors and forces acting on it
basically, the communities of organisms + the physical, abiotic environment
What is a metaecosystem?
a group of ecosystems that are connected by the flow of energy, materials, and organisms
What is a landscape? what is an example?
an area of land or water that is made up of multiple ecosystems (ex. a watershed)
What are the 2 major differences between metaecosystems and landscapes?
metaecosystems are a group of interconnected ecosystems that experience exchanges of energy, material, and organisms
landscapes are an area of land with multiple ecosystems
metaecosystems are:
- MASS-CONSERVING (ie., no resource input/output, just continued cycling)
- can be SPATIALLY DISCONNECTED (ex. islands)
landscapes are:
- NOT mass-conserving (ie., there’s a dispersal of resources - inputs + outputs)
- SPATIALLY CONTINUOUS
What is an example of a metaecosystem?
a string of islands separated by ocean
What is an example of a landscape?
a watershed - an area that separates waters flowing into different rivers, basins, oceans, etc
define a biome
a large region dominated by similar ecosystems
What is the old French term for forest? what does it mean?
La forêt or forés = a vast expanse of land covered by trees
Describe how the tension between forest exploitation and conservation has been ongoing since the 3rd millennium BCE in Ancient Middle East
the Epic of Gilgamesh was the first record of mass deforestation (in Mesopotamia) in which the Cedars (Cedrus = true cedars) of Lebanon were felled to build shelters and Gilgamesh the Sumarian King defeated Humbaba, the protector of the forest, to harvest the Cedrus
later, the forestry industry took off in Greece and Asia Minor and the Roman empire profited
Pliny’s ‘Natural History’ records the concern for overharvesting of trees and the need for reforestation/conservation for human existence
What are the 2 subdisciplines of forest ecology?
autecology
synecology
Define autecology
a subdiscipline of forest ecology that studies the interactions of an INDIVIDUAL organism or SINGLE species with its biotic and abiotic environment
= species ecology
What are the 2 types of autecology?
physiological ecology
population ecology
Describe physiological ecology
a type of autecology (species ecology) that studies the effects of abiotic and biotic environment on the PHYSIOLOGY of an INDIVIDUAL organism
What is an example of physiological ecology?
cold hardiness on trees
a physiological response to temperature
Describe population ecology
an autecology branch (species ecology) that focuses on population dynamics, structure and distribution of a single species
What is an example of population ecology?
how populations of Garry Oak have expanded, decreased, been distributed, age ranges have changed etc over time
Define synecology
a subdiscipline of forest ecology that studies the connections between groups of organisms or coexisting communities
What are the 5 types of synecology?
community ecology*
evolutionary ecology
ecosystems ecology*
landscape ecology*
global ecology
- = know for this course
Describe community ecology and give an example
a type of synecology that studies the interactions between individuals and populations of DIFFERENT species
ex. predator-prey relationships
Describe evolutionary ecology and give an example
a type of synecology (not key for this course) that studies that interactions between the environment and/or communities and the GENETIC make up and variability of populations
ie., how genotypes change over time
ex. Darwin’s finches
describe ecosystems ecology and give an example
a type of synecology that studies the interactions between the STRUCTURAL and FUNCTIONAL components of an ecosystem
ex. the local C cycle in a forest
describe landscape ecology
a type of synecology that studies the spatial patterns and the interactions between local communities and ecosystems
ie., multiple ecosystems interacting
describe global ecology and give an example
a type of synecology that studies the interacts between land, water and the atmosphere
ex. the global C cycle
What defines a forest ecosystem?
the presence and dominance of trees
What dictates the existence of a forest ecosystem?
the presence of trees is dependent on the abiotic and biotic conditions of the area
such as the interactions with other plants, organisms, soil, abiotic features like precipitation, temperature, natural disturbances, light, nutrients
What are the 4 requirements for a viable ecosystem?
source of energy = light
raw material supply = nutrients like C, N, P, K, S, water
mechanisms to store and recycle raw materials = not a constant input of materials (ex. leaves store N)
mechanisms of persistence (ie., ability to recover and/or resist disturbances)
What is an example of a forest’s mechanism for storing and recycling raw materials?
leaves store lots of N
xylem tissues store water
live organisms store C which is released and reused when dead and decomposed
What is an example of a forest’s mechanism for persistence?
fire resistant cones = recovery
presence of secondary metabolites to prevent herbivory = resist
What are the 5 major attributes of an ecosystem? Describe them briefly
structure: both biotic and abiotic components
function: exchange of energy and matter between abiotic and biotic components
complexity: multiple and often unpredictable pathways between causes and effects
interaction and interdependence: the interconnection of biotic and abiotic components
temporal change: structure and function are continuously changing over time
What are the 6 major layers of a forest ecosystem?
mineral soil
humus layer
forest floor
understory
canopy
emergent layer
Describe the mineral soil layer of a forest ecosystem
mainly composed of mineral (sand, silt and clay) material from the weathering of the parent material
A, B, C horizons underneath the O(humus) layer
Describe the humus layer of a forest ecosystem
mainly composed of organic material from the decomposition of flora and fauna (rich in OM, usually dark brown layer)
Describe the forest floor layer of a forest ecosystem - What sublayers can it have?
mostly made up of dead plant matter (ex. fallen leaves, decomposing logs, fine roots, fungal hyphae, dead forest fauna)
sublayers:
Litter layer (no decomposition yet)
Fermentation layer (decomposition has begun)
Describe the understory layer of a forest ecosystem - what are the 2 sublayers?
the bushes, shrubs, juvenile trees that live in the shade of the canopy
sublayers: shrub (moss, grass, non-woody) and herbaceous layers (woody bushes)
Describe the canopy layer of a forest ecosystem
the overlapping and intertwining branches and leaves of mature trees
What are the 4 crown classes of the forest canopy?
dominant trees
codominant trees
intermediate trees
suppressed (overtopped) trees
based on where the tree crown is in the canopy layer
What classifies a dominant tree? What is an example?
when its crown reaches above the general canopy layer
the tallest and usually at the sides - receive the most light
ex. maples
What classifies a codominant tree? What is an example?
when its crown creates the general canopy layer
usually make up the largest mass of crown and get mostly light from above and shade from sides
ex. maple, birch
What classifies an intermediate tree? What is an example?
trees with crowns in the lower part of the general canopy
ex. spruce, hemlock
What classifies a suppressed/overtopped tree? What is an example?
trees with crowns that do not reach the general canopy
ex. young or more shade tolerant trees
Describe the emergent layer of forests - what biome are these usually found in?
usually in a tropical rainforest biome
consists of a few trees that are scattered throughout and reach much higher above the general canopy
(usually the tallest and older trees)
How does the proportion of OM in the soil change from the forest floor level to the parent material?
it decreases with depth
T or F: most coniferous forests in Canada have an emergent layer
false, most coniferous canopies in Canada have a more even general canopy layer
Explain how ecosystems can be redundant?
many functions in an ecosystem can be done by more than one species (ex. mycorrhizae)
What is a foundation species?
a dominant species within a community
ex. coastal douglas fir makes up almost the entire forest canopy
What is a keystone species?
a species with a unique, specific and essential role within an ecosystem
ex. salmon, sea otter, wolves
What is a keystone process?
a process within an ecosystem that is unique and essential for the maintenance of the ecosystem
ex. fire in a Ponderosa Pine forest for maintaining the open ecosystem
What is a keystone ecosystem?
an ecosystem that provides unique and essential habitat for important components of the biodiversity of an area (ie., the ecosystem contributes disproportionately to biodiversity)
ex. riparian ecosystems
Explain how ecosystems are dynamic but also balance and stable
ecosystems are constantly changing over time, but show
balance in the maintenance and sustainability of for ex., genetic diversity, species composition, community structure, soil/atmospheric chemistry
stability in that the changes occurring are not drastic, but within specific ranges to maintain key processes
What are the 2 main components contributing to ecosystem stability?
resilience and resistance
Describe ecosystem resilience and give an example
an ecosystem’s ability to recover from a disturbance (ie., the speed of recovery)
ex. regeneration of a forest after a fire
Describe ecosystem resistance and give an example
the ability of an ecosystem to persist through a disturbance
ex. a fire, strong wind
What features of a forest ecosystem are key to increase resistance and resilience?
biodiversity
continuity (less fragmentation)
structure and functional complexity
reduced stressors
In what ways can a forest ecosystem change?
life history stages (regeneration to maturation)
after disturbances
climate change
soil changes
interactions between species within the community (ex. pine beetle)
Define ecological succession
the process of change within a forest ecosystem that occurs after a disturbance
What is a sere?
the entire process/sequence of community and ecosystem changes that occur after a disturbance (ie., from pioneer community to mature forest)
What is a seral stage?
the specific stages within the sere (sequence) of ecological succession following a disturbance
ex. the moss/lichen pioneer community, the grasses/herbs/shrubs/seedlings
What are the 2 major degrees of ecological succession in forests?
primary
secondary
define primary succession - give an example of a type of disturbance that would cause this
highly devastating disturbance to the ecosystem
removes organisms above soil surface and the soil and soil organisms so that a new community must start from raw material with no biotic community
ex. landslide
How long does primary succession take? why?
a very long time (100s-1000s of years) because the biotic community must start from scratch
even the soil is removed
Describe secondary succession and give an example of the type of disturbance that can cause this
a disturbance removes some or all of the aboveground organisms but NOT the soil or soil organisms (or seed/spore bank)
ex. clearcutting, fire
How long does secondary succession take?
a slow process, but not as long as primary (100s of years) depending on the climate
Why does primary succession take longer than secondary?
primary succession occurs when the entire ecosystem, including the soil and soil organisms, have been removed
secondary succession occurs when the soil and soil community is still intact - this provides a huge head start for recovery
What is an example of secondary succession in BC?
Barkerville over 150 yrs
forest was completely cleared (but soil and some trees remained)
150 yrs later, forest has regenerated around the old town
What is a geological example of primary succession?
the succession following the retreating glaciers during the Ice Age (over ~18,000 years)
What was the overall message of the Ice Age/succession slides?
a LOT of changes have occurred in forest ecosystems in North America since the Ice Age (~18,000 YA) and mature forests are established/establishing
