Transcript secondary succession

TOPIC 7 – FOREST
SUCCESSION
Why
do Forests Change over Time?
 Human
and Natural Disturbances
Seasonal
Changes
Ecological Succession
 Climax
Community
 Pioneer Species
2
Types of Succession
 Primary
The
and Secondary
Role of Fire in Succession
 Forests
may be altered or disturbed over
time due to 2 MAJOR FACTORS:
 HUMAN DISTURBANCES
 NATURAL DISTURBANCES
 Logging
Activities
 Clearing
roads)
land (ex: farming, cabins,
 Pollution
garbage)
(ex: acid rain, air pollution,
 Global
warming (changes in weather and
climate)
 Ozone
Depletion (more sun exposure)
 Natural
climate change
 Species
extinction
 Volcanic
Activity
 Floods
 Forest
Fires
 WHAT
ARE THEY?
 Short-term Changes that Occurs from
Year to Year
 WHAT
ARE SOME EXAMPLES?
 Losing leaves in fall, build-up of snow
in forest in winter, changes in
temperature and daylight hours, etc.
 WHAT


IS FOREST SUCCESSION?
It is the natural series of LONG-TERM ecological
changes that occurs in a forest after a
significant disruption.
Unlike seasonal changes, succession changes a
forest so that it is never the same again.
 There
are two stages to the succession
process:


PIONEER SPECIES
 FIRST STAGE
CLIMAX COMMUNITY
 LAST STAGE
After a disturbance, a new forest begins!

The first organisms to grow in an area which has
been disrupted.

They require a lot of light and generally short-lived.

These pioneers provide nutrients for other
organisms to come and form habitats in the area.

Examples include:
 Lichen
 Grass
 Moss
 Raspberries/Blueberries

After undergoing a series of successions over time,
the CLIMAX COMMUNITY is formed.

They are slow-growing and long-lived.

It is the FINAL, STABLE, COMPLEX, and
SUSTAINABLE community of dominant organisms
in an area.

It is the LAST stage of succession.

In a boreal forest, these are generally
SOFTWOOD species.
 PRIMARY
SUCCESSION
 SECONDARY SUCCESSION
 This
type begins in an
area where there is NO
SOIL nor PREVIOUS LIFE.
 Examples of areas:




Lava field
Sand dune
After a glacier
After an earthquake
 Could
take 300 y to reach
climax community!
 BEFORE
AFTER (2 y)
This type occurs in an
area that has been
cleared of vegetation, but
STILL HAS SOIL at the
start.
 Examples of areas:






Clear-cut
Over-browsing by Animals
Insect Damage
Forest fire
Could take 75 y to reach
climax community
 How
long does it take for a forest to recover
from a fire?

75 Years
 IT
IS natural, especially in boreal forests.
 IT
CREATES
REGENERATION
OPPORTUNITIES





Large areas of land
opened up for
growth
Old unhealthy trees
are destroyed
Nutrients back to
soil
Some species (ex:
black spruce) need
soil to regenerate
Creates new
habitat
 Threatens
human
communities
 Could eliminate
trees used for
harvesting
operations
 Destroy habitat and
food sources of some
Species
 Could change the
Natural Age/Mix of
Forest
TOPIC 8 – OLD
GROWTH FORESTS
 DEFINITION
and TYPES
 CHARACTERISTICS
 IMPORTANCE/VALUE
 OLD
GROWTH FORESTS in NL
 Old
Growth Forests are not
simply “old.”
 DEFINITION:
A
Forest that has had NO
RECENT HUMAN OR NATURAL
DISTURBANCE (such as
harvesting, fire, insect
damage, wind throw)
 AKA
“Ancient Forest”
 Type

One - PRIMARY
NOT INFLUENCED OR DAMAGED by
humans
 TYPE

TWO - SECONDARY
DISTURBED by humans
 OLD
TREES
 MULTIPLE
 NO
AGE TREES
SIGNS OF RECENT DISTURBANCE
 MULTI-LAYERED
 PRESENCE
of SNAGS AND DEADFALLS
 Trees
are close to
MAXIMUM life expectancy
 Old
trees does not
necessarily mean LARGE
trees!
 Often
WIDELY spaced.
 Although
old trees are dominant, there is a
MIX of trees of different ages.
 The
forest has passed through the NATURAL
DISTURBANCE PERIOD, which means there has not
been a major fire or insect infestation.
 Lower
 Middle
 Upper
 This
LOGS
SHRUBS
TREES
layering is called
STRATIFICATION
 Old
growth forests have an
abundance of fallen logs, leaning
trees, stumps and snags.
 Standing
dead trees are called
SNAG.
 Large
logs or bits of wooden
debris on the ground are called
DEADFALL.
 ECOLOGICAL
 ECONOMIC
 SOCIAL
VALUES
VALUES
VALUES

VALUE 1 - Old growth forests are habitat for wildlife.
 EXAMPLES

NL MARTEN
 Prefer thick, shady old growth forest to
hide from predators and easily find prey.
 EXAMPLES


...
SPOTTED OWL
 Requires snags that are
common in old growth
forest for nest habitat
 http://archives.cbc.ca/envir
onment/endangered_species
/clips/8982/
BOREAL FELT LICHEN
 Prefers coniferous old
growth forest
 Threatened in NL by logging
and air pollution from
Holyrood Generating Plant
 VALUE
2 - Old growth forests are CARBON SINKS.

They store carbon for long periods of time, keeping
this carbon out of the atmosphere.

The cutting of these trees increases Atmospheric
Carbon Dioxide.
 VALUE

3 – RESEARCH VALUE
Old growth forests provide SCIENTIFIC information
about the understanding of forest processes that
humans have not influenced.
 Medicinal
and Botanical products
 Ecotourism
 Timber-related
products
 Old
growth forests have AESTHETIC value, where
we want to protect nature as it stands without
disturbance.
 Old
growth forests have SPIRITUAL value,
especially to groups such as First Nations people
who have deep and historical attachments to
nature.

http://archives.cbc.ca/IDC-1-75-6793926/science_technology/clearcutting/clip11
 Old
growth forests in NL are
classified as WET BOREAL
 They are unique because of
high MOISTURE levels, and
thus very rare FOREST
FIRES.
 They are dominated by
CONIFEROUS trees.
 Trees can range from 100 to
250 years of age.
FUTURES FROM FORESTS: FOREST ECOLOGY
FUTURES IN
FROM
NEWFOUNDLAND
FORESTS: OLD GROWTH
AND LABRADOR
FORESTS
Main River: Old Growth balsam fir forest at the
base of the Great Northern Peninsula
Map: http://www.aquatic.uoguelph.ca/rivers/main.htm
Main River
was depicted
on one of five
stamps in
Canada Post's
1991 Canada's
River Heritage
series
FUTURES FROM FORESTS: FOREST ECOLOGY
FUTURES IN
FROM
NEWFOUNDLAND
FORESTS: OLD GROWTH
AND LABRADOR
FORESTS
Newfoundland and Labrador’s first Heritage
River (designated in 2001)
Located at the base of the Great Northern
Peninsula, and it joins White Bay near Sop’s
Arm
Flows south-easterly 57 km from headwaters
through expanses of Boreal forest and lush
island meadows, known locally as the Big
Steady
Source: Parks and Natural Areas, Department of Environment and Conservation, Canadian Heritage River System
FUTURES FROM FORESTS: FOREST ECOLOGY
FUTURES IN
FROM
NEWFOUNDLAND
FORESTS: OLD GROWTH
AND LABRADOR
FORESTS
The watershed contains a diversity of
vegetation ranging from shrub barrens and
wetlands to old growth forest, providing
habitat to a variety of waterfowl and wildlife
including the Newfoundland marten
Managed by Parks and Natural Areas Division
of the Department of Environment and
Conservation
To protect the fragile Main River ecosystem,
guidelines have been established by the
Department of Environment and
Conservation:
Source: Parks and Natural Areas, Department of Environment and Conservation; Photos: Lem Mayo, Canadian Heritage River System
 GAP
REPLACEMENToccurs here

INDIVIDUAL OR SMALL GROUPS OF TREES die and
leave small openings in the forest canopy

This increased SPACE allows small trees to grow and
develop, a process known as RELEASE.

BALSAM FIR AND BLACK SPRUCE are two trees that
“lie in wait” for many decades for the chance to crop
up in these openings.

As a result, trees may be OLD BUT NOT TALL.
 MAIN
RIVER INDICATOR
SPECIES


Two species living in NL old growth
forests are thought to be INDICATOR
SPECIES, species that indicate the
OVERALL HEALTH of the
ECOSYSTEM THEY OCCUPY
The two species are:
 BLACK-BACKED WOODPECKER
 NL MARTEN
 Much
controversy has surrounded Main River,
since it is many things to many people:
A
majestic old growth forest region.
 A habitat to the at risk NL marten.
 A unique Canadian Heritage River.
 A logging ground for CBPPL.
 A tourist attraction.
 http://archives.cbc.ca/environment/environ
mental_protection/clips/3936/
FUTURES FROM FORESTS: FOREST ECOLOGY
FUTURES IN
FROM
NEWFOUNDLAND
FORESTS: OLD GROWTH
AND LABRADOR
FORESTS
Activities not permitted
• Timber harvesting
• ATV use
• New cottage
development
• Mineral exploration
Activities Permitted
• Salmon and trout
fishing
• Hunting - big and small
game
• Snowmobiling
• Outfitting and
adventure tourism
• Backcountry hiking and
camping
• Canoeing/ kayaking
Source: Parks and Natural Areas, Department of Environment and Conservation; Photos: Canadian Heritage River System