Microsite Selection and the Informed Planter
A CRITICAL STEP
A Planter's Guide to
Recognizing Optimum
Microsites
Microsite Planting
What is it?
Microsite planting is choosing the best location to
plant a seedling to ensure its optimum health and growth. This spot
must
have most of the good things a seedling needs.
Why do it?
Planters are the last critical link in the long chain of events that
strives
to grow high quality trees. Being able to quickly select the best
microsite
will increase seedling survival and growth and will greatly
benefit the
forest that will follow.
What's in it for the planter?
Planting the best microsite does not have to slow you down! Generally,
the
best microsite is the easiest to plant. You will learn that a good
spot,
such as a natural raised mound, can have less rock or other impediments
to
planting.
Easier Planting = Faster
Planting
Growth Limiting Factors
Few sites have all the right growing conditions in the ideal amounts.
Usually a site is lacking one or more necessary elements to the point
that
seedling survival and growth is affected. This is a growth limiting
factor.
Some of the most important ones are explained below.
Seedling Requirements and Growth Limiting Factors
The following conditions are necessary for seedlings to survive and
grow.
- Air - required by seedling top and roots to grow;
- Light- needed to produce food and foliage;
- Soil - provides structure to support tree and to distribute
moisture,
nutrients and air;
- Humus - important source of nutrients for tree growth. Well
decomposed humus
should be maintained when planting a tree.
Soil - The Growing Medium
Soil is critical to the survival and growth of all plants including
seedlings. Poor soil structure can limit survival and growth. Pore
space in
soil is necessary for air, water movement, and for roots to grow. Good
soil
includes approximately 50% pore space.
Disturbed Soil
When soil is compacted the pore space available for air, water and
roots is
drastically reduced. When pore space is not available or is flooded,
roots
will die back.
Avoid planting on skid roads and trails unless instructed to do 50
by your
supervisor. The soil here is usually too compacted to support healthy
growth
of seedlings.
Soil Temperature
Soil temperature significantly affects seedling growth. For example,
where
the climate is cold and moist, a raised site provides better
aeration/drainage than wet, saturated soils and this results in warmer
soil
temperatures and better root growth.
Soil Water
Soil water is often a critical growth limiting factor. Raised
microsites are
generally well drained while low microsites are usually moist. Roots
need
both air and water to grow. Maintaining the proper balance is critical
to
good root growth.
Moisture conditions vary from site to site and change during the
year. If
uncertain, ask if the site you are planting has a soil moisture concern
and
what is the best microsite to select.
Competing Vegetation
Sometimes seedlings must compete with the surrounding vegetation. On
sites
with aggressive vegetation like salmonberry, thimbleberry and black
twinberry, use your spacing tolerance - plant away from the
brush
Mechanical Site Preparation
After logging, it is sometimes necessary to improve the natural
microsites
to ensure reforestation success. Treatments may include prescribed
burning,
herbicides, or more commonly, mechanical site preparation (MSP). MSP is
site
preparation carried out by machines. Different machines (e.g., ripper
plow,
disc trencher, excavator mounder, Bräcke scarifier) alter the site
in
different ways.
What Does MSP do?
- MSP creates well-drained microsites when the soil is too wet.
- MSP creates sites that retain moisture when the soil is too dry.
- MSP creates porous microsites when the soil is too compacted.
- MSP creates raised planting spots that dry out and warm up faster
than
the surrounding ground on cold sites.
- MSP clears competing vegetation out of the way to give seedlings a
head
start.
Where an area has had MSP, it is important for you to recognize the
best
microsites and to know how to plant them. On MSP sites you should be
told
where to plant. If in doubt - ask your supervisor!
MSP is expensive! It is important to take
advantage
of MSP treated sites and
plant correctly.
What Can a Planter Do?
By learning to better recognize and choose a microsite, a limiting
factor or
site condition may be avoided and the seedlings will have a better
chance of
surviving and growing.
The current survival rate averaged for the province, measured two
years
after planting, is an excellent 87 per cent. You as a planter have
contributed to this success.
The Bottom Line
- Microsite planting is very important.
- If you are not sure where to plant...ask your supervisor.
- The results of planting correctly will provide benefits for a long
time.
For more information on microsite planting, contact:
- Regeneration Specialist
- Forest Practices Branch
- B.C. Ministry of Forests
- Victoria, B.C.
- (250) 387-8903