Parameters of Increment Gross increment or volume : all material at end of period Net increment or volume : live material at end of period Think about your pay-slip from work… --- is
Trang 1Parameters of Increment
Gross increment or volume : all material at end of period
Net increment or volume : live material at end of period
Think about your pay-slip from work… - is the total you earned; -
is what you get to put in your pocket
Trang 2Parameters of Increment
Amount grown, harvested or not.
Height, diameter, volume or biomass
Amount grown which can or has been harvested
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Gross increment Natural losses Net increment
Trang 3Parameters of Increment
CAI : Current annual increment
2013
2014
Trang 4Parameters of Increment (cont.)
PAI : Periodic Annual Increment
Average increment per year over a 5 or 10 year period
On average, how
tall have I grown
each year from
When I was 5 until when
I was 15?
Ex 1680 cm at 15 years, 1780 cm at 25 years, PAI = ?
4
Trang 5Parameters of Increment
MAI: Mean Annual Increment
Average increment per year over a stand’s lifetime The maximum sustainable production rate
Ex 1800 cm at 60 years, MAI
= ?
On average, how tall have I grown each year since I was born?
Trang 6Parameters of Increment: CAI
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CAI = T2 - T1
The CAI varies from year to year being affected by seasonal conditions and treatment For this reason, it is common practice to express the
increment as a mean over a period of years, termed the periodic mean
annual increment (PMAI or PAI)
The increment over a
period of one year at
any stage in the tree’s
history/ stand’s history
(e.g CAI 1969/70, age
25-26 years)
Trang 7Parameters of Increment: PAI
Y is the yield (volume,
height, DBH, etc.) at
times 1 and 2 and T1
represents the year
starting the growth
period, and T2 is the
end year.
The maximum point on the curve of PAI is the same as the inflecting point on a graph of yield versus time The inflection point is the point corresponding to the fastest change in yield.
Trang 8Parameters of Increment: MAI
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The mean annual increment over the whole period from
origin to a specific age The specific age must be given
when quoting MAI figures
where Y(t) = yield
at time t
Trang 9The interrelationships of the CAI and MAI
As long as the CAI exceeds the MAI, the MAI curve must rise since each added yearly increment improves the average After the CAI culminates, the MAI curve begins to flatten, reaching a maximum at the point of intersection of the two curves Beyond this, the MAI falls but at a slower
Trang 10The interrelationships of the CAI and MAI
Stand characteristics CAI and MAI - a case study in Croatia
(South East European Forestry)
Trang 11The interrelationships of the PAI and MAI
When MAI and PAI are graphed together, the point in which they intersect
is called the biological rotation age The biological rotation age is the age
in which a stand should be harvested to maximize long-term yield.
Trang 12Stand growth models
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Trang 13Even-aged Stand Growth
Trang 14Rotation
In even-aged systems, the period between
regeneration establishment and final
cutting
Rotation age/length can be based on any
criteria…
14
Trang 15Financial Rotation
The age of a stand where the financial return from
harvesting is at a maximum
Trang 16Pathological rotation
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The age of a stand after which stand health declines
rapidly
E.g harvesting before trees get heart rot
Heart rot in Red Pine
Trang 17Ecological Rotation
The age of a stand after which some ecological value
of a stand decline
E.g early or mid- successional habitat
Trang 18Parameters of Increment
18
The MAI (Mean Annual Increment) is the volume of wood growing on one hectare of forest during one year (m3/ha/year)
on average since the forest has been established For a tree plantation, the MAI is the present total growing stock volume
of one hectare divided by the total age The total age of the natural forest is not known