| Introduction |
Phenology is the study
of periodicity phenomena in nature. Knowledge about the timing and
the duration of certain life cycle events provides valuable information
about the condition of trees and the effects of climate fluctuations
and changes on them. Within the Level II programme, phenology means
the observation and recording of the yearly development stages of
the trees, as well as biotic and abiotic (damaging) events. This will
provide additional, complementary information on the status and development
of the condition of forest trees throughout the year. This information
will be of special importance when the data are evaluated in combination
with other data obtained from the Level II plots, such as meteorology,
deposition, crown condition and increment. Long term phenological
observations will help to determine the course of the annual development
stages of the trees on the Level II plots. Possible changes in the
timing of phenological phases (starting time, length of period and
magnitude) can subsequently be explained in relation to environmental
factors of natural and/or human origin. This knowledge can be used
to explain observed changes in tree condition, such as crown condition,
growth and nutrient status. Because the annual rhythm of trees is
known to be sensitive to changes in weather and/or climatic conditions,
phenology is of special interest for the study of the effects of climate
warming on forest condition. |
Photo: Egbert Beuker |
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There are two levels of phenological
observation on Level II plots. Monitoring at the plot level records
those phenological phenomena and biotic and abiotic (damaging) events
and which are observed during a cursory examination of the trees
on the plot and its buffer zone. A cursory observation of the plots
is made at regular intervals. The observations can be made by field
staff visiting the plot for other reasons, such as collection soil
water or litterfall samples. Monitoring at the individual tree level
makes more detailed observations on the conditions of selected individual
trees. These observations are made more frequent, especially during
critical phases, and require training for the staff. Since 2000,
both levels have been a official part of the ICP Level II programme,
although only optional.
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Photo: Teijo Nikkanen |
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The manual for phenological
observations on Level II plots, which was published in November
1999, was prepared during a series of meetings of the ad hoc
working group on phenology of the Expert Panel on Meteorology
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An updated version of the manual was approved
in 2004.
This manual is the basis
for these sites. These sites are intended to provide additional
information and examples of the different phenological phases
and major damaging events of the major tree species on the
Level II plots. The sites also include examples (photographs)
that can be used to test the skills of the observers, which
is an important part of the Quality Control of the submitted
data.
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