Download Phenological Observation Guide of the International Phenological

Phenological Observation Guide
of the International Phenological Gardens
(Revised version of the observation guide of 1960)
1. General Remarks
In order to obtain comparable values from the observations made in International
Phenological Gardens, an agreement on the selection and definition of the phenological
phases is necessary.
The most important precondition of obtaining comparable observation values is the exact
definition of the phenological phases which are observed. Above all, it is necessary to always
cover the same phase of development (phenological phase) of the plant. Containing the
experience made in the course of time in various countries the Phenological Observation
Guide serves this purpose.
In order to examine the regularities of the annually repeating development of the vegetation
as well as the dependence of this periodical development on the environment – especially on
weather and climate -, remarkable stages of growth, whose entrance dates can be
determined to a certain day, must be observed. One of these striking stages of growth, which
are called “phenological phases”, is e.g. the beginning of flowering; while on the preceding
day all flower buds are still closed, several flower buds are open on the entrance day. This
day is noted as the beginning of flowering.
For other phenological phases such as the leaf unfolding, the ripening of fruits, the autumn
colouring and the leaf fall a certain day can hardly be fixed. But even for these difficult
phases a certain day should be indicated, i.e. instead of stating „1st - 5th November“ one
should indicate „2nd November“ as the date at which the phenomenon concerned was best
developed. It is impossible to fix this date later. Only the observer himself can make a
decision in difficult cases.
It has to be regarded that on every observed plant not the exceptionally very early appearing
of the first open flower but the opening of several flowers have to be noted. The other
phenological phases have to be treated the same way.
Each individual tree or shrub is observed separately in the International Phenological
Gardens. If more than one individual exist in an IPG, the mean entrance date has to be
noted.
1
2. Definition of phases
Leaf unfolding
The first regular surfaces of leaves become visible in several places (about 3 to 4) on the
observed plant. The first leaf of a plant has pushed out of the bud up to its leaf stalk (petiole).
Mayshoot
This is the first spring sprout of the conifers (firs, pines). The buds open and the protecting
involucra come off the bud edges. The involucra either stick to the buds or fall down. The
needles are not yet expanded.
St. John’s sprout
Almost regularly the first sprouts of oaks and mountain ashes are followed by a second
sprout, the “St. John’s sprout”. Buds that are already developed for the next year are caused
to sprout prematurely by weather factors. These second sprouts can be recognised by their
fresh colour. The state of the first leaf unfolding is repeated: the first leaves of the sprout
have their typical forms but not yet the final size of the full-developed leaves.
Beginning of flowering
The first regular flowers have opened in several (about 3 to 4) places of the observed plants.
The anthers of anemophilous plants are scattering pollen. If there is strong wind, the first
scattering of pollen can easily be recognized in all anemophilous plants. If calm is prevailing,
the observer should shake the branches in order to find out whether the first flowering has
occurred. In trees bearing catkins this phase can easily be recognized because the catkins
turn round their longitudinal axis when opening and change their colour.
General flowering
This is the phase in which more than half of the blossoms of the observed plant have
opened.
First ripe fruits
The first fruits have ripened in several places (about 3 or 4) of the observed plant. Succulent
fruits have entirely taken on their definite colour; capsular fruits burst out of the hulls (without
external influence).
Autumn colouring
More than half of the leaves (> 50 %) of the observed plant have changed their colour,
including those leaves which have fallen all at once in large quantities. This regular colouring
of the leaves in autumn is caused by low temperatures. It must be distinguished from the
withering of leaves which entails their discolouring due to drought during the summer
months. This so-called drought-discolouring of leaves which may already occur in July in dry
years and in dry places must be observed separately.
Leaf fall
More than half of the leafs (> 50 %) of the observed plant have fallen.
2
3. Observation programme
According to the plant species the following phases have to be observed:
IPG-No. plant
3
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
First ripe fruits
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
St.John's sprout
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
Leaf fall
x
x
x
x
Autumn colouring
x
General flowering
Mayshoot
Leaf unfolding
Botanical Name
English Name
Larix decidua
European larch
Picea abies (early)
Norway spruce
Picea abies (late)
Norway spruce
Picea abies (north)
Norway spruce
Pinus silvestris
Scots pine, Fir
Betula pubescens
White birch, Downy birch
Fagus silvatica 'H'
Common beech
Fagus silvatica 'D'
Common beech
Fagus silvatica 'T'
Common beech
Populus canescens Grey poplar
Populus tremula
Trembling poplar, Aspen
Prunus avium 'B'
Wild cherry, Mazard, Gean
Prunus avium 'L'
Wild cherry, Mazard, Gean
Quercus petraea
Sessile oak, Durmast oak
Quercus robur 'W'
Common oak, Pedunculate oak
Quercus robur 'B'
Common oak, Pedunculate oak
Robinia pseudoacacia Locust, Common robinia, False acaci
Sorbus aucuparia
Mountain ash, Rowan
Tilia cordata
Small-leaved lime
Ribes alpinum
Alpine currant, Mountain currant
Salix aurita
Roundear willow
Salix acutifolia
Pussy willow, Goat willow
Salix smithiana
Smith's willow
Salix glauca
Grey leafed willow
Salix viminalis
Basket willow
Sambucus nigra
Common elder
Corylus avellana
Hazelnut
Forsythia suspensa Forsythia
Syringa vulgaris
Common lilac
Beginning of flowerin
111
121
122
123
131
211
221
222
223
231
235
241
242
251
256
257
261
271
281
311
321
323
324
325
326
331
411
421
431
phenological phase
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
x
4. Remarks to single plant species
Larix decidua (larch)
The appearance of the first fine pale green needles, which are arranged in fascicles when
the buds burst, corresponds to the leaf unfolding. The phase designations „autumn colouring“
and „leaf fall“ should be applied by analogy to the turning and fall of the needles. More than
half of the needles of a plant (> 50 %) are colouring resp. fall.
Pinus sylvestris (pine/ Scots pine)
The date of “beginning of flowering” has started as soon as male flowers have started to
dust. It must be considered that the phase “mayshoot” already starts when the brown
involucra comes off the edge of the bud. Sometimes the cover still sticks to the young
needles, sometimes it falls off at once.
Betula pubescens (white birch)
„Beginning of flowering“ respectively „general flowering“ should be recorded when in spring
the long cylindrical catkins (male blossoms) at the terminal growing points, which have been
there since the last autumn, begin to shed their pollen. The short and thickset female catkins
emerging in spring when foliation takes place should not be observed.
„Leaf unfolding“ should be recorded when the first leaf has come out of the bud up to its
petiole (leaf-stalk).
The date of „first ripe fruits“ should be recorded when for the first time the small brown
winged fruits are blown down from the tree.
Fagus silvatica (common beech)
Concerning the date of “beginning of flowering” it must be considered that the beech usually
does not flower each year. Particularly after a rich harvest of beech-nuts flowers or fruits fail
to appear in the following year. Near the limits of the natural distribution the years of
flowering and dissemination get more and more rare. Sometimes late frosts destroy the
development of flowers to beech-nuts. Therefore the “beginning of flowering” can not be
observed as an annually returning phenomenon in every garden. However, even the
climatically influenced and more or less frequent appearance of years with flowering and
dissemination provides very valuable and interesting information.
Autumn colouring: the date when half the leaves (> 50 %) have turned reddish brown.
Populus canescens (grey poplar) and Populus tremula (aspen)
For this catkin bearer the shedding of pollen by the male blossoms in spring should be
recorded as “beginning of flowering“. After flowering the catkins fall off.
Prunus avium (bird cherry)
The exact date of “beginning of flowering” is easily determined because of the shining white
petals.
However, the exact date of the first ripe fruits is hard to tell. They must be juicy and
completely coloured.
Quercus robur (common oak)
Because of the fresh colour the “St. John´s sprout” can be identified clearly.
The date of “first ripe fruits” starts as soon as the first healthy fruits (acorns with their
characteristically longitudinal stripes) fall down the tree. Concerning the ripeness of fruits it
must be considered that acorns which are destroyed by vermin and have fallen down
prematurely are not noted as ripe.
4
Robinia pseudoacacia (locust)
The phases „leaf unfolding“, „beginning of flowering“ and „general flowering” start
comparatively late. Because of their pinnate (feathered) leaves and their scented white
papilonaceous flowers hanging down they can easily be identified. The „beginning of
flowering“ should be recorded when the first few flowers at the base of some inflorescences
- about 3 or 4 - on the observed tree have opened.
„General flowering“ is reached when more than half of the inflorescences (umbels) have
opened almost all their flowers.
Sorbus aucuparia (mountain ash)
“Leaf unfolding” has starts as soon as the pinnules of the first leaves have completely
unfolded but have not yet reached their entire size.
“Beginning of flowering” starts when at the umbels the first 3-4 flowers are opened. “General
flowering” is noted when at the umbels of the tree more than half of the flowers are opened.
It is very difficult to note the exact date of “first ripe fruits”. During the time in question the
berries have to be observed very carefully to note for the first time the day when the coral red
colour of the berries change to their last shade.
Tilia cordata (lime)
The date “beginning of flowering” can easily be determined.
Ribes alpinum (alpine currant)
The „beginning of flowering“ has started when the first few flowers at the base of a few
(about 3 or 4) inflorescences on the observed shrub have opened.
The exact determination of the date of „first ripe fruits“ is rather difficult, as the ripening of the
berries of an inflorescence does not occur uniformly and the transition to the full colour of
ripeness comes about little by little. „First ripe fruits“ should be recorded when the majority of
the berries of a few inflorescences - about 3 or 4 - have ripened up to the edge of the
inflorescence, i.e. when they have reached their definite colour.
Salix (willows)
The stage when the buds have come out of the brown protective scale leaves (volucra) and
show their well known silver-grey hairs should not be considered as the beginning of
flowering. At the „beginning of flowering“ the golden yellow stamens of the male flowers
should be visible.
Sambucus nigra (elder)
“Beginning of flowering” starts when at the inflorescences (umbels) the first 3-4 flowers are
opened. “General flowering” is noted when at the inflorescences of the tree more than half of
the flowers are opened.
The exact determination of the date of „first ripe fruits“ is rather difficult as the ripening of the
berries of an inflorescence does not occur uniformly and the transition to the deep black
colour of full ripeness comes about little by little. „First ripe fruits“ should be recorded when
the majority of the berries of a few inflorescences – about 3 or 4 - have become ripe up to the
edge of the inflorescence, i.e. that they have reached their definite colour.
Corylus avellana (hazelnut)
The “beginning of flowering” has started when the first catkins have completely stretched and
lose pollen.
The first fruits are ripe as soon as the first healthy fruits fall down the tree. With the “first ripe
fruits” it must be considered that fruits which are destroyed by vermin and have fallen down
prematurely must not be noted down as ripe.
5