This manual describes
how different plants over-winter, different plant adaptations to winter and the difference
between evergreen and wintergreen plants. The field study focuses on the study of green
plants under the snow cover and includes selection and location of sites, description of
vegetation cover and report preparation.
This field study has instructional video
featuring real students conducting the ecological field techniques in nature. Each video
illustrates the primary instructional outcomes and the major steps in accomplishing the
task including reporting the results.
Introduction
This activity is aimed at the study of plants which are found green under snow. It is
advised to choose several biotopes (habitats) which greatly differ from each other,
for instance, dark-coniferous (spruce) forest, light-coniferous (pine) forest,
deciduous forest and meadow. It is necessary to locate sites in each habitat. All the snow
should be dug out from these sites, then all green plants should be counted and
determined. The activity will result in lists of species and relative numbers of green
plants in different habitats.
Measuring tapes, shovels and plant guidebooks (illustrated ones are preferable) will be
required for the lesson.
Prior to practical work, a teacher should start from an introduction into the theme
of study, so that students will better understand results of subsequent studies and
obtained results. The teacher should discuss with students the problem of life conditions
for plants in winter, plant adaptations to unfavorable weather conditions, and
classification of plants which winter- green.
Plant adaptations to weather conditions
It is commonly known that winter is a hard and unfavorable season for plants.
Insiccation is the main threat to plants in winter. This is the largest danger,
as water in soil gets frozen. If any part of the plant starts drying out in winter, it
will inevitably die. As it is known, there is no water transportation within the plant in
winter, so it cannot replenish water losses. At the same time, water evaporates well in
winter (just remember how quickly fabrics get dry in frost).
Thus all plant adaptations to winter are aimed at reduction of water losses. The
main method of trees and shrubbery for fighting the dryness of winter is by the abscission
of leaves. Plants that employ this method are called deciduous, as all their leaves fall
in autumn and live during only one season. The plants receive their necessary amount of
light and water in spring and summer, as their large leaves work efficiently enough to
provide plants with nutrients for the beginning of the following season. Such plants fall
into dormancy in winter as they spend almost no water and do not photosynthesize.
Coniferous plants use another method - there is little water in their needles, as
non-freezing essential oils, alkaloids and sugars dominate. All physiological processes in
coniferous plants, including photosynthesis, are very slow; however, they can proceed in
low temperatures, even in winter. The leaves of coniferous trees evolved into needles,
which are quite hard and are protected with a layer of wax in order to minimize water
losses. Each leaf (needle) lives for 2-5 years, and they fall not all at the same time,
but in turns in the course of a year.
Additional methods of protection for trunks and branches, the subereous
layer of bark, and bud scales - reduce winter losses of water and ensure long wintering
of the mentioned plants.
Delicate herbage is quite another matter. Their main method of survival in winter is by
complete dying off of the above-ground part (perennial plants) or the whole plant (annual
plants), or special "tangled" adaptations (evergreen and winter-green plants). This
lesson will be devoted to the latter two types of plants.
Evergreen and winter-green plants under snow
The main condition of existence of herbaceous green plants in temperate climates is the
presence of enough snow cover.
The main function of snow in the given case is protective or heat-insulating. Snow
cover has a loose structure due to the shapes of snowflakes. Interstices among snowflakes
are filled up with air, which is characterized by low heat conductivity, so we owe such a
wonderful property of snow to air. The air, as we sometimes (but incorrectly) say, "is a
good insulator."
Due to the low heat conductivity of snow, day-to-day temperature variation penetrates
into the snow cover only for a depth...
This was only the first page from the manual and its full version you can see in the
Our Paperback and eBooks on Amazon, Google Play and App Store
This manual describes
how different plants over-winter, different plant adaptations to winter and the difference
between evergreen and wintergreen plants. The field study focuses on the study of green
plants under the snow cover and includes selection and location of sites, description of
vegetation cover and report preparation.
Our Paperback and eBooks on Amazon, Google Play and App Store