Deciduous forests are characterized by trees that shed their leaves seasonally. The dominant biome is located between 23-38 degrees north and south latitude. Leaf abscission is aided by anatomical changes in the abscission zone and production of reactive oxygen species in response to stress. There are five zones within deciduous forests: tree stratum, sapling, shrub, herb, and ground. Temperate deciduous forests experience four seasons while tropical/subtropical forests have long dry seasons causing trees to shed leaves and open the canopy.
1. DECIDUOUS FORESTS
Deciduous means "falling off at maturity" or
"tending to fall off", and is typically used in
reference to trees or shrubs that lose
their leaves seasonally
2. The corresponding biome is the
Deciduous Forest, or Temperate
Forest biome. The latitude range is
anywhere from 23 ° north to 38 °
south.
3.
4. LEAF ABSCISSION
Chemical mechanism
◦ A variety of reactive oxygen species or
"ROS" (namely H2O2, but
also superoxide, singlet oxygen and radical
hydroxyl) are generated by plants during
times of stress (biotic and abiotic)
including UV light, cool temperatures,
excessive light, pathogens, parasites, and
high salinity. The presence and continuous
production of these ROS causes disruption in
the homeostasis of the cellular components,
leading to metabolic dysfunction and
expression of cell wall degrading enzymes.
5. Severance of the leaf is aided by
anatomical changes in the abscission
zone where two tissue zones
differentiate; the one nearest the stem
accumulates suberin in the cell
walls—blocking the flow of materials—
while cells of the separation layer on
the blade side simply disintegrate. The
suberized zone left on the stem after
the leaf falls is called the leaf scar
6.
7. In deciduous forests there are
five different zones
Tree Stratum zone
Sapling zone
Shrub zone
Herb zone
Ground zone
8.
9. Types of Deciduous Forests
Temperate
deciduous forest
Tropical and
subtropical
deciduous forest
10. Temperate Deciduous Forests
The temperate deciduous forest has
a temperate of four seasons. Temperate
deciduous forests get about 950 to 1500
millimeters of rain annually, which is the
second most of all the biomes. They
have summer highs of about 27 to 32°
Celsius with winter lows of around -1 to -
15° Celsius.
11. Temperate forests are found in the
eastern 1/3rd of North America,
in western Europe,
in China, Korea, Japan and Australi
a There is also a bit down in the
southern tip of South America.
12. Tropical and Subtropical
Subtropical Forests
is located at tropical and subtropical
latitudes. Though these forests occur
in climates that are warm year-round,
and may receive several hundred
centimeters of rain per year, they have
long dry seasons which last several
months and vary with geographic
location.
13. during the drought a leafless period
occurs, which varies with species
type. The shedding of leaves allows
trees to conserve water during dry
periods. The newly bare trees open up
the canopy layer, enabling sunlight to
reach ground level and facilitate the
growth of thick underbrush
14. HUMAN IMPACT
Urbanization
GlobalWarming
Deforestation