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DECIDUOUS FORESTSDeciduous 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
The corresponding biome is the Deciduous Forest, or Temperate Forest biome. The latitude range is anywhere from 23 ° north to 38
° south.
LEAF ABSCISSIONChemical 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.
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
In deciduous forests there are five different zones
Tree Stratum zone
Sapling zone
Shrub zone
Herb zone
Ground zone
Types of Deciduous Forests
Temperate deciduous forestTropical and
subtropical deciduous forest
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.
Temperate forests are found in the eastern 1/3rd of North
America, in western Europe, in China, Korea, Japan and Australia There is also a bit down in
the southern tip of South America.
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.
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
HUMAN IMPACT
UrbanizationGlobal WarmingDeforestation