#20 Broadleaf Forests Flashcards
What structure allows tree to grow so tall
Lignin: a chemical that is the building block of wood, first appearing 400 million years ago
What is lignins purpose
provide structural strength to allow the plant to stay upright and maintain structure outside of the growing season
What are gymnosperms? How do they reproduce?
known as conifers or softwoods, have needle-like leaves which are evergreen
reproduce through. exposed seeds nestled within cones
Why did angiosperms take over during the cretaceous period?
known as broadleafs or hardwoods
- their more efficient and rapid means of production using flowers and fruit, allowed them to adapt to different climates and patterns of climate change.
went on to dominate all climates except the boreal forest
Do hardwoods (angiosperms) lose their leaves
not in all climates, in the tropics they retain their leaves
where do broadleafs dominate compared to conifers
broadleaf forests dominate in warmer temperatures, conifers dominate in the cooler climate and
Temperate deciduous forests:
- do they lose their leaves?
- high or low productivity?
- where are they located?
leafless during the winter
can be exposed to drought or flood during the summer
high productivity
located in humid termperate forests in Europe, Asia and North America.
nearly all original forests have been clear for lumber, agriculture, mining and urban development
What is the average growing season in Eastern North America?
160 days
What environmental factors change from forest to grasslands?
- P/E (price to earning ratio) drops below 1
- annual precipitation drops below 60cm
- fire, drought and variability frequency increases
- prairie soils favour fibrous roots of grasses
- mycorrhizal fungi are absent in prairie soils
Structural Components of the Temperate Deciduous Forests
- four strata in highly developed, uneven-aged forests (canopy, lower canopy trees, shrubs, and ground layer)
Why would temperate deciduous forests have high humidity?
high transpiration and poor air circulation due to the microclimate created
What is the function of temperate deciduous forests?
- Function to accumulate and cycle large amounts of nutrients (nitrogen)
- 90% of nitrogen is incorporated in the mineral soil through the death of small lateral roots, litter fall, and leaching from leaves
How have humans impacted Deciduous Forests?
- destruction in Europe was complete by the middle ages, most forests remaining are semi-natural
- North American destruction occurred rapidly 200 years ago through fragmentation, smaller ownership, different species composition in regenerating forests
- introduction of diseases and insects, as well as invasive species have also contributed to to the rise in tree mortality
how do temperate deciduous forests compare/contrast to boreal forests
Deciduous forests have lower LAI (more light reaching the forest floor), more animal life, more complex structure, longer and warmer growing season, higher NPP and biomass, faster litter decay, more rapid mineral cycling
where are temperate woodlands located
southern US and mexico
