Chapter 4 Flashcards
Terrestrial Environment
What are the constraints to the colonization of land from water? (3 main)
Dessication
Water Balance
Hydration
What was the first colonizing organism of land?
Bryophytes (ferns!)
How does the density of air being less on land than water play a role in land organisms? (overall explanation, 3 specific traits that are caused by this)
There is lower drag on movement of organisms and an increase in the effect of gravity.
Causes animals to have internal/external skeletons
Fungi to have chitin
Plants to have cellulose
What short-term effects does the highly variable environment have on organisms?
Influences metabolic processes. Highly influenced by temperature due to all metabolic processes relying on enzymes (which have optimal temperatures for function!)
What long-term effects do the highly variable terrestrial environments have on organisms?
Effects distribution and evolution of organisms
What absorbs more light: A forest or a meadow? why?
Forest. Due to it having several canopies, allowing for more light to be absorbed (it also contains different pigments to accept more light)
How is foliage density expressed?
as leaf area, where the leaves are flat and leaf area is measured on one or both sides.
Cannot measure based on amount of leaves, since leaves vary in size and shape
What is the Leaf Area Index formula?
Leaf Area Index (LAI) = area of leaves per ground unit area. (leaf area m^2 / ground area m^2)
What happens as you move from the top of the tree canopy to the ground as it relates to LAI and light?
Cumulative leaf area / LAI increases, and light decreases.
What are the 3 different types of radiation that plants can detect? How do they influence plant growth?
PAR - Photosynthetically Active Radiation
FR - Far Red Radiation
R - Red Radiation
Transmittance of light/radiation varies
What is PAR? How much of it does it transmit?
Photosynthetically Active Radiation. Wavelengths used by plants for photosynthesis
400-700nm
PAR < 10%
What is FR? What is its transmittance?
Far Red Radiation. 730 nm
More than PAR.
What is R radiation
Red Radiation. 660 nm
What is soil?
Soil is the basis of terrestrial ecosystems. It is both abiotic and biotic.
How do we get soil? (2)
Mechanical/Physical Weathering
Chemical Weathering
What are examples of mechanical/physical weathering? (4)
Water, Temperature, Wind, Organisms
All of these break rocks and minerals into smaller particles BUT do NOT change them chemically
What are examples of chemical weathering (2)
Soil organisms
Organic material
^Water is important for these processes. This chemically transforms the original rocks and minerals, changing the pH by causing acid/base reactions
What are the 5 parts of soil formation?
Parent Material
Biotic Factors
Climate
Topography
Time
Describe the parent material factor of soil formation
Material from which soil develops. Physical character and chemical composition that are important in determining soil properties.
Describe the biotic factor of soil formation
Plants, animals, fungi/bacteria play different roles such as “changing” light into an organic carbon, breaking up plant material, digging into soil, decomposition to increase organic material/inorganic nutrients.
Describe the climate factor of soil formation
Temperature/Precipitation/Wind are abiotic factors that influence the physical/chemical breakdown of parent material.
Weathering, leeching, and plant growth is maximized under warm temperatures and plenty of water.
Describe the topography factor of soil formation
Steep sloves vs more level land. Steep slopes are more nutrient poor due to increased water run off/erosion/soil creep.
Describe the time factor of soil formation
Formation of well-developed soil can take thousands of years but can be destroyed in seconds.
What can parent material originate from? Name the scientific name and description (5)
Underlying Bedrock
Till - Glacial deposit
Eolian - Windborne sand/silt
Colluvium - gravity moving material down slopes
Fluvial - sediments carried by flowing water, lots of organic material
List the different properties that soil is distinguished by (5)
Color
Texture
Structure
Moisture
Depth
How does color help distinguish soil? What do certain colors represent (3)
Color does not directly influence soil function, but helps determine other chemical and physical properties.
Dark soil - organic matter present
Blotchy (yellow-brown/gray) - water saturated soil
Other colors - indicate parent material, rocks, and minerals
How does texture help distinguish soil?
Based on proportion of different-sized soil particles.
Soil texture affects pore space in soil, which is important for movement of air and water as well as root penetration.
What are the 3 different soil size particles?
Sand - largest - can see with naked eye
Silt - medium - difficult to see with naked eye
Clay - smallest - microscopic - greatest water-holding capacity
What are the ideal ratio of soil particle:pore space?
50:50 soil particle : pore space
What is a soil profile?
Sequence of horizontal layers visible in the soil.
What are horizons?
The layers in a soil profile. Each horizon has a different physical, chemical, and biological characteristic
List the Horizon layers top to bottom (9 layers - including the sublayers)
O - Oi - Oe - Oa - A - E - B - C - Bedrock
O horizon
Organic layer. Partially decomposed organic material
Oi - surface, undecomposed leaves and twigs
Oe - middle - partially decomposed
Oa - Bottom - dark humus layer
A horizon
Topsoil. Water flows down through this layer, leaching minerals and soil particles to lower layers.
E - Eluviation. Common in forest soils. Due to leaching.
B Horizon
Subsoil. Contains less organic matter. Usually more dense than A horizon, so more difficult for roots to penetrate.
C Horizon
Unconsolidated material. Mainly composed of the parent material from which the soil is developed. Very little biological activity or weathering
Light availability within a forest is lowest in the….
ground layer
Organisms that live in aquatic systems experience limited temperature fluctuations due to water’s …….
high specific heat
Soil is formed from the layer of unconsolidated debris overlaying hard, unweathered rock referred to as….
regolith
Soils developing from sand and silt carried by the wind are referred to as….
Eolian
Soils rich in iron oxide….
yellowish-brown or reddish
The available water capacity is highest for…
intermediate clay loam soils
The most shallow soils occur in/on ….
steep slopes
Which soil holds the most water?
clay loam in a valley
Which wavelength of light penetrates through plant cover the farthest?
Far-red (730nm)
