Photosynthetically Active Radiation (PAR)

380-740 mm visible light

Atmospheric Filtering

-Ozone layer Absorbs much of blue and violet -Molecules of gas in the atmosphere scatter -(Reflect in many directions) blue light -Hence the blue sky -Water vapor scatter all visible light hence clouds are white -Dust scatters the reds, yellows, and oranges -About half of the PAR is filtered out by the atmosphere

Leaf Interception

-Leaves felect between 6 and 12% of PAR -Mostly the greens and yellows -Leaves transmit between 10 and 15% of PAR -Mostly greens and yellows -Leaves absorb 73% to 84% of PAR they recieve

Leaf Area Index (LAI)

Surface area of leaves (m) divided by the square meter of ground -The greater the LAI, the more light is intercepted by leaf tissue (more photosynthesis) -LAI can tell you what part of the plant is doing the most photosynthesis

Understory

Leaves are presented at a more perpendicular angle to the incoming light than canopy level leaves

Canopy

Leaves get so much light that angle does not affect the photosynthetic rate -Due to the LAI at the top of forests, shrub lands, grasslands, etc -Less light reaches the ground

Organic Matter

-Leaves, stems, roots, animal remains, feces, bacteria and fungi -Does not last forever -Ups the water holding capacity (for photosynthesis) -Ups the nutrient holding capacity - Decayed organic matter is called humus -Soils with a lot of organic matter are often acidic

Inorganic Matter

Pedon

Parent Material

Residual/remaining in place or transported Is a factor of soil formation

Topography

The art of mapping the physical features of a place, or the outline of a form of a place -Lower flat lands soils are more developed (water moves low)

Mechanical Weathering

Physical breakdown of the parent material into soil particles/gravity, freeze/thaw cycles, root action

Chemical Weathering

Chemical change of the soil -oxidation, leaching (water), effects of organism living in and on the soil

Leaching

Humus

Decomposed organic matter

Litter

Field Capacity (FC)

Water held by capillary action -Soil organic matter, clay or silt increases FC -Higher FC, more photosynthesis -Holds more water between precipitation events

O Horizon

Fresh and partially decomposed organic material

A Horizon

Organic and mineral matter, some leaching

E Horizon

*Bottom of A layer* Organic and mineral matter, max leaching (Eluviation)

B Horizon

Mineral matter -Layer to which leaching is deposited (Illuvation)

C Horizon

Weathered mineral matter (parent)

R Horizon

Unweathered mineral matter

Hard Pans

Caliche Layer

-Root penetration -Access to deep water -Higher evaporation -Not good for life

Gelisols

One of the 12 soil orders Develops soon top of permafrost -Shallow -Little development

Andisols

One of the 12 soil orders Volcanic ejecta -High mineral content -High water holding capacity -Fine particles -Fertile soils

Histosols

One of the 12 soil orders Almost all organic matter (wetlands)

Vertisols

One of the 12 soil orders High clay soils, deep cracks, and dry lake beds

Oxisols

One of the 12 soil orders -Highly weathered soils -Soils of warm tropics and subtropics

Ultisols

One of the 12 soil orders Same as Oxisols but with more clay accumulating in B horizon

Aridsols

ONe of the 12 soil orders Dry habitats (Sagebrush flatlands) -Low in organic matter -Caliche layers (some)

Alfisols

One of the 12 soil orders -Idaho forests (Island park) -Small conifer forests -Hardwood forests (east) -Precipitation not in growing season (needed in winter)

Mollisols

One of the 12 soil orders Deep penetration of organic matter -High nutrient capacity -High field capacity -Grasslands -Precipitation during growing season

Spodosols

One of the 12 soil orders Acidic ash colored (due to conifers) -Conifer forests of east and Northwest -Precipitation not in growing season

Entisols

One of the 12 soil orders Flood plain soils -Repeated deposition of sediments

Inceptisols

One of the 12 soil orders Shallow to moderate development -Steep sloped-alluvial fans