Ecological Succession

what is ecological succession

the gradual process of change and replacement of some/all species in a community

pioneer species

first organisms to colonize a newly available area (begins succession)

climax community

a stable community that generally stays the same unless it’s disturbed

once organisms start to thrive….

the other starts dying

primary succession

starts with bare rock/ bacteria, lichen, moss

secondary succession

starts with pre-existing soil/ grasses and small plants

what are lichens

mutualistic association between fungi

why are forest fires beneficial

destroys under brush to prevent bigger fires/ return nutrients back to the soil

order of forest (bottom to top)

forest floor, understory layer, canopy layer, emergent layer

what makes land arable (a place to grow crops)

soil nutrients, texture, size particles

when is soil considered fertile

if it can support growth of healthy plants

when does soil form

when rock is broken down into smaller fragments by wind, water, and chemical weathering

how is texture of soil determined

based off the proportion of sand, clay, and silt

order from largest to smallest of soil textures

gravel, sand, silt, clay

clay

microscopic particles that feel sticky when wet but forms compact mass when dry

silt

fine particles with floury texture

sand

visible and relatively coarse particles with poor water retention

gravel (not apart of soil texture triangle)

large, visible rock fragments

ability to compact (sand silt clay)

low moderate high

air space (sand silt clay)

high moderate/high low

soil fertility (sand silt clay)

low moderate/high moderate/high

water-holding capacity (sand silt clay)

low moderate/high high

water/air permeability (sand silt clay)

high moderate/high low

what are soil horizons

horizontal layers with distinct physical features

O horizon

contains humus/ most amount of organic material

order of soil horizons (top to bottom)

O, A, E, B, C, R horizons

A horizon

top layer in mixed soil

e horizon

zone of eluviation

what is eluviation

sideways or downward movement of dissolved material within soil caused by rainfall

r horizon

bedrock