Envi 101 Lec 15 Forest Ecosystems

Forest Ecosystem Services

soil erosion prevention/reduction

oxygen

intake of CO2 (carbon-sink)

rec use - hiking, camping, etc.

Types of Forest

Old Growth Primary
Second Growth forest

Old Growth Primary Forest

uncut or regrown forest that has not been seriously disturbed by human activities or natural disasters for 200+ years

high biodiversity - lots of diff ecological niches

Second Growth Forest

stand of trees resulting from secondary ecological succession

usually contains pines, oaks

less biodiversity

Tree Plantation

aka tree farm

forest that has been planted with only 1 or 2 species, all around the same age

commercial forest

drawbacks:

low biodiversity
less ecosystem services
repeated cutting down and replanting can diminish soil health (organic matter like leaves and trunks not returned to the earth after death)
disease spread can be a huge issue

tree harvesting techniques

selective cutting - harvesters cut likely the most mature trees

clear-cutting -- cut away an entire portion

strip cutting - cut one row, give other rows time to grow back, etc.

Surface fires

burn undergrowth and leaf littler

burn away flammable material to prevent more destructive fires

release seeds from cones of trees and stimulate germination of those seeds

control destructive insects and tree diseases

Crown fires

fires in the crown of trees - treetops

more destructive
when there have been less surface fires, a lot more fuel to burn through

kills wildlife
destroy most vegetation
increase topsoil erosion

climate change leads to hotter, drier conditions out west, so longer fire seasons

Deforestation

the temporary or permanent removal of large expanses of forest for agriculture, settlements, or other uses

leads to...
less biodiversity
unable to go thru secondary succession
carbon sink lost

Forests in the US

30% of US land area is forest

provides habitat for over 80% of the country's wildlife

protected forests thru National Forest system -- no clearcutting

Tropical Rainforests

small land area - immense biodiversity

less forest due to palm oil, soybean plantations, cattle grazing, logging

Sustainable Management

identify and protect highly diverse forest areas
stop logging in old-growth forests
stop clear-cutting on steep slopes
leave most standing dead trees and fallen logs for nutrient cycling and potential habitat

Prescribed burns

carefully planned and controlled fires can help remove the flammable

relies on the education of homeowners and people in the area

Reduce demand for harvested trees

60% of the wood consumed in the US is wasted unnecessarily

use non-tree fibers, reusable items, limit consumption

Ecological Restoration

replant forests
remove invasive species
remove dams for rivers to flow

rehabilitation

turning a degraded ecosystem into a functional or useful ecosystem - not necessarily the same as it once was

Restoration

returning a degraded habitat or ecosystem to a condition as close as possible to its original state

Steps of ecological restoration

identify causes of degradation

stop the degredation

reintroduce keystone species to help restore natural eoclgical processes

protect the area from further degredation