Download File - Mrs. Sturges APES and Environmental Systems

Land Use- Parks, Rangelands, Forestry
Public Lands
Public lands are classified by their use and can be used for many different purposes such as grazing, timber production,
cropland, recreational use, mineral extraction and preservation. Most public lands can be categorized as:
1. National parks- public lands protected from resource extraction and development but open to nature
appreciation and recreation. Yellowstone, Sequoia, Yosemite and Crater Lake are all examples of National Parks.
2. National wildlife refuge- federally protected area that preserves lands and waters for the conservation of fishes,
wildlife, and plants of the United Stats. These areas serve as havens for wildlife but also encourage wildlife
dependent activities such as hunting, fishing, wildlife observation, photography, environmental education and
other public uses (as long as they are compatible with scientific principals of fish and wildlife management)
3. National wilderness areas/preserves- Areas within existing federal lands (national parks, national forests,
national wildlife refuges and land managed by the Bureau of Land Management) that are off-limits to
development (including the development/use of roads) but are open to hiking, nature study and other lowimpact public recreation. Grazing, mining and buildings are prohibited in wilderness areas.
4. National forest- public lands set aside to grow trees, produce
timber and protect water quality. Can also be used for livestock
forage, water resources, mining, fishing, hunting as well as habitat
for fish and wildlife. National forests were established in response
to the rampant deforestation. The depletion of the eastern US
forests prompted a system of forest reserved—public land set
aside to grow trees, produce timber, protect water quality and
serve as insurance against scarcities of lumber. National forests
cover 8% of the nation’s land area. National forests fall under a
policy of multiple use—meaning that the national forests were to
be managed for recreation, wildlife habitat, mineral extraction
and various other uses, however timber production was most
often the primary use. In 1976 Congress passes the national Forest
Management Act that mandated every national forest draw up a
plan for renewable resource management
Worldwide forest usage.
5. National Resource land- public land regulated by the Bureau of Land Management that is primarily used for
mining, livestock grazing, oil and natural gas extraction
We can also look at how the land is used to classify public lands Multiple land use- land that can be used for logging, mining, grazing, recreation, hunting, timber harvesting,
mineral/oil extraction and conservation. Examples: National Forests and National Resource lands
 Moderately restricted land use- National Wildlife Refuges are areas where land is used to protect habitats The
U.S. Fish and Wildlife Service administers the national wildlife refuges, that provide protected habitats for
wildlife but also in many cases encourage hunting, fishing, wildlife observation, environmental education and
other public uses. They are the only federal lands managed for the primary purpose of protecting wildlife.
 Restricted land use- Both National Parks and National Wilderness Areas/Preserves are examples of restricted
land use areas. National parks preserve and interpret the country’s historic and cultural heritage (battlefields,
memorials, etc) and protect wilderness areas. Parks can be used for camping, hiking, fishing and boating. 49% of
the National Park system is wilderness. Threats to National Parks include increased visitors to parks that can
bring in non-native species, air pollution, human activities adjacent to the park as well as limited funds available
for maintenance. National Wilderness Areas/Preserves are road-less areas in National Parks, Wildlife Refuges or
National Forests. They are set aside with the intent of preserving large tracts of intact ecosystems or landscapes
and allow limited human use such as hiking, fishing, camping, non-motorized boating, hunting, and horseback
riding.
Threats to U.S. Parks
All the problems plaguing urban areas are found in popular national parks during peak seasonal use including crime,
vandalism, litter, traffic jams, and pollution of soil, air and water. In addition, thousands of resource violations, from
cutting live tress to collecting plants, minerals and fossils to defacing historical structures with graffiti and setting fires,
are investigated in national parks each year. Park managers have had to reduce visitor access to environmentally fragile
park areas degraded from overuse
Rangelands
Rangelands are large, dry, undeveloped, open grasslands used primarily for cattle grazing. Rangelands are semiarid
ecosystems and are therefore susceptible to fires and other environmental disturbances—they include grasslands,
tundras, scrublands, alpine areas and savanna. Rangelands cover 26% of the Earth’s land surface. If humans overuse
rangelands, they can easily lose biodiversity. Careful management is required to prevent damage to soil loss as a result
of overgrazing. Grazing by animals stimulates grass to grow and remove dead material. However, overgrazing can occur
when too many animals are grazed for too long on a section of pasture and the grass does not have enough time
between cropping to regrow. Exposed soil may then become colonized by invasive species or eroded by wind or rain.
When overgrazing occurs in combination with an extended drought, once-fertile rangeland can be converted to desert.
The reduced grass cover caused by over grazing allows winds to erode soil. Even when the rains return, land degradation
is so extensive that the rangeland may not recover. Water erosion removed the little bit of remaining topsoil, and the
sand left behind forms dunes. This
progressive degradation, which induces
unproductive desert like conditions on
formally productive rangeland (or
tropical dry forest) is called
desertification. Desertification reduces
the agricultural productivity of
economically valuable land, forces many
organisms out and threatens
endangered species. The Taylor Grazing
Act was passed in 1934 to halt
overgrazing. It converted federal
rangelands from a commons to a
permit-based grazing system. The
Bureau of Land Management manages
most public rangelands in the U.S.
Forestry
The idea of sustainable forestry followed acknowledgement of the damage done by unrestricted logging of old growth
forests. For forestry to be sustainable, demand for timber must be balanced with the regrowth of seedling. Sustainable
forestry allows timber demands to be met without over-exploiting the timber-producing trees. Different methods for
logging are used depending on the type of forest being logged.
This allows the various services provided by forests to remain
undisrupted.
Examples of Ecosystem Services
Purification of air and water
Preservation of soil and renewal of soil fertility
Prevention of flooding due to runoff
Regulation of climate
Maintenance of biodiversity
Movement and cycling of nutrients
Aesthetic beauty
Deforestation
Deforestation is the clearing and loss of forested areas. It has
altered landscapes and ecosystems across much of our planet. As
we eliminate some forests and alter others, we lose biodiversity, worsen climate change and disrupt the ecosystem
services that support societies. The alteration, fragmentation and outright loss of forested land represent one of our
society’s primacy challenges.
Types of Forests:
Old Growth Forests are climax communities. They have remained undisturbed by natural events and human interference
for many hundreds of years. Old growth forests are ecologically significant because of their high biodiversity and they
are often home to endangered or endemic species. Larger forests also play a part in climate modification
Second Growth Forests result from secondary ecological succession after a major forest disturbance such as fire or
logging. At first, these forests may have quite different characteristics from the original community, especially if
particular tree species were removed completely by logging. As the forest develops, the trees are often of the same age
so that a single canopy develops.
Commercial plantations/tree farms/tree plantations are specifically planted and grown for the production of timber or
timber based products. These forests are virtual monocultures containing a specific timber tree. These trees have often
been selectively bred to produce straight trunked, uniform trees that grow quickly and can be easily harvested and
milled. Because of their cycle of planting and
harvesting, tree plantations never develop into
mature, ecologically diver forests. If too many
planting and harvesting cycles occur, the soil
may become depleted of important nutrients
such as calcium.
Maximum Sustainable Yield
With tree-harvesting, and any type of resource
extraction, it is important to know the
maximum sustainable yield of the ecosystem.
The maximum sustainable yield is the max
amount that can be harvested without compromising the future availability of that resource. When we want to obtain
the maximum amount of a resource we need to know how much a given plant or animal population can be harvested
without harming the resource as a whole. In theory, a population grows at its maximum rate when its approximately half
the carrying capacity.
Clear Cutting
A section of a mature forest is selected (based on tree height, girth or species) and all the trees are removed. During this
process the understory is destroyed. A new forest of economically desirable trees may be planted. In plantation forests,
the trees are generally of a single species and may even be genetic clones. Often the entire area will be replanted as the
same time, so all the resulting trees will be the same age. Because they are exposed to full sunlight clear clear-cut tracks
of land are ideal for fast growing tree species that achieve their maximum growth rates with large amounts of fiect
sunlight. Other species may not be so successful, which can lead to a reduction in overall biodiversity. Clear Cutting is a
very productive and economical method of managing a forest, however it is also the most damaging to the natural
environment. In plantation forests, this may not be of concern and may not affect sustainability, but clear cutting of old
growth forests causes enormous ecological damage. Clear-cutting, especially on slopes, increases wind and water
erosion, which causes the loss of soil and nutrients. Erosion adds silt and sediments to nearby streams, harming aquatic
populations. Clear cutting also increases the amount of sunlight that reaches rivers and streams and the increased
sunlight raises the water temperature.
Selective Cutting/Logging
A mature forest is examined, and trees are selected for removal based on height, girth or species. These trees are felled
individually and directed to fall in such a way as to minimize the damage to the surrounding younger trees. Mature trees
are cut individually or in small clusters while the rest of the forest remains intact to allow the forest to generate
naturally. The trees left produce seeds that germinate to fill the void. The forest is managed in such a way as to ensure
continual regeneration of young seedlings and provide a balance of tree ages that mirrors the natural age structure.
Seed-tree cutting
In the seed-tree approach, small numbers of mature and vigorous seed-producing trees are left standing so that they
can reseed the logged area. Almost all trees are harvested from an area; a scattering of desirable trees is left behind to
provide seeds for the regeneration of the forest.
Shelterwood cutting
In the shelterwood approach, small numbers of mature trees are left in place to provide shelter for seedlings as they
grow. These lead to even-aged stands of trees. In the first year of harvest, undesirable trees species and dead or
diseased trees are removed. The forest is then left alone for a decade in which the remaining trees continue to grow and
new seedlings become established. During the second harvest, many mature trees are moved but some of the largest
trees are left to shelter the
young trees. The forest is then
allowed to regenerate on its
own for another decade. A
Third harvest removed the
remaining mature trees, but by
this time a healthy stand of
younger trees is replacing the
mature ones.
Strip cutting
Strip cutting is a type of
timber harvesting
practice in which a strip
of trees is removed that is
narrow enough to be
naturally re-seeded. The
next year a new strip is
cut and essentially the
forest is clear-cut over a
decade which decreases
the overall damage.
Slash and Burn
Slash and burn agriculture is the process of cutting down the vegetation in a particular plot of land, setting fire to the
remaining foliage, and using the ashes to provide nutrients to the soil for use of planting food crops. Places where open
land for farming is not readily available because of dense vegetation are the places where slash and burn agriculture is
practiced most often. When used properly, slash and burn agriculture provides communities with a source of food and
income. Slash and burn allows for people to farm in places where it usually is not possible because of dense vegetation,
soil infertility, low soil nutrient content, uncontrollable pests, or other reasons. However, slash and burn agriculture
contributes to a number of reoccurring problems specific to the environment such as deforestation, erosion, nutrient
loss and loss of biodiversity.
Selective cutting, seed-tree, shelterwood, and strip cutting require logging roads to carry equipment and workers to and
from. These roads fragment the forest habitat (which leads to changes in species diversity), and they compact the soil
(which leads to nutrient loss and reduction of water infiltration).
Ecological Sustainable Forestry
The goal to this approach
is to maintain all speciesplant and animals- in as
close to a natural state as
possible. Some loggers
have even returned to
using animals such as
horse to pull logs in order
to reduce soil
compaction, although the
costs of such methods
make it difficult to
compete with
mechanized logging
practices.
Forest Fires
In many ecosystems, fire is a natural process that is important for nutrient cycling and regeneration. When fires
periodically move through an ecosystem, they liberate nutrients tied up in dead biomass. In addition, areas where
vegetation is destroyed by the fire can provide openings for early successional species.
Prescribed Burns/Controlled Burns are designed to remove excess flammable material in a section of forest, and so
significantly reduce the risk of a wildfire. This is done in colder seasons where the risk of the burn becoming
uncontrollable is reduced. The controlled burns also help to stimulate new growth. Controlled burns are carried out to
prevent small surface fires from becoming crown fires or out of control wildfires. Surface fires burn debris close to the
ground and can be of benefit to a forest. Crown fires are large, extremely hot forest fires that often destroy large trees
and forest. Ground fires are fires that burn material underground (such as peat) but may emerge to cause surface fires.
Pros
-
many plant species require fires for seedling
germination
-destruction of old trees provide light gaps which
encourage young tree growth
regrowth provides food for herbivores
reduce the risk of wild fires
Cons
-
can be destructive to huge plots of plant and
animal species
can threaten structures
can accelerate erosion