Forests and Wildlife

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Chapter 7

• Forests and Wildlife

Big Question Can We Have Them and Use Them Too?
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Case Study Trying to Save a Small Owl from
Extinction
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ForestryKeeping Our Living Resources Alive

• For both forests and commercially valuable
  wildlife, the traditional goal has been the
  maximum sustainable yield

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Modern Conflicts overForestland and Forest
Resources

• How do you define a forest?
• Growing trees has become a profession called
  silviculture
• Forests also have had religious, spiritual, and
  aesthetic importance

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• At the heart of the conflict are the two
  different kinds of values, utilitarian and
  nonutilitarian
• Muir and Pinchot personify the two viewpoints

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• Good friends at first, but not for long
• For Muir, concern for nature overrode concern for
  the common man

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• The dam at Hetch Hetchy led to one of their
  greatest arguments

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• Forests provide indirect benefits
• Public-service functions
• Retarding soil erosion
• Habitats for endangered species and other
  wildlife
• Recreation
• Climate

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Controversial Questions

• Should a forest be used only as a resource to
  provide materials for people and civilization?
• Should a forest be used only to conserve natural
  ecosystems and biological diversity?
• Can a forest be managed for timber harvest and
  also meet recreation, landscape beauty and
  spiritual needs?
• Can we achieve sustainable forests?
• What role do forests play in our global
  environment?
• What is natural in a forest?
• How much old growth do forests need?

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A Modern Foresters View of aForest

• Most foresters consider the sustainability of the
  timber harvest, and the entire range of goals for
  managing forests
• So why would a forester want to clear-cut a
  forest?
• Cost
• Many commercially valuable trees are
  early-successional, requiring open forests

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• Why wouldnt you clear-cut?
• Harvest late-successional species
• Clear-cutting can be very hard on the ecosystem
• Natural disturbances may be sufficient to keep
  the forest open

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The Famous Hubbard Brook Experiment

• What happens to an ecosystem when you clearcut?
• 1965, all the trees and shrubs were cut in a
  small watershed

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• One dramatic result was a much greater
  concentration of nitrate in the stream
• Stream water runoff increased 30 for the first
  three years after clearing

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Are There Other Ways toHarvest Trees?

• Shelterwood cutting takes dead and less desirable
  trees first, and mature trees later
• Seed-tree cutting removes all but a few mature
  seed trees to promote regeneration of the forest
• In selective cutting, individual trees are marked
  and cut. Sometimes smaller, poorly formed trees
  are thinned
• In strip-cutting, narrow rows of forest are cut,
  leaving wooded corridors

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• Forests offer one advantage over other ecosystems
• Trees provide information about age and growth
  rate

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International Aspects of Forestry

• Cutting forests in one country affects other
  countries
• Deforestation and erosion in Nepal has increased
  flooding in India likely a permanent problem

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• Today, deforestation occurs largely in the
  developing world
• Satellites are a new and useful tool to monitor
  deforestation
• During 1960-1990, Asia
• cleared 30 of its trop-
• ical forests, Africa 18,
• Latin America 18,
• and the world as a
• whole 20

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Plantation Forestry

• Why not just plant trees for harvesting and leave
  natural forests alone?
• But plantations are accused of being unnatural
  and bad land use

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• On average, plantations are ten times as
  productive as other forests
• Timber demands might be met by 4 of worlds
  forests if managed as plantations

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Indirect Deforestation

• A more subtle cause of the loss of forests is
  indirect deforestation - the death of trees from
  pollution or disease
• Why trees are dying appears to involve a number
  of factors
• Acid rain, ozone, and other air pollutants weaken
  trees and make them more susceptible to disease
• Global warming could cause widespread damage.

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Wildlife Management
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Wildlife ManagementTraditional Wildlife
Management

• Modern conflicts about wildlife are similar to
  those about forests
• How has wildlife been faring?
• Many species of wildlife have declined greatly in
  abundance, some have become endangered, and some
  have gone extinct

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Bison on the Range and Then Mostly Off the Range

• How many bison were there to begin with?
• Perhaps 50 million?

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• How could that many buffalo actually disappear?
• Many hunters believed the buffalo could never be
  brought to extinction because there were so many
• Numbers fell from millions down to just 50

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• Should we harvest wildlife for our food and
  clothing? Or do all living creatures have an
  intrinsic right to exist?
• Aldo Leopold struggled with these two points of
  view
• Known as the father of wildlife management
• Leopold developed the Land Ethic - all Earths
  resources have the right to exist in a natural
  state, and our role should shift from conqueror
  to citizen and protector

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• The use of science to manage animal populations
  began with the logistic growth curve
• The logistic growth curve says how much you can
  harvest
• How well did this approach work?

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Test CasePribilof Island Reindeer

• The islands seemed perfect for introduced
  reindeer - lots of plants and no predators

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• Even so, something went very wrong with the
  Pribilof Islands reindeer
• Population initially increased, then declined
  severely

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• There was plenty of their favorite food in the
  summer
• Grasses, small flowering plants and shrubs
• But the situation was different in winter
• Reindeer moss lichens
• More females died because they were carrying
  calves and required additional nutrition
• It didnt happen overnight

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• What can we learn from the story of the Pribilof
  Islands reindeer?
• There was a lag effect in the populations
  response to changes in its habitat
• The death rate was higher for certain parts of
  the population
• The population was controlled by an environmental
  bottleneck

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• The logistic equation does not take these into
  account
• Even so, the logistic curve has been important
• Managing marine fisheries, endangered species
  such as the great whales, and game populations

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Improved Approaches toWildlife Management

• Four principles of wildlife conservation
• A safety factor in terms of population size
• Concern for the entire community of organisms and
  all the renewable resources
• Maintenance of the ecosystem of which the
  wildlife are a part
• Continual monitoring, analysis, and assessment

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Time Series and Historical Range of Variation

• How do we decide what is a sustainable population
  if the natural population is always changing?
• One answer is to consider a range of population
  levels natural
• time series of population estimates provide the
  historical range of variation
• Such records exist for only a few species

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Example American Whooping Crane

• In the late 1930s, the population was 14 - also
  the number born each year
• We can use this historical range to estimate the
  probability of extinction

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• Prediction was very low - less than one in a
  billion
• As predicted, whooping cranes have continued to
  increase
• Breeding programs have further boosted the number
  of whooping cranes

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Managing Two or MoreSpecies at a Time Do
Predators Matter?

• It appears that predators probably play a smaller
  role than we thought

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• Predators can have large effects in some cases
• Mosquito fish can greatly reduce mosquito
  abundance
• An absence of predators can have a major effect

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Summary

• Debate continues about how to balance human needs
  with that of nature
• We need to recognize the role of change in the
  ecosystem and address the fact that it is a
  dynamic system not static and constant
• We need to recognize the damage that we have done
  in the past and make the future goal encompass
  sustainable yields in a changing environment