SUGGESTED DEFINITIONS OF "MAJOR IMPACT" FOR SELECTED ASPECTS OF THE BIOPHYSICAL AND SOCIO-ECONOMIC ENVIRONMENT
ENVIRONMENTAL ASPECT OR SOCIO-ECONOMIC CONCERN |
EXAMPLE OF THRESHOLD OF "MAJOR IMPACT" |
Slopes |
If the slope angles, local geology and soils, and rainfall patterns are such that
more than 5 percent of a project area exceeding 1 km2 is likely to become
unstable. |
Soils |
Soil erosion likely to affect visibility and measurability more than 20
contiguous ha of land. |
Loss of nutrients, organic matter, CEC or mycorrhizae, compaction, laterization,
rutting or induced poor drainage that will prevent forest regeneration on more than 50 ha
of land. |
|
Sediment |
Accelerated sedimentation likely to shorten the life span of reservoirs by years,
to require dredging of navigable waterways, or to destroy spawning grounds or benthos that
support subsistence or commercial fisheries. |
Water Resources |
Denudation of forested watershed likely to cause downstream flood losses that are
measured in human lives and in monetary terms. |
Induced turbidity, eutrophication or other alteration of water quality likely to
eliminate one or more key species in the aquatic foodchain, or likely to require technical
modification of waterworks, or likely to affect a subsistence or commercial fishery. |
|
Down-basin decreases in flows, especially low flows, that interface with domestic
or agricultural with drawls of water. |
|
Climate and Air Quality |
Ground temperatures and humidity levels so altered that seedlings of valuable
tree species can no longer survive or germination can no longer take place. |
Forest removal in a semi-arid region that is likely to cause the advance of the
desert. |
|
Removal of a forest that effectively screens one or more settlements from high
winds or dust storms. |
|
Vegetation |
Likelihood that high forest will not regenerate itself on land set aside for
forest growth. |
Likelihood that entire species will become extinct. Clear-cutting more than 1 km2
in a region known for its high diversity of plant species in a particular regional,
national or sub-continental context. |
|
Likelihood that seed trees of the prime timber species will not survive selective
logging. |
|
If more than 1 km2 of adjacent uncut forest is likely to be affected
by mechanical injury, windthrow, altered hydrologic conditions, illegal felling or
intensified shifting cultivation. |
|
Likelihood that persistent weeds will invade more than 100 ha and effectively
prevent the regeneration of forest. |
|
Wildlife and Fisheries |
Elimination of rare, endangered or protected species of animals. |
Elimination of more than one-third of the population of any one species
(obviously, in the case of some endangered species, the elimination of even a few
individuals could have serious genetic repercussions). |
|
Destruction of key habitats (nesting sites, preferred feeding grounds, aerial
pathway, etc.) of rare, endangered or protected species. |
|
Displacement of animals in such numbers as to cause crop losses or detectable
reproductive stress in the displaced and receiving populations of animals. |
|
Creation of new access to endangered or other vulnerable species likely to be
used by poachers. |
|
Traditional Cultures Subsistence Economy |
Any likelihood of violent conflict between forestry and workers and local
residents. |
Likelihood that the subsistence economy will be replaced by a cash economy
(whether or not it is desirable). |
|
Any now contact with forest dwellers not previously in contact with the dominant
culture and economy. |
|
Any destruction of traditional habitats and supplies of food, fuel and
construction or handicraft materials that will create a dependence on the outside economy. |
|
Damage to or destruction of burial grounds, trees, sites or other features of
religious or other cultural value. |
|
Employment arrangements that disrupt traditional folkways but make it impossible
to return to these folkways once the forestry operations are over. |
|
Any intensifications of shifting cultivation that is judged to be beyond the
carrying capacity of a region. |
|
Demographic-Economic Expansion |
Need to invest in new schools, public buildings, hospitals, roads and
recreational facilities. |
Waste generation that requires investment in new disposal facilities. |
|
Employment and other economic benefits to more than 5 percent of the local
population. |
|
Deferral or abandonment of mining, agricultural, tourist or other economic plans
because of conflicts with forestry activities. |
|
Likelihood that influx of newcomers will require the increased intervention of
public-safety, public-health or welfare authorities. |
|
Any new settlement, planned or spontaneous. |
|
Epidemiology |
Any increase in the rate of incidence of already present diseases or the
introduction of new diseases that requires the intervention of public-health authorities. |
Conservation |
Any measurable damage to established conservation areas (national parks,
protection forests, strict nature reserves, game reserves, species sanctuaries). |
Forest removal or forest roads in areas identified for possible preservation or
conservation status. |
|
New road network and major interruption of habitat (eg., segmentation of gallery
forest) in the buffer zone around a park or nature reserve. |
|
Damage, including visual degradation, that precludes further use of a well
recognized public recreational area, even if it lacks legal status as such. |