St. Johns/New Madrid RSEIS - Endangered Species & Wetlands ...

2.3.1 Other Mitigation Techniques, in Addition to Reforestation
Reforestation of agricultural areas was selected as the overall compensatory mitigation
strategy in previous NEPA documents. One major difference between this RSEIS 2 and
the previous NEPA documents is that additional mitigation techniques are being analyzed
in addition to reforestation. Benefits to mid-season fish rearing habitat can be achieved
by converting existing habitat to a higher-valued habitat (e.g., agriculture to bottomland
hardwoods, agriculture to permanent waterbody). The difference in habitat value is
reflected in the HSI values.
2.3.2 Transition Period
As previously stated, mitigation measures usually involve the alteration of one habitat
type to a different habitat type that is of higher value to the resource. This is reflected in
the different Habitat Suitability Index (HIS) values for each respective habitat type. For
instance, bottomland hardwoods are of higher HSI value for selected floodplain fishes as
compared to cropland. The 2002 RSEIS did not account for the transition period needed
to change from one habitat type to another for mitigation purposes. However, this RSEIS
2 accounts for this transition period.
The HEP methodology usually involves calculating transition periods over the life of the
project to account for growth and other factors that provide gains to habitat suitability.
The 2002 RSEIS did not account for this growth period. It would take many years for
reforested bottomland hardwoods to grow to a point that they reach maximum benefit for
floodplain fishes (bottomland hardwoods HSI value). Bottomland hardwoods provide
additional cover (trunk, leaves, twigs, etc.) to rearing fishes that are not found in
agricultural and fallow areas. Forest maturation is not a necessary precursor for the
provision of some benefits for floodplain fishes. Transition periods were broken into two
different types of bottomland hardwood reforestation (i.e., fast growing species and slow
growing species).
Black willow and cottonwood are representative of fast growing species. The Corps
estimated that it would take 10 years to achieve the maximum benefit for floodplain
fishes from planting fast growing species on agricultural areas.
Bald cypress and red oaks are representative of slow growing species. The Corps
estimated that it would take 20 years to achieve maximum benefit for floodplain fishes
from planting slow growing species on agricultural areas. Results from the WAM and
the terrestrial HEP indicate that red oaks provide the greatest benefits to waterfowl and
terrestrial wildlife.
Impacts from construction and gains from compensatory mitigation were calculated as
HUs, but the 2002 RSEIS did not account for transition periods. However, this RSEIS 2
accounts for the transition period. By utilizing the HEP methodology (USFWS, 1980),
HUs are annualized over the 50-year project life. Therefore, for the purpose of this
Draft RSEIS 2
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