Environmental Engineering Reference
In-Depth Information
Fig. 2.54 Impacts of the large woody debris on fluvial processes ( L is the length of the woody debris; and W is the
channel width) (after Wallerstein et al., 1997) (See color figure at the end of this topic)
Table 2.4 Summary of pioneer, intermediate, and hardwood species suites and their characteristics, which occur
d uring the recovery period after channel incision in west Tennessee (after Hupp, 1992, revised)
Vegetation
succession
Pioneer species
(Suite 1)
Intermediate species
(Suite 2)
Hardwood species
(Suite 3)
Time
Late Stage IV
Stage V
Stage VI
Species
Salix nigra, Betula nigra, Acer
negundo, Platanus occidentalis,
Populus dehoides
Carpinus caroliniana, Fraxinus
pennsylvanica, Taxodium
Populus dehoides, Nissa aquatica
Quercus lyrata, Q. nigra,
Q. pagadofolia, Q. phellos,
Fagus grandifolia
Bank stability
Ruderal, unstable sites
Stable conditions
Mature, stable conditions
Light requirements Shade intolerant
Moderately shade tolerant
Shade tolerant
Plant life cycle
Fast-growing, short-lived
plants
Slow-growing, long-lived plants
Slow-growing, long-lived
plants
Reproduction
Extensive asexual reproduction Rare asexual reproduction
Rare asexual reproduction
Seed life
Abundant short-lived seeds
Long-lived seeds
Short-lived seeds
Seed dispersal
Wind and/or water dispersal
Wind and/or water dispersal
Animal dispersal
Seed timing
Seed release in late spring
Seed release in late summer
Seed release in late
summer/fall
a time that coincides with lowered stream flow elevations exposing fresh surfaces for establishment.
These species tolerate moderate to high amounts of mass wasting and accretion and generally require
high amounts of light. Additionally, upland ruderal species may establish high on the former floodplain
and its banks, where overbank flows have been eliminated, or nearly so, because of the degraded channel.
A second intermediate suite (Suite 2, Table 2.4) of riparian vegetation establishes late in the recovery
period (late in stage V) and generally requires stable banks, low amounts of accretion, and tolerates low
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