River Ecology and Restoration - River Dynamics and Integrated River Management - page 629

10.1.2.1 Terrestrial Ecosystem
The terrestrial ecosystem comprises the plant community, amphibians, reptiles, mammals and birds. The
plant community is an essential basic element for the stream ecology. The ecological integrity of a river
is directly related to the integrity and ecological characteristics of the plant communities that make up
and surround the river. The biological communities depend on these plant communities as a valuable
source of energy. The plants also provide a physical habitat and moderate solar energy fluxes to and from
the surrounding aquatic ecosystem. Figure 10.5 shows the terrestrial plant community by the upper Dadu
River in Sichuan Province, China. The high density of vegetation develops in the valley and on the
slopes, which provides the primary product for the aquatic ecosystem.
The primary product for ecology is provided by plant communities. Only a small amount of this
organic material is stored as above- and below-ground biomass, while senescence, fractionation, and
leaching to the organic soil layer in the form of leaves, twigs and decaying roots are the components of
the annual loss of a significant fraction of organic matter. This annual loss of organic matter represents a
major storage and cycling pool of available carbon, nitrogen, phosphorus and other nutrients, for it is rich
in biological activity of microbial flora and microfauna.
The characteristics of the plant communities directly influence the diversity and integrity of the faunal
communities. In general, complex floral community supports complex faunal communities. The faunal
composition is a function of the following habitat features of river corridors: (1) permanent water; (2) high
primary productivity and food availability; (3) spatial and temporal contrasts in cover types; (4) critical
microclimates; (5) horizontal and vertical habitat diversity; 6) effective seasonal migration routes; (7) high
connectivity between vegetated patches.
Following disturbances to the land, whether they be naturally occurring or resulting from human
activity, plant succession occurs, in which pioneer species well-adapted to bare soil and plentiful light are
gradually replaced by longer-lived species that can regenerate under more shaded and protected
conditions. The most common natural sources of disturbance within a river valley are flooding and
channel migration. Knowledge of natural succession in a stream corridor can be very useful for restoration
practitioners and should be taken advantage of by planting hardy, pioneer species to stabilize an eroding
bank, while planning for the eventual replacement of these species by longer-lived and higher-succession
species.

Fig. 10.5 Terrestrial pant community by the Dadu River in Sichuan Province, China