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Intl. J. of Mol. Ecol. and Conserv. 2012, Vol. 2, No.3, 15-20
http://ijmec.sophiapublisher.com
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interactions in aboveground food webs can influence
soil food webs and vice versa (Hines, 2006), causing
reciprocal shifts in community composition between
the plant and soil communities (Van der Heijden and
Horton, 2009). Networks such as those between plants
and mycorrhizal fungi interactions are increasingly
recognized as critical in restoration plant growth
especially in associations between plants and
consumers, and the ultimate composition of
aboveground
and
belowground
communities.
Processes such as nutrient and carbon influxes have
been proved to be driven by aboveground and
belowground linkages at the community level
(Fortunel, 2009). Some aboveground-belowground
processes have already been utilised (for example
interactions of plants with aboveground herbivores
and the abiotic soil environment) while others are yet
to be exploited in restoration ecology (Kardol and
Wardle, 2010). We might therefore try to fully
utilise these aboveground and belowground links as
there is a lot potential to gain in restoration output using
cheap materials (herbivores, mycorrhizal fungi etc.).
Hydrology has been ranked as the most important
factor that will influence the success of a wetland
restoration (Mitsch and Gosselink, 1993). Factors
such as depth, duration, and periodicity of inundation
in a wetland are often related to plant establishment,
litter decomposition, soil properties, plant distribution
and growth (Kolka et al., 2000). The importance of
identifying patterns in the hydrological characteristics
in evaluating the impact of restoration activities, and
the potential for long-term restoration success should
not be underestimated. Drainage patterns influence the
oxidation state of the substrate, partly determining the
chemical form of soil and pore water constituents,
microbial and vegetative communities being
supported, and the rates of degradation, mineralization,
and subsidence in a wetland ecosystem (Mitsch and
Gosselink, 1993). The water table, which may be
influential in supporting first colonizers, can also be
lowered by woodlands. By regulating the water table
(and the associated hydrological cycles) restorationist
can actually determine what kind of plants to establish
in a wetland.
2 Dispersal, colonization and migrations
Although recreating some appropriate abiotic site
conditions is necessary, it is often not sufficient in
restoring species-rich communities such as grassland
communities (Bischoff, 2002). Shortage of propagules
can be a serious bottleneck in plant restorations, and
seed banks of some plants especially grassland species
are transient or of short-term (McDonald et al., 1996).
Input of seeds from outside is often necessary to
re-establish populations. The probability of such
inputs depends on the distance to source populations
and dispersal abilities of the species. Currently there
is relatively limited knowledge on dispersal abilities
of plant species so that it can fully applied in
restoration ecology (Bishoff, 2002) and the
relationship between dispersal/colonization dynamics
and habitat arrangement, particularly in the face of
natural and human-induced disturbances, is also
poorly understood for most systems (Palmer et al.,
1997). Some studies suggest that mowing and grazing
(e.g. Strykstra et al., 1997) can enhance dispersal
processes in grasslands. In many tropical regions seed
dispersal by animals dominates as the form of
dissemination of propagules and has the potential to
facilitate restoration of native vegetation on degraded
sites (Wunderle, 1997). However efficiency of
dispersal by animals can be limited by isolation of a
restoration site, availability of dispersers and size of
seeds (Strykstra et al., 1997). Because of such
challenges, initial restoration work normally involve
active planting of vegetation, before complementation
by dispersal sources and large-seeded species might
have to planted as well as due to their relative
immobility, to return to primary forest. An
understanding of the general movements of species in
areas (source sink relationships) gives restoration
managers insights; not all species needs to be
reintroduced but if movements are facilitated then
species can migrate to new sites. Reserves are
therefore important not only to secure vital ecosystem
interactions, water quality and ecological memory but
also as potential “species banks” that can be allowed
to disperse to degraded sites. Reserves will help in
re-establishing ecological memory for ecosystem
resilience, natural successional processes and capacity
for renewal.