Linking Restoration and Ecological Succession (Springer ... - Inecol

Chapter 8 Integrating Restoration and Succession 177
can remove species pools and the ecosystem may have changed to a new state
that does not provide the resource base for the original species (see Chapter 4).
Second, use of ecosystems for goods and services can change in the future
and so yesterday’s goals may no longer seem reasonable. Third, in some cases
restoration targets are years away. Finally, restoration targets are likely to change
as novel species combinations appear, invasive organisms dominate, native
plants become rare or extinct, or climate changes. All of these challenges suggest
that multiple possible targets with broadly defined parameters are most likely to
succeed (Fig. 8.2). These targets may include a mosaic of habitats or functional
groups of species within a locale.
8.7.3 Ecosystem Functions
The goal of ecological restoration is to establish a self-sufficient ecosystem
that requires minimal or no continuing human inputs in order to provide a continuing
supply of goods and services. The more visible structural components
(e.g., vegetation height, cover or biomass, species richness and distribution)
are often emphasized at the cost of ensuring the proper functioning of the abiotic
components (e.g., nutrient dynamics, productivity, the water cycle, soil
structure, decomposition) . The two aspects are interdependent because manipulations
of one inevitably result in change in the other.
Evaluation of the success at achieving restoration goals (Fig. 8.1; R3,4) is
frequently carried out by monitoring easily measured parameters of standardized
ecosystem functions. Ecosystem dynamics are complex, but by assuming
some processes dominate in particular locations it is possible to develop a set
of indicators to assess the direction of change following management actions
(Walker and Reuter 1996; see Chapter 5). In some cases the focus may be on
terrestrial measures, while in others impacts of land-use or changes to land-use
are better measured in streams or other water bodies. Some parameters of soil
fertility, for example, are easily measured and provide a critical gauge of soil
development and nutrient dynamics (see Chapter 3). Measures of subsets of
ecosystem functions across successional seres or stages can provide values to
help establish benchmarks for restoration management and evaluation. These
measures can also be used as input variables for process-based models (see
Chapter 5).
Long-term field studies of successional changes can also help place a timeline
for recovery and identify critical points where further intervention is needed.
For example, recovery of tropical forests on abandoned, paved roads in Puerto
Rico was characterized by the sequential recovery of soil pH, soil organic
matter, litter mass, soil moisture, soil nitrogen, and, finally, species richness
(Heyne 2000). Species composition did not return to control levels in the
80-year chronosequence.
8.8 Conclusions
We have focused on why lessons learned about species and ecosystem change
from studies of plant succession are central to the practice of restoration. However,
restoration has much to assist the study of succession (see Chapter 1).
Bradshaw (1987) and others have observed that restoration activities offer an