Restoration, Preservation, Conservation: ... of What? ... and How?
R. H. (Dick) Richardson
Section of Integrative Biology, School of Biological Sciences,
University of Texas at Austin.
The Lotka-Volterra model of population growth and species interaction is
the theoretical foundation for the study of the ecology of communities. The basic
logistic growth model for one species was generalized to accommodate a
specified number of species with competitive interactions in a community.
Studies of both experimentally controlled and “natural” populations have
described the dynamics of predator/prey oscillations, competitive exclusion, and
other classic population growth patterns. Nevertheless, none of the results have
high predictive success, and few can be generalized to actual populations in the
ecosystem. Theoretically the model does not account for colonization or
extinction, and does require that all species in the community be included. Yet I
have never seen Homo sapiens included in the community matrix of an
ecological study of an ecosystem. In reality, ecological theory gives us
descriptive terminology, but little foundation for predicting the effects of
introductions, extinctions unrecognized species or human effects. Consequently,
most studies have limited relevance in actual community management.
Certainly we cannot predict the effect of humans. We affect communities through
ignorance, anecdotal evidence, or extrapolation that seems reasonable. The
presence of Homo sapiens arguably is the most important competitive force in
the ecosystem! In essential ways we manage biodiversity more as a social art
than as applied science.
Restoration, preservation and conservation of natural resources depends
fundamentally on community ecology, regardless of theory or lack thereof.
Communities and the ecosystem are dynamic, and the component species and
their relationships contribute to resilience and survival of all species in a
community. These dynamics have common features. Energy flows through all
biological systems, originating with the transformation of solar energy into
chemical bonds in organic compounds. These compounds are transformed many
times, but eventually the solar energy becomes heat, carbon dioxide, water and
mineral salts. Heat represents energy lost. The remaining energy flows through
the community. The efficiency of transfer is reflected in the interactions among
individuals and species. The changes in chemical compounds cycle the minerals
of the ecosystem.
Water, essential for all life, ranges in percent on Earth from the metabolic
component (0.0003%) to rivers (0.0003%), atmospheric water (0.0024%), soil
(0.0114%), lakes (0.0156%), ground water (0.6%), ice caps and glaciers (2.37%)
and the salt water in oceans (97%). The hydrologic cycle moves this water from
the ocean through all of these components and back to the ocean. The
ecosystem moderates the global hydrologic cycle, particularly affecting terrestrial
evaporation and ground water storage. Floods are frequent and severe where
the ecosystem controls are missing.
The words preservation and conservation imply a static community, while the
word restoration seeks return to a former state. No more than time’s arrow can
be reversed, can stasis be maintained, or recovered. The interplay between the
biosphere, geosphere, and atmosphere, sometimes called Gaia, creates our
planet’s unique features. It is these dynamic relationships that should be
considered when preservation, conservation and restoration are addressed. We
can manage only the dynamics. This talk will sketch how effective management
is possible.