Newsletter and Technical Publications
Freshwater Management Series No. 5
Guidelines for the Integrated Management of
- Phytotechnology and Ecohydrology -
perspectives for the global application of phytotechnologies
Since the early 1990s, economists have begun to recognise the role of environment in
providing "amenity" services and general life support (Victor 1991). In many
cases, over-exploitation of the Earth’s ecosystems has reached the point where
some of these ecosystems can no longer provide demanded benefits. Economists
are now starting to consider ecosystem services as a positive, quantifiable
value that must be considered in the management of environmental and economic
interactions (Daily et al. 2000). An
example of the application of this concept is Earth Sanctuary Ltd., a firm
listed on the Australian Stock Exchange. The firm purchased 90,000 hectares of
land, restored the native vegetation and wildlife, and is earning income from
tourism, consulting, and wildlife-related products. The firm is also providing
ecosystem services such as carbon sequestration, as well as new "environmental
products" related to clean water. In addition, the firm emphasises biodiversity
in its vision for forest development; timber is considered to be a "by
product". An hypothetical Australian farm business in the next 20 years, in
terms of ecosystem goods and services, is anticipated to derive only 65% of its
income from the traditional commodities of wheat, wool, and timber. The
remainder of its income would be derived from water filtration (15%), carbon
sequestration (7.5%), salinity control (7.5%), and biodiversity maintenance (5%).
to a sustainable solution is the development and application of principles of
valuation based on an integration of ecological and economic understanding.
These should include:
- Identification of ecological alternatives (e.g.,
constructed wetlands versus
conventional mechanical sewage treatment plants).
- Identification and measurement of impacts of
alternatives based upon their full economic costs (e.g., labour, capital, and
long term biophysical and social impacts).
- Valuation and comparison of consequences of the status quo versus
alternatives based on
comparable units of human well-being now and in the future.
The role of human activity as a major factor in
shaping the biosphere has been steadily increasing. Valuation and validation of
ecosystem services provide an appropriate economic framework within which the
use of phytotechnologies and ecohydrology form appropriate alternatives for the
restoration of ecosystem structure and services, and management of sustainable
J. The "green feedback" concept
During the Earth’s
evolution, interplanetary torque and solar modulation determined the sequential
changes in global climatic conditions. This, in turn, determined temperatures,
patterns of water supply, and distributions of plant cover. Plant cover
development, as has been noted, is a function of sufficient water and energy.
Plant cover helps to stabilise heat budgets by reducing temperature extremes
and wind speeds. This, in turn, creates favourable conditions for further plant
development and higher rates of conversion of energy, nutrients, and water into
biomass. This process can be described as positive "green feedback" (Zalewski 2000).
Increased plant biomass within the landscape,
especially in the temperate, subtropical, and tropical areas where energy flows
have been intensive, creates good conditions for speciation and, in
consequence, increased biological diversity. Under these conditions, the
surplus energy accumulated in plant tissues enhances the potential for
development of alternative paths of energy flow within the ecosystem. The
productive and diversified structure of such plant communities, under
non-catastrophic conditions and within a stabilised temperature regime, creates
conditions for the diversification of animal communities. This should be
considered as one of the major mechanisms stimulating diversification of biota
as a whole. Thus, the accumulation of biomass within the landscape stabilises
the water mesocycle and enhances opportunities for the sustainable use of resources.
This "green feedback" concept can be described as follows:
- ENERGY (conversion of radiation energy to
chemical energy) - Plants control over 80% of the energy flow through the
ecosystem. Plant biomass, to a great extent, determines the amount of water
retained on the landscape, and, thereby, stabilises the temperatures and heat
budget. (For example, afforestation of
grasslands or agricultural areas increases the amount of water retained on the
landscape by two orders of magnitude.)
- HYDROLOGY - The transfer of water from the landscape to the atmosphere by plants
improves the quality of freshwater resources and reduces the probability
of catastrophic events by stabilising the water budget at the local,
regional, and global scales.
- BIOGEOCHEMISTRY - Increasing global plant biomass increases carbon and nitrogen
sequestration from the atmosphere, thus providing a mitigating influence
to help balance global climate change patterns. Biota are also a major
factor in the weathering of the Earth’s crust. The enhancement of biomass
will help close biogeochemical cycles and reduce the transfer of nutrients
and pollutants from the terrestrial ecosystem to the aquatic ecosystems of
lakes, reservoirs, and coastal zones, where the accumulation of carbon and
nitrogen in trophic chains occurs.
- BIODIVERSITY - Increasing the biomass and diversity of plants in the landscape will
increase the biodiversity of animals, which, in turn, will reduce the
impact of pest species on wild and agricultural plants.
PRODUCTIVITY - Modifications of the abiotic and biotic factors by plants
can help drive climatic factors and biotic interactions toward conditions
that can enhance crop quantity and quality.
(For example, a reduction in the range of temperature extremes
creates more favourable conditions for plant growth; lower wind speeds
reduce water losses to atmosphere by evaporation; and reduction of erosion
increases the amount of organic matter and nutrients in the soil available
for recirculation within the land and water system.)
OF POLLUTED AND DEGRADED LANDSCAPES - Phytotechnologies, or
phytoremediation activities, enhance the elimination of pollutants and the
restoration of evolutionary ecological processes,
energy flows, and nutrient circulation.
- BIOENERGY - Higher plant biomass in the system permits the incremental use of
primary productivity for bioenergy production on a sustainable basis.
- EMPLOYMENT - The restoration and sustainable use of a diversified landscape requires
more manpower than large-scale monoculture use. This provides additional
opportunities for employment.
VALUATION AND VALIDATION - The economic valuation and validation of
ecosystem services provides an effective framework for the implementation
of sustainable resource management strategies.
Given all of these potential benefits, the
fundamental question arises: Should we cover the entire globe with tree
The answer to this question is no. The real
goal of ecohydrological and phytotechnological applications is to elaborate the
scientific basis for achieving balance and sustainability within ecosystems by
the restoration of hydrological cycles and ecological processes, measurable at
the basin scale by energy flow and nutrient dynamics. Achieving this goal
enhances the capacity of ecosystem to absorb human impacts.
Increasing population creates the need for enhanced ecosystem
services, such as water quality improvement, agricultural production, bioenergy
production, new technologies, tourism, and recreation. Achievement of this
degree of enhancement must be based on an understanding of the underlying
biological and biogeochemical processes. Earth evolutionary studies, amplified
by studies in the Earth sciences, molecular biology, and engineering, should
lead to employment opportunities, improved quality of life, and recognition of
the cultural and aesthetic value of the landscape. The first step toward this
goal should be to develop predictive models of alternative plant cover
development scenarios, under different climatic, hydrological, pedological, and
socio-economic conditions. The implementation of phytotechnologies on a global
scale should diminish the effect of global climate change and reduce the
probability of occurrence of catastrophic events.
Finally, the "green feedback concept" should be
viewed as an important opportunity to establish the new technologies to
compensate for high rates of population growth and high levels of resource
- Due to the degradation of plant cover, water has
become a non-renewable resource in many areas of the globe.
- Plants are important in regulating the energy,
water, and nutrient dynamics of the various ecosystems of the Earth. Plant
cover is a fundamental condition for making water a renewable resource. Plant
cover can be restored through the application of phytotechnologies at the basin
scale in order to maximise water cycling through plants.
- According to Odum (1989), the ecosystem may be
considered to be a cybernetic system because it is been driven by an internal
feedback mechanism to ensure maximum biomass, productivity, and efficiency
through a series of successional stages. In light of these facts, it has been
suggested that control of this process by managing the "green
energy, water, and plants is crucial for the maintenance of ecosystem homeostasis.
- The wide range of physiological performance and
adaptive capacity among plant species can serve as an effective tool for the
restoration of ecological processes and increase potential for the ecosystem to
absorb human impacts.
- The main factor limiting progress toward
sustainable development is a lack of interdisciplinary scientific co-operation
and understanding. As scientists, we often tend to deal with single species,
single factors, and individual processes extracted from the surrounding
multidimensional relationships in which they exist in nature. In reality, the
biosphere is characterised by complex causal interactions. In providing
efficient solutions, our understanding of the complex causal relationships and
processes which exist in various spatial and time scales - from molecular to
basin and biosphere, and from paleologic to prognosis of future processes -
must be improved.
The integration of phytotechnologies and ecohydrology provides the scientific basis
for an effective interdisciplinary approach toward the sustainable management
of biosphere resources (Figure 4.7).
|Fig. 4.7. The integration use of phytotechnologies
for sustainability of water resources in the agricultural landscape. (lager