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Today: Ecosystem Ecology Overview Brief history Unique CSU role. The ultimate abomination. L. Slobodkin once said that ecology without species is the ultimate abomination.
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L. Slobodkin once said that ecology without species is the ultimate abomination.
There are many ecologists who feel, like Slobodkin, that ecosystems are simply collections of species, and the properties of the constituent species are what determines the nature of the ecosystem
A different school of thought holds that the species that we see are the ones that fit into the ecosystem, and that it is the ecosystem that determines what species belong to it.
The study of the movement of energy and materials, including water, chemicals, nutrients, and pollutants, into, out of, and within ecosystems (Aber & Melillo)
The study of the interactions among organisms and their environment as an integrated system (Chapin)
Ecosystem structure – what is there and how much (C, N stocks, biomass, inorganic and organic pools…)
Transfers of energy and materials from one pool to another
Can be transfers within the ecosystem, or transfers between the ecosystem and its surroundings (e.g., other ecosystems)
For example, photosynthesis is a key ecosystem process, providing the energy feeding the entire system
Respiration – another key ecosystem process –returns CO2 to the atmosphere
Weathering, Evapotranspiration, Nutrient uptake,
As with communities and populations, delineating ecosystem boundaries can be arbitrary
How do we decide where to draw the lines around an ecosystem?
Depends on the scale of the question being asked
Small scale: e.g., soil core, appropriate for studying microbial interactions with the soil environment, microbial nutrient transformations, trace gas fluxes...
Stand: an area of sufficient homogeneity with regard to vegetation, soils, topography, microclimate, and past disturbance history to be treated as a single unit. This is appropriate for studying whole-ecosystem gas exchange (e.g. CO2 or H2O exchange), net primary productivity, plant-soil-microbial nutrient and carbon fluxes
Watershed studies use streams as ‘sampling device’, recording surface exports of water, nutrients, carbon, pollutants, etc., from the watershed
Hubbard Brook Experimental Forest
Natural Boundaries: sometimes, ecosystems are bounded by naturally-delineated borders (lawn, agricultural field, lake) and appropriate questions include whole-lake trophic dynamics and energy fluxes (e.g. Lindeman)
Much like other sub-disciplines, early ecosystem studies assumed -- Equilibrium
1) closed systems dominated by internal elemental cycling
2) self-regulation and deterministic
3) stable end points or cycles
4) absence of human influence and disturbance
Contemporary – non-equilibrium view recognizing
1) losses and gains
2) dynamics influenced by external & internal factors
3) no stable equilibrium
4) disturbance a natural component of their dynamics
5) human activities have a pervasive influence
Tansley – term coined and concept introduced in 1935…but
Stephen Forbes – 1887. Midwestern ecologist, founder of the Illinois State Natural History Survey, studied lakes and noted that in lakes “matter circulates, and controls operate to produce an equilibrium…In this microcosm, nothing can be fully understood until its relationship to the whole is clearly seen…The lake appears as an organic system, a balance between building up and breaking down...”
Forbes’ ideas were not well-known or influential because he published in the Peoria Science Association Bulletin (later Bulletin of the Illinois Natural History Survey).
Lindeman – Trophic dynamic aspect of Ecology (1942). Trophic relationships and energy flow
Eugene Odum – Fundamentals of Ecology textbook (1953) placed ecosystem and biogeochemical cycles at the beginning of the book instead of the traditional chapters on organisms, populations, communities and their interactions.
Side note: Text was prompted and written partly as a consequence of a disagreement in the Zoology Dept. at U. Georgia…Odum tried to include Ecology in the core curriculum in the late 1940-50’s but was voted down…a criticism of his colleagues was that Ecology had no “principles”. Odum compiled a list of what he felt were principles in Ecology and these became his chapters.
Odum’s text led with his view of the Ecosystem concept – “any entity or natural unit that includes living and non-living parts interacting to produce a stable system in which exchange of materials between the living and non-living parts follows circular paths is an ecosystem. The ecosystem is the largest functional unit in ecology…”.
Howard Odum (younger brother) played a key role in this text…he was studying under Hutchinson at the time & Eugene credited Hutchinson’s ideas (via Howard’s class notes!) as having a huge influence. Howard also reviewed all the chapters and contributed one on systems ecology.
The ecosystem concept became popular after WWII; it involved information theory and used computers and modeling…it was machine theory applied to nature!
The concept promised an understanding of complex systems and was to provide a means of managing the environment through an understanding of the structure and function of ecological systems.
It extended the holistic concept to the modern world…
-- Golley 1993.
W. Schlessinger (Institute of Ecosystem Studies)
J. Mellilo (Woods Hole)
P. Vitousek (Stanford)
P. Matson (Stanford)
G. Likens (Hubbard Brook and Inst. of Ecosystem Studies)
J. Meyer (Georgia)
S. Carpenter (Wisconsin)
Ecosystem processes are controlled by: state factors, interactive controls, and feedbacks
State factors set boundary conditions – Hans Jenny (1941)
Climate – broad geographic influence on biome distribution
Parent material – local influence on soil type
Potential biota – which organisms can occupy a site
Topography – microclimate
Time – evolution, weathering
Interactive controls: factors that both control and are controlled by ecosystem characteristics.
Resources: energy and materials used to support organisms’ growth and maintenance
Modulators: physical and chemical properties that affect organisms’ activity, but are neither ‘consumed’ nor depleted
Although ecosystems in their entirety are very complex, most ecosystem ecologists will specialize on a specific process or component.
This specialization is why system modelers are so important to the field.
Atomic Energy Commission. Strong supporter of Ecosystems Research from the 1950’s-1960’s
Radioactive tracers tracked through various ecosystem components and trophic levels, there were many radiation experiments in ecosystems!
IBP – 1964 - 1974
LTER - 1981
Association for Ecosystem Research Centers - 1985
Coweeta Experimental Forest
Savanna River Ecology Lab – radiation studies
International Biological Program – Original theme: Biological basis of human welfare.
Original action areas: conservation, human genetics and improvements in the use of natural resources
Morphed into: Understanding biological productivity as a basis for human well-being
Ultimately, a largely ecosystems program studying productivity at the biome level.
US efforts led originally by E. Odum
Grassland biome studies led by CSU’s George Van Dyne
Described as a workaholic and very enthusiastic
35 when he was appointed Director of the
Grassland Biome program in 1967
He taught himself computer programming at nights and on weekends in grad school and had been on the faculty (Animal husbandry) at CSU, and Montana State before moving to Oak Ridge Natl. lab and Univ. of Tennessee (before returning to CSU)
Success = grant $ and publications (things you could measure)
Management style: memos and tables of organization, not personal relations…
Expertise by 1967 was clearly modeling
Asked for $2 million (in 1967 = $12 million today!) to study: producers, consumers, decomposers, abiotic drivers at one intensive and many extensive grassland sites; modeling would integrate the work…
80 investigators involved and over 60 identified projects
Not funded! Revised version of $700,000 was funded a year later.
Later requested $2.2 million (for a 1 year period = $36 million today for a standard 3-yr grant!) to “study various states of the grassland ecosystems to determine interrelationships of structure and function, to determine the variability and magnitude of rates of energy flow and nutrient cycling, and to encompass these parameters and variables in an overall systems framework and mathematical model”.
Or give us enough $, we will measure everything important, build a model and understand all important components of grasslands related to productivity!
About ½ the funding requested was ultimately received…a huge investment for one biome, and unprecedented in ecology – even for today…
- Management of large numbers of scientists and technicians was impossible
- Inherent conflict between goals of individual projects of the investigators and the overall project goals arose
- Top-down dictates bothered ecologists who were used to being in charge
- Ecologists tired of being “technicians” and left
- Students were hired but not well-trained, and data quality suffered
Thus, research was increasingly criticized
- Bickering between those in IBP and those “outside” increased and funding from NSF was decreased
- Gaps between specialists who studied key systems components and modelers widened – there were no people between them to interpret the data
- “Integrators” (senior scientists) were hired, but it didn’t help
Van Dyne went on sabbatical (1972) after several years of working 7 days a week…
While on sabbatical, one of the senior scientists wrote a renewal proposal with de-centralized leadership and more independent projects…
When he returned, Van Dyne was furious and went to NSF demanding that he be restored to full authority…he was denied… and came back and told the staff that, despite just being awarded $2 million, the program was shutting down and they should look for jobs! CSU asked him to resign and he lost the program completely in 1974
Other senior scientists continued with parts of the program and Van Dyne remained involved till 1976
Eventually, Van Dyne, who wife left him during the turmoil, died of a heart attack at 49 in the CSU Range Science Dept in 1981.
IBP Program in general and the grassland project in particular couldn’t live up to its promises and was viewed from the outside as a failure
Not fair -- much good science resulted at the ecosystem component and process level, but the promised whole-system model and complete understanding was never achieved (despite $16.3 million from 1968-1976 - $80 million in today’s dollars).
Other biome programs (tundra, desert, coniferous and deciduous forest) were organized differently and independently so integration among biome programs was difficult (1800 scientists were involved!). Other biome programs failed in their own ways as well…
- Good science, tremendous model development
- Ecosystems Studies Program at NSF resulted from IBP
- NREL at CSU was established and benefited greatly, and today continues the modeling and systems approach
Earth System and Global Change
Impact of human activities on Earth has led to the need to understand how ecosystem processes affect not only the land surface but the atmosphere and oceans as well…
NEON! (more later…)