Future of ecology

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A recurring theme in ecology is that some environments are inherently unsuitable for organisms

Since some environments are less suitable for some species than other environments, intensity of interactions obviously will differ between regions

However, the terms used to describe these habitats are difficult to quantify

Harper (1982, After Description, in The Plant Community as a Working Mechanism) criticized these terms as being "little more than the observer judging what I don't think I'd like if I was a buttercup, kangaroo, flea, beatle, etc."

Inability to specify units for these terms has serious consequences for the development of pop'n and community ecology:

1. We can not synthesize existing literature on environmental gradients since we do not know how to compare the habitats being investigated

2. We can not move towards predictive ecology since we do not know how to describe the degree of unsuitability of a habitat to predict a particular ecological trait

3. We can not evaluate many published concepts and hypotheses that use this non-operational vocabulary

One proposed sol'n to this problem is to measure many environmental factors in each area being studied

Over 60 years ago, Clements (1935 Ecology 16:342-363) pointed out that physical and chemical measures must be expressed in terms of plant functions and community structure

Clements suggested that "community phytometers are often desirable and these range from sod cores and sown and plant quadrats to closures of several sorts."

Clements' suggestion seems to be the obvious way of making this concept (unsuitability) operational

An example: comparing stress and competition in 2 plant communities (Keddy 1989 Fig. 7.5, p. 149)

Gradients of exposure to waves are common features of shorelines

Waves produce an obvious disturbance gradient, but also a fertility gradient (from infertile, sandy, wave- washed beaches to fertile, organic, sheltered bays)

To test whether this produces a stress gradient, ramets of a common shoreline rush (Juncus pelocarpus) were transplanted to the 2 ends of the gradient

To measure stress differences, some plots were cleared of all other plants

To compare intensity of competition w/ effects of stress, replicates were set up w/ ramets transplanted into established veg.

Results:

Beaches (sand) are "stressed" compared to bays (organic soils)

Interference is much more intense in bays than on beaches

Conclusions: these sites have very different levels of stress, and there is a clear inverse relationship between stress and interference

Different levels of generality are necessary for different ecological scales

Ultimately, ecological theory may consist of a series of nested models

Specific models for mgmt. of indiv. systems will use site-specific info and species nomenclature

These models will be nested w/in more general (conceptual) models dealing w/ relationships among state variables and functional groups of organisms

To judge scientific progress, we must have an agreed-upon goal

Weiner (1995 J. Ecol. 83:153-158) indicated that ecology should observe 3 principles: (1) strive for prediction and testable explanations; (2) appreciate and incorporate natural history; (3) use new approaches

The ultimate test of ecological theory is whether ecologists can really say anything useful about the world

Thus, we must continuously keep applications in mind

Keddy: "We can develop all the elegant models we wish, live distinguished academic careers, publish numerous well-cited papers, and so on, but the ultimate test of the value of our work is whether we really can make predictions about the real world."

Kuhn (1970, The Structure of Scientific Revolutions) noted that scientists tend to choose "answerable" questions rather than important ones

We can begin by dividing scientific ideas into 2 classes: hypotheses and concepts

Hypotheses are predictive and falsifiable statements about nature (i.e., candidate explanations);

Concepts are not falsifiable, although they may be part of every scientist's thinking. They provide a conceptual framework which helps to organize hypotheses, and which may lead people to new creative insights.

Ecology has placed considerable emphasis on concepts, little on hypotheses --> result that "we have become modern scholastics interminably discussing questions which cannot be solved or tested scientifically." (Peters 1980, Synthese 43:257-269; see also Peters' book, A Critique for Ecology)

The value of different kinds of questions and different kinds of approaches depends on the relative emphasis that we place on hypotheses and concepts

If the construction of ecological theory is our objective, published studies are useful to the extent that they allow prediction of patterns in nature

Alternatively, concepts have utility if we see science as an activity which expands the horizons of human experience. In this case, we can be satisfied if we increase our 'understanding' of nature.

Judging the value of different research goals and methods also requires consideration of how scientific progress actually occurs

at one end of a continuum, data and facts are everything; at the other end, they are unimportant and are collected only to amplify belief systems

Positions along the continuum, acc. to Keddy:

1. Science primarily involves the patient collection of facts

2. Data are important for falsifying hypotheses, and original hypotheses drive scientific progress (Popperian view)

3. Data are collected to solve small technical problems, but there is a larger context or paradigm shared by scientists

4. Science is primarily political

5. Science is part of the entertainment industry, and the objective of scientific papers is to tell entertaining stories to a well-educated audience

Choosing a question for research

This is the most important part of the scientific process, and the most subjective

Hypothesis testing is where most scientists can avoid psychological bias, because there are specified rules to follow

Interpreting results of tests also may be highly subjective

There are an infinite number of questions to be answered in science. Why study competition, as ecologists have done for the last several decades? Keddy suggests that the focus on competition is closely related to the social setting of ecologists; he offers 6 suggestions:

1. Culture

2. Excitement

3. Gender bias

   Levels of aggression differ between genders (Maccoby and Jacklin 1974, The Psychology of Sex Differences):

   • males are more aggressive than females in all human societies for which evidence is available

   • behavioral differences arise early in life

   • similar differences occur in subhuman primates

   • aggression is related to levels of sexual hormones, and can be manipulated by experimentally modifying levels of these hormones

4. Taxonomic bias

   Ecological research is highly atypical of organisms occupying the earth

5. Scientific community structure

   W/in the scientific system itself there is competition for ltd. research funding, and competition for space in journals--likewise w/in academic depts

6. Elitism

   Relatively few indivs. set the agenda for science, and these indivs. share a strong bias in selection of model systems

   • elites may act directly to exclude an issue from discussion

   • subordinants may anticipate the negative reaction of elites and ignore proposals or suggestions that would disturb the elite

   • underlying values of society itself may prevent serious consideration of alternative programs and policies

Keddy (1992, J. Veg. Sci. 3:157-164) suggested the following goals for community ecology:

1. Development of "assembly rules" (sensu Diamond 1975, Assembly of species communities, pp. 342-444 in Ecology and Evolution of Communities)

   Diamond has been criticized for the methods he proposed to create assembly rules; although his proposed methods were flawed, the goals he proposed were fine

   Objective of assembly rules:

   Given (1) species pool and (2) an environment, can we predict the abundance of organisms actually found in that environment?

2. Development of "response rules"

   Objective of response rules:

   Given (1) a specified assemblage of spp., (2) total species pool, and (3) a specified disturbance or treatment, can we predict the composition of a future community?

   Again, we need knowledge of key life-history traits in the species pool, and the way in which spp. interact w/ basic types of disturbances

   This requires a combination of:

   description (to delineate spp. pool, to define initial states of systems, and to describe naturally-occurring states resulting from disturbances),

   comparison (of attributes of species --> necessary ecological info on spp. in the pool), and

   experimentation (to determine which traits provide the capacity to predict responses to different kinds of disturbances)

Which systems should be studied?

Different groups of organisms differ in their importance in the functioning of ecosystems

Groups also differ in abundance in the biosphere

Let's return to studies of interactions, where we began the semester:

Tansley's (1914) Presidential Address to the British Ecological Society dealt w/ contemporary issues in studying competition

focus on release experiments and the virtues of generality

Clements et al. (1929, Plant Competition: An Analysis of Community Functions)

included thorough review of competition concepts back to Malthus

extensive series of transplant experiments for studying competition

studies designed to assess competition for different limited resources (light, water, nutrients)

summary of consequences of competition for community organization

So, we had a clear statement of conceptual approaches for plant ecology research over 85 yr ago, followed by a synthesis over 70 yr ago

What does this tell us about the progress of ecology as a science?

Why did it take so long for field experiments to be popularly accepted by plant ecologists?

Why did (& does) plant ecology continue to be dominated by description?

Several hypotheses:

Human tendency to seek dichotomies

for ecology:

does competition or predation structure communities?

holistic vs. reductionist approaches

Scientists are rewarded for solving answerable questions, not important ones

Focus on inappropriate study media

Obstacles to communication

Weiner (1995) provides positive feedback for those of us who are critical of, and cynical about, the progress of ecology ("Ecology should be taught with a high degree of skepticism and cynicism")

Nontheless, there are good reasons to be optimistic about the future of ecology

the world needs general, predictive ecological theory for conservation and sustained use of the natural resources

we should be intellectually and ethically satisfied by pursuing ecological research

It appears that most of the obstacles to ecological research have more to do w/ psychology of scientists than w/ ecological systems