Complexity, individuation and function in ecology Part II, sec 1 Complexity in ecosystems, systems ecology Prof. John Collier (Departamento de Filosofia, Universidade de Kwazulu-Natal, África do Sul. Pesquisador Visitante do Laboratório de Ensino, Filosofia e História das Ciências (LEFHBio), Programa Ciência sem Fronteiras)

Outline 1.Implications for observation (scale, kind) a.Scale as a factor in observation, choice and its problems b.Approaches to ecology, diversity, lack of unification 2.Implications for management a.Scale, lack of integration at boundaries b.Unintended consequences c.Ignorance of true dynamics This section is mostly based on Allen and Hoeskstra.

Scale factors 1 Observation – Scale is a choice of the observer. – It is partly determined by the observer’s preferred approach to ecology. – Once scale is chosen, the system dynamics should guide data collection and analysis. – Failure to get coherent results suggests a failure to choose the right scale. – Inputs and outputs to the presumed system should be distinguished from dynamical closure that expands the dynamical scale.

Scale factors 2 Management – Changing things at one scale can have unintended effects at both larger and smaller scales. – Management should depend on consideration of how the managed system is embedded, e.g., national parks in rural farming areas in Africa; wolves in Yellowstone Park. – Merely preserving biodiversity (species) is not sufficient, and may hurt the system. – Humans are everywhere, so there is no such thing as an unmanaged (pristine) ecosystem.

Krebs cycle

Embedding of Krebs cycle

Level integration

Cycles involve differing scales

Nutrient flow

Ecosystem scale in watersheds

Scale dependence of complexity

Complexity scale dependence, forests

Sometimes scale reduction works

Ecosystem modelling methods There are several approaches to ecosystems. They are not integrated and there is no simple scale dependence. They are: 1.Landscape criterion 2.Ecosystem criterion 3.Community criterion 4.Organism criterion 5.Population criterion 6.Biome and biosphere criterion

The criteria are not independent Although each criterion has its own methods, they overlap in various ways so that they are mutually dependent. There is no simple scale dependence of criteria, so we cannot separate them by scale. There is no available integration under an ecological supertheory. Even individuation within most of the criteria is not well-defined.

Oversimple model of levels

Layer cake model

Ecosystem cycles can aid unification All stable ecosystems involve cycles of various sorts. Showing how these cycles interact can help in combining models. This can show flows and forces, giving a dynamical model. This facilitates testing models.

Example: nutrient flow

Cycle unification

“Ecology is a box of bagels”

Potential problems with ecosystems and ecosystem management Potential problems with ecosystems and ecosystem management are scale dependent. Independent models using differing criteria can lead to differing conclusions about stability. Even within a single criterion, scale dependence, both spatial and temporal, can lead to differing conclusions about stability. I will go into details in a later lecture, but here are some theoretical examples.

Spatial dependence of surprise

Temporal dependence of surprise

Temporary avoidance of catastrophe

Conclusions 1 Scale is a choice, but we can choose the wrong scale for our purposes. We need to pay attention to embedding of scales. Complexity is scale dependent, both in time and space. Ecosystems are made up of cycles, with differing spatial and temporal scales. These can help with closure issues.

Conclusions 2 Ecosystem models use various non-integrated criteria. Although it seems at first that the criteria depend on scale, this is mistaken. Integrating cycles is the best way to go. “Ecology is a box of bagels” Ecological surprises and disasters are spatially and temporally scale dependent. Therefore, choosing the wrong scale can miss them.