The Basics of Complex adaptive systems theory

Nota:

• ecosystems wit no historical analogue 

1. An ecosystem will be altered by directional environmental drivers or the addition or loss of an important species (biotic changes)
   1. New state: internal restructuring due to new biotic and abiotic interactions further alters community compositions

      Nota:

      •  though changes in abundances or species losses, through changes in biogeochemical interactions (resulting in novel ecosystem) 
2. New silvicultural challenges are arising with changing human desires, loss species and climate change
   1. Now we should
      1. Manage forests to provide a variety of desired ecossytem goods and services at an acceptable cost
      2. Ensure ability of managed forest to adapt to diverse and unexpected future conditions
      3. Prescribe and promote novel ecosystems
      4. Increase ecosystem resilience and adaptability, and promote desirable outcomes
      5. Paradigm shift in forestry to complexity science
         1. Viewing forest as complex adaptive systems can provide silviculture a new conceptual framework
            1. Managing for complexity involves thinking careful about types of interactive processes that occur within forests and how they enable forests to self-organize with minimal intervention after disturbance
         2. Increase resilience to stress
         3. Much of the order/pattern we see in the world comes, not from top down control, but from local-level (bottom-up) interactions among system components (self-organization).

1. Interactions among the parts cause the behaviour of the whole to be more than the sum of its parts

Nota:

• among components and with the environment, which channels energy and allowing ecosystems to self-organize, function and evolve. 

Nota:

• Occur wen organisms receive feedback from their environment and modify their behaviour accordingly, allowing control over the destiny of the ecosystem,

1. Positive feedback

   Nota:

   • Mutualisms
2. Negative feedback

   Nota:

   • competition, or density-dependant control; behaviour changes in response to resource limitations
3. Fast-forward mechanism

   Nota:

   • Trees produce waxes to prevent water loss during drought; resins to pitch out bark beetles that bore into the bark 

Nota:

• Complex estruture that emerges out of interactions and feedbacks among the parts 

Nota:

• The whole is greater than it's parts

Nota:

• Means that changes are maintained within certain bounds, and key patterns and processses are protected and maintained 

1. Productivity and stability

   Nota:

   • of ecosystem comes from complex interactions among the many parts, and the positive and negative feedbacks between those parts

Nota:

• No skin; local ecosystems are part of an interacting network of ecosystem that compose landscapes, region, the earth. 

Nota:

• Because the boundaries are diffuse; system is open to the outside 

Nota:

• Each ecosystem comprises numerous smaller systems and at the same time is part of a hierarchy of larger ecosystems

Nota:

• resulting from the adaptation and evolution of organisms that comprise the community 

Nota:

• because organisms evolve in an somewhat ordered yet random fashion 

Nota:

• resource limit on photosynthesis
• making relationships somewhat unpredictable with surprising consequences 

1. Non-linear réponses

   Nota:

   • can have threshold changes with non-catastrophic reponses, where the response can be reversible if the conditions change back to initial conditions; 
   1. Non-catastrophic

      Nota:

      • where the response can be reversible if the conditions change back to initial conditions
   2. Catastrophic reponses

      Nota:

      • where there is a bifurcation (split) into a new state that is not reversible when conditions change back to initially conditions 

Nota:

• genes or structure (CWD remaining from previous disturbances

Nota:

• i.e. following disturbance

1. Uncertain future conditions

   Nota:

   • Implies allowing forest development to follow a variety of possible paths
2. Ill-defined boundaries

   Nota:

   • outside influences inherent chanracteritcis of forest ecosystem dynamics 
3. Never at equilibrium

   Nota:

   • Adopt view that ecosystem structures and process are continually changing and this change is important 
4. Self-regulated

   Nota:

   • Occurs through positive and negative feedback loops; requires new multi-scale approaches 
5. Develop unexpected properties

   Nota:

   • iportant factor in ecosystem resilience -creativity 
6. Affected by initial conditions/previous states

   Nota:

   • remember previous states (i.e.  coppice systems, present day structural retention)