The Basics of Complex adaptive systems theory

The Basics of Complex adaptive systems theory

1. Novel Ecosystems

   • As climate changes, there will be an increasing number of novel ecosystems
     • ecosystems wit no historical analogue 
     • An ecosystem will be altered by directional environmental drivers or the addition or loss of an important species (biotic changes)
       • New state: internal restructuring due to new biotic and abiotic interactions further alters community compositions
         •  though changes in abundances or species losses, through changes in biogeochemical interactions (resulting in novel ecosystem) 
     • New silvicultural challenges are arising with changing human desires, loss species and climate change
       • Now we should
         • Manage forests to provide a variety of desired ecossytem goods and services at an acceptable cost
         • Ensure ability of managed forest to adapt to diverse and unexpected future conditions
         • Prescribe and promote novel ecosystems
         • Increase ecosystem resilience and adaptability, and promote desirable outcomes
         • Paradigm shift in forestry to complexity science
           • Viewing forest as complex adaptive systems can provide silviculture a new conceptual framework
             • 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
           • Increase resilience to stress
           • 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).

2. Characteristics of a complex adaptive system (CAS) ecosystem

   • has many parts that interact
     • Interactions among the parts cause the behaviour of the whole to be more than the sum of its parts
   • Web of interactions and interdependencies
     • among components and with the environment, which channels energy and allowing ecosystems to self-organize, function and evolve. 
   • Feedbacks
     • Occur wen organisms receive feedback from their environment and modify their behaviour accordingly, allowing control over the destiny of the ecosystem,
     • Positive feedback
       • Mutualisms
     • Negative feedback
       • competition, or density-dependant control; behaviour changes in response to resource limitations
     • Fast-forward mechanism
       • Trees produce waxes to prevent water loss during drought; resins to pitch out bark beetles that bore into the bark 
   • Sel-orginzed from the bottom up
     • Complex estruture that emerges out of interactions and feedbacks among the parts 
   • Synergy: Emergent properties
     • The whole is greater than it's parts
   • Stability
     • Means that changes are maintained within certain bounds, and key patterns and processses are protected and maintained 
     • Productivity and stability
       • of ecosystem comes from complex interactions among the many parts, and the positive and negative feedbacks between those parts
   • Diffuse boundaries
     • No skin; local ecosystems are part of an interacting network of ecosystem that compose landscapes, region, the earth. 
   • Non-euqilibirum
     • Because the boundaries are diffuse; system is open to the outside 
   • Hierarchical
     • Each ecosystem comprises numerous smaller systems and at the same time is part of a hierarchy of larger ecosystems
   • Adaptive
     • resulting from the adaptation and evolution of organisms that comprise the community 
   • Indetermined
     • because organisms evolve in an somewhat ordered yet random fashion 
   • Non linear relationships/reposnses
     • resource limit on photosynthesis
     • making relationships somewhat unpredictable with surprising consequences 
     • Non-linear réponses
       • can have threshold changes with non-catastrophic reponses, where the response can be reversible if the conditions change back to initial conditions; 
       • Non-catastrophic
         • where the response can be reversible if the conditions change back to initial conditions
       • Catastrophic reponses
         • where there is a bifurcation (split) into a new state that is not reversible when conditions change back to initially conditions 
   • System memory
     • genes or structure (CWD remaining from previous disturbances
   • Sensitive to initial conditions
     • i.e. following disturbance
   • Viewing and managing forest as complex adaptive systems
     • Uncertain future conditions
       • Implies allowing forest development to follow a variety of possible paths
     • Ill-defined boundaries
       • outside influences inherent chanracteritcis of forest ecosystem dynamics 
     • Never at equilibrium
       • Adopt view that ecosystem structures and process are continually changing and this change is important 
     • Self-regulated
       • Occurs through positive and negative feedback loops; requires new multi-scale approaches 
     • Develop unexpected properties
       • iportant factor in ecosystem resilience -creativity 
     • Affected by initial conditions/previous states
       • remember previous states (i.e.  coppice systems, present day structural retention)