Ecosystem functioning and services

Ecosystem functioning and services

1. Ecosystem and services

   • Ecosystems are dynamic interrelated collections of living and non-living components organised in self-regulating units
   • Ecosystem by scale
     • Microbial to global
     • Biotically defined
       • Foundation species
       • Ecological unit
     • Abiotically defined
       • Nature of physical environment

2. Systems

   • Systems are built on connectivity, within ecosystems or between ecosystems.
   • Systems by connectivity
     • E.g. fish moving between geographical regions
     • A system defined by connectivity: subcomponents of system cannot be treated in isolation
   • Members of the system
     • Spatial relationship
       • e.g. Ecosystems are usually biotically or abiotically defined
     • Connectivity of processes relationship
       • E.g. Food-web, Nutrients etc
       • Network of ecosystems

3. Ecosystem function

   • What ecosystems do: it is an old concept
     • Nutrient uptake
     • Bioturbation
     • Biomass production
   • Functions at different scales
     • Microbial scale
       • Plankton ecosystem
         • Primary production etc
     • Big scale
       • Plankton ecosystem
         • Regulation of fisheries and food webs etc
     • Global ecosystem
       • Climate regulation
   • 'Functioning'
     • Operating of and/ or performances of:
       • Selected processes and properties of the system. E.g. oxygen uptake, bioturbation.
       • The system as a whole. E.g. How the systems life-persistence mechanisms work.
     • The roles played in the workings of the system. E.g. role played by predator, prey etc. NTR: Same role can performed by different actors.
     • Providing benefit to people. ECOSYSTEM SERVICES. Noticable difference is the benefit a system provides.

4. Ecosystem services

   • Ecosystem provide goods and services to people. This distunguishes itself from "functions".
     • "Services by natural environments that benefit people"
   • Four classes of services. (PRSC).
     • Provisioning service. E.g. food, water etc
     • Regulation service. E.g. Carbon sequestration, Coastal proctection
     • Supporting services. e.g. Nutrient cycling, primary production
     • Cultural services
   • Constanza et al. 1997. 33 trillion dollars for global ecosystem services per annum
     • Cost benefit analysis: cost of maintaining/ cost of losing

5. Failing functions and services

   • Will occur when services or expected function change or fail.
     • E.g. natural coastal protection loss leads to terrestrial land erosion
     • E.g Poor water quality for fish leads to mortality
   • Why do ecosystems fail?
     • There are key cornerstones that must be met
       • Intrinsic abiotic and biotic properties
         • Species compostion
         • Chemical and physical gradients
       • Extrinsic forcing agents and links
         • Drivers such as climate weather tc.
         • Factors associated with biotic and abiotic connectivity.
     • Thresholds
     • Tolerance and gradient ranges
       • Systems exist within their tolerance range along gradients in abiotic and biotic factors.
         • Systems lie along multiple interacting gradients.
   • Functional regime
     • Made up of the intrinsic biotic and abiotic properties
     • Extrinsic forcing agents and links

6. Conclusion

   • Function will depend on where, along the gradients of interacting intrinsic and extrinsic regimes the system is positioned.
     • Shift a gradient and it will affect the system and the whole functional regime.
     • Systems might collapse if the nature of inherent and external properties shift too far from system tolerance ranges.
     • Regime shift
       • Shift in general characteristics of biotic/ abiotic factors
       • Extremes can also result in regime shifts. But are determined by value and duration