An Ecosystem is the dynamic complex of plant, animal and micro-organism communities and their non-living environment interacting as a functional unit.
Ecosystem function is dependent upon the dynamic relationships within species, among species and between species and their abiotic environment, as well as the physical and chemical interactions within the environment.  Ecosystem function is determined by the interactions between biodiversity dynamics, ecosystem processes, and abiotic factors.
Ecosystem process is an intrinsic characteristic whereby an ecosystem maintains its integrity.  Processes include: decomposition; production; nutrient cycling; and fluxes of nutrients and energy.
Ecosystem properties describe the size, biodiversity, stability, organisation, and the internal exchanges of materials, energy, and information among different assemblages, as well as other properties that characterise an ecosystem (including ecosystem functions and processes).
Ecosystem ‘stability’ or ‘robustness’ express the dynamic properties of an ecosystem. An ecosystem is considered stable or robust if it retains the ability to return to its original state after a perturbation, exhibits low temporal variability, or does not change dramatically in the face of a perturbation.
Ecosystem resilience refers to an ecosystems capacity to recover from severe disturbance and return to a pre-disturbed state with no alteration to structure or outputs.  Resilient ecosystems are able to maintain taxonomic composition, structure, ecological functions, and process rates.  Resilience is a function of biodiversity at all scales: genes, species, landscapes, and spatial diversity within and amongst ecosystems.  Reduced resilience can lead to uncertainty about future ecosystem condition. 
Ecosystem resistance is the capacity of an ecosystem to withstand the impacts of drivers without displacement from its present state.
Ecosystem limits refer to different factors present in the environment that control biotic and abiotic processes within an ecosystem.  The ecosystem threshold describes the point or level at which new properties begin to emerge in an ecological system which invalidates predictions based on relationships that apply at lower levels.
Ecosystem Condition describes the capacity of an ecosystem to yield services, relative to its potential capacity. 
Condition of ecosystem service refers to the capacity of an ecosystem service to yield benefits to people, relative to its potential capacity.
Ecological redundancy, functional redundancy or functional compensation is a characteristic of ecosystems where more than one species can carry out a particular process.  Redundancy may be total or partial; that is, a species may replace other species entirely or it may compensate some of the processes in which the other species are involved.