The concept of emergent properties refers very clearly to, and must be seen in tight connection with, at least two other
Table 1 Some ecosystem orientors
Properties of the dominating species
Short life spans
Properties of production Small biomass High P/B ration Low respiration Small gross production
Properties of nutrient flows and cycles Simple, rapid, and leaky Small storage Extrabiotic
Small amounts of detritus Rapid nutrient exchange Short residence times Minor chemical heterogeneity Loose network articulation Low diversity of flows Undeveloped symbiosis
Properties of the community Low diversity Poor feedback control Poor spatial patterns
Thermodynamic and integrative system properties
Poor hierarchical structure
Close to equilibrium
Low exergy storage
Small total entropy production
High specific entropy production
Small level of information
Small internal redundancy
Small path lengths
Poor indirect effects
Small respiration and evapo-transpiration Small energy demand for maintenance
Slow growth K-selection
Qualitative development Large size Long life spans Narrow niches
Large biomass Low P/B ratio High respiration Medium gross production
Complex, slow, and closed cycles Large storage
Intrabiotic nutrient distribution scheme
Large amounts of detritus
Slow nutrient exchange
Long residence times
High chemical heterogeneity
High network articulation
High diversity of flows
Developed feedback control Developed spatial patterns
Developed hierarchical structure
Far from equilibrium
High exergy storage
High total entropy production
Small specific entropy production
High level of information
High internal redundancy
High path lengths
Developed indirect effects
High respiration and evapo-transpiration
The features, that are optimized throughout natural successions, provide several characteristics of emergent properties: They are only observable at the ecosystem level (which is the typical and the lowest logical level to describe, e.g., cycling phenomena), and they are based on self-organized processes. They can not be explained on the basis of knowledge of the parts alone, and the emergence-creating processual linkages between the sub systems are non-linear processes. From the hierarchy-based viewpoint also the additive features (e.g. size, biomass, life spans) can be categorized as emergent properties because their extensions are dependent on the scale of observation and because they also are based on internal system interrelations.
concepts often occurring in literature on modern ecosystem theory, the concepts of hierarchy and self-organization. In connection with hierarchy, the emergent properties are seen as outcomes of ecosystem organization where supersystems are formed with subsystems as constituents and where the properties are observable at the supersystem level only. Here the emergent property is an outcome of a certain way of organization. To exemplify this point, we might look at the following hierarchical features:
1. Individual level: individual nutrition budgets - foraging strategies.
2. Population level: species nutrition efficiencies - intras-pecific food competition.
3. Ecosystem level: nutrient cycling - food webs.
4. Landscape level: lateral nutrient transfers - food webs including large scale predators.
On the other hand, the ability of biological systems to arrange themselves in a special manner, for example, in a hierarchical way, is in itself a property which emerges as a consequence of the properties of its constituents, but the organization and the function for sure cannot always be foreseen. Thus, the capability of self-organization can be seen as an emergent property itself (Figure 1).
The existence of emergent properties is based on the system's organization (built up by structures and functions) whereby the interrelations (energy, matter, water and information flows, communications) play an important role. Some conditions of the system's state add up to the increased chances that emergent properties will appear. For example, instabilities seem to be important conditions that support emerging processes, especially referring to evolutionary emergence. Stable periods may lead to the emergence of new structures through bifurcations. As systems move toward the state of minimum dissipation they are, at the same time, moving toward
bifurcation points with possibilities of further evolution to occur. Similarly broken symmetries, complementarity has been proposed as a global mechanism.
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