The Nature of the Changes

River meandering, oscillation in the geographical ranges of species, land abandonment, forest fragmentation, reclamation, and urban sprawl are some of the changes that commonly occur in natural and modified environments.

A change can be defined as any modification occurring in a system state (from individual to biosphere) produced by a broad variety of abiotic and/or biotic factors that introduce or subtract energy and information to the system.

Changes can be considered modifications in the availability of an expected resource or pattern and the temporary or permanent impossibility for species, populations, communities, ecosystems, and land mosaics to incorporate the new conditions.

Every type of change is scaled differently, as are the processes involved. The processes responsible can operate at the individual-based landscape on the emergent properties at the neutrality-based landscape scale.

Landscapes, which are also considered interacting collections of patches, are continuously under change, and it is possible to distinguish changes inside the components and changes that occur when external forces act on the system. But a landscape can also be considered a container of different levels of organized complexity according to a hierarchical perspective (Allen and Starr 1982, Allen and Hoekstra 1992) and changes occurring at one level can be integrated with changes at other levels.

Changes in the environment are "relativistic" properties. Without a standard of comparison, we cannot evaluate a change. Changes occur in space and time separately or contemporarily. Changes occur at individual, population, community, ecosystem, and landscape levels.

We will focus on the individual level as well as on the landscape level, considering the population and community levels as "secondary" and "paradigmatic" levels of resolution and not the primary front of "genuine changes." However, emergent properties of populations and communities do have relevant effects on the scaled dynamics.

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