Terrestrial Palaeoecology and Global Change

Introduction
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I.2. Global change: general
In complex systems, an external forcing is either damped by negative feedbacks or
escalated by positive feedbacks. A switch from one mode to another makes evolution of
such systems intermittent rather than gradual, hence the inconsistency of gradualistic
theories.
The system we deal with in global change research is the biosphere as defined by
Vernadsky (1967 and earlier work), i.e. the shell of the earth encompassing all living
matter and the products of metabolism, including those buried in sedimentary rocks. This
is an open system perpetually reproducing organic life by recycling matter, with the main
source of energy outside the planet.
The biospheric functions are directed by the goal of biological production with minimal
wastes. The biospheric structures are determined by their functions in the life-producing
system. We are concerned with structural changes (such as the loss of biological
diversity) but these are on the surface, conveying a deeper level of functional change.
Neither structure nor function can be fully understood without unravelling the history.
This is what palaeontology is about.
The biosphere is superimposed upon the earth crust, hydrosphere and atmosphere.
Heterogeneity of these substrates predetermines division of the biosphere
into a great number of life-producing units, ecosystems, with their specific biotas.
The ecosystems are linked by a perpetual flow of matter, through the continental
runoff to the oceans and a backflow of oceanic production over trophic channels,
providing for functional integration of the biosphere. An impact affecting any of
the biospheric functions would inflict a reaction spreading over the mosaic of interrelated
ecosystems.
Evolution of functional systems is governed by the general system laws, which,
for closed systems, are the classical thermodynamic laws. Closed systems evolve in
the direction of a maximal entropy production. Conversely, an open system minimizes
its entropy production (Bertalanfy, 1960; Prigogine, 1980; Kondepude & Prigogine,
1999) by drawing matter and energy from external sources and by exporting
wastes. Each open system thus affects the neighbouring systems and is in turn affected
by them. Any talk of biotic evolution going on independently of any environmental
change is therefore meaningless. A history of the biosphere is the outcome
of complex interactions with cosmic, geological and, recently, mental systems leaving
their traces in the fossil record.
The Darwinian metaphor of the geological record as a book written in an unknown
language, with most pages torn away and the remaining showing a few lines each, is a
frustrating reminder of the fact that the still popular theory of evolution was built on a
notoriously unsafe theoretical, as well as factual, foundation. Not only is the record more
complete presently than in the Darwinian time, but also room for speculations is narrowed
by the modern methods of measuring evolution rates. The once popular notion