Palaeoecology - the ecology of past times.
Ecology is the study of the interconnected web of the natural world and embodies all energy and resource inputs and outputs. Theoretically there is only one ecosystem, the global or even universal ecosystem. However we often break the environment being studied up into smaller, more manageable ecosystems, maybe a desert, a bog, a pond or lake, a mountain range. This becomes more problematical in determining the edges of such ranges.
A lot of the focus of living organisms in palaeoecology is on plant life – plants don’t move like animals, they are more indicative of the long term environmental conditions and as such successful plant growth is a proxy for the environment. They shed parts during their lifetime – leaves, seeds, pollen or spores, branches – which may be incorporated into sediments as fossils.
There is a fundamental difference between ecology and palaeoecology, though ecological analysis and understanding underpins them both. That difference is time.
Ecology embodies the study of the earth systems of now, environments and populations, behaviour and habits that can be observed and measured. However change, particularly slower rates of change – the growth of trees, the spread of populations, the accumulation or erosion of sediments, changes in weather patterns and climate – is harder to measure, requiring long time series of observations. Even with these analysis requires the assumption of the direction of change. Increasingly warmer weather patterns over a number of years may represent a change in climate; it may equally represent fluctuations within accepted limits and just be an aberration. A fourth year of cold weather may alter the conclusion – and the longer the time series of observations, the more certain of the direction of change.
In palaeoecology direct observation of living systems is severely restricted to the small part of the environment that has been preserved, either as fossil remains of living organisms, sedimentary structures, isotopic proxies for climate or atmospheric conditions. But the changes that occurred over long periods can be observed from these clues, and predictions that are so hard in ecology are laid bare to view in palaeoecology.