by Claudia Havranek, United Kingdom, ELP 2014
Written on August 7, 2014.
In an environment working alongside people for 35 different countries, all with different expertise, you become aware of different ways of looking at a problem. It’s safe to say in an environmental program, everyone is looking at the same problem: how to better our changing environment. The approaches and specialties of each person however vary greatly, and it was after a networking event, after we had been shooed out of the Blum Center and the lights had been switched off, palaeoecology was discussed.
Palaeoecology, where data is taken from fossils to reconstruct previous ecosystems may be the key to many current ecological problems. From the palaeodata, the idea of resilience has taken form in ecology: from a concept to actual data, and it may provide a missing link in ecological management strategies.
Resilience is not a new idea to ecology. Holling first introduced the concept of resilience in ecology in 1973, however several definitions have since been published. There are two distinct definitions: ecological resilience and engineering resilience. Ecological resilience is the resistance of a system to perturbation without changing structure or function. Engineering resilience is the recovery of a system to equilibrium following perturbation. Together, these definitions allow the resilience of an ecosystem to be used in interpretation of ecosystem responses to changing conditions, and switches between alternative stable states.
The concept of resilience provides a well-theorized area of study, which has (and will continue to be) furthered through palaeoecology. There is some data, in fact, to suggest that ecosystem management should focus on resilience, and recognize alternative stable states in ecosystems over a centennial and millennial time frame, through the use of palaeodata.
One problem in the study of resilience of ecosystems to environmental change is a lack of long-term data sets. Most conservation strategies currently rely on neo-ecological data sets spanning up to 50 years, however palaeodata may extend beyond this, to identify the longer scale processes shaping ecosystems. Palaeoecology involves studying past ecosystems and environmental conditions, through the use of proxies (e.g. fossil pollen time-series). Previous environments may be reconstructed, using multi-proxy and multi-core data to identify correlations over time between ecosystem changes and potential drivers of change.
Through palaeodata, the processes behind ecosystem resilience may be better understood. As such, palaeodata has been used to break the assumption of biotic equilibrium responses in ecosystems, as well as improving understanding of early warning signals, which occur before critical shifts in the state of an ecosystem. Palaeodata reveals that ecosystems move between alternative stable states, surpassing critical thresholds, and ecosystems may show hysteresis.
This theory of resilience, backed up by palaeodata, has several key implications for conservation. Firstly, the identification of early warning signals may be used to predict catastrophic shifts, and result in the implementation of appropriate management strategies. Secondly, restoration projects can be guided by the level of ecosystem change needed for a reversion to a previous state, especially in ecosystems exhibiting hysteresis, where restoration may be challenging. Thirdly, conservation efforts may focus on improving resilience, through identifying traits of resilience, rather than specific states.
The Erhai lake-catchment system in southwest China provides an example of how palaeodata may be used to inform current management techniques. Proxy data over 3000 years show that restoration to an undisturbed pre-1400 YBP state is unachievable within human timescales, due to the exhibition of hysteresis. Risk of further degradation however is low, as the system is highly resilient.
Palaeoecology and the concept of resilience present a method and a concept that are currently vastly underutilized in ecosystem management. Understanding the theory of ecosystem responses to perturbation, and how this may be a result of the resilience of a system, has and will continue to be furthered through palaeodata. Palaeoecology can reveal long-term processes and history important to current ecosystems, and so should be utilized more in the future, alongside neo-ecology, to inform conservation decisions.