Modelling the way for conservation

Think tree hollow simulation Maturetree and the Species-Area Curve – models have been used extensively in our attempts to unravel the complexity of nature, allowing us to better understand ecosystem processes.  Models enable us to simulate these processes by illustrating scientific research, which make them a useful tool to aid decision making in conservation. Recently in Nature, Purves et al. (2013) justifies the need to take modelling in the field of ecology to the next level by building General Ecosystem Models (GEMs).

The comment made in Nature (Purves et al. 2013) can be accessed here

The comment made in Nature (Purves et al. 2013) can be accessed here

GEMs are analogous to circulation models in climate science and simulate the broad-scale structure and function in ecosystems – the largest scale in the definition of ‘biodiversity’. In other words, fundamental ecosystem processes that drive the distribution and abundance of organisms such as feeding, reproduction, migration and death would be encoded in a GEM, defining the ‘rules at play’ in entire ecosystems.

Parrotfish chomping off a coral. Photo taken in Christmas Island.

Parrotfish chomping off a coral.

Ultimately, GEMs will provide a common framework for different types of ecosystems on multiple scales. With GEMs, ecologists could effectively model population changes, assess overall ecosystem health and resilience, and even explore how any ecosystem may respond to pressures such as climate change and habitat fragmentation over time.

Need to know which/how many trees we can remove/how often we can remove them from a temperate forest such that the system recovers and maintains its resilience in the long term? With GEMs, we will have an answer given what we already know about our ecosystems.

Is it possible to compute such complex systems?

The authors acknowledge the challenges in GEM-building – starting from convincing ecologists that they can and should be built. Yet, the task does not seem impossible with positive outcomes from a prototype. In GEMs, organisms are grouped into ‘cohorts’ based on their function in the system.

A tropical ecosystem in Palau

A tropical ecosystem has too many species and it would take a very long time to describe all of them. By grouping organisms that are similar enough based on their functions, we could model ecosystems based on these groups.


Coral reefs are extremely diverse ecosystems. An integrated tool for modelling marine ecosystems incorporating biophysical, economic and social factors, Atlantis, has been developed by CSIRO.

GEM potential

“Throughout the history of ecology, most researchers have resisted abstraction because ecological complexity is so obvious in nature … But comprehensive species-specific data will always be in short supply (at least 80% of the millions of species of Earth are undescribed), so a better understanding of ecosystems demands a broad-brush approach.”

With a large proportion of species undescribed, and probably even going extinct without us knowing, perhaps the function and resilience of entire ecosystems should take priority in conservation. To know how and what to conserve we have to understand the system first, and by attempting to build GEMs we can also identify areas in need of more research to allocate funds effectively.

In this article, Stirzaker et al. (2010) explains the concept of a requisite simplicity in understanding complex systems: where conceptual clarity and scientific rigour is retained while discarding some detail. This is different from being simplistic, which leads to error.

GEMs could provide a requisite simplicity in biodiversity conservation, especially because it delivers integrated information that is useful at an implementation level. Not forgetting socio-economic-political factors, GEMs will definitely not be the only guide in decision-making. With an urgent need to respond to biodiversity in decline, ecologically sound GEMs could enable ecologists to identify solutions and predict ecosystem responses in a timely and cost-effective manner.

Although the construction of actual GEMs may seem far-fetched, I feel that the rationales behind GEM-building are very logical, and it will be interesting to see more developments like this in the field.

Isis Lim / BSc
(The photos in this post were taken by me)

About Biodiversity Conservation Blog

I am an Associate Professor at The Australian National University and convene a (very awesome) course called Biodiversity Conservation. Myself and students in the course contribute to this blog.
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1 Response to Modelling the way for conservation

  1. A thought-provoking article Isis. I agree with you that criticism is often unfairly directed at models because of their “requisite simplicity”. Simulation models have the potential to inform us about the relative importance of different variables or impacts in complex systems where inituition does not, even if the full complexity of the system being modelled cannot be captured. GCMs or models of our economy are cases in point.

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