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Ecological Tipping Points and Warning Signs

Thursday, July 30, 2015, by Nathan Justice
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It takes a very special kind of person to be an ecologist. They must be tenacious, inquisitive, and most importantly, they must demonstrate unyielding optimism.

A common goal amongst ecological scientists is to better understand the world around us, and to capitalize on this knowledge in order to facilitate Nature's narrative with minimal human interruption. Ecology, along with sibling-branches like conservation biology, wildlife biology, and forestry, have a tendency to feel like an uphill battle in pursuit of this goal. Despite the appearance of ecological processes progressing at a leisurely pace, scientists often find themselves in a race to understand swiftly changing paradigms. This race is the product of a surfeit of anthropogenic factors that are hastily altering the rules in which human growth and development must abide by in order to persist in a manner we are familiar and comfortable with.

The adversity ecology as a discipline must resolve stretches across nearly all aspects of society. This abstract, multifaceted obstacle manifests itself in areas such as public policy, economics, public health, climate science, agriculture, foreign relations, and international development, among many others that are largely out of scope for ecological scientists alone. It is my humble belief that a viable panacea for ecologists to overcome this adversity is to "fight fire with fire." That is to say, to solve problems across multiple disciplines, it is fruitful to engage and mobilize individuals in those disciplines. There are certainly tenacious, inquisitive, and optimistic individuals in other fields who's knowledge, skills, and passions are beneficial to the amplification of unifying goals in ecology.

As a personal example - I love studying biology, but throughout my time in college I have found myself delving more and more into the world of computer science. I initially took interest in this field as a means of applying computational skills in biological research, but over time I seem to be straying more and more into traditional product development. Fortunately, given the benefit of participating in the Harvard Forest Summer Research Program, I have the opportunity to blend my budding skills in software engineering with ecology research.

The project I am contributing to this summer is a computational tool that will allow researchers, regardless of their familiarity with formal programming languages, the ability to simulate ecosystem dynamics and perform tipping point and early warning signal analyses. The overall goal of this project is to implement the computational tool as a series of comprehensive and user-friendly web applications.

Before describing ecological tipping points and early warning signals, it is best to (re-)establish some foundational knowledge. Ecosystems are capable of exhibiting multiple stable states, each of which can be detailed as steady and persistent in the foreseeable future. Ecological resilience, or the ability to assimilate changes and persist with minimal transformation, is often used to gauge the stability of an ecosystem's state. Generally, humans and other wildlife are accustomed to a preferable ecosystem state, thereby relying on ecological resilience to provide ample opportunity to adapt to inevitable state changes.

Despite indication of ecological resilience, seemingly stable ecosystems are susceptible to abrupt and drastic changes from one state to another. These ecosystem state changes are often termed "tipping points" - analogous to tipping points described in economic and socio-cultural dynamics. A commonly used example of an ecosystem tipping point is the sudden emergence of algae blooms in a small pond or lake by eutrophication, a process which leads to a dramatic decline in both producer and consumer populations.

The complexity of ecosystem state change is compounded by the knowledge that an alternative ecosystem state, the product of a tipping point, is often not transient. That is to say, alternative states induced by tipping points are often themselves stable states. Alternative states typically exhibit unique population and ecosystem dynamics and feedbacks compared to the state observed before a tipping point, making the process of reversion exceptionally challenging.

Unexpected tipping points are increasingly more likely to occur as human impacts continue to affect and alter ecosystem dynamics across the biosphere. Ecosystem dynamics both before and after a tipping point are more easy to understand retrospectively. However, retrospective analysis holds little weight in proactive and efficient socio-cultural decision making. Systematic changes in human behaviors are likely necessary to hinder or adapt to the repercussions of ecosystems being driven across tipping point thresholds.

Mounting ecological research suggests tipping points can be simulated with mathematical and statistical models. In addition, these models and simulations have the potential to illuminate early warning signals, which are probable indicators that proceed an imminent tipping point threshold. Not all ecosystem models posses the ability to produce early warning signals. However, there are still classes of models that are viable candidates for researchers to use with early warning detection in tipping point simulations.

In essence, the web applications I'm working on are meant to serve as a tool to help people who are studying ecosystem dynamics. A personal goal of mine throughout this summer has been to build something that is not only relevant to experienced scientists, but also have the tool be something that is usable by a student whose newly learning about these concepts. Ideally, I would love to some day down the road hear about my web applications also being used in a classroom setting as a visual and exploratory teaching tool.

I'm still uncertain as to whether or not I'm tenacious, inquisitive, or optimistic enough to be an ecologist. However, in pursuit of this enlightenment, I am eager for many opportunities to apply my cross-disciplinary interests to help realize ecological goals.

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