Ecological Restoration (BIO 409) Dr. McEwan Lecture 5: Biodiversity and Restoration

Concept Review Niche Complementarity: This is an idea about the relationship among species in creating or perpetuating some ecosystem property. One way to illustrate this is to think about species fitting together sort of like puzzle pieces. As you add species the picture gets clearer…in the analogy, as you add species to the ecosystem, its functionality increases accordingly. One example that is currently ‘hot’ is the idea that as you add tree species to a forest, that forest’s capacity to capture and sequester carbon increases. This concept carries a whole load of assumptions with it…and it certainly has not been clearly proven for all systems and/or all ecosystem functions. If Niche Complementarity is occurring, you would expect a linear relationships between the function and species diversity- as you add species- the function linearly increases. One outstanding issue is whether (apparent NC) is because of increasingly filled niche space or whether you just happen to pick up a species that is good at that particular job as you add species (aka, Sampling Effect). This issue is very much alive in Ecology right now. Application for Restoration are obvious…

Concept Review Functional Groups: There are a lot of species in the world. A LOT. In many cases it is very difficult, if not impossible, to address this diversity from a scientific perspective, much less from the perspective of management. One way to simplify this diversity is to focus on an individual’s functions, rather than its taxonomy (i.e., its evolutionary relationship to other organisms). If you can “bin” species depending on function then management or restoration could, potentially, focus on functional groups. An obvious example is aquatic insects which are very often classified into functional groups such as shredders, collector-gatherers, and predators.

Concept Review Species Redundancy: If we think about species as functional participants in ecosystems- providing a specific capacity/outcome/function, it can lead to the idea that some (or maybe even many) species are providing identical, or at least measurably similar, attributes to the system. Thus, the idea of species redundancy. But, don’t think of this in a negative context…like there are useless species in an ecosystem. No serious ecologist would hold such a myopic view. Instead, thinking about it from this perspective allows the identification of species that are MORE crucial to preserve/restore…those that provide a specific function when no other species do. Some examples, for instance, N-fixing plants, or maybe a shredding insect. So as a restorationist, you could potentially focus on CREATING redundancy, to make the restoration more stable.

Concept Review Species Redundancy: If we think about species as functional participants in ecosystems- providing a specific capacity/outcome/function, it can lead to the idea that some (or maybe even many) species are providing identical, or at least measurably similar, attributes to the system. Thus, the idea of species redundancy. But, don’t think of this in a negative context…like there are useless species in an ecosystem. No serious ecologist would hold such a myopic view. Instead, thinking about it from this perspective allows the identification of species that are MORE crucial to preserve/restore…those that provide a specific function when no other species do. Some examples, for instance, N-fixing plants, or maybe a shredding insect. So as a restorationist, you could potentially focus on CREATING redundancy, to make the restoration more stable.

Diversity concepts Biodiversity and Restoration: One of the most important questions in ecology right now is about the relationship between diversity and ecosystem function. Does changing diversity chance an ecosystem’s functional capacity? Diversity and Disturbance Diversity and Productivity Diversity and Invasion Diversity and Ecosystem Function

Intermediate Disturbance Hypothesis

Intermediate Disturbance Hypothesis, Applications for Restoration?

Productivity-Diversity Hypothesis

Diversity Productivity

Measures of Productivity Measures of Diversity

Here is an example from a paper that I am working on right now. In this case the axes are flipped, biomass on the y, diversity on the x. These are plots in forests of Taiwan (see below). The idea here (and this is a very definite application of the theory) is that we need to understand whether more diverse forests store more carbon. Management for “biodiversity” is relatively common now, and management for “carbon sequestration” is becoming an imperative of many agencies. How do these two concepts fit together? Are more forests also better at storing carbon?

Huston (1979) presented a generalized model: The Dynamic Equilibrium Model of Diversity

How do disturbance and productivity relate to one another? The Dynamic Equilibrium Model of diversity of Huston (1979). You read this figure like a topographic map, where the orange is the peak. So there is a peak in diversity at intermediate levels of both diversity and productivity. In restoration projects you may have gradients in both productivity and diversity.

Diversity and Invasion: This is a live argument in Ecology right now. Some have argued that more diverse ecosystems should be LESS susceptible to exotic invasion. Because niche space is all taken up…the system is in effect “closed.” There have been a number of studies providing support for this claim

Diversity and Invasion: This is a live argument in Ecology right now. Some have argued that more diverse ecosystems should be MORE susceptible to exotic invasion. More diverse systems ususally occur in what kinds of conditions (*hint, two slides back*). Those conditions also promote invasion! This debate is ongoing…no answer yet.

Is there a generalized relationship between diversity and ecosystem function in restoration?