Events & Media


A PhD Dissertation Defense

"Managing ecosystem services in the face of uncertainty:
what is the role of biodiversity?"

Laura Dee
PhD Candidate
Bren School

Tuesday, August 18, 2015
8:00 a.m.
Marine Science Institute Auditorium (1302)

Faculty Advisor: Steve Gaines
Committee Members: Christopher Costello, Bruce Kendall, David Tilman, Jennifer Caselle

The conservation community is increasingly focused on managing nature explicitly for ecosystem services that provide benefits to humans, rather than for its intrinsic value. Though often debated, the consequences of conserving ecosystems for their services rather than for the explicit goal of biodiversity protection are not clear. While biodiversity can contribute to ecosystem services, this scientific link is fraught with uncertainty. How many and which species to protect is thus an important challenge for applied and theoretical environmental science, as well as new policy initiatives, such as the intergovernmental platform on biodiversity and ecosystem services (IPBES).

First, I will present new theory to address the extent to which a goal of ecosystem service provision creates a significant economic incentive for biodiversity protection when facing uncertainty over how biodiversity produces services. I derive the level of biodiversity protection that maximizes ecosystem service provision under uncertainty and define a criterion that can be used to determine when managing for ecosystem services economically justifies broad-scale biodiversity protection. I illustrate the utility of this criterion, applying it to several ecosystem services across locations (pollination, wave attenuation, and carbon storage).

Next I consider factors other than uncertainty that may increase or decrease alignment between management for ecosystem services versus biodiversity conservation. Specifically, I review studies of pollination, carbon storage, and coastal protection across ecosystems to address 1) the role of abundance, dominance, and richness in providing these services; and 2) whether the species providing these services also form habitats that might promote broader biodiversity co-benefits.

Finally, I aim to reduce uncertainty about the role of biodiversity in the provision of a specific ecosystem service (fisheries yields) in variable climates. I develop theory to predict the consequences of within-year temperature variability for yields and explore the role diversity might play in offsetting potential impacts. I hypothesize that higher functional diversity (FD), measured with traits related to species’ responses to temperature, can mitigate impacts from temperature variability on yields. Using a global marine fisheries dataset, I find that within-year temperature variability reduces yields but current FD of targeted species largely offsets this effect, avoiding annual losses of 8% on average globally relative to if FD were degraded to the lowest level observed in the data.

As a whole, this dissertation contributes our understanding of when management strategies targeting ecosystem services versus biodiversity conservation align or diverge.


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