Cows lounge in a tree-dotted pasture in central Chile
Cows lounge in a tree-dotted pasture in central Chile. The site provided a case study for ecologists to evaluate the utility of efforts that seek to quantify ecosystem services. Credit: Meredith Root-Bernstein
Source: Earth’s Future

To make their research more useful for policy makers, ecologists strive to collect data and provide answers to questions about the services ecosystems provide to humans: food, freshwater, timber, fuel, erosion and flood control, carbon storage and climate regulation, and more.

A number of national and international bodies are concerned with defining and assigning monetary value to these so-called ecosystem services, and in many cases, research funding decisions are based on how well a study might shed light on various ecosystem services. More than 1,000 scientific papers containing the phrase “ecosystem services” are published each month.

Theoretically, this research framework should benefit all parties involved: policy, industry, ecology, and the people living within a given ecosystem. To learn more, Root-Bernstein and Jaksic explored the intricacies underlying the ecosystem services framework. They found that the framework might not actually be doing much good for either science or society.

The researchers started by reexamining a study they had previously conducted, which was designed to quantify ecosystem services. That previous study took place in a silvopastoral habitat—a pasture for animals, such as cows or sheep, within a wooded area—in central Chile. The researchers had set out to examine the environmental processes influencing the number of new trees growing in an area, or tree recruitment, and the contributions of those trees to ecosystem services, such as water circulation and carbon storage. They plotted a gridded map showing the locations of tree seeds (a short, flowering acacia is the only type of tree found in the woodland) as well as areas where grazing sheep would likely disperse the seeds.

As far as they could tell, however, no tree recruitment occurred in the time frame of the study. As such, they could draw no conclusions about the factors increasing tree recruitment or their contributions to ecosystem services.

A habitat used as pasture for animals in central Chile. Credit: Meredith Root-Bernstein

In their reexamination, the researchers realized there were two ways they could have done the study differently to get results. First, they could have mapped the movement of ecosystem services across the landscape, using genetic analysis or lidar to track the seeds or tracking the movement of the sheep and other animals that may have affected seed dispersal. But this method would not have told them anything about causality or how to improve conservation management. Alternatively, they could have planted acacia tree seeds under different conditions and then compared their growth. But although this technique would have shed light on the factors causing tree recruitment and on ways to improve management, it would not have provided any information about ecosystem services. The researchers went wrong, they concluded, by combining the two approaches.

But a bigger problem lay in not considering economic factors. The researchers had hoped to produce data that would help landowners understand the value of silvopastoral land and how to increase it. But, they realized, if landowners were making a decision about whether to keep silvopastoral habitat or convert it to an orchard, they would not need these data to make their decision. More than likely, the landowners would be concerned with factors such as the potential revenue versus initial costs (seed, irrigation, and insecticide) or the availability of a carbon compensation scheme, which would pay them for offsetting emissions by not cutting down native trees.

Because the landowners could get all of this information by looking at market prices, the researchers concluded that their initial study (as designed) was a waste of time and effort. Even in the event that a landowner wanted to consider the nonmonetary benefits of a silvopastoral habitat, such as the enjoyment of natural landscape, a study quantifying this enjoyment as an ecosystem service is probably not what would change the owner’s mind about how to use the land.

After drawing upon their own study and consulting relevant literature, the researchers came to the realization that many ecologists today are asking questions that are irrelevant to real-world needs and desires. As a result, they’re generating data that do not help solve real-world problems.

The authors also found that a number of assumptions about ecosystem services are mistranslated across ecology, policy, and industry. The ecosystem services framework, they discovered, often muddies ecology studies by shifting the focus away from understanding causality and toward specific analytical tools that don’t always fit the ecological question at hand. One example they pinpointed was the inappropriate use of maps, models, and other tools. Maps are commonly used in policy making and are effective at showcasing the spatial distribution of data. However, they can be impractical for communicating various traits, behaviors, interactions, and patterns that, for instance, change over time but not space.

A current popular idea is that policy must justify itself with data, and science must likewise justify itself to policy makers. But as this study shows, when science takes its methodology from policy, the results are often flawed. Fortunately, years of research in ecology—as well as conservation, anthropology, natural history, and myriad other fields—reveal more effective pathways forward. (Earth’s Future,, 2017)

—Sarah Witman, Freelance Writer


Witman, S. (2017), Are studies that evaluate ecosystem services useful?, Eos, 98, Published on 02 August 2017.

Text © 2017. The authors. CC BY-NC-ND 3.0
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