It probably wasn't fun to be on hands and knees in the hot sun, clipping, identifying and measuring plants and plant litter, looking for a pattern that a prominent scientific paper had recently stated did not exist.
So you can bet it's satisfying to ALES rangeland ecology researchers Edward Bork and Cameron Carlyle that their painstaking work has now helped clarify a very long, global debate.
Working with a large network of scientists worldwide, who studied grasslands of every type in all climate zones, they helped reaffirm a theory of diversity that had been under attack. Known as the humped-back model, it says that plant diversity peaks in grasslands of intermediate (medium) productivity, while high- and low-productivity grasslands tend to have fewer plant species.
"Working with an unusually large network of data we were able to see that pattern," said Carlyle, an assistant professor in AFNS who, along with Bork, took samples at the Faculty of ALES' Mattheis Research Ranch, 175 km east of Calgary.
"In addition to finding the pattern itself, we were also able to conclude that the pattern held across a wide range of spatial scales (i.e. individual observational or sampling sizes) within these grasslands."
The data set also included samples from the ALES' Roy Berg Kinsella Research Ranch in central Alberta, collected by JF Cahill from the Faculty of Science at the University of Alberta. All told, the landmark study involved 62 scientists from 19 countries and six continents, who examined 30 sites. The findings refute a four-year-old paper by Peter Adler of Utah State University, which concluded that empirical patterns between biodiversity and productivity are weak and inconsistent.
"It's important to come to a consensus on the pattern because it changes how we might look at, interpret and manage, low-, moderate- and high-productivity sites, particularly if the conservation of plant diversity is an important objective," said Bork, who is the Mattheis Chair in Rangeland Ecology and Management.
For instance, under the humped-back model, conservation of overall plant diversity may be more dependent on strategically retaining and enhancing grasslands of intermediate productivity. Meanwhile the conservation of biodiversity in high- and low-productivity sites may focus particular attention on a smaller group of plant species to ensure their functional role in the ecosystem is maintained.
Many other management decisions on grasslands are also dependent on knowing whether there's a vital relationship between biomass and biodiversity, said Bork.
"We can all agree that biomass is pretty darn important," he said. "That's what we feed to livestock, use to provide cover for songbirds, to prevent soil erosion, and to provide carbon capture. If there was universal agreement that there wasn't a relationship between plant diversity and biomass, and if biomass is what we inherently focused on, then what incentive exists for society to care about biodiversity, much less manage it?"
Yet that line of thought could be harmful overall, he said, since other studies show more diverse communities are more resistant to environmental change and associated economic risk. Biodiversity creates stability. Knowing what fundamental level of diversity we are managing for at a given location, environment and expected level of productivity, sets the baseline for grassland managers.
The study acknowledges that other disturbances, such as cattle grazing, fire and drought, are also important drivers of grassland diversity. However, some of those can be manipulated by management, for example through grazing intensity or fire suppression, said Bork.
"But if we don't know what the inherent pattern is to begin with, then how do we manage our own disturbances for the betterment of diversity, and vice-versa?"
Despite the study's large volume of data - made even more powerful because it comes from both highly concentrated data within local sites and from many different environments globally - Bork still expects some resistance to its findings.
However, the study's authors believe that Adler et al.'s conclusions might have been skewed because their data used a shorter range of total biomass values among sites, did not explore a wide range of observation sizes within grasslands, and also did not include plant litter, which is known to be a strong determinant of production in grasslands.
For their part, Bork and Carlyle are intrigued by other questions prompted by the data. They are already looking at the relationship of grazing and biodiversity, and are interested in how much of the overall plant diversity in Alberta's grasslands is comprised of introduced species as opposed to native species.
The study, Worldwide Evidence of a Unimodal Relationship Between Productivity and Plant Species Richness, was led by Lauch Fraser at Thompson Rivers University in Kamloops, B.C. and was published in the prestigious peer-reviewed journal, Science.
So you can bet it's satisfying to ALES rangeland ecology researchers Edward Bork and Cameron Carlyle that their painstaking work has now helped clarify a very long, global debate.
Working with a large network of scientists worldwide, who studied grasslands of every type in all climate zones, they helped reaffirm a theory of diversity that had been under attack. Known as the humped-back model, it says that plant diversity peaks in grasslands of intermediate (medium) productivity, while high- and low-productivity grasslands tend to have fewer plant species.
"Working with an unusually large network of data we were able to see that pattern," said Carlyle, an assistant professor in AFNS who, along with Bork, took samples at the Faculty of ALES' Mattheis Research Ranch, 175 km east of Calgary.
"In addition to finding the pattern itself, we were also able to conclude that the pattern held across a wide range of spatial scales (i.e. individual observational or sampling sizes) within these grasslands."
The data set also included samples from the ALES' Roy Berg Kinsella Research Ranch in central Alberta, collected by JF Cahill from the Faculty of Science at the University of Alberta. All told, the landmark study involved 62 scientists from 19 countries and six continents, who examined 30 sites. The findings refute a four-year-old paper by Peter Adler of Utah State University, which concluded that empirical patterns between biodiversity and productivity are weak and inconsistent.
"It's important to come to a consensus on the pattern because it changes how we might look at, interpret and manage, low-, moderate- and high-productivity sites, particularly if the conservation of plant diversity is an important objective," said Bork, who is the Mattheis Chair in Rangeland Ecology and Management.
For instance, under the humped-back model, conservation of overall plant diversity may be more dependent on strategically retaining and enhancing grasslands of intermediate productivity. Meanwhile the conservation of biodiversity in high- and low-productivity sites may focus particular attention on a smaller group of plant species to ensure their functional role in the ecosystem is maintained.
Many other management decisions on grasslands are also dependent on knowing whether there's a vital relationship between biomass and biodiversity, said Bork.
"We can all agree that biomass is pretty darn important," he said. "That's what we feed to livestock, use to provide cover for songbirds, to prevent soil erosion, and to provide carbon capture. If there was universal agreement that there wasn't a relationship between plant diversity and biomass, and if biomass is what we inherently focused on, then what incentive exists for society to care about biodiversity, much less manage it?"
Yet that line of thought could be harmful overall, he said, since other studies show more diverse communities are more resistant to environmental change and associated economic risk. Biodiversity creates stability. Knowing what fundamental level of diversity we are managing for at a given location, environment and expected level of productivity, sets the baseline for grassland managers.
The study acknowledges that other disturbances, such as cattle grazing, fire and drought, are also important drivers of grassland diversity. However, some of those can be manipulated by management, for example through grazing intensity or fire suppression, said Bork.
"But if we don't know what the inherent pattern is to begin with, then how do we manage our own disturbances for the betterment of diversity, and vice-versa?"
Despite the study's large volume of data - made even more powerful because it comes from both highly concentrated data within local sites and from many different environments globally - Bork still expects some resistance to its findings.
However, the study's authors believe that Adler et al.'s conclusions might have been skewed because their data used a shorter range of total biomass values among sites, did not explore a wide range of observation sizes within grasslands, and also did not include plant litter, which is known to be a strong determinant of production in grasslands.
For their part, Bork and Carlyle are intrigued by other questions prompted by the data. They are already looking at the relationship of grazing and biodiversity, and are interested in how much of the overall plant diversity in Alberta's grasslands is comprised of introduced species as opposed to native species.
The study, Worldwide Evidence of a Unimodal Relationship Between Productivity and Plant Species Richness, was led by Lauch Fraser at Thompson Rivers University in Kamloops, B.C. and was published in the prestigious peer-reviewed journal, Science.