Finding answers in the forest
Over 1000 km wide, the Canadian boreal forest exists as a massive tract, one that spans a distance reaching from Newfoundland and Labrador all the way to the far northern Yukon. It is described as the lifeblood for economies, the heartbeat of Aboriginal peoples and the lungs of the Earth; and from all these perspectives, the realities of climate change threaten its viability. Dr. Sue Ziegler’s work in the boreal forest of Newfoundland and Labrador is analyzing how a changing climate will affect the forest itself, and seeks insight into the greater implications of an altered ecosystem.
An associate professor in the Department of Earth Sciences at Memorial University and the current Canada Research Chair in Environmental Science, Dr. Ziegler’s research has a variety of applications. One aspect of her work looks at how specific features of the boreal ecosystem are affected by a change in temperature. By comparing zones of varying temperatures across the province’s boreal forest, her goal is to help forecast the future effects of climate change.
The Newfoundland and Labrador Boreal Ecosystem Latitudinal Transect (NL-BELT), part of the Canadian Forest Service’s National Network of Latitudinal Transects, was established a little over two years ago as a group of four study sites in western Newfoundland and southern Labrador. All are located within major river hydrologic regions and are situated along a vertical line running north to south. The most northerly site is in the region of the Eagle River near Cartwright, followed by Salmon River near Main Brook, Humber River and then the Grand Codroy as the most southerly location.
The NL-BELT links forest ecosystems that are similar in as many ways as possible in terms of species, age of trees, soil types, and slope aspect. The locations differ significantly in latitude and therefore climate, which is demonstrated by a range of more than 5 degrees [Celsius] in mean annual temperature among the research sites. Information about temperature, moisture and other weather related data is continuously monitored and compared across the BELT by Dr. Ziegler and her colleagues. Conditions in the warmer southern sites provide indicators that will help predict how climate change will affect those areas located further north.
“We’re hoping to discover indicators relevant to climate variation by looking across the transect for differences,” said Dr. Ziegler. “It’s risky because it’s big in scale, but we’re constraining it by combining what we do across the transect with experimentation in the lab.” By combining the two, she hopes to identify chemical indicators based on the lab work that can be used to make predictions, and then see if those hypotheses are confirmed in the field and over time.
Within this province, Dr. Ziegler is partnered with the Centre for Forestry Science and Innovation (CFSI) within the Department of Natural Resources and the Canadian Forest Service (CFS), to set up infrastructure at each location as well as co- ordinate with community groups and individuals who can help maintain the sites and collect samples. Dr. Ziegler and her group, including Memorial PhD candidate Jennifer Bonnell, M.Sc.’02, research assistant Jamie Warren and Dr. Jérôme Laganière, a post-doctoral researcher, are directly collaborating with researchers from the CFS Atlantic Forestry Centre in Corner Brook, CFSI, University of Kansas, and the University of South Carolina. These partnerships and collaborations are driving this recently funded, large scale Natural Sciences and Engineering Research Council (NSERC) project.
But the scope of this project doesn’t end with these partnerships. Summer students, full-time employees, volunteers, and partners in the provincial Forestry Service at offices situated in NL-BELT communities are involved as well. Trained to assist in data collection and sampling, these individuals will also advise on any changes that may occur in the study areas, monitoring data loggers and other equipment that have been permanently established on the sites.
“The participation of people from the surrounding communities is very important. People living in the area can be aware of what we are doing and can participate as stewards of that area,” explained Dr. Ziegler. “There’s a real ownership to their involvement and they are extremely helpful in providing these services. We can’t be there all the time, and they have important insight gained from living in these regions.”
As part of her comparative analysis of data from across the NL-BELT, Dr. Ziegler is looking at the enormous reservoirs of carbon stored in boreal forest soils. Given that the four study sites are all located within major river hydrologic regions, another goal of the project is to improve our understanding of what happens to soil carbon in boreal forest ecosystems by linking the aquatic and terrestrial systems.
“Boreal reservoirs of carbon stored in peat and forest soils are enormous,” explains Dr. Ziegler. “When this organic carbon is converted to C02 by microbes in the soil and is released into the atmosphere, it ultimately plays a role in climate change. A potential for positive feedback exists where the C02 is released into the atmosphere and this greenhouse gas causes warming, which in turn causes microbes to convert more of the stored carbon to C02. So the real question here is whether there is evidence for such positive feedback and how it may or may not persist with climate warming.”
To answer these questions, Dr. Ziegler must determine what regulates the formation of carbon in the forest soils, and how it responds to climate warming. When those carbon reservoirs are extrapolated on a global scale, it becomes clear that these questions are very important to those studying and modeling climate change.
“One of the challenges we have in understanding this process lies in the fact that we can’t just go out and measure soil carbon and say it’s this amount now, and 10 years later re- measure and find out if it has been reduced”, she said. “The problem is that we are attempting to quantify a small change in a huge and varied expansive pool or reservoir, but given the large size of this pool, such a small change is very important but elusive.”
To address that challenge, Dr. Ziegler is taking samples from the aquatic systems draining from the land. Due to the homogeneous nature of the dissolved material in water, testing aquatic systems for the relevant chemical indicators is likely far more effective than punching out and testing samples of soil across the landscape. The latter approach typically yields many variable results even within a small area of the forest.
This work is ongoing, and Dr. Ziegler continues to actively address questions about how to identify reliable indicators of carbon formation and release in forest soils.
“One of the very long-term goals of this work is to discover what regulates the chemical composition of organic matter in streams,” she said. “Does the chemical information carried by water from soil upstream also carry signatures of environmental change that has occurred in the landscape? If we can reliably predict changes in soil through key chemical signatures, developing relationships between soil within the catchment areas with those in the associated streams will be the next key step. By developing such relationships, we may be able to monitor those very important yet elusive changes in the landscape relevant to climate and other aspects of environmental change.”