Future Forests:
Understanding the effect of tree diversity in planted forests under a rapidly changing climate
About
Increasing tree diversity in planted forests can enhance ecosystem services such as wood production, soil carbon sequestration, and biodiversity value. Ireland is currently missing its decarbonisation targets and ambitious afforestation plans form a major part of Irelands climate mitigation strategy. Diversification of Irish forests is also a key component of national forest policy. However, we know little about how tree diversity-ecosystem function relationships will materialize under a changing climate.
Understanding interactions between tree mixtures and climate change will aid the design of climate-smart forests. Using a novel design that utilizes open-source micro-controller technologies, Future Forests is initiating the first field-based experiment to examine how tree monocultures and mixtures will respond to elevated atmospheric carbon dioxide and warming. This experiment will provide a platform for testing mechanisms controlling responses of tree monocultures and mixtures to climate change. Future Forests will combine field-based, environmental growth chamber, and modelling approaches that explore diversity-mediated responses of trees to elevated carbon dioxide, warming and drought. Future Forests is funded by Science Foundation Ireland.
Project Partners and Collaborators
Project team
Dr John Devaney, Maynooth University (Principal Investigator)
Dr Wenguang Tang, Postdoctoral Researcher, Maynooth University
Timothy Coffey, PhD candidate
Ryan Murphy, Research Assistant
Project collaborators
Dr Grace Cott, University College Dublin
Professor Jennifer McElwain, Trinity College Dublin
Dr Roy Rich, Smithsonian Institution
Dr Masumi Hisano, Hiroshima University
Research Tasks
Task 1:
Establish field-based multi-factor global change experiment
To test tree seedlings responses to climate variables under field conditions, our collaborators have developed a novel, low-cost CO2 and temperature control and monitoring system that utilizes open-source micro-controller technologies. We will apply this design to elevated CO2 and warming experiments using open-top chambers in the field. Twelve 3m x 3m chambers will be constructed with transparent vertical sidewalls and a frustum with an opening at the top to allow for air exchange. Unlike most warming experiments, we will actively control both aboveground and belowground temperature using in infrared heating lamps and soil warming cables.
Twelve open-top chambers for assessing tree seedling responses to climate change at the Maynooth University Sustainable Ecosystems Research Station.
Aerial view of our recently constructed open-top chambers for assessing tree seedling responses to climate change.
Task 2:
Aboveground and belowground responses of tree monocultures and mixtures to future climate
We have planted seedlings of alder Alnus glutinosa, birch Betula pubescens, and oak Quercus robur (n = 1500). Native broadleaf species were selected for their importance in natural and planted woodlands in Ireland, and their contrasting aboveground and belowground traits (e.g. shade tolerance, successional chronology, root morphology, mycorrhizal associations). Seedlings are planted in monoculture and mixture subplots in the open-top chambers.
Over three growing seasons, we will assess aboveground physiological, morphological, and phenological responses in monoculture and mixture subplots. Physiological measurements will include leaf gas analysis, chlorophyll fluorescence, biomass, and Carbon/Nitrogen analysis. Belowground measurements will include measuring fine root productivity and soil nutrient status.
Ultimately, by examining how species respond to elevated CO2 and temperature in both monocultures and mixtures, we aim to inform forest establishment and management under a rapidly changing climate.
Seedlings planted in open-top chambers at the Maynooth University Sustainable Ecosystems Research Station.
Project researchers Tim Coffey (left) and Dr Wenguang Tang (right) at open-top chamber with 100 seedlings of oak, alder, and birch.
Task 3:
Role of tree diversity in mediating drought effects in forests under elevated CO2 and warming
We are utilising state-of-the-art growth chamber facilities at Maynooth University and the Variable Light and Atmospheres (VAL) Lab at Trinity College Dublin to assess tree seedling responses to water availability under elevated CO2 and warming. The work involves three related experiments carried out by Future Forests PhD student Tim Coffey. This year, we are assessing the impact of warming on monocultures and mixtures of oak, alder, and birch. Bare-rooted ~50cm seedlings are grown for 6 months in fully replicated mesocosms temperature-controlled growth chambers at Maynooth University, with temperature set to either control (monthly average temperature for the 1981-2000 reference period) or control +3 °C. Responses to warming and diversity will be measured using a combination of gas analysis, chlorophyll fluorescence, plant water potential (Ψ), root architecture and biomass.
Using a similar design and measurements to experiment 1, in year 2, physiological responses of trees to rainfall variability under control and elevated temperature treatments will be tested. In year 3, we will grow tree seedlings in monoculture and mixture mesocosms in well-watered or drought treatments under a year 2100 climate change scenario using the SFI funded VAL Lab at Trinity College Dublin.
Seedlings of oak, alder, and birch growing in environmental growth chambers at Maynooth University.
Task 4:
From planted saplings to mature trees - exploring tree diversity effects under a changing climate in established forests
To aid the creation of new, climate-smart forests, the focus of this project is on determining how tree diversity impacts the establishment and growth of young forests under future climate scenarios. However, an additional key question is the extent to which tree diversity impact mature forests over longer timescales. One approach to address this question is analyse long-term forest inventory data that tracks tree diversity, mortality and growth in permanent sample plots over timescales that capture ongoing environmental change (e.g. elevated CO2, temperature, and drought). We hope to use inventory data from European temperate forests to assess the relationship between diversity, growth, and mortality of trees under the changing atmospheric CO2 concentrations, temperatures, and precipitation levels of the past 40 years.