2024 HARPER PRIZE SHORTLIST: For the next two weeks, we are featuring the articles shortlisted for the 2024 Harper Prize. The Harper Prize is an annual award for the best early career research paper published in Journal of Ecology. Lena Sachsenmaier’s ‘Forest growth resistance and resilience to the 2018–2020 drought depend on tree diversity and mycorrhizal type’ is one of those shortlisted for the award.
About the paper:
- What is your shortlisted paper about, and what are you seeking to answer with your research?
Our research explores whether mixing tree species enhances forest resistance and resilience to extreme drought, considering the role of mycorrhizal associations—mutualistic relationships between trees and fungi. Tree species typically associate predominantly with one of two main mycorrhizal types: arbuscular mycorrhiza (AM) or ectomycorrhiza (EM), which differ in their morphology, physiology, and their water and nutrient uptake processes. We analysed tree growth data from a young tree diversity experiment in Germany (MyDiv) to assess how different tree communities — varying in species richness and in mycorrhizal types of the tree species — responded to the severe 2018–2020 drought. While species richness alone did not improve drought resistance and resilience, only mixtures containing both AM- and EM-associated tree species outperformed their respective monocultures during and after drought. This underscores the potential importance of mycorrhizal type diversity in shaping forest responses to climate extremes.
- Were you surprised by anything when working on it? Did you have any challenges to overcome?
One of the things that surprised me the most was learning how little we actually know about mycorrhizal associations in drought. I was new to the field at the time and naively thought it was an established area with only a few specific research gaps. But very few studies, for example, have directly compared the two so different mycorrhizal types AM and EM in terms of functional differences. How the whole symbiosis performs under drought, how much the water transport via fungal hyphae accounts for, or the extent to which mycorrhizal type plasticity allows trees to adjust to drought are all exciting and open questions that need to be answered.
Perhaps challenging was the growth dataset of over 5,000 trees in 7 different years. As it was my first time working with such a large inventory dataset, it took me quite a long time to find, analyse, and correct all the inconsistencies before I could start the actual analysis.
- What is the next step in this field going to be?
To better predict tree vulnerability to climate extremes, evidence is needed across several key areas. First, a detailed investigation at the tree neighbourhood level is essential, as this is where interactions between trees take place. Most studies so far concentrated on the tree community level, including our shortlisted paper. Second, comprehensive data on the hydro-functional traits of individual tree species are crucial for understanding their physiological strategies. Third, it is equally important to consider the below-ground perspective, enabling us to grasp how the mycorrhizal symbiosis responds to soil water scarcity.
- What are the broader impacts or implications of your research for policy or practice?
Our results highlight the potential of mixtures comprising tree species with different mycorrhizal types for effective forest restoration strategies, particularly in the face of an increasing frequency of extreme drought events such as the 2018–2020 drought.
About the author:
- How did you get involved in ecology?
As a child, I had a tree house in an old plum tree behind the house and could spend hours climbing, watching insects, and simply enjoying ‘my’ tree. During my teenage years, I became deeply concerned about the deforestation of the Amazon rainforest and organized campaigns to raise awareness about its consequences. Throughout this time, and to this day, the forest has been the best place for me to clear my mind and find peace. I wanted to learn more about this place and other ecosystems, about the impacts of climate change, the loss of biodiversity, and the links to society and our actions —so I decided to study biology and geography. During my master’s thesis in Sumatra (Indonesia), I finally became captivated by ecological research. Whilst I first became a school teacher and spent two wonderful years teaching young inquisitive minds, my curiosity for science never faded. Finally, I found the courage to pursue my passion and applied for a PhD in forest ecology.
- What is your current position?
Currently, I am still a PhD student in the working group Systematic Botany and Functional Biodiversity of Leipzig University in Germany, closely connected to the German Centre for Integrative Biodiversity Research Halle-Leipzig-Jena (iDiv) in Leipzig and part of the International Research Training Group TreeDì, focussing on Tree Diversity Interactions.
- Have you continued the research your paper is about?
I continued researching tree diversity’s potential to mitigate drought effects, focusing on a functional approach. We assume that a tree’s water-use strategies are crucial for its growth during extreme drought. In the same experimental setting, we, therefore, measured various water-related traits of leaves and branches to explore whether hydro-functional dissimilarity to the surrounding tree neighborhood can enhance growth during drought.
- What one piece of advice would you give to someone in your field?
Even though much of today’s research happens in front of a computer, I believe that staying connected to our research objects is crucial. Spending time in the forest helps me think more deeply about trees’ complex ecology. My advice is to get out into nature because it’s the best way to truly understand and appreciate the systems we study.
Find the other early career researchers and their articles that have been shortlisted for the 2024 Harper Prize here!
