The Journal of Ecology Editors are delighted to announce that Fernando Maestre is our Eminent Ecologist award winner for 2024!
In recognition of his work, we asked Fernando to put together a virtual issue of some of his favourite contributions to the journal. Fernando has also written this blog series, and was interviewed by Richard Bardgett about about how he started his career in ecology, how he uses his work to inform decision making, and the advice he’d give to someone about to embark on a career in ecology. Fernando’s full blog series can be found here: Part 1 | Part 2 👇 | Part 3 (coming soon) | Part 4 (coming soon) | Part 5 (coming soon)
Part II. On biotic interactions and beginning a scientific career
Being a scientist was not something I had in mind as a child. I had no direct scientific or academic references in my family other than my uncle Rafael Maestre, who was an expert on Calderón de la Barca, a key figure in the theatre of the Spanish Golden Age (1590-1681). He inculcated in me the curiosity about teaching as a potential career, the importance of tenacity and hard work to achieve our goals (something that I also learned at home as my father had two jobs and my mom worked too), and the wonderful world of books (his house was virtually a library with a few thousand books that always captivated me). During my early adolescence I wanted to be a medical doctor but when I was 15-16 years old, I started to learn more and worry about environmental degradation and the impact of human activities on our planet. Two books, Earth on Balance from Al Gore and The Silent Death from the Spanish naturalist Joaquín Araujo, had a lasting impact on me at the time. I decided that I wanted to put in my two cents to contributing to solving these problems by making a professional career in the environmental sciences. After carefully listening to what my then girlfriend and now wife told me (“Fernando, if you study Biology how are you going to make a living?”) and to the desires of my father, who would have preferred that I study law or economics so I could continue with the family business, I decided to study Biology. I have to say that I got their full support, despite not being fully convinced at the time that this was a good choice.
My journey as a scientist started early after joining the University of Alicante as a Biology undergraduate. I keep very vivid memories on how much I enjoyed classes such as Zoology, Botany, Plant Physiology, and Ecology. During the second year of my degree I started to collaborate with professors and students in the Department of Ecology (Jordi Cortina, Josep Raventós, and Martín de Luis among others). Despite doing fieldwork in Ulex parviflorus-dominated shrublands which was not nice nor easy, very soon after these first field experiences I decided I wanted to pursue a PhD in Ecology, and I had the opportunity to do so at the University of Alicante thanks to a fellowship awarded from the Ministry of Education of Spain. The study of plant-plant interactions, and of facilitation, was the focus of my PhD research and early days as a scientist (1999-2002). This was not a topic I was very familiar with as an undergraduate (during my university years, the literature and textbooks focused on competition when covering the topic of plant-plant interactions) but was a proposal made by my PhD advisors, Jordi Cortina and Susana Bautista, who suggested that I frame my PhD in the context of exploring the role of these interactions for restoring alpha grass (Stipa tenaccisima) steppes and to diversify Aleppo pine (Pinus halepensis) plantations in semiarid areas of South-Eastern Spain. I eagerly stepped into this topic and started my PhD, which involved planting hundreds of shrub seedlings across multiple years in multiple experiments to explore the effects of S. tenacissima and P. halepensis on shrub seedlings and the mechanisms behind them.
None of my PhD experiments on plant-plant interactions (Maestre et al. 2001, 2002, 2003a, 2003b, 2004; Maestre & Cortina 2004) were published in Journal of Ecology. However, they set the stage for my first paper in the journal and the first of this virtual issue, a meta-analysis aimed at evaluating the degree of empirical support of the stress-gradient hypothesis (SGH) in drylands (Maestre et. Al. 2005). The SGH, put forward by Mark D. Bertness and Ragan M. Callaway in a seminal and very influential article (Bertness & Callaway 1994), was virtually guiding all research on positive plant interactions in the late 1990s. The results of some of my PhD field experiments did not follow SGH predictions (i.e., that facilitation should be more prevalent/important as stress increases) and this motivated me to further investigate to gather the degree of empirical support for this prediction in arid environments. I had to wait until my postdoc at Duke University (2003-2005), which I did thanks to a Fullbright Fellowship from the Spanish Government and the acceptance from my then postdoc supervisor and now long-term friend and collaborator James F. Reynolds. At Duke I had access to a wonderful library and collection of journals not available in Alicante to get the data needed for this meta-analysis. I still remember the awe of entering into the Department of Biology’s library archive and being able to read virtually every journal I could imagine since volume 1, issue 1! The results of this meta-analysis (“None of our meta-analyses indicated that the magnitude of the net effect provided by neighbors, whether positive or negative, was higher under high abiotic stress conditions, and facilitation does not therefore appear to increase in importance with abiotic stress”) were received with great skepticism by some colleagues but with great support by others, who also found that their findings did not fit predictions from the SGH. These findings also led to an exchange in the journal about their validity and interpretation (Lortie & Callaway 2006, Maestre et al. 2006). While digesting some of the criticisms received when the paper was published was difficult at the time, almost 20 years later I look back at this work with affection. It not only was my first paper in the journal, and one that has been very well cited, but most importantly it contributed to generating a much-needed debate and discussion on plant-plant interactions and how they change along environmental gradients. This work also stimulated further research and reviews that have advanced our understanding of this important topic. Plus, it taught me a very important lesson that I have always tried to follow: always be nice to colleagues, particularly to early-career researchers who put lots of illusion on every paper they write and that don´t have the experience to handle fierce criticisms by more senior colleagues.
Disagreements are normal in science, and when conducted in a polite and collegial manner can lead to important advances and unexpected collaborations. A good example of this is the second article of this virtual issue (Maestre et al. 2009). Here we joined forces with Ragan M. Callaway and Christopher Lortie to present an extension of the SGH that provided specific and testable hypotheses that reconcile potential discrepancies among previous studies. Working on this article was a very enjoyable experience. I keep very good memories of all the back-and-forth discussions that led to the final article, which based on the number of citations it has accumulated so far has also been quite influential (it is my most-cited first-author article so far) and has stimulated further research on this important topic. The process leading to this article is also a good example that we can find common ground within disagreements and that moving forward by working and thinking together can lead to great things.
In 2005 I returned to Spain after two wonderful years at Duke thanks to a “Ramón y Cajal” fellowship from the Spanish Ministry of Education and Science. I had the chance then to start my own lab at Rey Juan Carlos University in Móstoles, where I continued to study plant-plant interactions, the mechanisms behind them, and their impacts on ecosystem functioning in dryland environments. This was the focus of the PhD of one of my first students, Santiago Soliveres. Santiago is one of the most creative scientists I ever had the chance to work with. He was never afraid to work on very difficult, complex, and understudied topics, such as species coexistence and intransitive competitive interactions, a topic where he has made very important contributions (e.g., Soliveres & Allan 2018) – the third article of this virtual issue (Soliveres et al. 2015) is a good example of this. In this work Santiago gathered a comprehensive database from drylands and alpine environments to test whether facilitation can enhance coexistence by giving species an advantage when rare. We found that facilitation was stronger for rare than for common species, and strongly decreased with the abundance of the facilitated species even after accounting for the distance of each species from its ecological optimum. I learned a lot from this work, which in my humble opinion constitutes an elegant attempt to introduce facilitation into mainstream ecological theory by linking the known positive effects of facilitation on diversity with modern coexistence theory.
The next article of the virtual issue is one derived from the PhD of Miguel Berdugo (Berdugo et al. 2019), who was co-supervised by Santiago Soliveres, Sonia Kéfi (from CNRS in Montpellier, France), and myself. Here we aimed to disentangle the interplay between species-specific environmental preferences and micro- (facilitation and competition) and macroscale (climatic conditions) determinants of species abundance within dryland plant communities. The results of this study showed that the degree of community specialization to aridity mediates the relative importance of plant–plant interactions in determining species abundances in global drylands. Something that I really appreciate about this article is the elegant combination of approaches followed, which include the use of species distribution modelling, field data from a global survey, and co-occurrence matrices (plus some additional complex statistics) to address complex but very important questions. As one can appreciate by reading it, this article is not your common article written by a PhD student and is a clear testament of the skills and capabilities of Miguel who clearly showed his potential to become a leading scientist from the very beginning of his scientific career.
I will close this first post by making a reflection of the importance and value of mentoring as a two-way interaction, and of the gift that is learning from your students. At the beginning I was worried when smart students like Santiago and Miguel came to discuss questions or the results of methods that I did not fully understand. But very soon I realized that this was not a problem but rather an opportunity. Instead of limiting them to work strictly with the methods and approaches that I was familiar with, I encouraged students to enter unknown territory and to learn new concepts and techniques I was not familiar with if they wished to do so. And when I could not provide the help they needed, I facilitated connecting them with colleagues that could help them to navigate uncharted waters. Doing so has been highly beneficial to me and to all my students and has helped me to shape a key mentoring objective: to help all lab members to fulfil their potential and professional goals, and provide them with the time, the support, and attention they need for doing so. This is not only the right thing to do but something that has allowed me to learn a lot and to substantially enrich and improve my own work, making me a better scientist (and person) along the way.
Fernando T. Maestre, King Abdullah University of Science and Technology.
Literature cited
Berdugo, M., Maestre, F. T., Kéfi, S., Gross, N., Le Bagousse-Pinguet, Y., & Soliveres, S. (2019). Aridity preferences alter the relative importance of abiotic and biotic drivers on plant species abundance in global drylands. Journal of Ecology, 107, 190–202.
Bertness, M. D., & Callaway, R. (1994). Positive interactions in communities. Trends in Ecology & Evolution, 9, 191–193.
Lortie, C. J., & Callaway, R. M. (2006). Re-analysis of meta-analysis: Support for the stress-gradient hypothesis. Journal of Ecology, 94, 7–16.
Maestre, F. T., Bautista, S., & Cortina, J. (2003a). Positive, Negative, and Net Effects in Grass–Shrub Interactions in Mediterranean Semiarid Grasslands. Ecology, 84(12), 3186–3197.
Maestre, F. T., Bautista, S., Cortina, J., & Bellot, J. (2001). Potential for Using Facilitation by Grasses to Establish Shrubs on a Semiarid Degraded Steppe. Ecological Applications, 11, 1641–1655.
Maestre, F. T., Bautista, S., Cortina, J., Dı́az, G., Honrubia, M., & Vallejo, R. (2002). Microsite and mycorrhizal inoculum effects on the establishment of Quercus coccifera in a semi-arid degraded steppe. Ecological Engineering, 19, 289–295.
Maestre, F. T., Callaway, R. M., Valladares, F., & Lortie, C. J. (2009). Refining the stress-gradient hypothesis for competition and facilitation in plant communities. Journal of Ecology, 97, 199–205.
Maestre, F. T., & Cortina, J. (2004). Do positive interactions increase with abiotic stress? A test from a semi-arid steppe. Proceedings of the Royal Society of London. Series B: Biological Sciences (Suppl), 271, S331–S333.
Maestre, F. T., Cortina, J., & Bautista, S. (2004). Mechanisms underlying the interaction between Pinus halepensis and the native late-successional shrub Pistacia lentiscus in a semi-arid plantation. Ecography, 27, 776–786.
Maestre, F. T., Cortina, J., Bautista, S., & Bellot, J. (2003b). Does Pinus halepensis facilitate the establishment of shrubs in Mediterranean semi-arid afforestations? Forest Ecology and Management, 176, 147–160.
Maestre, F. T., Valladares, F., & Reynolds, J. F. (2005). Is the change of plant–plant interactions with abiotic stress predictable? A meta-analysis of field results in arid environments. Journal of Ecology, 93, 748–757.
Maestre, F. T., Valladares, F., & Reynolds, J. F. (2006). The stress-gradient hypothesis does not fit all relationships between plant–plant interactions and abiotic stress: Further insights from arid environments. Journal of Ecology, 94, 17–22.
Soliveres, S., & Allan, E. (2018). Everything you always wanted to know about intransitive competition but were afraid to ask. Journal of Ecology, 106, 807–814.
Soliveres, S., Maestre, F. T., Berdugo, M., & Allan, E. (2015). A missing link between facilitation and plant species coexistence: Nurses benefit generally rare species more than common ones. Journal of Ecology, 103, 1183–1189.