Jiri Dolezal, researcher at the Institute of Botany of Czech Academy of Sciences, presents his latest manuscript ‘Contrasting biomass allocation responses across ontogeny and stress gradients reveal plant adaptations to drought and cold’, discusses how plants manage to survive 80 years and highlights the importance of moving beyond scientific dogmas.
About the paper
What’s your paper about?
The story is about how the highest occurring plants on this planet have adapted to survive extreme environmental conditions. Vascular plants inhabiting elevations between 5500 and 6000 m in High Himalayas have to cope with cold air, high UV radiation, strong winds, lack of nutrients and water. The way they cope with these multiple stresses is likely to change during their ontogenesis. Young plants must first be rooted in an unstable substrate and monopolize locally available soil nutrients and water, as well as producing enough carbohydrates through leaves for growth, respiration and storage before investing in stems and reproductive organs. Adult plants, on the other hand, may invest mainly into massive belowground stems (rootstock) to protect the meristems against recurrent frost. However, how plants adjust their allocation priorities depending on size and age across stress gradients remain largely unknown in wild populations. Therefore, we focused on small alpine plants living at the highest elevations on earth to better understand how they adapted to live up to 80 years.
What is the background behind your paper?
Uneven allocation of resources to different structures and functions within plants is an essential aspect of plant adaptations and responses to changing environment. As such, plant biomass allocation has attracted the interest of numerous ecologists and evolutionary biologists. Our current knowledge about plant is either derived from: (1) comparative interspecific studies providing a general perspective of size-independent variation in plant biomass; (2) field studies comparing plant biomass allocation in different species or populations from contrasting habitats, primarily focusing on mineral nutrition and light; or (3) precise intraspecific studies on plants cultivated under controlled conditions with a more specific focus on different sources of plasticity in allocation patterns (e.g. environmental or ontogenetic plasticity). Despite their respective strength, the first approach usually neglects intraspecific sources of variation in natural populations, the second approach often lacks information about plant age, and the third is often difficult to extrapolate to field situations. Given the important evolutionary and ecological implications of biomass allocation in plants, integrating this disparate information within wild populations in the field would contribute to deepen our understanding of species adaptations and their distributions.
How did you come up with the idea for it?
The idea came during the preparation of our book “Anatomy, age and ecology of high-mountain plants in Ladakh, the Western Himalaya” (Doležal et al. 2018). We discovered that many alpine plants in High Himalayas are truly long-lived and their successful age dating opened new avenues for ecological research on their adaptations including ontogenetic changes in biomass allocations.
What are the key messages of your article?
Our study showed that multiple causes of size differences, such as age and environment, interact to produce a complex and population-specific outcome on biomass fractions and allometric relationships. Our results illustrate that these allometric scaling relationships found within a species are not constant. The uneven allocation of resources to different structures and functions during ontogenesis and across species elevation range reflects plant adaptations to different levels of low-temperature and water stress. Omitting these sources of variation and their interplay could lead to erroneous conclusions about the limiting constraints the environment exerts on plant growth and evolution.
How is your paper new or different from other work in this area?
Our contribution is new by explicitly testing the role of size and age and their interactions on how plants invest their resources in competing structures (roots vs stems vs leaves) with different basic functions (water absorption, assimilation, mechanical stability, etc.). In fact, most allocation studies lack plant age information and, therefore, changes in mass fractions are usually related to plant size instead. However, individuals of the same size may vary greatly in age, and certain plant allocation patterns may be age-related and not size-related (e.g. onset of reproduction). Plant age information is also important in detecting environmental impacts on biomass allocation strategies, such as at what age plants exposed to drought invest more in roots and less in stems or leaves. Age determination has long been reserved for trees and shrubs, but recent advances in quantitative wood anatomy make it possible to accurately determine the age and growth of most herbaceous dicotyledons (Doležal et al., 2018).
Does this article raise any new research questions?
The role of age, size and environment in allocation priorities across taxa and habitats. New research should test the interactions of these variables. This is the key to understanding how plant adaptations have evolved.
Who should read your paper (people that work in a particular field, policy makers, etc.)?
Anyone interested in understanding the basic mechanisms of plant adaptation to cold and drought.
About the research
What is the broader impact of your paper (outside of your specific species/study system)
Allometric biomass partitioning theory, although debated, could produce a general baseline for plant biomass allocation across taxa. However, our results illustrate that these scaling relationships found within a species are not constant. Instead, our study showed that multiple causes of size differences, such as age and environment, interact to produce a complex and population-specific outcome on biomass fractions and allometric relationships. Understanding the departure from the possibly universal scaling relationship, the residuals around the general trend. Omitting these sources of variation and their interplay could possibly obscure the general rules or could even lead to erroneous conclusions about the limiting constraints the environment exerts on plant growth.
Did you have any problems setting up the experiment/gathering your data?
No, this was a sort of natural experiment thanks to the ability of our target species to occupy contrasting habitats (steppe, alpine, subnival) and live for 80 years.
Where you surprised by anything when working on it?
By the presence of high plant plasticity even in these extreme and conservative conditions
What are the big questions still to answer?
What controls the longevity of a plant, what delays aging, making a plant almost immortal.
What would you like to do next?
Going back to mountains and collect plants to test similar questions.
About The Author
How did you get involved in ecology?
I have had a relationship with nature since I was a child, because I grew up in the countryside and helped my parents with the small farm. I became involved in ecology as a scientific discipline at university through my mentors, namely Jan Leps and Petr Smilauer, and in the late 1990s I underwent rigorous training as a doctoral student in Japan with my mentor Toshihiko Hara. I am especially grateful to the late Fritz Schweingruber for teaching me plant anatomy.
What are you currently working on?
I am currently studying anatomical, physiological and morphological adaptations of high mountain plants to better understand how they cope with cold and drought. We are currently focusing on plants from High Himalayas, but also tropical alpine plants from Africa or desert plants from drylands such as Gobi in Mongolia or Sonora and Mohave in USA. We want to find out what makes some herbaceous plants living for decades in cold or dry environment, why they are senescing slowly and what kind of cellular processes are behind high longevity.
What’s your current position?
I am a head of the Department of Functional Ecology at the Institute of Botany, Czech Academy of Sciences.
What project or article are you most proud of?
I think I am most proud of my 12 years of research in the Himalayas, where I spent 1-2 months with colleagues and students every summer. I learned a lot from them and I hope I also gave them something.
What is the best thing about being an ecologist?
Ecology is a demanding scientific discipline because it needs knowledge from various scientific disciplines, such as taxonomy, soil science, chemistry, climatology, or biostatistics.
Knowledge of these disciplines is essential to understanding how nature works. In addition, because nature is extremely rich, learning about nature and the ecological principles that shape it will never stop entertaining you.
What is the worst thing about being an ecologist?
The best thing about ecology is the opportunity to get to know the secrets of nature, and this is also very often a source of great frustration, because the discovery of the unknown takes time, focusing on the synthesis of various pieces of evidence. It can be a detective work and may not always lead to success, which can be a source of disappointment and frustration.
What do you do in your spare time?
Nothing special, I cook for my three children, I repair the house, I play some sports (I ski in winter, football and bike in summer), and I love mushroom picking at the beginning of autumn.
One piece of advice for someone in your field…
Find your own path and rebel a little against ‘scientific dogmas’. To progress the field of ecology, do no stay in your comfort zone, but expose yourself to new, unknown and bit hostile conditions.
Bibliography
Doležal, J., Dvorský, M., Börner, A., Wild, J., & Schweingruber, F. H. (2018). Anatomy, age and ecology of high mountain plants in Ladakh, the Western Himalaya. Springer.
Functional Ecologists 