Tsipe Aavik: The role of interactions must not be ignored during ecological restoration

In this post, assistant professor Tsipe Aavik from University of Tartu presents her collaborative perspective paper ‘The joint effect of host plant genetic diversity and arbuscular mycorrhizal fungal communities on restoration success’. She discusses the importance of looking at invisible components of biodiversity to improve restoration, the necessity of doing collaborative studies and her proud on transmitting science to general public.   

About the paper

Figure: Me and my daughter on one of our little hikes with family. The photo has been taken a while ago because now I very rarely happen to be in front of the camera, but am mostly the one behind the camera taking the photos of the moments in our life.
Me and my daughter on one of our little hikes with family. The photo has been taken a while ago because now I very rarely happen to be in front of the camera, but am mostly the one behind the camera taking the photos of the moments in our life.
  • What’s your paper about?

In our conceptual paper, we explore whether jointly addressing two invisible, yet very important components of biodiversity – plant population genetic diversity and the diversity of arbuscular mycorrhizal fungi hosting them – could have a potential to enhance restoration success.

  • What is the background behind your paper?

The authors of the paper can be divided roughly into two based on our ‘pet’ research objects. Some of us have focussed on exploring the patterns of arbuscular mycorrhizal fungi (AM fungi), whose role despite their microscopic size in determining the well-being of plants can be immense. The other folks have looked at another invisible but fundamental component of biodiversity, i.e., genetic diversity of plants. Implementing our scientific knowledge for improving restoration and conservation is important for all of us.

Surprisingly, although the significance of both aspects, i.e., mycorrhizal fungi and plant genetic diversity, in restoration has been recognized for a while already, there is practically no understanding whether addressing and maximising these two components simultaneously can have additional benefits for restoration. Besides, there is little knowledge about the role of host plant genotypes in determining the course and benefits of interactions with mycorrhizal fungi. Thus, we decided to join the forces and explore these questions further.

  • How did you come up with the idea for it?

The idea emerged while drafting the proposal for a joint project within the frames of a CELSA network, which facilitates collaboration among a group of European universities. Within the frames of this collaborative project, we as the ecologists from two universities aimed to combine our knowledge and experience, and make a qualitative leap in restoration theory forward. Three research groups involved in this study: Landscape Biodiversity Group and Plant Ecology Group from the University of Tartu (Estonia), and Plant Conservation and Population Biology Research Group from the Catholic University of Leuven (Belgium).

The ideas reflected in our paper have been in the air for a while already. Indeed, we are not the first ones to suggest exploring the effects of the genetic diversity of cooperating partners (in our case it was host plants and mycorrhizal fungi) on the outcome of interactions, although, to the best of our knowledge, looking at these aspects in the context of restoration has not been done before. An increasing application and lowering costs of molecular tools has made testing related hypotheses more feasible. Also, being on the doorstep of the United Nations Decade of Restoration, which would highly benefit from solid ecological understanding of interaction networks, we found that the time is indeed ripe for taking further steps in this field.   

Figure: More than 75 % of terrestrial plants associate with arbuscular mycorrhizal fungi (AM fungi). These little microorganisms provide multiple benefits for their host plants, such as improving plant nutrition, and providing resistance to abiotic stress and pathogens. Therefore, the role of AM fungi cannot be ignored during restoration. The photo depicts a plant root with AM fungal vesicles (Photo author: Tanel Vahter).
More than 75 % of terrestrial plants associate with arbuscular mycorrhizal fungi (AM fungi). These little microorganisms provide multiple benefits for their host plants, such as improving plant nutrition, and providing resistance to abiotic stress and pathogens. Therefore, the role of AM fungi cannot be ignored during restoration. The photo depicts a plant root with AM fungal vesicles (Photo: Tanel Vahter).
  • What are the key messages of your article? Who should read your paper (people that work in a particular field, policy makers, etc.)?

The core message of our paper for restoration practitioners is that the invisible components of biodiversity can be very important in determining the outcome of restoration actions. First, we stress that maintaining and achieving the genetic diversity within plant species is comparable to an insurance policy, which helps restored plant populations to cope with environmental change. Second, we emphasize the role of mycorrhizal fungi, which can often be the key players in determining restoration success through forming mutually beneficial relationships with vascular plants to be restored. Third, we discuss whether maximising these two components simultaneously would have a potential to increase restoration success even further.

The core message to the research community is that our understanding of the causes and consequences and context-dependence of plant-fungal interactions are still very limited. However, numerous restoration initiatives underway offer good opportunities for shedding light on these gaps in knowledge.

  • How is your paper new or different from other work in this area? Does this article raise any new research questions?

Although in restoration theory, the role of both, i.e., genetic diversity and mycorrhizal fungi, has been acknowledged before, the joint effects of these components have not been tested previously, at least not in wild species (first steps have been taken with cultivated species, though). Yet, community genetic studies (mind, there are still only a few of these, and even less about plants and AM fungi!) have suggested that the genotype of a host plant can determine the diversity and community composition of species interacting with the plant with downstream effects on the functioning of the interaction network.

Figure: United Nations Decade of Restoration will bring along many restoration projects on thousands of hectares. We, researchers, can use restoration frameworks as large-scale experimental set-ups for filling some gaps in fundamental knowledge. The photo has been taken on an alvar grassland in Estonia. Thousands of hectares of alvar grasslands were restored in a large-scale LIFE EU project 'LIFE to Alvars', which serves as a good example of collaboration between researchers and practitioners (Photo author: Mart Meriste).   
United Nations Decade of Restoration will bring along many restoration projects on thousands of hectares. We, researchers, can use restoration frameworks as large-scale experimental set-ups for filling some gaps in fundamental knowledge. The photo has been taken on an alvar grassland in Estonia. Thousands of hectares of alvar grasslands were restored in a large-scale LIFE EU project ‘LIFE to Alvars’, which serves as a good example of collaboration between researchers and practitioners (Photo: Mart Meriste).   

Such gaps in knowledge can also strongly undermine the success of ecological restoration. Furthermore, they relate to several other unanswered questions in restoration theory, such as the consequences of an increasing use of commercially propagated seeds in restoration. For example, we do not have a good overview how commercial seed multiplication affects genetic variation in seeds used for restoration nor do we know how the genotypes coming from seed company gardens would affect biological interactions of plants with soil microbes, pollinators and other organism groups in the wild.

We have just stepped into the United Nation Decade of Restoration. This means that numerous restoration initiatives are going to take place in the forthcoming years. The paper emphasizes that we should make use of these multitude of projects to learn more about the nature of biological interactions, and their dependence on within-species diversity (i.e., genetic diversity) of interacting partners and environmental context.

About the research

  • What is the broader impact of your paper?

The idea for composing such a manuscript was rooted from authors’ motivation to contribute to the success of conservation activities with our scientific knowledge. The reader can see that in our paper, we deal with various issues related to conservation and restoration, such as the problems of using commercially propagated seeds in restoration, consideration of local adaptation etc. Thus, we believe that our paper certainly has broader relevance for conservation and restoration biology.

In the paper, we focus on exploring the relationships between genetic diversity of host plants and AM fungi, and the context-dependence of these interactions. However, the proposed framework of landscape community genomics can also be applied for studying interactions between other organism groups, for example, plants and other soil microbes, or plants and pollinators.  

  • Why is it important? What does your work contribute to the field? What are the big questions still to answer?

We have rather good knowledge about the patterns of vascular plants across different scales. Thanks to the advances of molecular techniques, our understanding of the diversity of invisible microbial dwellers in the soil world, such as mycorrhizal fungi, has tremendously increased. By now, we also know that these tiny organisms may play vast role in plants’ lives from enhancing plant nutrition to preventing them from the harmful effects of abiotic stress and pathogens.

However, numerous questions have yet no clear answer. Does it matter for plant fitness how many different taxa of mycorrhizal fungi are interacting with the plant? What is the role of environment (e.g., nutrient-poor vs nutrient-rich soil)? Why are some plant species obligately mycorrhizal, while others seem to manage also without mycorrhizal partners? Are specific plants and fungi co-adapted to living together? If so, how can we take it into account in restoration? What is the effect of commercial seed multiplication on biotic interactions? Our team of authors hope that the paper helps to bring out those gaps, which are particularly relevant in the context of restoration, and offers a framework for shedding more light to these questions.

  • What is the next step in this field going to be? What would you like to do next?

By now, it is clear that for the preservation of biodiversity and related ecosystem services, maintaining interaction networks is absolutely vital. Alarmingly, it has been suggested that many important interactions are disappearing at a greater speed than taxonomic diversity. Thus, restoration needs to move beyond the recovery of species and has to focus on restoring and sustaining interaction networks. Yet, specific practical steps need to be preceded by solid understanding of the importance, characteristics and mechanisms of interactions. Thus, I would like to believe that there will be a qualitative leap towards studies, which will fill the gaps in fundamental knowledge of interactions as well as the emergence of studies demonstrating the best practices for maintaining and restoring these interactions.   

About The Author

  • How did you get involved in ecology?

I grew up in an urban environment. However, as a teenager I happened to spend a couple of weeks in a beautiful Estonian wooded meadow in Viidumäe Nature Reserve. I was amazed by the unique features of this habitat, which unfortunately has become very rare as a result of land use change over the past century. The structural diversity created by different species of trees and bushes scattered here and there reminded me kind of a fairy landscape. Also, the herb layer of these grasslands is unbelievably rich with more than 70 vascular plant species per square meter occurring on some Estonian wooded meadows. The grassland looked like it had been designed by a very skilled landscape architect or a gardener with an amazing taste for structural diversity. Yet, we know that wooded meadows have evolved over centuries as a result of moderate human intervention (mowing and grazing) and we have inherited these unique landscape from our predecessors. I think it was there, in this wooded meadow, when I had the ‘click’ to become a biologist and an ecologist.

Springtime Laelatu wooded meadow Estonia. These beautiful fairy-tale like landscapes, which offer habitats for numerous species (in Laelatu, 76 vascular plant species were recorded on one square meter), have inspired many Estonian ecologists, including the author, Tsipe Aavik (Photo: Tsipe Aavik).
Springtime Laelatu wooded meadow Estonia. These beautiful fairy-tale like landscapes, which offer habitats for numerous species (in Laelatu, 76 vascular plant species were recorded on one square meter), have inspired many Estonian ecologists, including the author, Tsipe Aavik (Photo: Tsipe Aavik).
  • What are you currently working on?

Currently I am working on a landscape genomic project with a focus on a characteristic grassland plant, cowslip (Primula veris). We are interested whether recent grassland loss has influenced patterns of genetic diversity and gene flow in grassland plants, but also aim to understand whether such abrupt habitat changes have caused some shifts in adaptive genetic variation. Interestingly, this project gave start to another much greater initiative, citizen science campaign “Looking for Cowslips”. In spring, the campaign expanded to a pan-European scale and aims to explore the consequences of landscape change on a specific reproductive trait of cowslips, i.e., heterostyly. During the preparation of the manuscript, I got even more inspired by the fascinating world of interactions between plants and other organisms, and besides continuing the mentioned activities hope to start making little steps towards exploring interactions.

  • What’s your current position?

I work as an Assistant Professor of Macroecology in the Department of Botany, University of Tartu, Estonia.

  • What project/article are you most proud of?

It is very difficult to bring out something specific. I see my all projects and papers as important milestones on the road of becoming an ecologist. However, as a researcher who has examined the impact of human activities on biodiversity, I consider science communication and engagement in conservation a very important part of my work and life. Perhaps this is why my most positive work-related emotions come from our citizen science campaign “Looking for Cowslips”. It has been very heart-warming to see numerous people, including many children, exploring cowslip floral morphology, more specifically heterostyly. Besides unexpected scientific findings, we received so much positive feedback from participants and collaborators. All of this gives hope that people are eager to learn more about ecology and this way also contribute to conservation.  

  • What is the best thing about being an ecologist?

Perhaps the greatest thing is the possibility to learn about the functioning of nature – from the background of the broad-scale patterns of biodiversity to the gene-level functioning of organisms. Almost every day I learn something new, something I did not know about before. It is like being on an exciting journey, where every now and then one can choose paths to continue by making decisions about the next research directions to be taken and proposing hypotheses to be tested. And of course, it is even greater when one can contribute with even a tiny bit of new knowledge to this complex set of knowledge about ecological patterns and processes. 

  • What is the worst thing about being an ecologist?

Psychologically, it is challenging to witness, either with one’s own eyes or from a multitude of papers and reports, the worsening status of nature. As much as possible, we as ecologists try to implement our knowledge into practical decision-making. Unfortunately, it is not an easy path as often there are no positive consequences to our attempts.

More of a practical problem, but also psychologically difficult to endure is the lack of stability in the life of a researcher. Ecology is a competitive field and it can be hard to obtain research financing. Our income is 100 % project-based, but it is a challenge to look into future and make longer plans when there is no security about one’s next year’s salary, not to talk about covering the costs of lab consumables and other equipment.

  • What do you do in your spare time?

I have three kids who fill basically all the time that is left from work. Together we bake and cook, wonder in the woods, read books and play, occasionally make a small fire in our garden and prepare sausages instead of a proper evening meal, and try to handle the daily family mess in one way or another. In the evenings when kids are asleep and we still have some mental energy left, I enjoy conversing with my other half on all kinds of topics. Whenever there is a possibility, as a former bookworm, I take time for reading. Every now and then, I go jogging or walking to maintain a healthy mood.

  • One piece of advice for someone in your field…

Despite the difficult moments you may face on your path as an ecologist (and there are many – starting from the anxiety caused by biodiversity loss, lack of permanent position and research funding, rejections to your great ideas and manuscripts etc.), when you may feel like turning back to all of it, try not to give up when science is the thing that can make you excited to the bottom of your heart. At the same time, do not forget keeping good balance between work and the rest of life, enjoy the company of family and friends, and nature. I must admit, that these advices I have to give myself every now and then as well …

Read the research in full here

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