New paper published – Oak gall wasp infections of Quercus robur leaves lead to profound modifications in foliage photosynthetic and volatile emission characteristics

Text by Linda-Liisa Veromann-Jürgenson

Everyone with keen eyes that has been walking in wooded areas in the recent years must have noticed small growths on tree leaves called galls. Sometimes the infections can be massive, where it is hard to find one healthy leaf for a whole tree. This prompted the idea to study the physiological effects of galls on trees as such intense infections must have consequences. Furthermore, we were interested whether and how do plants protect themselves once they have been infected. We started the huge task of collecting data about the penalties of gall infections on tree physiology with oaks. An enormous diversity of gall wasp species can parasitize oak leaves, but the physiological implications of different gall wasp infections are poorly understood. We analysed the effects of infections by four different gall wasp species (Neuroterus anthracinus, N. albipes, Cynips divisa and C. quercusfolii) on foliage photosynthetic characteristics and volatile emission rates in Quercus robur that grow in Tartu Tammik planted by important people that have resided in or visited Tartu. Our work indicated that gall wasp infection resulted in major reductions in foliage photosynthesis rates and elicitation of emissions of green leaf volatiles, mono- and sesquiterpenes and benzenoids in infection severity-dependent manner. Different gall infections resulted in unique emission blends, highlighting a surprisingly selective host volatile response to various gall wasps.

Citation: Jiang, Y., Veromann‐Jürgenson, L. L., Ye, J., & Niinemets, Ü. (2017). Oak gall wasp infections of Quercus robur leaves lead to profound modifications in foliage photosynthetic and volatile emission characteristics. Plant, Cell & Environment, DOI: 10.1111/pce.13050 (link to full text)

oak galls

Oak galls (pic by Ülo Niinemets)


Oak trees (Quercus) are hosts of diverse gall-inducing parasites, but the effects of gall formation on the physiology and biochemistry on host oak leaves is poorly understood. The influence of infection by four species from two widespread gall wasp genera, Neuroterus (N. anthracinus and N. albipes) and Cynips (C. divisa and C. quercusfolii), on foliage morphology, chemistry, photosynthetic characteristics, constitutive isoprene and induced volatile emissions in Q. robur was investigated. Leaf dry mass per unit area (MA), net assimilation rate per area (AA), stomatal conductance (gs), and constitutive isoprene emissions decreased with the severity of infection by all gall wasp species. The reduction in AA was mainly determined by reduced MA and to a lower extent by lower content of leaf N and P in gall-infected leaves. The emissions of lipoxygenase pathway (LOX) volatiles increased strongly with increasing infection severity for all four species with the strongest emissions in major vein associated species, N. anthracinus. Mono- and sesquiterpene emissions were strongly elicited in N. albipes and Cynips species, except in N. anthracinus. These results provide valuable information for diagnosing oak infections using ambient air volatile fingerprints and for predicting the impacts of infections on photosynthetic productivity and whole tree performance.

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Our share of most influencal scientist

Text by Lauri Laanisto

Last week Clarivate Analytics released it´s annual list of top researchers – the ones that are considered most influential among their discipline (link to methodology). Estonia had altogether 7 scientist in that list (compared with last year´s 4), six from from the University of Tartu (TÜ) and one from the Estonian University of Life Sciences (EMÜ), containing more than 3,000 influential natural and social science researchers from around the world. (For example nobody from the other Baltic states, Latvia and Lithuania, made it to the list.)

From those 7 most influential Estonian researchers 4 (!!!) are members of our centre of excellence: Ülo Niinemets, Martin Zobel, Urmas Kõljalg and Leho Tedersoo. So one can say that EcolChange really is the dominant force in Estonian science.


This is how you get to the list…. not (pic from here)


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EcolChange seminar – Andy Taylor about Scotland’s forgotten Kingdom

Joint Seminar of Department of Botany, Doctoral School of Earth Sciences and Ecology Centre of Excellence EcolChange

Andy Taylor is fungal ecologist at the James Hutton Institute, Scotland. He visits Department of Botany as an opponent at PhD defence of Sten Anslan on November 24th, at 10.15 in auditorium 1019 in Chemicum, Ravila 14a, Tartu.

Title of the talk: Scotland’s forgotten Kingdom

Time: Thursday, 23. November 2017 at 15.15

Place: Tartu, Lai 40-218 (Vaga auditorium)


If there is a kindom, there is a king (screenshot from The Last King of Scotland, 2006)


The surface of Scotland like much of northern Europe was wiped clean by the last glaciation. This should mean that all the biodiversity present today should have appeared in the last 10,000 years.  We have been investigating the symbiotic fungi associated with many of our native plant species in relation to past history and climate and have found strong climatic structuring of communities and remarkably species rich communities associated with rapidly declining arctic alpine vegetation in Scottish mountains. The appearance of endemic fungal species suggests that there may have been vegetated, ice free Nunataks from which at least part of the Scottish flora and mycota may be derived. I will give an overview of these investigations.


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EcolChange seminar – Annika Meitern about the daily dynamics of aspen´s physiological traits

Seminar of Department of Botany and Centre of Excellence EcolChange

Annika Meitern is PhD student at the Department of botany.

Title of the talk: Daily dynamics of xylem sap properties and plant hydraulic traits in hybrid aspen

Time: Thursday, 16. November 2017 at 15.15

Place: Tartu, Lai 40-218 (Vaga auditorium)


Aspen´s sap (pic from here)


Plants have to cope with very different environmental conditions, which vary circadially enormously in most habitats, shaping daily patterns in physiological processes including long-distance water transport and xylem sap properties. The daily dynamics of physico-chemical properties of xylem sap and their covariation with tree hydraulic traits was investigated in hybrid aspen (Populus tremula L. × P. tremuloides Michx) in field conditions. The study provides new understanding on the environmental drivers that influence such dynamics.

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EcolChange seminars – There´s more than one next week!

Next week, on Thursday, there will be two EcolChange seminars with altogether three presentations. At first there is the seminar in the Department of Geography, and then, overlappingly, in the Department of Botany.


Doctoral School of Earth Sciences and Ecology, Centre of Excellence EcolChange and PhD/MSc students seminar of Department of Geography

Time: Thursday, 09. November 2017 at 14.15

Place: Tartu, Tartu, Vanemuise 46-246

at 14.15
Kim Yrjälä, University of Helsinki
Microbial ecology of Finnish peatlands

at 15.00
Timo Sipilä, University of Helsinki
Genomics of yeast Taphrina betulina, a causative agent of Witch’s Broom disease of silver birch


Seminar of Department of Botany and Centre of Excellence EcolChange

Sten Anslan is PhD student in the team of biological interactions ecology.

Title of the talk: Handling high-throughput sequencing data in metabarcoding studies

Time: Thursday, 09. November 2017 at 15.15

Place: Tartu, Lai 40-218 (Vaga auditorium)


The high-throughput sequencing (HTS) methods provide speedy assessment of community structure from environmental samples. These methods yield millions of DNA sequences, which require bioinformatics expertise to process large amount data to species inventory records. In this seminar, I’ll give a brief overview about handling HTS data and introduce user-friendly analysis platform PipeCraft.


It´s like the old joke about how Ilya Muromets reached a crossroad… (painting by VM Vasnetsov “A Knight at the Crossroads”, 1882; pic from here)

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New paper published – Think globally, research locally: emerging opportunities for mycorrhizal research in South America

Text by Guillermo Bueno

Two members of the plant ecology team led by Martin Zobel (Maarja Öpik and Guillermo Bueno) were invited as keynote speakers to a symposium on „Mycorrhizal Symbiosis in the Southern Cone of South America“ in Valdivia, Chile (March 6-9). The symposium was organized by our collaborators: Prof. Roberto Godoy and PhD student Cesar Marin (Austral University of Chile) and Patricia Silva Flores (University of Concepcion), among others. The meeting was a relevant gathering point for South American and European mycorrhizal researchers. As a result of the exciting discussions and ideas exchanged, a relevant network initiative started; the South American Mycorrhizal Research Network ( This network is a horizontal scientific community directed towards the progress of mycorrhizal applications, research and public outreach in South America. One of the aims of the network is to overcome the lack of local South American perspectives in the ongoing and future global initiatives, facilitating the integration of South American mycorrhizal research into the world leading mycorrhizal research. A more detailed summary of the scientific relevance of the meeting can be found in this meeting report published in the New Phytologist.

Citation: Bueno, C. G., Marín, C., Silva‐Flores, P., Aguilera, P., & Godoy, R. (2017). Think globally, research locally: emerging opportunities for mycorrhizal research in South America. New Phytologist, 215(4), 1306-1309. (link to full text)

bueno myc south america 01

The last two global studies exploring the diversity of mycorrhizal fungi, with large sampling gaps in rich biodiversity regions, such as South America. Pink dots correspond to sampling sites from Tedersoo et al. (2014) and blue dots from Davison et al. (2015). – Figure 1 from the paper.

bueno myc south america 02

Logo of the South American Mycorrhizal Research Network (, launched just after the meeting. – Figure 3 from the paper



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EcolChange seminar – Lauri Laanisto about intraspecific trait variability in plants

Seminar of Department of Botany and Centre of Excellence EcolChange

Lauri Laanisto is senior researcher of macroecology at Estonian University of Life Sciences

Title of the talk: Intraspecific trait variability – what, why, and maybe even a little how

Time: Thursday, 02. November 2017 at 15.15

Place: Tartu, Lai 40-218 (Vaga auditorium)


Phacelia secunda from Chile is the focal species in this seminar (pic from here)


Common assumption is that interspecific trait variation (ITV) contributes more to functional variability than intraspecific variation. Yet, some recent studies have shown that ITV can play significant role in affecting community assembly and species interactions. ITV is estimated to be responsible for 1/3 of functional variability within a plant community. However, general patterns of ITV are yet to emerge in trait ecology. I´ll try to give a little overview of ITV – what it is, why it could be important to measure it, and how does it work. And demonstrate some fresh patterns widening the perspective of ITV studies.

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New paper published – Niche differentiation and expansion of plant species are associated with mycorrhizal symbiosis

Text by Maret Gerz

Mycorrhizal symbiosis affects the realized niches of plant species

Mechanisms of coexistence has fascinated ecologists for a long time and one of the proposed ways is minimizing competition by niche differentiation. According to this, to coexist, species must differ in their realized niches (i.e. coexisting species must have distinct resource and habitat requirements). Traditionally, the realized niches are thought to be affected by competitors, but recent hypotheses state that symbiotic relationships could also be important.

Therefore, in a paper published in Journal of Ecology, we investigated whether and how the associations with symbiotic mycorrhizal fungi alter the realized niches of vascular plant species, using plant species co-occurrence data from the Netherlands and plant mycorrhizal trait data. We found that, indeed, plants with different mycorrhizal statuses and types had distinct environmental preferences. In addition, the ranges of environmental conditions which plant species tolerate (niche widths), depend on the mycorrhizal status and mycorrhizal type. Specifically, facultatively mycorrhizal plant species had wider niches compared to obligately and non-mycorrhizal plants, indicating that the ability of the faculatively mycorrhizal plants to regulate the presence of the symbiosis plays a key role in determining the range of habitats these plants can occupy. Regarding mycorrhizal types, ecto- and ericoid mycorrhizal plants had wider niches than plant species with other mycorrhizal types. For the ectomycorrhizal plants the underlying mechanisms can possibly be the higher diversity of ectomycorrhizal fungal symbionts and positive plant-soil feedbacks, whereas for the ericoid plants the mechanisms remain unclear.

The differences in plant niches among distinct groups of plants indicate that mycorrhizal symbiosis is an important contributing factor to plant coexistence, and this information could also help predicting vegetation change due to climate change or human impact.

Gerz JEcol 2017

Realized niche volume for obligately (OM) mycorrhizal, facultatively mycorrhizal (FM) and non-mycorrhizal (NM) status, for arbuscular (AM), dual (AEM), ecto- (EcM), ericoid (ErM) and orchid (OrM) mycorrhizal type, and for flexible (FL) and inflexible (IFL) plants. (Graph 2b from the paper.)

Citation: Gerz, M., Bueno, C. G., Ozinga, W. A., Zobel, M., & Moora, M. (2017). Niche differentiation and expansion of plant species are associated with mycorrhizal symbiosis. Journal of Ecology, DOI: 10.1111/1365-2745.12873 (link to full text)



  1. Mycorrhizal symbiosis is a widespread association between plant roots and mycorrhizal fungi, which is thought to contribute to plant niche differentiation and expansion. However, this has so far not been explicitly tested.
  2. To address the effect of mycorrhizal symbiosis on plants’ realized niches, we addressed how mycorrhizal status (i.e. the frequency of occurrence of mycorrhizal symbiosis), flexibility (i.e. the ability to grow both with and without mycorrhizal symbiosis) and type of a plant species affect the realized niche optima, widths and volumes. For this, we used co-occurrence data from the flora of the Netherlands along soil fertility, moisture, pH, salinity, light and temperature gradients. Phylogenetic dependency of the species was taken into account using phylogenetic generalized least squares models.
  3. We show that facultatively and flexibly mycorrhizal plants have the widest niches compared to non-mycorrhizal and obligately mycorrhizal, and inflexible plants respectively. Among obligate plant symbionts, ecto-and ericoid mycorrhizal plants exhibited the widest niches compared to plants with other mycorrhizal types. Also, plants with different mycorrhizal statuses and types differed in their realized niche optima.
  4. Synthesis. Our results indicate that mycorrhizal symbiosis mediates plant niche differentiation and expansion, facilitating the understanding of current distribution patterns of plant species, as well as predicting shifts in plant distribution and dominance due to environmental changes.





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EcolChange seminar – Lei Yang about wetland analysis

Centre of Excellence EcolChange and PhD/MSc students seminar of Department of Geography

Speaker: Prof. Lei Yang,  National Sun Yat-sen University, Kaohsiung, Taiwan

Title of the talk: Comparison Analysis of Blue Carbon Sink Effects between Salty Constructed Wetlands and Natural Coastal Wetlands Vegetated with Mangroves

Time: Wednesday, 01. November 2017 at 16.15

Place: Tartu, Vanemuise 46-327 (J.G.Granö auditorium)


Surplus shapes in mangroves (pic from here)


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EcolChange seminar – Gordon McNickle about plant foraging games

Seminar of Department of Botany and Centre of Excellence EcolChange.

Gordon McNickle is professor at Purdue University, Indiana, USA. He visits Department of Botany as an opponent at PhD defence of Sirgi Saar on October 26th, at 13.15 in Vaga auditorium, Lai 40, Tartu.

Title of the talk: Plant foraging games: scaling from resource uptake strategies to communities and ecosystems

Time: Friday(!), 27. October 2017 at 11.15

Place: Tartu, Lai 40-218 (Vaga auditorium)


The plant that foraged too much… (screenshot from Roger Corman´s “The Little Shop of Horrors”, 1960)

Plants have plastic growth responses to resource availability and distribution that allows them to deal with patchiness. Plants also have remarkably sophisticated responses to neighbouring plants, adjusting their growth and allocation to enhance competitive ability. These plant responses to neighbours are best described using evolutionary game theory. Dr. McNickle will discuss these plastic growth behaviours of plants, scaling their effects from nutrients up to ecosystems.

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