In the world-wide leaf economics spectrum (Wright et al. 2004, Nature) variability of three key traits: photosynthesis rate, leaf nitrogen content, and leaf dry mass per area of 2500 species (from study sites with highly variable mean annual humidity and temperature) fall along the single axis of this three-trait space. However, the striking question has been what actually is the parameter that drives LES relationships.

Fine roots are the principal organs for absorption of water and nutrients in soil, and their growth patterns control forest production and sustainability. In most boreal and temperate forest trees, the fine root nutrient acquisition is often mediated by ectomycorrhizae and soil and rhizosphere bacteria. Despite our growing understanding of the importance of fine roots and their associated mycorrhiza and bacterial communities in the rhizosphere for carbon and nutrient cycling in forests, studies of the functioning and adaptability of “the root-mycorrhiza-bacteria continuum” to a range of environmental conditions are still in their infancy.

Invertebrate herbivory in the tundra is prevalent and sensitive to climate change.

Recent studies have shown that biotic interactions influence macroecological patterns and global dynamics, stressing the need to consider them outside local or regional scales. In the context of global changes affecting the dynamics and fate of whole biomes, we still know little about the role of key biotic interactions. In this study, the intensity of invertebrate background herbivory (low intensity but chronic biomass removal) on one common tundra plant (Betula nana-glandulosa complex) is investigated along the tundra biome in relation to latitude and climate.

Author: Taavi Paal

Title: Immigration limitation of forest plants into wooded landscape corridors

Supervisor: Dr Jaan Liira, University of Tartu, Estonia

Dissertation was accepted for the commencement of the degree of Doctor
philosophiae in plant ecology and ecophysiology at the University of Tartu on
March 6, 2017 by the Scientific Council of the Institute of Ecology and Earth
Sciences, University of Tartu.

The inability of many plant species to disperse to environmentally suitable sites after the Last Glacial Maximum limits plant diversity within Europe. Dispersal may also limit species occupancy of potentially suitable sites within their distribution ranges, resulting in a large proportion of species being absent from those sites (i.e. these sites have high dark diversity). Dark diversity has already been mapped at the European scale (see Ronk et al.2015 and a blog post), however, in our recent study (Riibak et al. 2017, Journal of Biogeography) we take a step further to explore the ecological mechanisms determining large-scale dark diversity.

Saaremaa yellow rattle (Rhinanthus osiliensis) is the only endemic species of the island of Saaremaa, Estonia. This rare insect-pollinated plant prefers to grow in calcareous spring fens, which are naturally relatively rare and have largely disappeared due to severe land use change during the last century. These changes included extensive drainage of wetlands and consequent overgrowth of former fens with trees and bushes. Such landscape changes may have serious impact on the persistence of species growing in these habitats.

Researchers from Estonia and Switzerland studied regional morphological differentiation of two closely related hybridising (and “taxonomically difficult”) species – Carex flava and Carex viridula. We asked whether due to genetic admixing of the two species within regions, variation between species within regions may be small and variation within species between regions similar between the two. 

Another paper by Ülo´s former postdoc Lucian, who does a lot of small experiments, where they measure all sorts of factors that could affect organic volatile emissions in plants. This time the focus is on the interplay between an oak and a moth. The topic is actually pretty interesting, or more precisely – it is something that we need to study. Climate change and the loss of ecosystem services like pest control (whether due to climate change or not) will change the invertebrate herbivore dynamics on plants in forseeable future. How significantly will it change the things, especially on small scale. So far we have very little idea about that. And this study tries to take the first steps in this direction.

I am overjoyed that I have my first article for my PhD accepted! It is now published in Journal of Experimental Botany.

[This is a repost from Meelis Pärtel´s Macroecology Workgroup blog]

Understanding which species are going to establish within a given community (i.e. invasion) is one of the most fundamental pursuits in ecology. In today’s era of global change, this is especially important given the threat of exotic species to native biodiversity. Many hypotheses have been developed in attempts to answer this question, but two predominate. The first is that newly establishing species need to be similar enough to the species at the site to survive the environmental conditions at that site, but dissimilar enough to avoid strong competition with the resident species for the limited available resources (i.e. Darwin’s naturalization hypothesis).

Understanding the distribution of plant mycorrhizal traits of the European flora should guide us to keep understanding and to expand our curiosity about the ecological roles and distribution of the mycorrhizal symbioses in plant communities. For instance, knowing that the proportion of AM plant species decreases at higher latitudes, may support previous hypotheses about AM symbioses claiming to be inefficient in cold conditions. As well, knowing that obligately mycorrhizal plants are poorly distributed in higher latitudes but not so poorly distributed at higher elevations and lower latitudes, open the hypothesis about the effect of glaciation on the distribution of plant mycorrhizal traits.

Understanding which species establish in which habitats is fundamental to community ecology and to more applied pursuits, such as the restoration of degraded sites and the prevention of invasion by exotic species. Jonathan Bennett and Meelis Pärtel from macroecology workgroup of the University of Tartu developed a method that compares the characteristics of species across the regional species list, the site-specific species pool and locally observed species to predict which other species will be able to establish. 

Recent years have been ground-breaking in describing the diversity patterns of arbuscular mycorrhizal (AM) fungi. These microscopic fungi live in plant roots and receive carbon compounds from the plant in exchange of nutrients. In natural conditions, one plant individual can harbour more than ten taxa of AM fungi. Interestingly, AM fungal communities in the roots of plants in same habitat can be remarkably different. However, we have little information what determines the composition of AM fungi in plant roots and with this study we aimed to contribute to filling this gap.

A week ago, academician, and the professor of Plant ecology in the University of Tartu, and also one the team leaders in EcolChange, Martin Zobel, celebrated his 60th birthday. All the best wishes to him!

Recently published paper by Liina Saar, Meelis Pärtel and Aveliina Helm together with Francesco de Bello from Czechia (University of South Bohemia) in Oecologia revealed that grasslands with regular and long management history are assembled differently from abandoned grasslands and young developing grasslands, although these habitats seem visually similar. 

Alvar grasslands are probably one of the better-studied ecosystems in Europe. They are narrowly distributed in Swedish islands, Estonia, and tiny bits also in western Russia near St Petersburg. (Though, rather similar ecosystems can be also found around the Great Lakes area, in Northern America.) And somehow it has also happened that the density of good plant ecologists is also high in aforementioned countries…

Man made disturbances and environmental pollution are the reality of contemporary world, however, such long-term created environmental gradients are handy to describe ecological processes (community dynamics) otherwise difficult to observe in natural conditions or test in experiments. 

What limits forest plant migration along wooded corridors?

Europe’s natural forest is heavily fragmented by agricultural land. Such isolation threatens the long-term persistence of forest biodiversity. The concept of patch-corridor-matrix system suggests that isolated patches can be ecologically connected by a corridor network. As forest-specialist plants (termed also as “ancient forest plants”) are adapted to a stable forest environment and are considered to be poor long-distance dispersers, their use of wooded corridors hasn’t got much attention.

I like that this paper starts with a metaphor: “Chlorophyll (Chl) is a double-edged sword for plants.” Because “This molecule is capable of harvesting sunlight, initiating the process of photosynthesis, but it also involves an unavoidable risk of photooxidation.”Though I´m not sure whether this metaphor indeed holds water. The edges of this metaphoric sword seem to be awfully uneven. Especially because plants have developed pigments against it. And this paper tries to figure out which edge would cut the holder.

Forked spleenwort, Asplenium septentrionale, is a mainly petrophilous fern species in European mountains and rare on acidic siliceous rocks in lowland areas of the continent, where habitats are fragmented and populations isolated. In Estonia, the single extant population occupies a restricted area and is threatened by human disturbances. An introduction project of the species was prepared to estimate the potential to form new populations in new protected sites using ex-situ propagated young sporophytes as transplantation material, by comparing the recruitment biology of three different donor populations.