EcolChange seminar – Vigdis Vandvik about integrating experimental and gradient approaches to climate change impacts on plant populations and communities

Seminar of Department of Botany and Centre of Excellence EcolChange

Vigdis Vandvik is professor at University of Bergen, Norway and head of the Centre of Excellence in Biology Education (bioCEED). In her presentation she will introduce a large-scale experiment and other studies targeting climate change effects on European ecosystems.

Title of the talk: Integrating experimental and gradient approaches to climate change impacts on plant populations and communities

Time: Thursday, 14. September 2017 at 15.15

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

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Large scale heathland restoration experiment in Dwingerweld (pic from Vigdis Vandvik´s Twitter feed)

Prof. Vandvik visits Department of Botany as an opponent of PhD defence of Liis Kasari on September 15th, at 10.15 in A.Vaga auditorium, Lai 40, Tartu.

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New paper published – Adaptive root foraging strategies along a boreal–temperate forest gradient

Text by Ivika Ostonen

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.

In this paper we analysed adaptive foraging mechanisms of ectomycorrhizal and fine roots of Picea abies, Pinus sylvestris and Betula pendula along a gradient from temperate to subarctic boreal forest (38 sites between latitudes 48°N and 69°N) in Europe. The study was carried out in cooperation with colleagues and research groups from Finland, Germany, United Kingdom and Lithuania.

Root tips with their symbiotic fungi and associated bacterial communities are metabolically most active, making many of their traits, both quantitative and qualitative characteristics, good indicators of root system adaptability. We used variables describing tree resource uptake structures and processes (absorptive fine root biomass and morphology, N concentration in absorptive roots, extramatrical mycelium (EMM) biomass, community structure of root-associated EcM fungi, soil and rhizosphere bacteria) to analyse relationships between root system functional traits and climate, soil and stand characteristics. As a result, we constructed a conceptual, multidimensional framework applicable to the description and analysis of resource capture strategies employed by the root-mycorrhiza-bacteria communities in forest soils.

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Figure. A conceptual scheme of fine root foraging strategy related to latitudinal climate and soil carbon : nitrogen (C : N) gradient from boreal to temperate forests. The soil C : N ratio increases from left to right, from N-rich temperate forests to N-poor northern boreal forests. Foraging strategies are based on the adaptation of biomass allocation to absorptive fine roots associated with fine root turnover rate, fine root morphology and changes in root-associated ectomycorrhizal (EcM) fungi and rhizosphere bacterial communities. The EXTENSIVE strategy refers to investment in larger absorptive fine root biomass per forest stand basal area (BA; kg m -2), whereas the INTENSIVE strategy denotes the tendency to establish smaller absorptive root biomass, associated with functional changes in root morphology and a larger reliance on EcM and bacterial communities in the rhizosphere. (Figure 7 in the paper)

Our concept of fine root foraging strategies puts forward the notion that quantitative differences in absorptive fine root biomass per stand basal area are concurrent with changes in root morphology. At the same time, a foraging strategy involves qualitative shifts in multitrophic interactions in the rhizosphere involving host trees, ectomycorrhizal fungi and associated bacteria.

We integrated the root-mycorrhiza-bacteria continuum into the concept of adaptive fine root foraging and showed that the variety of alternatives within the root-mycorrhiza-bacteria continuum enables adaptive root foraging in both northern subarctic boreal and southern temperate forests. We provided strong empirical evidences that bi- and trilateral shifts in the root-mycorrhiza-bacteria continuum are part of changing biomass and nutrient cycling fluxes along climatic and environmental gradients,  driving fine root foraging efficiency and affecting essentially the potential of forest trees adaptability in global change.

Citation: Ostonen, I., Truu, M., Helmisaari, H. S., Lukac, M., Borken, W., Vanguelova, E., … & Truu, J. (2017). Adaptive root foraging strategies along a boreal–temperate forest gradient. New Phytologist, DOI: 10.1111/nph.14643 (link to full text)

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Fine roots that are not so fine, but at the same time completely fine (pic from here)

Summary

The tree root–mycorhizosphere plays a key role in resource uptake, but also in the adaptation of forests to changing environments.

The adaptive foraging mechanisms of ectomycorrhizal (EcM) and fine roots of Picea abies, Pinus sylvestris and Betula pendula were evaluated along a gradient from temperate to subarctic boreal forest (38 sites between latitudes 48°N and 69°N) in Europe. Variables describing tree resource uptake structures and processes (absorptive fine root biomass and morphology, nitrogen (N) concentration in absorptive roots, extramatrical mycelium (EMM) biomass, community structure of root-associated EcM fungi, soil and rhizosphere bacteria) were used to analyse relationships between root system functional traits and climate, soil and stand characteristics.

Absorptive fine root biomass per stand basal area increased significantly from temperate to boreal forests, coinciding with longer and thinner root tips with higher tissue density, smaller EMM biomass per root length and a shift in soil microbial community structure. The soil carbon (C) : N ratio was found to explain most of the variability in absorptive fine root and EMM biomass, root tissue density, N concentration and rhizosphere bacterial community structure.

We suggest a concept of absorptive fine root foraging strategies involving both qualitative and quantitative changes in the root–mycorrhiza–bacteria continuum along climate and soil C : N gradients.

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New paper published – Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome

Text by C. Guillermo Bueno

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Tundra in Svalbard through pinhole (pic by Lauri Laanisto)

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. C. Guillermo Bueno from the University of Tartu was part of the research team led by Isabel C. Barrio and Mikhail V. Kozlov. They collected samples from 56 locations across the tundra biome in the first coordinated effort to measure invertebrate herbivory in tundra, outside the well-studied effects of insect outbreaks. Background herbivory was detected at nearly all tundra sites. The intensity of background herbivory, although low, was mainly associated with higher temperatures and, as such, is likely to increase in a warmer Arctic. This paper represents the first coordinated effort combining two international research networks in the tundra: the Herbivory Network and NeAT (Network for Arthropods of the Tundra).

Citation: Barrio, I. C., Lindén, E., Te Beest, M., Olofsson, J., Rocha, A., Soininen, E. M., … Bueno, C. G, … & Bråthen, K. A. (2017). Background invertebrate herbivory on dwarf birch (Betula glandulosa-nana complex) increases with temperature and precipitation across the tundra biome. Polar Biology, doi:10.1007/s00300-017-2139-7 (link to full text)

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Trend of herbivory (damaged leaves) along the temperature gradient in the tundra sites

 

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Location of the sites, with the size of the circles relative to the number of samples taken (see full publication for details)

 

Abstract:

Chronic, low intensity herbivory by invertebrates, termed background herbivory, has been understudied in tundra, yet its impacts are likely to increase in a warmer Arctic. The magnitude of these changes is however hard to predict as we know little about the drivers of current levels of invertebrate herbivory in tundra. We assessed the intensity of invertebrate herbivory on a common tundra plant, the dwarf birch (Betula glandulosa-nana complex), and investigated its relationship to latitude and climate across the tundra biome. Leaf damage by defoliating, mining and gall-forming invertebrates was measured in samples collected from 192 sites at 56 locations. Our results indicate that invertebrate herbivory is nearly ubiquitous across the tundra biome but occurs at low intensity. On average, invertebrates damaged 11.2% of the leaves and removed 1.4% of total leaf area. The damage was mainly caused by external leaf feeders, and most damaged leaves were only slightly affected (12% leaf area lost). Foliar damage was consistently positively correlated with mid-summer (July) temperature and, to a lesser extent, precipitation in the year of data collection, irrespective of latitude. Our models predict that, on average, foliar losses to invertebrates on dwarf birch are likely to increase by 6–7% over the current levels with a 1 °C increase in summer temperatures. Our results show that invertebrate herbivory on dwarf birch is small in magnitude but given its prevalence and dependence on climatic variables, background invertebrate herbivory should be included in predictions of climate change impacts on tundra ecosystems.

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IAVS 2017 in next week

Text by Lauri Laanisto

Next week the town of Giuseppe Tomasi di Lampedusa – or Palermo, as it´s sometimes called – will host this year´s annual meeting of vegetation scientists from all over the world. It will be the 60th annual symposium of the IAVS, and the topic is: “Vegetation patterns in natural and cultural landscapes” (link to conference home page).

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If anybody is interested to have a closer look of some of the stuff that we do in EcolChange, this conference is quite a good place. There will be numerous talks by plant ecologist working within the Centre of Excellence framework. Final schedule is not yet made public, but as far as I know Aurele Toussaint and Carlos P. Carmona will do an oral presentation. Liis Kasari and Kersti Riibak will have posters. Also a lot of people who have deep associations with EcolChange, like Francesco de Bello, Lars Götzenberger, Triin Reitalu, And I will have a talk as well.

See you in Palermo!

 

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Two EcolChange seminars this week with three presenters – Prinzing/Santonja/Young

Seminar of Department of Botany and Centre of Excellence EcolChange

This week we have not one, but two EcolChange seminars:

First, on Tuesday, 23. May  2017 at 15.15 in Tartu, Lai 40-218 (Vaga auditorium)

Andreas Prinzing will do a presentation “Do good neighbors compensate for bad climate?”

And Mathieu Santonja will talk about “Plant diversity mitigates the negative effects of climate change, via soil biota and litter decomposition”

 

Andreas Prinzing is Professor at the University of Rennes 1, France.

Do good neighbors compensate for bad climate?

Abstract:

Evolutionary proximate neighborhoods reduce vulnerability of seedlings to climatic stress and soil fungi mediate this effect

Climate is changing and is becoming warmer and drier in large part of Europe. As a result, tree species such as oaks (Quercus petraea) are at a risk of strong decline. The classic strategy of foresters is to introduce genotypes coming from warmer or drier provenances and likely being adapted to warm and dry climates. However, this strategy results in the loss of local genotypes and it does not account for non-climatic constraints, such as biotic interactions – the impact of tree neighbors or natural enemies. We focus here on oaks (Quercus petraea) and their most vulnerable stage, seedlings. We studied germination, survival, growth and budburst of seedlings within a natural mosaic of soil microclimates and manipulated the biotic neighborhood: the distance of seeds / seedlings to adult oaks, the species identity of these oaks, the evolutionary distance of the ambient canopy, the density of seeds / seedlings and the presence of pathogenic fungi. The results suggest that germination and first year growth show particularly strong relationships to neighborhood, environment and their interaction. Specifically, seedlings develop better in moist soils and under an evolutionarily proximate canopy and such a canopy in addition reduces the negative impact of dry soils. Overall, the impact of climate change on regeneration of this major forest tree-species might be mitigated by changing the evolutionary neighborhood in which the regeneration takes place.

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Quercus petraea forest (pic from here)

Mathieu Santonja is Teaching and Research Assistant at the University of Rennes 1, France.

Plant diversity mitigates the negative effects of climate change, via soil biota and litter decomposition

Abstract:

We tested how plant community diversity and climate change (through decreased precipitation) impacts soil biota and litter decomposition in two Mediterranean ecosystems: a shrubland dominated by Quercus coccifera and a forest dominated by Quercus pubescens.

In the shrubland, multi-species litter showed higher microbial abundance, lower bacterial diversity and higher fungal diversity compared to single-species litter. C and N release increased with increasing litter species richness. Drier conditions increased microbial diversity, reduced net N release from litter and led to higher and more frequent synergistic effects on C release. The results suggests that shifts in plant community composition may have stronger impacts on litter decomposition and nutrient cycling than relatively subtle changes in precipitation.

In the forest, drier conditions affected decomposers negatively, directly by reducing fungal biomass and detritivorous mesofauna, and also indirectly by increasing the predation pressure on detritivorous mesofauna by predatory mesofauna. Increased drought strongly decreased decomposition but the presence of several plant species in the litter mitigated this effect. Hence, faster decomposition in diverse litter mixtures might compensate slower decomposition under drier condition in this ecosystem.

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Bacterial stamp – 9th Microbiology Congress in Moscow in 1966 (pic from here)

And then, on Thursday, 25. May  2017 at 15.15 in Tartu, Lai 40-218 (Vaga auditorium

J. Peter W. Young will do a talk about “Do bacteria have species?”

J. Peter W. Young is professor emeritus at York University, UK. He is a guest of Doctoral School of Earth Sciences and Ecology and in addition to the seminar he will hold round-table discussion with PhD students and early career scientists: Thursday May 25th, 10.30 in Lai 40 coffee room

 

Abstract:

We classify all organisms into species, but bacteriologists have always done it a little differently.  In the past two decades, we have acquired major new insights into bacterial genomes, diversity and evolution, and I believe it is time to rethink the species concept as applied to bacteria.  On the one hand, bacteria have species equivalent to the species of sexual eukaryotes, defined by recombination and barriers to recombination.  On the other hand, the dynamic nature of the bacterial accessory gene pool leads to high genetic and phenotypic diversity among members of the same species.   We can define species in a consistent and stable way, but the species name will not tell us all we need to know about a bacterium.  We also need a list of its most relevant accessory gene modules.  This has important implications for current attempts to describe the diversity of bacterial communities, as well as for our understanding of pathogens and their evolution.  I will illustrate these ideas with our own evidence from rhizobia, the symbiotic nitrogen-fixing bacteria.

Kumar N, Lad G, Giuntini E, Kaye ME, Udomwong P, Shamsani NJ, Young JPW, Bailly X (2015) Bacterial genospecies that are not ecologically coherent: population genomics of Rhizobium leguminosarum. Open Biology, 5: 140133. doi: 10.1098/rsob.140133

Remigi P, Zhu J, Young JPW, Masson-Boivin C (2016) Symbiosis within symbiosis: evolving nitrogen-fixing legume symbionts. Trends in Microbiology 24: 63-75 doi:10.1016/j.tim.2015.10.007

 

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Taavi Paal defended his PhD thesis: congratulations!

Text by Lauri Laanisto

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.

Opponent: Prof. Lander Baeten, Ghent University, Belgium

Commencement: Council hall of the University of Tartu, 18 Ülikooli Street,
Tartu, on 10 May 2017 at 10.15 a.m.

Full text of the thesis can be found here.

Thesis is based on following publications:

Liira, J. & Paal, T. (2013) Do forest-dwelling plant species disperse along
landscape corridors? Plant Ecology 214:455–470. (link to full text)

Paal, T., Kütt, L., Lõhmus, K. & Liira, J. (2017) Both spatiotemporal
connectivity and habitat quality limit the immigration of forest plants into
wooded corridors. Plant Ecology 218:417–431. (link to full text) (link to blog post)

Lõhmus, K., Paal, T. & Liira, J. (2014) Long-term colonization ecology of
forest-dwelling species in a fragmented rural landscape – dispersal versus
establishment. Ecology and Evolution 4(15):3113–3126. (link to full text)

Paal, T., Zobel, K. & Liira, J. Plant traits indicate that various ecological
filters limit forest species use of wooded green corridors. Manuscript.

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Taavi on stage (though, not defending the thesis…) (pic from here)

Abstract:

Large-scale agricultural and sylvicultural activities have led to the fragmentation and isolation of both ancient and recent forests in landscape. In afforested areas, the formation of forest-specific vegetation is impeded by the inhospitable surrounding agricultural matrix and by poor dispersal ability of many forest plants. Landscape corridors are proposed as a means to increase the connectivity between species source and target habitats, therein wooded corridors should enhance the dispersal of forest-specific species. The aim of this thesis was to evaluate the functionality of wooded landscape corridors as dispersal enhancing landscape elements for forest plants of deciduous forests. The results of this thesis indicate that wooded corridors in their present state do not perform well as dispersal enhancing structures for specialist forest plants. Even in well-connected corridors, most of forest specialists colonised only the first 5–10 m of the corridor, and only very few species could migrate to isolated corridors. Mainly those forest plants are successful that utilise long-distance dispersal vectors, such as mammals or birds, and those that can tolerate habitat edge mediated conditions dominating in corridors. Positive signals of the use of corridors by forest-dwelling plants were mostly created by shade tolerant generalist species. Analysis results showed that forest species can be supported only by wide corridors that are directly connected to ancient (source) forest, and those that have structures reducing edge effects. Such structures are formed in corridors with a double line of mature trees (e.g. old alleys) that have wide-arching canopies and lateral side branches. Landscape planning and conservation management of rural landscapes should target first on existing wooded corridors before planting new tree lines, as the formation of suitable habitat conditions takes decades or centuries.

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EcolChange seminar – Alar Rosentau about sea-level changes and coastal settlements in Baltics

Seminar of the Centre of Excellence EcolChange + Seminar of Department of Botany and Doctoral School of Earth Sciences and Ecology

Alar Rosentau is senior researcher at the Department of Geology, Tartu University.

Title of the talk: Sea-level change and early coastal settlements in Eastern Baltic

Time: Thursday, 18. May 2017 at 15.15

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

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Depiction of Stone Age settlement in our region (pic from here)

Abstract:

Results of the interdisciplinary research which combines palaeo sea-level and Stone Age settlement data from the Narva-Luga area in Eastern Baltic will be presented during the seminar. The oldest traces of human activity in Narva-Luga dated to 8.5–7.9 cal. ka BP are associated with the palaeo-Narva River in the period of low water level in the Baltic basin at the beginning of the Litorina Sea transgression. The coastal settlement associated with the Litorina Sea lagoon, presently represented by 33 Stone Age sites, developed in the area c. 7.1 cal. ka BP and existed there for more than 2000 years. Transformation from the coastal settlement back to the river settlement indicates a change from a fishing-and-hunting economy to farming and animal husbandry c. 4.4 cal. ka BP

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New paper published – Dispersal limitation determines large-scale dark diversity in Central and Northern Europe

Text by Kersti Riibak

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.

We used vegetation data on ca. 10 x 10 km grid cells across seven regions in Central and Northern Europe to compare dispersal-related traits of observed and dark diversity. Our results show that poor dispersal ability (i.e. low seed production and short dispersal distance) restricts largely species dispersal to potentially suitable sites in Europe (Fig. 1). However, dispersal limitation decreased with increasing human population size and agricultural land use, showing that human activities have helped to disperse many plant species in Europe.

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Fig.1. The log-ratio of seed production (upper graph) and potential dispersal distance (lower graph) between observed and dark diversity. Positive values indicate that absent plant species produce fewer seeds and have shorter potential dispersal distance than observed species (i.e. dispersal limited sites). Different lower case letters in the graph indicate significant differences between study areas.

Our results also indicate that the importance of dispersal limitation decreases either with strong abiotic stress or biotic resistance by resident vegetation. This means that in very stressful conditions, biodiversity is rather restricted by the establishment of poorly adapted species than dispersal. If the global change will be accompanied by warmer and moister conditions at high latitudes, dispersal limitation may become more dominant in the sparsely human inhabited regions of Northern Europe.

Citation: Riibak, K., Ronk, A., Kattge, J., Pärtel, M. (2017) Dispersal limitation determines large-scale dark diversity in Central and Northern Europe. Journal of Biogeography, doi: 10.1111/jbi.13000 (link to full text)

 

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The square means of dispersal (pic from here)

Abstract:

Aim

Previous studies indicate that many plant species present in a surrounding region are absent from potentially suitable sites (i.e. they constitute dark diversity). However, quantitative analyses are lacking where and why dispersal limitation occurs within species occurrence range at the continental scale. We test if species characteristics related to dispersal limitation, that is, low seed production and short potential dispersal distance, affect the formation of dark diversity at large spatial scales. In addition, we explore how the levels of dispersal limitation are affected by climate, landscape heterogeneity and anthropogenic activity.

Location

Seven study areas in Central and Northern Europe – Iceland, Finland, Estonia, the British Isles, the Netherlands, Germany and Switzerland.

Methods

We used data on vascular plant species occurrences in ca. 10 × 10 km grid cells from each study area. To estimate dark diversity for each grid cell, we applied geographical, biogeographical and environmental filters. Seed production was estimated directly (number of seeds per ramet), and indirectly from seed mass. We used several plant traits in combination (e.g. dispersal syndrome and seed characteristics) to estimate potential dispersal distance of seeds.

Results

Species contributing to dark diversity produced generally fewer seeds and had shorter potential dispersal distances than observed species. Dispersal limitation tended to decrease with increasing environmental stress, human population density and agricultural land use.

Main conclusions

Many species are absent from potentially suitable sites in Central and Northern Europe because of dispersal limitation, induced by low seed production and short potential dispersal distances. However, strong abiotic stress, biotic resistance and human activities have reduced the importance of dispersal limitation. This knowledge can be considered in the predictions of how changes in climate and land use affect biodiversity in the future.

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EcolChange seminar – Lander Baeten about long-term changes of forest biodiversity

Seminar of the Centre of Excellence EcolChange + Seminar of Department of Botany and Doctoral School of Earth Sciences and Ecology

Lander Baeten is professor at the Department of Forest and Water Management, Ghent University, Belgium. He visits Department of Botany as opponent of PhD defence of Taavi Paal on May 10th at 10.15 in the Senate hall (Ülikooli 18).

Title of the talk: Plant biodiversity change in the Anthropocene – the value of multiple-site community resurvey data

Time: Thursday, 11. May 2017 at 16.15

Place: Tartu, Ülikooli street 17

Abstract:

Global biodiversity is in decline, but this crisis does not necessarily filter down to the local scale. Indeed, globally distributed data sets have shown that increases and decreases in plant diversity can be equally likely. But even if the net diversity change is zero, this does not imply communities don’t change over time. However, we often lack appropriate data to study the potentially dramatic shifts in composition, especially over decadal time scales. This is where ‘legacy data’ come in. Resurveys of historical vegetation records provide invaluable information to study biodiversity dynamics, especially if multiple data sets are combined to cover broad gradients in climate and other drivers of change. I will discuss the opportunities and challenges related to such data and illustrate this with the forestREplot initiative, a database of forest understorey resurvey studies.

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New paper published – Genetic consequences of landscape change for rare endemic plants–A case study of Rhinanthus osiliensis

Text by Tsipe Aavik

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. For example, habitat loss is often accompanied by reduced population size, which has detrimental effects on the genetic diversity of plant populations. This, in turn, reduces the fitness of plants. Furthermore, at landscape scale, populations become isolated and are separated by hostile habitats, which may jeopardize the exchange of genes via pollen and seed flow between these populations. Lack of gene flow may further contribute to the extinction vortex of species endangered by habitat fragmentation.

We examined the effects of current landscape composition and landscape change during the last century on the genetic diversity of the endemic R. osiliensis. The study revealed that all examined populations of this rare species have recently experienced a severe bottleneck, i.e. a strong decline in population size. Furthermore, most populations suffered from high levels of inbreeding. These findings most likely reflect the consequences of the loss of the preferred habitats of R. osiliensis. We also found that a higher proportion of forests surrounding the populations caused a notable decrease in the genetic diversity within these populations.

Our study demonstrated that, most likely because of habitat fragmentation, rare species, such as the endemic R. osiliensis, are facing serious genetic consequences. To effectively organize the management of species endangered by fragmentation, it is important to keep in mind that in addition to the area and connectivity of suitable habitats, dispersal and pollen flow between populations is largely affected by the characteristics of the landscape matrix between suitable habitats.

Citation: Aavik, T., Talve, T., Thetloff, M., Uuemaa, E., Oja, T. (2017) Genetic consequences of landscape change for rare endemic plants – A case study of Rhinanthus osiliensis. Biological Conservation 210: 125-135. (link to full text)

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Rhinanthus osiliensis (pic from here)

Abstract:

During the last hundred years European landscapes have experienced an extensive change in structure including a substantial loss of wetland habitats. In the current study we examined the influence of landscape change and current landscape composition on the genetic diversity of Rhinanthus osiliensis, a very rare endemic plant with narrow distribution range restricted to calcareous spring and species-rich fens in western part of the island of Saaremaa, Estonia. We observed very high inbreeding in some study populations of R. osiliensis. Furthermore, bottleneck analysis revealed that in fact all examined populations had experienced a severe decline in population size in the recent past. This result indicates that the high levels of inbreeding in R. osiliensis are not only the consequence of the mixed mating system common in this species, but may at least partly be attributed to habitat loss. Indeed, the analysis of landscape change revealed a substantial decrease in the area of mires during the last century in all study landscapes. Unexpectedly, current habitat availability did not influence the measures of genetic diversity. Nevertheless, the allelic richness of R. osiliensis was negatively affected by the amount of forests, which may have acted as a barrier for pollen flow in this insect-pollinated plant. We conclude that the populations of habitat-specialist rare plants such as R. osiliensis are endangered not only by the loss of habitats but also by other changes in landscape composition, e.g. afforestation, leading to strong declines in population size accompanied by genetic bottlenecks, decreased genetic diversity and high inbreeding

 

 

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