Robert R. Junker

Robert R. Junker

Foto: Andreas Kolarik/Leo

Contact: 

robert.junker@sbg.ac.at

http://www.uni-salzburg.at/ecoevo/robert.junker

Functional Community Ecology

We investigate the structure and functional composition of diverse plant, animal and bacteria communities within ecosystems and along environmental gradients. We are particularly interested in how functional plant traits affect the behavior, distribution and diversity of insects and bacteria. Additionally, we track the functional responses of plant species and whole communities to global change components such as climate warming and the spread of invasive species. These approaches allow us to comprehensively evaluate the mechanisms underlying ecosystem processes and the vulnerability of ecosystem services.

Interactions between species naturally do not occur in isolation but are embedded in complex communities. Thus, the frequency and net effect of pair-wise interactions usually are modulated by other sympatric organisms that may alter the phenotype and/or the behavior of one or both interaction partners. To understand such multi-trophic interactions, we investigate how bacteria associated with plants affect ecosystem functions such as plant–pollinator or plant–herbivore interactions.

In studies in the lab and in the field (e.g. in the Austrian Alps and in Hawai’i), we analyze and manipulate the phenotype of plant species (e.g. scent emissions, coloration, morphology), examine interaction networks, reveal the composition and diversity of bacterial communities (e.g. next generation sequencing) and observe the behavior of animals as response to plant traits. In order to analyze the complex data gathered in these studies we apply and develop novel statistical tools to quantify the phylogenetic and functional diversity of communities and the niche size of species

 

Alpine related project: Functional responses of plant communities and plant-pollinator interactions to altitudinal gradients and climate change

Robert R. Junker & Martin Lechleitner

The year 2014 was globally the warmest since records started and thus represents the (provisional) peak of the general trend of global warming that is expected to continue, which has severe negative effects on biodiversity and ecosystem processes. In order to understand the causes and predict or even mitigate consequences of these impacts, it is mandatory to study present patterns of biodiversity and to quantify ecological responses of communities to environmental changes such as increasing temperatures. Spatial gradients such as those along mountain slopes as well as re-visitations of sites where historical vegetation surveys had been conducted represent powerful long-term and large-scale study systems to estimate effects of climate change on ecosystems. The diversity, characteristics, distribution, and relative abundance of functional plant traits in communities reveal information on community assembly and ecosystem functioning. In contrast to vegetative and life-history traits, such information remains largely unknown for flower traits despite their essential roles for important ecological processes such as sexual reproduction of plants and pollinator diversity. In the proposed study, the advantages of the altitudinal gradient of the Austrian Alps as well as historical vegetation surveys will be exploited to fill that important gap. The plant species present in communities located between 1500 and 2600 m a.s.l. will be phenotyped by a large set of vegetative but most importantly floral functional traits including the morphology, phenology, scent emissions and color. Additionally, the phylogenetic composition of the communities as well as the flower-visitor interactions will be considered. This extensive and comprehensive dataset will allow testing hypotheses on community assembly, the link between functional plant diversity and flower visitor diversity, and the functional responses of plant communities and interaction patterns to altitude and climate change. The anticipated results and conclusions will therefore provide a novel perspective on community ecology and assembly with implications for climate change and the vulnerability of natural ecosystems and the conservation of the alpine flora and fauna.

funded by FWF | Start: May 2016

Selected Publications:

Dynamic range boxes – A robust non-parametric approach to quantify size and overlap of n-dimensional hypervolumes. Junker RR, Kuppler J, Bathke AC, Schreyer ML, Trutschnig W (2016) Methods in Ecology and Evolution DOI: 10.1111/2041-210X.12611

Time-invariant differences between plant individuals in interactions with arthropods correlate with intraspecific variation in plant phenology, morphology and floral scent. Kuppler J, Höfers MK, Wiesmann L, Junker RR (2016) New Phytologist 210: 1357-1368

Experimental manipulation of floral scent bouquets restructures flower-visitor interactions in the field. Larue A-AC, Raguso RA, Junker RR (2016) Journal of Animal Ecology 85: 396-408

Microhabitat heterogeneity across leaves and flower organs promotes bacterial diversity. Junker RR, Keller A (2015) FEMS Microbiology Ecology 91: fiv097

Specialisation on traits as basis for the niche-breadth of flower visitors and as structuring mechanism of ecological networks. Junker RR, Blüthgen N, Brehm T, Binkenstein J, Paulus J, Schaefer HM, Stang M (2013) Functional Ecology, 27: 329-341