A functional group and life history approach to predicting plant community response to climate and land-use change
Final Report Abstract
Within the Plant Ecology department in Tübingen, a highly novel classification technique has been developed, which creates functional plant species groups defined by the climatic region from which they are most commonly found (Climatic Niche Groups CNGs). This approach is novel because it can provide for mechanistic evidence for species abundance changes in experiments, as opposed to modeling or observational approaches that rely on correlations and do not provide causality. Crucially, by using these CNGs we found clear response patterns for densities of annual species in the Eastern Mediterranean to experimentally altered global change parameters (rainfall and grazing). However, further knowledge and information about the precise traits and evolutionary adaptations that define each group would provide greater mechanistic explanation regarding their response and could improve future predictions. In addition, we still did not know if CNGs could be applied to different habitats around the world for further generalisations across habitats. Here we explored two main objectives: a) defining plant strategies of annual plants within the Eastern Mediterranean which could lead to greater resistance under climate change in a temporally variable environment; b) the application of the CNG approach to other long-term experiments in ecosystems around the world. Seed dormancy was explored as a key bet-hedging strategy, which potentially spreads the risk of extinction over many years in dry variable habitats. In the largest experiment of its kind, we performed a 2-year greenhouse seed germination experiment along an artificial irrigation gradient, which included 55 species from Israel from 2 sites. Species were classified into CNGs for interpretation, and under ideal water conditions, seed germination was as predicted: Dry distributed species germinated less (more seed dormancy) and wet distributed species germinated more. More intriguing were germination response slopes of CNGs when exposed to different water levels, which were ranked in hierarchical order across climatic niche distribution: Dry distributed species had the flattest / most equal germination fraction at different water levels, whereas wet distributed species were closely linked to water level, germinating little in low water, and a lot under high water. A further greenhouse experiment also investigated plant strategies of Israeli species, incorporating the CNG approach once more for interpretation of multi-species responses. Testing responses of 24 ecotypes under simulated drought, grazing (clipping), and competition, we explored commonly suggested theories of convergence in drought and grazing resistance strategies. While few differences were found between sites, classification of species using CNGs yielded clear directional results. Comparing fitness parameters under different treatments revealed that species commonly distributed in drier habitats were impacted upon by drought more so than species commonly distributed in wetter habitats, which suggests that exploiting wet conditions is a viable strategy of annuals to persist in dry variable climate. CNGs also showed clear patterns in response to grazing and confirm the hypothesis of great grazing resistance in dryland species. Finally, we applied the CNG approach to two further manipulation experiments: i) a fully factorial drought, warming and clipping, experiment across three sites in the Canadian prairies ii) a 16-year drought and warming experiment on a shrubland in Spain. Fascinating results emerged from both experiments using the CNG approach. In Canada, we showed that grazing in perennial systems selects in the same direction as warming (i.e. reduces the presence of warm distributed species); and also that grazing management has the potential to enhance the climate change selection effect (e.g. increasing the presence of dry distributed species under drought with grazing). In Spain, CNGs explained long-term patterns of change in total abundance, enhancing the interpretation of the findings tremendously. And notably, CNGs could only describe community changes for their respective climate parameter, suggesting specific adaptations to warming and drought that may lead to differential community-level selection to the two climatic variables. Overall, the project has succeeded in identifying plant evolutionary strategies and patterns of plant community response under field manipulation experiments, only highlighted through the use of the CNG approach. Further work is now planned in implementing this in a wider context to aid in the interpretation and prediction of plant community response to climate change.
Publications
- (2017) Phylogenetic structure of annual plant communities along an aridity gradient. Interacting effects of habitat filtering and shifting plant–plant interactions. Israel Journal of Plant Sciences 1–13
García-Camacho, Raúl; Metz, Johannes; Bilton, Mark C.; Tielbörger, Katja
(See online at https://doi.org/10.1080/07929978.2017.1288477) - (2013) Betting against change: Do seed dormancy strategies of Mediterranean annuals provide resistance to climate change? INTECOL BES annual meeting, London, UK
Bilton M.C., Tielbörger K., Rees M.
- (2014) Middle-Eastern plant communities tolerate 9 years of drought in a multi-site climate manipulation experiment. Nature Communications. 5(5102)
Tielbörger K., Bilton M.C., Metz J., Kigel J, Holzapfel C.. Lebrija-Trejos E., Konsens I., Parag H., Sternberg M.
(See online at https://doi.org/10.1038/ncomms6102) - (2015) Applying Climatic Niche Groups to experiments: Drylands go against predictions! PopBio – GFÖ, Tübingen, Germany
Bilton M.C., Tielbörger K., Metz J., Bangerter S., Slowik F. Cahill J.F., White S.
- (2015) Do nutrients explain dry species decreases under drought and grazing manipulations? CLIMMANI annual workshop, Poznan, Poland
Bilton M.C., Tielbörger K., Slowik F., White S., Cahill J.F.
- (2015) Response of plant Climatic Niche Groups to climate and grazing manipulations in Canada. PopBio – GFÖ, Tübingen, Germany
Slowik F., Bilton M.C., White S., Cahill J.F., Tielbörger K.
- (2016) Climatic niche groups: A novel application of a common assumption predicting plant community response to climate change. Perspectives Plant Ecology & Evolutionary Systematics
Bilton M.C., Metz J., Tielbörger K.
(See online at https://doi.org/10.1016/j.ppees.2016.02.006) - (2016) Shifting impacts of climate change: long-term patterns of plant response to elevated CO2, drought and warming across ecosystems. Advances in Ecological Research 55
Andresen L.C., Müller C., de Dato G., Dukes J.S., Emmett B.A., Estiarte M., Jentsch A., Kröel- Dulay G., Lüscher A., Niu S., Peñuelas J., Reich P., Reinsch S., Ogaya R., Schmidt I.K., Schneider M.K., Sternberg M., Tietema A., Zhu K., Bilton M.C.
(See online at https://dx.doi.org/10.1016/bs.aecr.2016.07.001)
