Estimating impacts of non-vascular vegetation on global biogeochemical cycles from the geological past to the future
Final Report Abstract
Non-vascular vegetation (in the following: NVV), consisting of mosses, lichens, terrestrial algae and cyanobacteria, has been suggested to have substantial impacts on global biogeochemical cycles, both in the geological past and today. In this project, we aimed at providing quantitative estimates on these effects based on a mechanistic, process-based modelling approach, called LiBry. We focused on three aspects: 1) the potential response of NVV to climate change and consequences for ecosystem functions provided by the organisms 2) the possible extent of nutrient limitation of growth of NVV under elevated CO2 3) the impacts of early NVV on global weathering rates and climate in the deep geological past. The LiBry model was evaluated based on field and laboratory experiments under varying environmental conditions, thereby accounting for functional diversity of NVV, both in the experiment and in the model, to be able to predict impacts of altered climate on the emerging community composition and associated biogeochemical processes. We found that NVV are subject to a trade-off between photosynthetic capacity and respiration costs, mediated by nutrient content of biomass, similar to vascular plants. Moreover, we observed further relations of respiration to other physiological traits, such as CO2 diffusivity. This work will serve as a basis for a more mechanistic model of autotrophic respiration and nutrient relations of NVV. Additionally, we applied the LiBry model to estimate nitrogen trace gas emissions by NVV in drylands at the global scale, finding substantial amounts that suggest that these fluxes may be important for NVV nutrient budgets. We determined an unexpected strong control of air humidity on the response of NVV to warming in drylands, and found that water stored in tree bark may be relevant for the growth and community composition of epiphytic NVV. On a more general level, we summarized the current knowledge on potential impacts of climate change on NVV and their associated ecosystem functions, and developed, on this basis, a research agenda for improved understanding, including several key topics such as acclimation, CO 2 fertilization, or feedbacks on climate. With regard to the role of vegetation for Earth’s climate in the geological past, we found a large potential impact of root evolution in lycophytes, the earliest vascular plants, on global weathering rates and, consequently, the CO2 content of the atmosphere, based on simulations for current, extant lycophytes. Moreover, we identified two ‘windows’ of opportunity for land plant expansion and diversification during the Phanerozoic as a result of suitable climatic conditions, based on a simplified general vegetation model. While we identified several key mechanisms and drivers related to NVV and their response to past and future climatic change, still further work is needed to better constrain central aspects of the NVV-climate relations, such as extended CO2 fertilization experiments and a comparison between Paleozoic and Proterozoic with regard to vegetation-climate feedbacks.
Publications
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Global NO and HONO emissions of biological soil crusts estimated by a process-based non-vascular vegetation model. Biogeosciences, 16(9), 2003-2031.
Porada, Philipp; Tamm, Alexandra; Raggio, Jose; Cheng, Yafang; Kleidon, Axel; Pöschl, Ulrich & Weber, Bettina
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Relative humidity predominantly determines long‐term biocrust‐forming lichen cover in drylands under climate change. Journal of Ecology, 109(3), 1370-1385.
Baldauf, Selina; Porada, Philipp; Raggio, José; Maestre, Fernando T. & Tietjen, Britta
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Bark Water Storage Plays Key Role for Growth of Mediterranean Epiphytic Lichens. Frontiers in Forests and Global Change, 4.
Porada, Philipp & Giordani, Paolo
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A dynamic local-scale vegetation model for lycopsids (LYCOm v1.0). Geoscientific Model Development, 15(5), 2325-2343.
Halder, Suman; Arens, Susanne K. M.; Jensen, Kai; Dahl, Tais W. & Porada, Philipp
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A research agenda for nonvascular photoautotrophs under climate change. New Phytologist, 237(5), 1495-1504.
Porada, Philipp; Bader, Maaike Y.; Berdugo, Monica B.; Colesie, Claudia; Ellis, Christopher J.; Giordani, Paolo; Herzschuh, Ulrike; Ma, Yunyao; Launiainen, Samuli; Nascimbene, Juri; Petersen, Imke; Raggio, Quílez José; Rodríguez‐Caballero, Emilio; Rousk, Kathrin; Sancho, Leopoldo G.; Scheidegger, Christoph; Seitz, Steffen; Van Stan John, T.; Veste, Maik ... & Weston, David J.
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Climate windows of opportunity for plant expansion during the Phanerozoic. Nature Communications, 13(1).
Gurung, Khushboo; Field, Katie J.; Batterman, Sarah A.; Goddéris, Yves; Donnadieu, Yannick; Porada, Philipp; Taylor, Lyla L. & Mills, Benjamin J. W.
