Of all functions supported by biodiversity productivity plays a pivotal role. On the one hand, productivity can be considered a summary variable that also captures other functions, as for example nutrient cycling and forest health. On the other hand, productivity is closely linked to important ecosystem services, such as timber production, and thus, provides important arguments for protecting biodiversity. For these reasons, productivity is measured in almost all current BEF experiments in grasslands, forests and other ecosystems. In our course, we i) explain how productivity has been measured in the Comparative Study Plots (CSPs) in Gutianshan and in the experimental sites in Xinganghshan, ii) identify the different components contribute to productivity, iii) discuss the mechanisms behind the positive biodiversity-productivity relationship, iv) summarize the main results on this topic from BEF-China, and v) compare our results with those from other BEF experiments. In the course, we would like to discuss the challenges in measuring the different components of productivity and explore new ways to measure them in the future.

Paper 1: Williams LJ, Butler EE, Cavender-Bares J, Stefanski A, Rice KE, Messier C, Paquette A & Reich PB (2021). Enhanced light interception and light use efficiency explain overyielding in young tree communities. Ecology Letters, 24, 996–1006. doi.org/10.1111/ele.13717.

Paper 2: Zeng W, Xiang W, Zhou B, Ouyang S, Zeng Y, Chen L, Zhao L & Valverde-Barrantes OJ (2020). Effects of tree species richness on fine root production varied with stand density and soil nutrients in subtropical forests. The Science of the total environment, 733, 139344. doi.org/10.1016/j.scitotenv.2020.139344.

Plant functional traits are important for ecological functions of a plant community and may affect, for example, ecosystem stability and carbon, water and nutrient balance. In the lecture part of this course day, we will learn about different categories of traits (e.g. growths traits, defense traits etc.), trade-offs between traits, and about trait variation between species, but also within species and even within individuals. Traits respond to their abiotic and biotic environment, and they reflect community assembly processes. On the other hand, traits affect plant performance and influence ecosystem processes and ecosystem services. In the seminar part, we will discuss selected papers reflecting the role of functional traits for BEF relationships in forests.

Paper 3: Bongers FJ, Schmid B, Bruelheide H, Bongers F, Li S, Oheimb G von, Li Y, Cheng A, Ma K & Liu X (2021). Functional diversity effects on productivity increase with age in a forest biodiversity experiment. Nature Ecology & Evolution. doi.org/10.1038/s41559-021-01564-3.

Paper 4: Gao Y, Yuan Y, Li Q, Kou L, Fu X, Dai X & Wang H (2021). Mycorrhizal type governs foliar and root multi-elemental stoichiometries of trees mainly via root traits. Plant and Soil, 460, 229–246. doi.org/10.1007/s11104-020-04778-9.

Recent research has highlighted the important role that higher trophic levels play in mediating biodiversity-ecosystem functioning (BEF) relationships, and have therefore underlined the importance of considering multitrophic linkages in ecosystem for an in-depth understanding of BEF relationships. Herbivores and pathogens as primary consumers are particularly relevant in this context, since they directly connect the primary producer level with higher trophic levels and therefore play a decisive role in the regulation of bottom-up and top-down control in ecosystems. In this session, we will look at the general theoretical expectations and current empirical findings—from BEF research in general and the BEF-China platform in particular—of how herbivores, pathogens and their higher-trophic level antagonists interact with each other and with the producer level (via their functional effects of herbivory, pathogen damage, predation and parasitism) to structure diversity patterns and ecological functioning across multiple trophic levels.

Paper 5: Rosenthal LM, Simler-Williamson AB & Rizzo DM (2021). Community-level prevalence of a forest pathogen, not individual-level disease risk, declines with tree diversity. Ecology Letters, 24, 2477–2489. doi.org/10.1111/ele.13871.

Paper 6: Muiruri EW, Rainio K & Koricheva J (2016). Do birds see the forest for the trees? Scale-dependent effects of tree diversity on avian predation of artificial larvae. Oecologia, 180, 619–630. doi.org/10.1007/s00442-015-3391-6.

Paper 7: Anthony MA, Crowther TW, van der Linde S, Suz LM, Bidartondo MI, Cox F, Schaub M, Rautio P, Ferretti M, Vesterdal L, Vos B de, Dettwiler M, Eickenscheidt N, Schmitz A, Meesenburg H, Andreae H, Jacob F, Dietrich H-P, Waldner P, Gessler A, Frey B, Schramm O, van den Bulk P, Hensen A & Averill C (2022). Forest tree growth is linked to mycorrhizal fungal composition and function across Europe. The ISME journal. doi.org/10.1038/s41396-021-01159-7.

Paper 8: Thakur MP, van der Putten WH, Wilschut RA, Veen GFC, Kardol P, van Ruijven J, Allan E, Roscher C, van Kleunen M & Bezemer TM (2021). Plant-Soil Feedbacks and Temporal Dynamics of Plant Diversity-Productivity Relationships. Trends in Ecology & Evolution, 36, 651–661. doi.org/10.1016/j.tree.2021.03.011.

Plant chemicals or metabolites are important factors in shaping biotic interactions in ecosystems. The entirety of all plant metabolites is the plant metabolome and the study of the metabolome is called (eco) metabolomics. In this session we will specify what the term (eco)metabolomics means. We will illustrate how ecometabolomic approaches help to understand particular ecological questions in BEF projects such as TreeDi. We will briefly discuss which analytical platforms are used and how to select the right one. Finally, we will specify how to sample plant and other organic materials for ecometabolomic analyses in the field.

Paper 9: Walker TWN, Alexander JM, Allard P‐M, Baines O, Baldy V, Bardgett RD, Capdevila P, Coley PD, David B, Defossez E, Endara M‐J, Ernst M, Fernandez C, Forrister D, Gargallo‐Garriga A, Jassey VEJ, Marr S, Neumann S, Pellissier L, Peñuelas J, Peters K, Rasmann S, Roessner U, Sardans J, Schrodt F, Schuman MC, Soule A, Uthe H, Weckwerth W, Wolfender J‐L, Dam NM & Salguero‐Gómez R (2022). Functional Traits 2.0: The power of the metabolome for ecology. Journal of Ecology, 110, 4–20. doi.org/10.1111/1365-2745.13826.

Paper 10: Endara M‐J, Soule AJ, Forrister DL, Dexter KG, Pennington RT, Nicholls JA, Loiseau O, Kursar TA & Coley PD (2022). The role of plant secondary metabolites in shaping regional and local plant community assembly. Journal of Ecology, 110, 34–45. doi.org/10.1111/1365-2745.13646.