New paper by Muiruri et al. in New Phytologist explored indirect effects of tree species diversity on herbivory via changes in leaf traits in the Satakunta tree species diversity experiment. We measured 16 leaf traits and leaf damage by four insect guilds (chewers, gall formers, leaf miners and rollers) on silver birch (Betula pendula) trees growing in one‐, two‐, three‐ and five‐species mixtures. A decline in the frequency of birch in mixed stands resulted in reduced leaf area. This, in turn, mediated the reduction in chewing damage in mixed stands. In contrast, associational resistance of birch to leaf miners was not trait‐mediated but driven directly by concurrent declines in birch frequency as tree species richness increased. Our results show that leaf trait variation across the diversity gradient might promote associational resistance, but these patterns are driven by an increase in the relative abundance of heterospecifics rather than by tree species richness per se. Therefore, accounting for concurrent changes in stand structure and key foliar traits is important for the interpretation of plant diversity effects and predictions of associational patterns.
Foliar fungi of silver birch (Betula pendula) were investigated in the Satakunta expeirment across a gradient of tree species richness using molecular high-throughput sequencing and visual macroscopic assessment. Sequencing revealed greater diversity of fungi on birch leaves than the visual assessment method. In general, no positive linear relationship between the fungal taxa detected by high-throughput sequencing and macroscopic assessment was found. Fungal community composition, but not fungal diversity or richness, was affected by the presence of other tree species admixed with birch. Analysis of specific fungal taxa indicated tree diversity effects at the local neighbourhood scale, where the proportion of birch among neighbouring trees varied, but not at the plot scale. In conclusion, both methods may be used to determine tree diversity effects on the foliar fungal community. However, high-throughput sequencing provided higher resolution of the fungal community, while the visual macroscopic assessment detected functionally active fungal species.
Read the whole paper here: http://www.nature.com/articles/srep41801
Sandra Barantal has presented the results from the NERC-funded project on relative importance of tree species and genetic diversity for above- and belowground processes in a boreal forest at the IUFRO Regional Congress for Asia and Oceania in Beijing, China, in October 2016.
In a new study conducted at the Satakunta forest diversity experiment we have shown that tree species diversity effects on pineapple gall adelgid on Norway spruce were mediated by changes in canopy cover around the host spruce trees. Our study therefore demonstrates that changes in forest structure may be critical to understanding the responses of herbivores to plant diversity and may underpin associational effects in forest ecosystems. Read the paper at http://dx.doi.org/10.1111/oik.03307
New paper by Haase et al. published in December issue of Oikos is based on data from three forest diversity experiments, including Satakunta. The study found contrasting effects of tree species diversity on tree growth and insect herbivory. Trees in mixtures tended to grow taller, but on average received more insect herbivory relative to monocultures. No tree species significantly benefited both in terms of increased growth and reduced herbivory when grown in mixtures. To improve both tree growth and resistance to herbivores in tree species mixtures seems therefore challenging. You can find the paper here: http://onlinelibrary.wiley.com/doi/10.1111/oik.02090/abstract
Results from the Satakunta experiments were presented at the the 13th European Ecological Federation (EEF) and 25th Italian Society of Ecology’s (S.It.E.) joint conference in Rome, Italy, on September 23rd 2015 as part of the symposium 'Biodiversity and Ecosystem Function experiments with trees' organized by Simone Mereu. Evalyne Muiruri presented results of the experiment with artificial caterpillars testing the effects of forest diversity on bird predation on arthropods whereas Sandra Barantal discussed relative importance of tree species and genetic diversity for leaf miner communities on birch.
Kris Verheyen and co-authors have published the first TreeDivNet paper, describing the worldwide network of tree diversity experiments of which Satakunta experiments are part. They describe the network, present some early results on the carbon sequestration and pest resistance potential of more diverse plantations (including data from the Satakunta experiment), and give recommendations for new, innovative experiments to complement the present network.
The paper can be found here: http://link.springer.com/article/10.1007/s13280-015-0685-1
One PhD project will explore effects of tree species diversity on wood ants in the long term Satakunta forest diversity experiment. More information here: http://london-nerc-dtp.org/forest-diversity-effects-on-wood-ants/
The other project will explore effects of tree species diversity on ecosystem services in the Satakunta experiment. More information here: http://london-nerc-dtp.org/forest-diversity-effects-on-ecosystem-services/
New paper by Muiruri et al. on effects of forest diversity on predation by birds published online in Oecologia: Do birds see the forest for the trees? Scale-dependent effects of tree diversity on avian predation of artificial larvae http://link.springer.com/article/10.1007/s00442-015-3391-6
New paper by Tedersoo et al. on effects of forest diversity on soil organisms is published online in ISME Journal: Tree diversity and species identity effects on soil fungi, protists and animals are context dependent
Katie Bott joins the Satakunta project as a field assistant and PhD student in Koricheva Lab at Royal Holloway University of London. Katie’s PhD will be on effects of forest diversity on ectomycorrhizal fungi diversity and edible mushroom production. Follow Katie’s adventures in Finland at Instagram @littlekatiebott and on Twitter @KatieBott1987