HighDiv-SRC is adopting the overall goal of tree diversity experiments to the applied realm of Short-Rotation Coppice plantations and their industrial applications. Hence, HighDiv-SRC aims to assess the effects of tree species diversity on various ecosystem functions and, ultimately, tree growth and yield stability (e.g. resistance to drought and pests) in short rotation coppice plantations. Particular focus is on ecosystem functions that are important for the assessment of ecological sustainability, such as water and nutrient use, carbon sequestration and biodiversity. The experiment was planted in Freiburg in spring 2015 and ended in winter 2019.

Location field experiment (Freiburg)

Design
The experiment follows a randomized block design with three replicates (blocks). Four species that are often used in commercial short-rotation plantations were planted in all theoretically possible combinations, i.e. plots with single species and mixtures of two, three and four species. Consequently, each block contains fifteen plots with different species combinations. Each plot contains nine subplots that will be used for specific assessments (e.g. litter decomposition, weed dynamics, soil biology). Planting density was about 15 600 ha^-1.

Schematic view of the plantation with the 3 blocks (blue, red, green), plot numbers (Pl), and species (W: Salix, Ro: Robinia, Pau: Paulownia, Pap: Populus)

Hexagonal planting design of monoculture, 2-species, and 3-species plots. In plots with three and four species, the species positions were randomized with the restriction that, within columns and lines, each individual had to be directly neighboured by an individual of a different species.

Site characteristics

location	Freiburg
former land use	grassland, sheep grazing
altitude	230 m
soil type	Cambisol
area	0.4 ha
no of plots	45
plot size	9.6 m x 9.6 m
no of trees planted	6480
planting date	spring 2015
end date	winter 2019
diversity variables	species richness
diversity gradient	1, 2, 3, 4 sp.
size species pool	4
species pool	Paulownia tomentosa Populus maximowiczii x trichocarpa Robinia pseudoacacia Salix schwerinii x viminalis 'Tora'
contact person	Michael Scherer-Lorenzen

Research
HighDiv-SRC tests the hypothesis that productivity and yield stability of bio-energy plantations can be enhanced by the use of appropriate species mixtures, and we attempt to quantify the effects of mixtures on ecosystem processes relevant to sustainability, e.g., nutrient cycling and carbon sequestration.
The research has implications for future bio-energy concepts, because new SRC plantations should comply with the sustainability requirements (e.g. biodiversity, C sequestration) for a carbon-neutral and environmentally friendly energy source.

Extra information
Send an e-mail to the contact person or explore the publications:
theses

• Arranz C (2020) Use of mixtures in short rotation coppice plantations to increase productivity. PhD thesis, University of Freiburg

papers

• Messier C, Bauhus J, Sousa-Silva R, Auge H, Baeten L, Barsoum N, Bruelheide H, Caldwell B, Cavender-Bares J, Dhiedt E, Eisenhauer N, Ganade G, Gravel D, Guillemot J, Hall JS, Hector A, Hérault B, Jactel H, Koricheva J, Kreft H, Mereu S, Muys B, Nock CA, Paquette A, Parker JD, Perring MP, Ponette Q, Potvin C, Reich PB, Scherer-Lorenzen M, Schnabel F, Verheyen K, Weih M, Wollni M, Zemp DC (2021) For the sake of resilience and multifunctionality, let's diversify planted forests! Conservation Letters e12829 - https://doi.org/10.1111/conl.12829
• Schweier J, Arranz C, Nock C A, Jaeger D, Scherer-Lorenzen M (2019) Impact of Increased genotype or species diversity in short rotation coppice on biomass production and wood characteristics. BioEnergy Research 12: 497-508 - https://doi.org/10.1007/s12155-019-09997-2
• Müller M, Klein A-M, Scherer-Lorenzen M, Nock CA, Staab M (2018) Tree genetic diversity increases arthropod diversity in willow short rotation coppice. Biomass and Bioenergy 108: 338-344 - doi:10.1016/j.biombioe.2017.12.001

July 2016	May 2017