Temporal dynamics of tree diversity effects on growth, mortality and biomass production (BIOTREE project)
Forestry
Final Report Abstract
Biodiversity is increasingly recognized as a key component of ecosystems that directly influences many ecological processes and functions. The largest fraction of biodiversity-ecosystem functioning research still comes from fast-growing and small-statured model systems such as grasslands. However, more recently scientists have started to study the effects of changing tree diversity in complex woody systems. In doing so, several tree diversity experiments have been established within the last 20 years, forming now a global network of such experiments. Here, we analysed the significance of tree diversity for growth, mortality and biomass production in one of the largest and oldest tree diversity experiments (BIOTREE), located in Thuringia, Germany. The BIOTREE project encompasses four different experiments at three sites, where new tree stands differing in tree diversity have been planted in the years 2003/2004, adopting different designs. In two experiments, gradients of tree species richness have been established. In a third experiment, differences in functional diversity have been created while keeping the number of species per plot constant. In a fourth experiment, species evenness and planting density have been manipulated. In total, more than 200,000 trees have been planted. In this project we extended existing time series of tree growth and mortality assessments with a new measurement campaign 16 years after planting. We quantified temporal scale dependencies of tree diversity effects on tree growth, mortality and biomass production. In general, we found highly species-specific growth and mortality rates across all experiments. Further, there was no general and strong positive tree diversity-productivity relationship across the different experiments. However, we observed a shift in the diversity-productivity relationship over time in one experiment, with initially neutral or weak negative relationships, which became positive and stronger with time. Thus, the emergence of a positive diversity-productivity relationship in temperate forest plantations requires significant time and is promoted by diversity at the neighbourhood scale.
Publications
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Changes in the direction of the diversity–productivity relationship over 15years of stand development in a planted temperate forest. Journal of Ecology, 110(5), 1125-1137.
Shovon, Tanvir Ahmed; Kang, Stephanie; Scherer‐Lorenzen, Michael & Nock, Charles A.
