Tree diversity effects on forest productivity increase through time because of spatial partitioning

Abstract

<jats:title>ABSTRACT</jats:title><jats:sec><jats:title>Background</jats:title><jats:p>Experimental manipulations of tree diversity have often found overyielding in mixed-species plantations. While most experiments are still in the early stages of stand development, the impacts of tree diversity are expected to accumulate over time. Here, I present findings from a 31-year-old tree diversity experiment (as of 2018) in Japan.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>I find that the net diversity effect on stand biomass increased linearly through time. The species mixture achieved 64% greater biomass than the average monoculture biomass 31 years after planting. The complementarity effect was positive and increased exponentially with time. The selection effect was negative and decreased exponentially with time. In the early stages (≤3 years), the positive complementarity effect was explained by enhanced growths of early- and mid-successional species in the mixture. Later on (≥15 years), it was explained by their increased survival rates owing to vertical spatial partitioning — i.e., alleviation of self-thinning via canopy stratification. The negative selection effect resulted from suppressed growths of late-successional species in the bottom layer.</jats:p></jats:sec><jats:sec><jats:title>Conclusions</jats:title><jats:p>The experiment provides pioneering evidence that the positive impacts of diversity-driven spatial partitioning on forest biomass can accumulate over multiple decades. The results indicate that forest biomass production and carbon sequestration can be enhanced by multispecies afforestation strategies.</jats:p></jats:sec>

Prolonged impacts of past agriculture and ungulate overabundance on soil fungal communities in restored forests

“…Forest restoration using tree species mixtures has recently received much social interest (Tatsumi, 2020; Verheyen et al, 2016). Plant diversity has often shown to have positive effects on soil fungal diversity in grassland experiments (Milcu et al, 2013; Scherber et al, 2010).…”