Species richness and functional-trait effects on fine root biomass along a subtropical tree diversity gradient

Climatic conditions, not above- and belowground resource availability and uptake capacity, mediate tree diversity effects on productivity and stability

“…Contrary to our first hypothesis (H1), tree species richness was not significantly associated with LAI or fine root biomass, which were considered as proxies for resource uptake capacity. These results contradict previous studies that reported positive associations between tree species richness and LAI (Peng et al, 2017;Unger et al, 2013) or between tree species richness and root biomass (Brassard et al, 2013;Zeng et al, 2020;Zeng et al, 2021) in both planted experiments and natural forests. The positive association between tree species richness and LAI can be driven by increased photosynthetic efficiency or reduced clumping of the leaf area at higher species richness, thereby enhancing the interception and/or use efficiency of incoming radiation at a given LAI (Hardiman et al, 2011;Hardiman et al, 2013).…”

Tree species mixing reduces biomass but increases length of absorptive fine roots in European forests

“…Studies reported a higher (e.g. Brassard et al, 2013;Sun et al, 2017;Valverde-Barrantes et al, 2015;Zeng et al, 2020) or lower biomass (Archambault et al, 2019;Bolte & Villanueva, 2006), or no changes in mixtures compared to pure stands (e.g. Bauhus et al, 2000;Finér et al, 2017;Ma & Chen, 2016;Peng & Chen, 2020).…”

Tree species mixing causes a shift in fine‐root soil exploitation strategies across European forests

“…Hence, the quantification of trait diversity using traitbased diversity indices (Laliberté & Legendre, 2010) may be useful for assessing underlying mechanisms of diversity effects. Positive relationships of such trait-based indices with standing biomass or productivity of fine roots were reported (Mahaut et al, 2020;Sun et al, 2017) while other studies did not observe such effects (Bakker et al, 2019;Zeng et al, 2020).…”

“…The considered traits were selected due to their important role for the plant economics spectrum (Freschet et al, 2010;Reich, 2014) and to avoid redundancy. Species abundance data were derived from the biomass proportions of the individual species' absorptive fine roots (Zeng et al, 2020).…”