The new growth (stem increments) of the shoots of shrubs in TSQs were measured

As plants may invest in growing shoots, for example to increase exposure to light, rather than investing in growing only in basal diameter, new growth of shrubs was also measured. We define new growth as recently grown and clearly distinguishable terminal shoot sections. The characteristics (twig colour, hairiness, carrying not fully unfolded leaves etc.) are species-specific, however, a protocol was developed accordingly (Shrub stem increment Protocol_clean_CW.docx). The time over which these new shoots have grown is not known. The general approach across all species, was to select the five thickest stems from the base (for multi-stemmed species) or five branches, including the apex (for single-stemmed individuals). Thereafter, these stems were followed upwards, continuously following the thickest stem at branching’s, until the thickness reached a diameter of 0.5cm (measured with a calliper). From this point, all new growths on the stem were measured using a measuring stick. The number of measurements (count) was, thereby, automatically noted too. Where the growth was longer than the 0.5cm mark, both the total length and the length from 0.5cm thickness were measured. For ViSe and CaCh, first and second flush were differentiated where present. Stems with fruit were also noted. Dead or broken-off stems were not measured/excluded. In addition to measuring growths by following the above-mentioned procedure (realised growth), the five longest growths per shrub were also measured. As some species, such as DiBu, have very few growths, this allows us to capture how well the shrub is able to grow, when growth is indeed present (potential growth).

BEF-China experiment, located near Xingangshang, Dexing City of Jianxi Province (Sites A and B)

Plants (Shrubs): Distylium buxifolium (DiBu), Viburnum setigerum (ViSe), Camellia Chemikiangoleosa (CaCh) and Distylium myricoides (DiMy)

For the final stem increment growth data, the first and second flushes from one new growth were totalled and were taken from the 0.5 cm diameter mark (see Supplementary Appendix 4). For growths which started before the 0.5cm mark (i.e. were longer), only the length from the 0.5 cm mark was used. For stems with first and second flushes with growths longer than from the 0.5 cm mark, the 2nd flush was calculated by subtracting the first flush from the length from the 0.5 cm mark. Finally, the percentage of the number of growths with first and second flushes (per individual) was calculated by dividing the number of stems with first and second flushes, by the total number of new growths on that individual (including longest stems). From the final data, four variables were extracted, using R (BAI_and_Stem_increments.R)