The growth (basal area increment (BAI)) of shrubs in TSQs. From 2023 to 2024 Site A and 2024 to 2025 Site B. BA calculated from individual circumference and diameter d10 measurements and summed for all stems per shrub. Difference in BA from one year to the next = BAI.

A protocol was developed in 2023 for Site A for measuring trees and shrubs of TSQs; including DBH, d10, height and canopy diameters. The same protocol was used in 2024 during the establishment of the TSQs in Site B. Minor adjustments were, however, made to improve this protocol. In 2024, the shrubs in the TSQs of Site A were remeasured, to evaluate how much they grew (especially in their d10) within one year. Similarly, the shrubs in the TSQs in Site B were remeasured in 2025.

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

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

As a result of the protocol, there can be multiple measurements of diameter and or circumference for multi-stemmed individuals. The different stems of an individual were, however, not marked. It is, thus, not possible to compare the growth of specific stems, making it necessary to calculate a total value for each shrub. Each circumference and diameter were, therefore, converted into basal area in R Studio (Version 2024.09.0+375), using the following formula (reference: Bettinger et a. 2017, Chapter 2 in Forest Management and Planning 2nd edition): BA=πr^2, where pi=3.14 and r is the circumference. The basal areas for all individual measurements of each shrub were totalled to get one value per shrub, per year. Debugging tests were performed to check for errors in the data. The final data for Site A provided measurements for 2023 and 2024 for 102 shrubs/TSQs. Site B resulted in 101 shrub/TSQ measurements for 2024 and 2025. The difference in basal areas between 2023 and 2024, and 2024 and 2025, for each shrub was calculated for Site A and Site B respectively; this was used as a measure of growth. Negative growths resulting from measurement mistakes, or the death of stems were checked manually for mistakes in the digitalisation of the data, and corrected accordingly. Where it was evident that stems had died, the measurements of all stems of that individual were ranked (from highest to lowest), and the years were compared. This made it mostly possible to identify which stem had died and to remove this stem from the data of the first year. Thus, the difference in growth between years only included stems present in both years. Where the measurements of the individual stems were very similar, a random stem was selected to be removed. Several negative growths could not be explained and occurred simply due to minor measurement differences (for example due to differences measuring tapes or people, as well as the swelling/decreasing of trunks during different hours of the day or different climatic conditions); these were left unaltered.