Moso bamboo (Phyllostachys edulis) invasion increases forest soil pH in subtropical China

Soil pH has cascading effects on terrestrial ecosystem functions by regulating the biogeochemical cycle, which can be altered by plant invasion. Bamboo invasion occurs throughout the world in both native and introduced habitats, especially in Asia. However, the effect of bamboo invasion on soil pH is still poorly understood. Here, we investigated the invasion-induced change in pH (CIP) with pairwise sampling from 215 bamboo-tree transects in subtropical China, including 203 pure bamboo forest (BF) plots, 188 mixed bamboo-tree forest (MBTF) plots and 199 non-bamboo-invaded tree forest (TF) plots. We found a significant increase in soil pH after bamboo invasion from 4.44 (+/- 0.03) in TFs to 4.52 (+/- 0.03) in MBTFs and 4.67 (+/- 0.03) in BFs. The CIP was related to the invaded forest type, with the largest changes in deciduous broadleaf (0.38 +/- 0.09) and mixed evergreen and deciduous broadleaf forests (0.38 +/- 0.10), followed by mixed needleleaf and broadleaf forests (0.24 +/- 0.05), and the smallest changes in evergreen broadleaf (0.19 +/- 0.03) and needleleaf forests (0.20 +/- 0.03). Further analysis showed that the CIP increased linearly with invasive bamboo density and was independent of climate factors. Overall, we provide the first evidence of a large-scale observation for bamboo invasion-induced forest soil pH increase. Our findings highlight that plant invasion should not be neglected as a driver of global change via its effects on soil pH.