Globally widespread woody encroachment into grass-dominated ecosystems has substantial consequences for carbon (C), nitrogen (N), and phosphorus (P) cycles. Despite its significance as an essential macronutrient, however, little is known regarding potential changes in the sulfur (S) cycle. We quantified S concentrations, stoichiometric relationships, and δ³⁴S values in the plant-soil environment to investigate landscape-scale changes in the S cycle following grassland-to-woodland transitions in a subtropical savanna. Plant tissues of woody species had significantly higher S concentrations and δ³⁴S values than those of herbaceous species, resulting in a landscape-scale correspondence between spatial patterns of S and δ³⁴S in surface soils (0–5 cm) and vegetation distribution, with higher S and δ³⁴S in soils beneath woody patches. These patterns were more subtle at soil depths > 5 cm. Woody plants had higher N:S ratios but comparable P:S ratios relative to herbaceous species, which contributed to contrasting spatial patterns between N:S and P:S ratios in surface soils. Sulfur in surface soils increased proportionally less relative to N, but proportionally more compared to P. Our findings indicate that grassland-to-woodland transitions amplify landscape-scale S dynamics, especially in surface soils, and create a S-enriched environment that enables woody plants to acquire sufficient S relative to demand to support their continued productivity and proliferation.

全球广泛的木本植物侵入以草为主的生态系统，对碳 (C)、氮 (N) 和磷 (P) 循环产生重大影响。然而，尽管它作为一种必需的常量营养素具有重要意义，但人们对硫 (S) 循环的潜在变化知之甚少。我们量化了植物-土壤环境中的S 浓度、化学计量关系和 δ ³⁴ S 值，以研究亚热带稀树草原从草地到林地过渡后 S 循环的景观尺度变化。木本植物组织的 S 浓度和 δ ³⁴ S 值显着高于草本植物，导致 S 和 δ ³⁴空间格局的景观尺度对应表层土壤（0-5 厘米）中的 S 和植被分布，木本斑块下土壤中的S 和 δ ³⁴ S较高。这些图案在土壤深度 > 5 cm 时更加微妙。与草本植物相比，木本植物具有较高的 N:S 比率，但具有可比的 P:S 比率，这有助于形成表层土壤中 N:S 和 P:S 比率之间的对比空间模式。表层土壤中的硫相对于 N 增加的比例较小，但与 P 相比增加的比例更多。 我们的研究结果表明，草地到林地的转变放大了景观尺度的 S 动态，尤其是在表层土壤中，并创造了一个富含 S 的环境，使木质植物获得相对于需求的足够 S 以支持其持续的生产力和增殖。