Extracellular Enzyme Stoichiometry Reveals Microbial Nutrient Limitation Under Construction Disturbance: A Case Study of the Wangbuqu Alpine Meadow in the Eastern Qinghai–Tibet Plateau

ABSTRACT Construction activities are becoming increasingly frequent in alpine meadow regions, yet their effects on soil nutrient status and microbial communities remain insufficiently quantified. Taking an undisturbed fresh meadow (FM) as the reference, we examined four types of construction‐induced disturbance within the same project: stacked turf (ST), tunnel portal slope (TPS), spoil pile (SP), and camping disturbance (CD). Approximately 1 year after construction commenced, surface soil samples were collected and analyzed for soil physicochemical properties, extracellular enzyme activities, microbial diversity, and microbial nutrient limitation inferred from enzyme stoichiometry. Construction activities significantly altered soil acidity–alkalinity and nutrient levels. Soil pH was 5.63 ± 0.04 in FM but increased to 8.04 ± 0.57 in TPS. Relative to FM, disturbed soils showed consistent decreases in alkaline‐hydrolysable nitrogen, soil organic carbon, readily oxidizable organic carbon, and dissolved organic carbon, whereas available phosphorus increased by 4.0% (TPS) to 58.8% (CD). Compared with the control, alkaline phosphatase activity decreased by 2.3% (SP) to 30.9% (TPS), and β‐glucosidase activity decreased by 1.6% (SP) to 40.3% (TPS). Microbial metabolism was generally dominated by nitrogen limitation, accompanied by a certain degree of carbon limitation. Relative to FM, microbial nitrogen limitation increased by 25.6% in TPS but decreased by 12.8% in CD. Construction activities overall increased soil microbial, especially fungal, α‐diversity, whereas the bacterial and fungal community compositions in ST and TPS diverged markedly from those in FM. These results indicate that, at an annual time scale, construction activities in alpine meadows induce soil alkalization, reduce plant‐available carbon and nitrogen and the activities of related nutrient‐acquiring enzymes, and modify microbial diversity and community structure. Among the four disturbance types, tunnel portal slopes exhibited stronger soil degradation and a lower potential for natural recovery. This study provides a basis for quantitative assessment of the impacts of construction activities on alpine meadow soils and microbial communities and for designing subsequent ecological restoration strategies.