Rainfall pulses mediate long-term plant community compositional dynamics in a semi-arid rangeland

1. Semi-arid rangelands, comprising more than 40% of the Earth’s land surface, provide critical ecosystem services. Worldwide, these ecosystems are experiencing rapid degradation due to overgrazing and precipitation changes. However, how plants respond to these interacting factors remains relatively unexplored, and precisely which and how rainfall factors determine plant community dynamics in rangelands has not been well developed.

2. We used a long-term (1953‒2018) dataset from semi-arid rangeland to investigate coupled effects of grazing intensity and rainfall intensity (the total amount of precipitation) on different groups of plant cover (herbaceous, woody, and cacti plants) using linear mixed-effects models, redundancy analysis and structural equation models. We examined how rainfall intensity influenced plant cover dynamics according to pulse size (intensity over time) categories, which we analyzed at three scales: yearly, within the wet season only (June to September), and wit...