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Precipitation events are becoming more intense as the atmosphere warms, but it remains unclear how precipitation intensification will affect plant growth in arid and semiarid ecosystems. There is conflicting evidence suggesting that larger precipitation events may either increase or decrease plant growth. Here, we report the growth responses of herbaceous and woody plants to experimental manipulations of precipitation intensity in a cold, semi-arid ecosystem in Utah, USA. In this experiment, precipitation was collected and redeposited as fewer, larger events with total annual precipitation kept constant across treatments. Results from the first two growing seasons revealed that more intense events ‘pushed’ water deeper into the soil, leading to an increase in woody plant growth. To provide a longer-term and more mechanistic understanding of this response, here we will be analyzing an additional two years of shrub stem radius growth, soil water content, new root growth, root area, and herbaceous plant growth. Additionally, we performed a depth-controlled water tracer experiment to describe grass, forb, and shrub rooting distributions in different treatments. Results have implications for understanding the increase in woody plant abundance around the world in the past 50 years, a phenomenon known as shrub encroachment, and for forecasting semi-arid ecosystem responses to climate change.

Publication Date



Logan, UT


precipitation, plant growth, Western U.S., climate change


Ecology and Evolutionary Biology | Natural Resources Management and Policy

Understanding How Changes in Precipitation Intensity Will Affect Vegetation in the Western U.S.