Effectiveness of forest density reduction treatments for increasing drought resistance of ponderosa pine growth

As the climate changes, it is increasingly important to understand how forests will respond to drought and how forest management can influence those outcomes. In many forests that have become unnaturally dense, “restoration treatments,” which decrease stand density using fire and/or mechanical thinning, are generally associated with reduced mortality during drought. However, the effects of such treatments on tree growth during drought are less clear. Previous studies have yielded apparently contradictory results, which may stem from differences in underlying aridity or drought intensity across studies. To address this uncertainty, we studied the growth of ponderosa pine (Pinus ponderosa) in paired treated and untreated areas before and during the extreme California drought of 2012–2016. Our study spanned gradients in climate and tree size and found that density reduction treatments could completely ameliorate drought‐driven declines in growth under some contexts, specifically in more mesic areas and in medium‐sized trees (i.e., normal annual precipitation > ca. 1100 mm and tree diameter at breast height