Key gaps in soil monitoring during forest restoration in Colombia

The knowledge of soil indicators during forest restoration is essential for understanding the recovery of ecosystem functionssuch as biomass production and water regulation. Despite this importance, in most restoration programs over the world, thesoil remains under-investigated. Here, we conducted a systematic literature review in order to determine: (1) the extent to whichsoil indicators are monitored during forest restoration in Colombia; (2) the type of soil indicators (e.g. physical, chemical, orbiological) that are used for the monitoring; and (3) the regions where soil indicators are measured. We found 34 studies thatreport soil indicators. The most frequently studied restoration sites were 0–5 years old (36%). The majority (71%) of the studiesonly measured the soil characteristics at the topsoil. Soil sodium (Na) and phosphorus (P) concentrations were the most com-mon chemical soil indicators reported by the studies. Soil biological indicators were the least frequently reported indicators.The studies rarely reported soil indicators that affect water movement directly. Of the retrieved studies, most included infor-mation about old-growth forests (63%) or degraded sites (56%) for comparisons with forests undergoing restoration. Basedon these results we provide recommendations for monitoring soil characteristics to assess the effectiveness of forest restorationprojects in Colombia, and other tropical countries