Restoration is increasingly being used to reverse degradation and destruction of forest ecosystems. With increasing investment in restoration, there is an urgent need to develop effective programs to assess treatment efficacy and effects. We conducted a global review of forest restoration assessments, in order to identify geographic trends in the locations where assessments have been implemented and the specific ecological attributes (ecosystem composition, structure, and function) and indicators being used to measure effects. We found that the number of forest restoration assessments varied by region and was not related to degree of degradation or restoration need. Some regions, like Africa, which have experienced high rates of forest loss and degradation, had few assessments. The majority (43%) of assessments included indicators for only two of three key ecological attributes (composition‐structure or composition‐function) and assessments on average used fewer than three indicators per attribute. The most commonly employed indicators for composition were richness and abundance of plant species and for structure were height and diameter of trees, variables that are generally relatively easy to measure. The use of functional indicators has been increasing over time and they are now more commonly used than structural indicators. The most common functional indicators were soil functions. Most investigators evaluated treatment effects for 6–10 years after implementation. Our findings related to gaps in analysis of ecological indicators can serve as a guide for developing monitoring and assessment protocols for current global forest restoration initiatives by 2020–2030.

Forest restoration is considered among the most affordable and effective practices to address ecosystem and biodiversity loss and mitigate the impacts of human-induced global change. Soils are intrinsically complex systems that mediate and regulate multiple processes and functions vital for forest ecosystem restoration. Although monitoring soil attributes are critical for evaluating the success of forest restoration projects, research, and development of soil function indicators are still limited. Here, we have reviewed the most commonly reported soil indicators in forest restoration research and their recovery trajectory on a global scale. We also identified and discussed less frequently used indicators that have the potential for monitoring ecosystem recovery. We found that soil indicators have considerably increased in the literature. However, research is regionally concentrated, and a significant proportion of publications neither considered reference ecosystems (41%) nor provided basic information about soil types (<21%). The most reported indicator types were chemical (76%) (e.g., soil carbon, nitrogen, and pH). A significant proportion of the studies (46%) performed long-term evaluations (>15 years) of indicators. The majority of the indicators tended to resemble the levels of the reference ecosystem in the long term, with a few exceptions (e.g., water content and bulk density). We identified several less used but more integrative indicators with great potential for monitoring forest ecosystem recovery (e.g., aggregate stability, oxidizable carbon, soil respiration, and enzyme activity). Our results emphasize the need to effectively develop standardized soil health indicators to monitor ecosystem recovery under different conditions and expand their use in underrepresented regions.