Active revegetation after mining: what is the contribution of peer-reviewed studies?

Abstract

Knowing the state of the art on research related to post-mining active revegetation can help to improve revegetation success and identify research gaps. We performed a systematic review about active revegetation after mining and identified 203 relevant studies. Most studies were performed in the USA (34%), in regions with a temperate climate (59%) and in abandoned coal mines (45%). The studies were focused on the plantation of woody species (59%) or sowing of herbaceous species (39%). The most widely evaluated treatments were the addition of amendments (24%) and fertilizers (21%), mainly with positive and neutral effects; in general, organic amendments presented more positive effects than inorganic amendments and fertilizers. We also identified studies on the effects of plowing, inoculation of microorganisms, nurse plants, herbivore exclusion and watering. The results of these treatments should be taken with caution, because they can vary according to the functional strategies of the introduced species and the local context, such as the degree of nutrient limitation in the mining area and abiotic conditions. Further research is needed in non-temperate climates, involving long-term monitoring and with detailed descriptions of the interventions to better interpret results and general implications of active revegetation of mining areas.

Keywords: Establishment; Mine; Planting; Rehabilitation; Sowing; Treatments.

Figure 1

Flow chart of the methodology used for database construction. N: number of studies selected at each step (see main text for details).

Figure 2

Number of studies identified through the literature search per year of publication. Gray bars (left Y-axis) represent the absolute number of reviewed studies per year. The black line (right Y-axis) represents the cumulative number of studies per year. Note: the literature search in 2017 includes works published up to July (N = 203).

Figure 3

Distribution of reviewed studies by country and climatic region. a) Number of studies reviewed by country. To synthesize the data, countries with the same number of studies were grouped (Groups 1 to 5). For example, Group 1 includes Spain and Brazil, with six studies each, totaling 12 studies. Group composition is described in the box (in parentheses, the number of studies per country). Dark and light orange bars represent the number of studies per country and the total number of studies per group, respectively. The numbers above the bars represent the number of studies per country or group of countries. b) Map of global distribution of studies on active revegetation after mining. Climatic regions follow Köppen classification (Köppen, 1936) (N = 203).

Figure 4

Flowchart showing the number of studies in the main categories into which they were classified and information obtained from each study.

Figure 5

Number of studies focused on sowing and/or planting, and life form of the introduced species (herbaceous or woody), of a total of 145 studies that assessed the performance of the introduced plants.

Figure 6

Number of studies assessing the effect of different types of treatments on plant performance after sowing, planting, or sowing and planting (one study may include multiple treatments) of a total of 145 studies that assessed the performance of the introduced plant.