Global drivers influencing vegetation during succession: Factors and implications

Question

Following a significant disturbance, vegetation development may, or may not reach the desired target. Here, we examine which relevant global environmental factors have a substantial impact on the course of spontaneous vegetation succession, and what their relative relevance is in achieving the desired outcome.

Location

Worldwide.

Methods

The outcome of vegetation changes in 528 studies describing spontaneous succession worldwide was classified at a simple, semi-quantitative scale: fully-successful, partly-successful, and unsuccessful, considering 10 different types of disturbances. Latitude, climatic factors (mean annual temperature, annual temperature range, mean annual precipitation, seasonality of precipitation), and biological factors (number of vascular plant species, and number of invasive alien species) were considered as explanatory variables. The ordination method (principal coordinate analysis) was used to visualize relationships among variables and their relationships to succession outcomes. For a detailed insight into the importance of the particular variables, we applied machine learning techniques, specifically one called “conditional random forest”. In addition, the effect of different types of initial disturbance was assessed using Generalized Linear Models.

Results

Globally, disturbance type emerged as the most influential factor in determining succession outcomes. The most successful were results from recovering vegetation after fire, whereas the most unsuccessful were those after volcano eruptions. For climatic factors, the success of succession decreased with a low annual temperature range and high temperature mean. Biological factors such as the number of invasive alien species and species richness had the least but significant influence on the succession success.

Conclusions

The most relevant factor determining the outcome of spontaneous succession was disturbance type, followed by temperature variables. Notably, latitude emerged as a practical proxy for many ecologically relevant factors. Therefore, we conclude that latitude may be a valuable predictor of the success of succession and, consequently, of the success of ecological restoration projects that are based on spontaneous succession.