Ecological drift (Box 1) is generally the most understudied of the four community processes, and has primarily been considered in microbes and terrestrial plant communities (e.g., Hubbell 2001). However, it should be noted that the more general process of stochasticity is increasingly studied by ecologists (Shoemaker et al. 2020). For example, rather than being studied directly, the strength of drift has been inferred from random variation in species abundance distributions (Chase 2010) or quantified as unexplained variation in community dynamics models (Vellend et al. 2014). Because few studies directly quantify drift, in particular across several ecosystem types, we know very little about how humans impact this process in terrestrial and freshwater communities (Figure 3).