Root competition can cause a decline in diversity with increased productivity

Abstract

Summary1 Plant community theory often invokes competition to explain why species diversity declines as productivity increases. Competition for all resources might become more intense and lead to greater competitive exclusion or, alternatively, competition for light only could become more intense and exclude poor light competitors. 2 To test these hypotheses, we constructed communities of seven old-field species using combined monocultures. Constructs experienced no interspecific competition, only shoot competition or only root competition, with and without fertilizer. Diversity in these limited interaction communities was compared to diversity in unfertilized and fertilized mixtures of the seven species. 3 Diversity decreased with fertilization in mixtures and in communities with only root competition. Shoot competition had small effects on the community and did not contribute to changes in diversity with fertilization. 4 Root competition may strongly impact plant community structure in unproductive communities where light never becomes limiting, or under non-equilibrium conditions following human disturbances.

Shallow landslides as drivers for slope ecosystem evolution and biophysical diversity

“…3f). Nonetheless, soil nitrogen could have also led to an increase in belowground plant competition and, consequently, in reduction of plant aboveground biomass (Rajaniemi et al 2003;Herbert et al 2004), as seen in the results from 2015 (Fig. 3d, f) and supported by the correlation tests (Fig.…”

“…4a). These processes may have led to a decrease in plant diversity (Gross and Collins 2000;Rajaniemi et al 2003), hinted at in the results from the toe stratum in 2015 when compared to 2014 (Fig. 3a, b).…”

“…woody species) could be the reason for the higher comparative species richness found after disturbance in landslide-prone zones (e.g. Myster and Walker 1997;Rajaniemi et al 2003;Soto et al 2017).…”

“…Original Paper competition for aboveground resources such as light (Rajaniemi et al 2003;Herbert et al 2004), leading to shifts in the composition and diversity of plant communities (e.g. Wilson and Tilman 1995).…”

“…However, plant interactions with the post-landslide abiotic slope features must be clarified to enhance the slope restoration success. These interactions are not yet entirely understood (Rajaniemi et al 2003;Restrepo et al 2009), and tools to adequately detect and interpret them are needed.…”