Resources do not limit compensatory response of a tallgrass prairie plant community to the loss of a dominant species

Abstract

1. The effect of species loss on ecosystem productivity is determined by both the functional contribution of the species lost, and the response of the remaining species in the community. According to the mass ratio hypothesis, the loss of a dominant plant species, which has a larger proportionate contribution to productivity, is expected to exert an overwhelming effect on this important ecosystem function. However, via competitive release, loss of a dominant species can provide the opportunity for other plant species to establish, thrive and become abundant in the community, potentially compensating for the function lost. Furthermore, if resource limitation is removed, then the compensatory response of function to the loss of a dominant species should be greater and more rapid than if resources are more limiting.2. To evaluate how resources may limit compensation of above-ground productivity to the loss of a dominant plant species, we experimentally removed the C 4 perennial tallgrass, Andropogon gerardii, from intact plant communities. We added water for 4 years, as well as nitrogen in the fourth year, to test the effect of resource limitation on the compensatory response.3. Overall, above-ground biomass production increased in the remaining community with both water and nitrogen addition. However, this increase in biomass production was not sufficient to fully compensate for the loss of A. gerardii, indicating water and nitrogen were not limiting short-term compensation in this community. 4. Following the removal of the dominant species, there was reordering of species abundances in the community, rather than changes in species richness. The C 4 grass Bouteloua curtipendula was the most responsive species, increasing by 57.9% in abundance with water addition and 91.0% with both water and nitrogen addition. Despite this dramatic increase in abundance, its short stature and lower per capita biomass production prevented this species from compensating for the loss of A. gerardii. 5.Synthesis. Short-term compensation after the loss of a dominant plant species can be hastened by increased resource availability, but ultimately full compensation appears to be limited by the presence and abundance of species in the remaining community that possess traits that allow them compensate for the species lost.

Short-Term Responses of Alpine Vegetation to the Removal of Dominant versus Sparse Species

“…Given that the N and P content in the soil of our experimental sites falls within the medium to high range (N: 4.66-12.62 g/kg, P: 0.62-0.65 g/kg) when compared to N and P values reported by other studies [19], so the high-altitude grasslands in our study site may not necessarily experience nutrient limitations. Chaves and Smith [36] similarly confirmed through removal experiments that resource availability was not a limiting factor in the compensatory effects observed within plant communities following the loss of the dominant species. In addition, short-term responses mostly involve partial compensation, as opposed to long-term experiments where full compensation may be achieved [21].…”

“…However, given that the alpine vegetation in our experimental site is accessible to both wild and domestic herbivores, an extended experiment duration could pose challenges in distinguishing the specific impact of the dominant plant species from that of herbivores on the alpine vegetation. Furthermore, even studies conducted over extended periods often yield varying findings, and full compensation is not consistently attained [31,36,37]. This could be attributed to variations in nutrient uptake efficiency among different species in high-altitude grasslands [38].…”

“…We conducted a removal experiment in a randomly selected grassland site with flat terrain and similar species composition early in the growing season. We established a total of six replicate sets of 1 m × 1 m plots [41], and each plot separated by a minimum of 1 m. Within each plot a total of four 0.5m x 0.5m subplots [36,41] were divided (a total of 24 subplots) and randomly subjected to four treatments as follows: (1) The removal of the abundant species, B.sinocompressus (AR); (2) the removal of the sparse species, P.secundiflora (SR); (3) the double removal of B.sinocompressus and P.secundiflora (DR); and (4) a control group with no removal treatment (NR). This design maximizes the likelihood that the experimental area will have a similar species composition.…”

Scaling‐up the biodiversity–ecosystem functioning relationship: the effect of environmental heterogeneity on transgressive overyielding

“…These studies typically conclude that more species are required to sustain ecosystem function at larger scales because different species drive functioning in different habitats, at different times or in different places. However, none of these studies conclusively show that one or a few species could not maintain function across different habitats, times or places as this requires understanding which species may or may not be able to compensate for the loss of others (Chaves and Smith 2021, Pan et al 2021, Diaz and Ernest 2022). Thus, it is still unclear whether more species are required to sustain ecosystem function as we increase spatial scale and, therefore, habitat heterogeneity.…”

Perennial herb diversity contributes more than annual herb diversity to multifunctionality in dryland ecosystems of North-western China

“…In particular, we suspect that vegetation dynamics and ecosystem reassembly continue in a context of reduced propagules, leading to a possible progressive loss of function. Under this hypothesis, the importance of plant diversity concerning the deterioration of ecosystem function may derive primarily from the effect on the recruitment of dominant species rather than from any direct effect of richness per se ( Wardle et al., 2013 ; Chaves et al., 2021 ). Consequently, whether we are considering the taxonomic, functional or phylogenetic dimensions of diversity, the influence of dominant and subordinate plant species on multifunctionality should be more fully understood in conjunction with richness and mass ratio effects.…”