Community maturity, species saturation and the variant diversity–productivity relationships in grasslands

Abstract

Detailed knowledge of the relationship between plant diversity and productivity is critical for advancing our understanding of ecosystem functioning and for achieving success in habitat restoration efforts. However, effects and interactions of diversity, succession and biotic invasions on productivity remain elusive. We studied newly established communities in relation to preexisting homogeneous vegetation invaded by exotic plants in the northern Great Plains, USA, at four study sites for 3 years. We observed variant diversity-productivity relationships for the seeded communities (generally positive monotonic at three sites and non-monotonic at the other site) but no relationships for the resident community or the seeded and resident communities combined at all sites and all years. Community richness was enhanced by seeding additional species but productivity was not. The optimal diversity (as indicated by maximum productivity) changed among sites and as the community developed. The findings shed new light on ecosystem functioning of biodiversity under different conditions and have important implications for restoration.

The Scaling of Host Density with Richness Affects the Direction, Shape, and Detectability of Diversity-Disease Relationships

“…For example, Guo et al [14] showed that non-monotonic relationships between biomass production and grassland plant richness exist, but only when a wide enough range of richness is sampled. In our model, if the host community size is smaller than that required for the community to begin saturating (e.g., if host community <20 species in Figure 2D), an amplification effect would be the logical expected outcome of diversity loss, but this expectation would change if more speciose communities were sampled.…”

“…However, a more realistic expectation might be that community abundance saturates with increasing richness. For example, saturation of total community biomass and percent cover has been documented in various plant systems [12]–[14]. Despite these observations, the effects of saturating host abundance on pathogen transmission have not been explored theoretically or empirically.…”

Duck Productivity in Restored Species-Rich Native and Species-Poor Non-Native Plantings

“…This approach differs from the original approach where 3-5 species of vegetation were used in the seed mix by including 16-32 species, a level that reaches a saturation point, thus, is more resistant to invasion of exotic species [36-38]. Similar to DNC, productivity and vegetation vigor within species-rich planted fields declines as the stand ages, however, proper disturbance of native vegetation that is adapted to the local environment and disturbance can eliminate the need to reseed plantings [15,39,40].…”

“…Low diversity plantings are more susceptible to invasion of exotic plant species and provide lower levels of productivity at maturity [38]. More diverse species rich plantings of 16–32 species in the Prairie Pothole…”

“…Region resist invasion of exotic species and maintain higher productivity at maturity, thus, should better support nesting birds relative to the fields of low-diversity native vegetation evaluated in the past [38]. A comparison of duck productivity between species rich (16-32 species) native plantings and DNC, however, has not been conducted.…”