The role of grazers on the long-term diversity and predictability of herbaceous communities

Informations

Funding country

Netherlands

Acronym

-

URL

-

Start date

1/4/2018

End date

2/27/2018

Budget

5,000 EUR

Fundings

Abstract

For more than a century it was assumed that abiotic factors (first) and biotic interactions (later) were the underlying forces driving the observed patterns of species composition, abundance and distribution in natural communities (these interactions currently fall within the niche theory). It was not until recently that the neutral theory of biodiversity was formalized and the role of dispersal limitation and chance were considered fundamental drivers of biodiversity patterns. Nowadays it is widely accepted that both apparently opposing views are taking place simultaneously and several factors affect the relative importance of each, finally shaping biodiversity patterns. Given the many benefits that biodiversity provides to humankind, along with the current trends showing biodiversity declines due to anthropogenic activities, there is an increasing pressure to understand how to conserve and restore biodiversity. Grazing with large herbivores is a common practice to increase biodiversity in natural areas. Grazing promotes plant species coexistence by relaxing competition light , something increasingly frequent in grasslands due to increased anthropogenically induced nitrogen deposition. Furthermore, evidence also suggests a prominent role of grazers on plant dispersal and diversity which depends on system productivity. Grasslands and salt marshes are two herbaceous systems with clear differences in biotic and abiotic conditions that generally lead to differences in functioning. Salt marshes are among the most productive systems worldwide, with relatively low diversity and high influence of abiotic stress that along with competition and facilitation has marked consequences on plant abundance and zonation patterns. Grasslands, in turn, exhibit higher diversity, are generally less productive, with abiotic stress playing a more subtle role in species zonation and abundance compared to biotic interactions. Besides their inherent differences in productivity and diversity, grazers can induce mosaics of short and tall vegetation in both systems. Particularly in grasslands, recent results revealed that in relatively short time spans, grazing promotes more predictable and less variable plant communities. However, it is not clear whether these results can be extrapolated to other herbaceous systems (e.g. salt marshes) or even if they may still hold over longer time frames. The proposed visit by Dr. Alberti will provide the opportunity to collaborate on a paper that identifies the role of grazers on the long-term diversity and predictability of herbaceous communities by answering a set of questions including: (1) Does long-term (> 25 years) large-herbivore grazing affect spatial and temporal β diversity? (2) Does long-term large-herbivore grazing regulate the relative importance of niche and neutral community assembly? (3) Are these results consistent across two contrasting herbaceous systems (salt marshes and grasslands)? The Conservation Ecology group has unique long-term (> 25 yr) datasets of grazing effects on different herbaceous systems, which are extremely rare in ecology and essential to address the general goal of this proposal.