Restored tallgrass prairies have reduced phylogenetic diversity compared with remnants

Abstract

Summary Ecological restoration is critical for mitigating habitat loss and providing ecosystem services. However, restorations often have lower diversity than remnant, reference sites. Phylogenetic diversity is an important component of biodiversity and ecosystem function that has only recently been used to evaluate restoration outcomes. To move towards prediction in the restoration of biodiversity, it is necessary to understand how phylogenetic diversity of restorations compares with that of reference sites, and where deficits are found, to evaluate factors constraining phylogenetic diversity. We quantified plant taxonomic and phylogenetic diversity in eastern tallgrass prairie, one of the most endangered ecosystems on earth. We measured diversity at large (site) and small (plot) scales in 19 restored prairies and compared patterns with those from 41 remnant prairies. To evaluate how environmental conditions and management actions influence outcomes, we tested the effects of soil properties and seed mix composition on diversity of restorations. Restored prairies were less phylogenetically diverse than remnants at both spatial scales. On the other hand, the total species richness of remnant and restored prairies did not significantly differ, but remnants had higher native richness. Restored communities were taxonomically and phylogenetically distinct from remnants. Soil properties (moisture and pH) influenced phylogenetic diversity and composition. There were positive relationships between the taxonomic and phylogenetic diversity of seed mixes and resulting diversity of planted assemblages (excluding volunteer species). Species in seed mixes were more closely related than expected by chance, and several clades found in remnant prairies were missing from seed mixes. Synthesis and applications. Restored tallgrass prairies had lower phylogenetic diversity than remnant prairies, which may contribute to the widely observed phenomenon of restorations not being functionally equivalent to reference sites. It is encouraging for restoration efforts that seed mix phylogenetic diversity predicted phylogenetic diversity of planted assemblages. This indicates that designing phylogenetically diverse seed mixes for restoration is beneficial. In addition, clades found in reference sites that are missing from restoration seed mixes could be added to new or existing restorations to reduce gaps in phylogenetic diversity. Further work on the effects of management on phylogenetic diversity is needed to advance restoration of biodiversity.

Interpreting variation to advance predictive restoration science

“…), to (iv) highly‐specific measures of communities, such as taxonomic composition (Matthews, Spyreas & Endress ; Turley & Brudvig ; Barak et al . ). Much of this ordering represents hypotheses in need of testing and, at present, we know of only one study that has performed such a test (Laughlin et al .…”

“…; Barak et al . )? And if so, will this new information help to shape restoration goals or quantify restoration success (Hipp et al .…”

Toward prediction in the restoration of biodiversity

“…), ecological resilience (Larios, Hallett & Suding ), community phylogenetics (Barak et al . ), and the roles of seed dispersal and plant functional traits for community assembly (Holl et al . ; Laughlin et al .…”

Are we close enough? Comparing prairie reconstruction chronosequences to remnants following two site preparation methods in Missouri, U.S.A.

“…Although prairie reconstructions may never fully support the biodiversity and ecosystem function provided by remnant prairie communities (Polley et al ; Bullock et al ; Barak et al ), they can provide conservation benefits, especially when compared to degraded and NN grassland communities (Rey Benayas et al ; Tonietto et al ; Trowbridge et al ). Studies have shown that increased floristic diversity through prairie reconstruction can result in increased diversity of other taxa (Rowe & Holland ; Tonietto et al ; Port & Schottler ).…”