Nick Gellie

Revegetation rewilds the soil bacterial microbiome of an old field

Ecological restoration is a globally important and well‐financed management intervention used to combat biodiversity declines and land degradation. Most restoration aims to increase biodiversity towards a reference state, but there are concerns that intended outcomes are not reached due to unsuccessful interventions and land‐use legacy issues. Monitoring biodiversity recovery is essential to measure success; however, most projects remain insufficiently monitored. Current field‐based methods are hard to standardize and are limited in their ability to assess important components of ecosystems, such as bacteria. High‐throughput amplicon sequencing of environmental DNA (metabarcoding of eDNA) has been proposed as a cost‐effective, scalable and uniform ecological monitoring solution, but its application in restoration remains largely untested. Here we show that metabarcoding of soil eDNA is effective at demonstrating the return of the native bacterial community in an old field following native plant revegetation. Bacterial composition shifted significantly after 8 years of revegetation, where younger sites were more similar to cleared sites and older sites were more similar to remnant stands. Revegetation of the native plant community strongly impacted on the belowground bacterial community, despite the revegetated sites having a long and dramatically altered land‐use history (i.e. >100 years grazing). We demonstrate that metabarcoding of eDNA provides an effective way of monitoring changes in bacterial communities that would otherwise go unchecked with conventional monitoring of restoration projects. With further development, awareness of microbial diversity in restoration has significant scope for improving the efficacy of restoration interventions more broadly.

Priority actions to improve provenance decision-making

Selecting the geographic origin-the provenance-of seed is a key decision in restoration. The last decade has seen a vigorous debate on whether to use local or nonlocal seed. The use of local seed has been the preferred approach because it is expected to maintain local adaptation and avoid deleterious population effects (e.g., maladaptation and outbreeding depression). However, the impacts of habitat fragmentation and climate change on plant populations have driven the debate on whether the local-is-best standard needs changing. This debate has largely been theoretical in nature, which hampers provenance decision-making. Here, we detail cross-sector priority actions to improve provenance decision-making, including embedding provenance trials into restoration projects; developing dynamic, evidence-based provenance policies; and establishing stronger research–practitioner collaborations to facilitate the adoption of research outcomes. We discuss how to tackle these priority actions in order to help satisfy the restoration sector’s requirement for appropriately provenanced seed.

Functional acclimation across microgeographic scales in Dodonaea viscosa

We studied a native Australian shrub—Dodonaea viscosa, or sticky hop bush—in the wild and in a gardening experiment and found that the species can readily adapt to different environments. Our findings are interesting because the plants we used came from sites with quite different environmental conditions, although they were only short distances apart. Our findings indicate that the potential risks associated with moving plants between sites with different environmental conditions are not likely to cause negative outcomes for restoration projects using this species, which is commonly used for restoration in southern Australia.

Growth responses of Baumea juncea (Cyperaceae) plants from inland artesian spring and coastal habitats to salinity and waterlogging treatments

Artesian springs of arid inland Australia provide permanent water that supports naturally fragmented wetland communities. Some plant species that occur at springs have more extensive populations in coastal wetland areas of Australia where they may experience quite different environmental conditions. The present study investigated the growth response of one such species, Baumea juncea (R.Br.) Palla (Cyperaceae), to salinity and waterlogging. Plants from each region were subjected to combinations of salinity (freshwater or 20% seawater) and waterlogging (unsaturated or saturated soil), in a factorial design, for a period of 5 months. All plants survived and although the final aboveground biomasses did not differ significantly among the treatment combinations, for spring plants, the relative growth of roots was greater in unsaturated soil than in saturated soil. For the growth parameters of total biomass, culm biomass and rhizome biomass, spring and coastal plants showed contrasting responses to the treatment combinations; for spring plants in fresh water, these parameters were greater in the saturated treatment than in the unsaturated treatment, whereas for spring plants in saline water, these variables were lower in the saturated treatment than in the unsaturated treatment. Coastal plants displayed the reverse pattern. For the remaining parameters of root biomass, root : culm ratio and aboveground : belowground biomass ratio, plants from spring and coastal regions grown under saline conditions displayed contrasting responses to waterlogging. Our findings showed that the growth responses of plants of B. juncea to waterlogging and salinity differ for spring and coastal plants, suggesting potential differential adaptation by populations in these disjunct and distinct environments.