Adam T. Cross

Microbial Functional Capacity Is Preserved Within Engineered Soil Formulations Used In Mine Site Restoration

Mining of mineral resources produces substantial volumes of crushed rock based wastes that are characterised by poor physical structure and hydrology, unstable geochemistry and potentially toxic chemical conditions. Recycling of these substrates is desirable and can be achieved by blending waste with native soil to form a ‘novel substrate’ which may be used in future landscape restoration. However, these post-mining substrate based ‘soils’ are likely to contain significant abiotic constraints for both plant and microbial growth. Effective use of these novel substrates for ecosystem restoration will depend on the efficacy of stored topsoil as a potential microbial inoculum as well as the subsequent generation of key microbial soil functions originally apparent in local pristine sites. Here, using both marker gene and shotgun metagenome sequencing, we show that topsoil storage and the blending of soil and waste substrates to form planting substrates gives rise to variable bacterial and archaeal phylogenetic composition but a high degree of metabolic conservation at the community metagenome level. Our data indicates that whilst low phylogenetic conservation is apparent across substrate blends we observe high functional redundancy in relation to key soil microbial pathways, allowing the potential for functional recovery of key belowground pathways under targeted management.

Defining the role of fire in alleviating seed dormancy in a rare Mediterranean endemic subshrub

Our study provides a foundational understanding of seed ecology and germination biology in the threatened Mediterranean-endemic carnivorous plant Drosophyllum lusitanicum, with data implicating fire-related cues as a significant ecological mechanism influencing recruitment. Seeds are physiologically dormant at release and germinate rapidly after exposure to short pulses of temperatures similar to those experienced in soils during the passage of fire (80-100°C). Understanding the ecological requirements of rare and threatened species such as D. lusitanicum is critical to the implementation of effective conservation initiatives, and an accurate understanding of their reproductive mechanisms dramatically increases the likelihood of such actions to succeed.

Biodiversity responses to vegetation structure in a fragmented landscape: ant communities in a peri-urban coastal dune system

Habitat fragmentation often results in significant degradation of the structure and composition of remnant natural vegetation, leading to substantial biodiversity decline. Ants are an ecologically dominant faunal group known to be sensitive to vegetation degradation following fragmentation. We examined ant diversity and composition in relation to changes in vegetation structure in remnant coastal vegetation in the global biodiversity hotspot of southwestern Western Australia. The key features of vegetation structure driving the species and functional diversity and composition of ant communities were measures of cover of vegetation and bare ground. However, these effects were highly idiosyncratic at the species level. Cluster analyses based on plant species composition classified plots into two groups corresponding to relatively intact and degraded vegetation respectively. Although systematic changes in plant diversity and vegetation structure were observed between the two groups, key features from an ant perspective (native plant cover and bare ground) remained unchanged. Vegetation degradation consequently had little overall effect on ant species composition and functional diversity. The major disturbance–related impact on ant communities was through invasion by exotic ants, especially Pheidole megacephala; however, this occurred only in close proximity to development. Our results suggest that the priority for conserving ant diversity in our coastal dune system is the prevention of invasion by exotic species.