Biology subjects

Brock, C.

Publications and source records attributed to Brock, C..

4 recordsLinked to original sources

bioRxiv2025

Dominance of indirect effects of deer populations on soil biodiversity

Deer abundances and distributions have expanded at increasing rates in several regions across the globe due to human-driven land use change, uncontrolled introductions and reintroductions, and insufficient top-down control by human or natural predators. Yet, the impact of unsustainable density of deer on the belowground component of ecosystems is understudied. Ireland is a good model for anthropic environmental context in which the population of large herbivores is not regulated by large predators nor planned hunting management. Through a combination of camera trapping paired with soil and vegetation surveys conducted with high-throughput technology, we monitored 50 sites in Irish woodlands to study the effect of varying sika deer (Cervus nippon) relative densities on soil biota. Site-level deer intensity of use correlated with vegetation through an increase in litter and moss quantity and reduction in understory vegetation. Furthermore, the effect covaried with soil pH and cascaded on soil microarthropod, bacterial and fungal communities, with more opportunistic taxa linked to high relative deer densities. We also found that variation in deer intensity of use directly affects vertebrate communities, which shifted towards a dominance of foxes, squirrels, cats and dogs - species more commonly associated to human-dominated landscapes - and a reduction in birds and mustelids, which also cascaded on soil biota. Our results thus support the hypothesis that deer overabundance has a strong potential to drive the structure of soil biota mostly through indirect effects via vertebrate fauna and vegetation, acting as a powerful ecosystem engineer. Future studies will have to experimentally tease apart the mechanisms underpinning the patterns documented in this study.

ecology↗

bioRxiv2023

Predicting forest damage using relative abundance of multiple deer species and national forest inventory data.

Human modification of landscape and natural resources have facilitated deer population irruptions across the world resulting in widespread human-wildlife conflicts. These conflicts occur across the field of natural resource management and negatively affect both the public and vested stakeholders when their livelihoods are placed at risk, for instance, the forestry sector. Deer, both native and non-native, at high densities can damage forest ecosystems impacting biodiversity and ecological functioning at multiple levels and can inflict large ecological and economic costs. The ecological drivers of forest damage and the roles of single and multiple co-occurring deer species is not well understood due to a lack of coordinated high resolution deer distribution, deer abundance and forest damage data. Here, we aim to disentangle the relationship between forest damage, forest characteristics and the roles deer play in damaging forest ecosystems. To achieve this, we adopt a novel approach integrating recent high resolution deer distribution data for multiple deer species (native and non-native) and combining them with forest inventory data collected in 1,681 sampling stations across Ireland to provide risk scenario predictions for practitioners to use on a national scale. Forest characteristics played a key role in the severity and type of damage risk that deer posed. We found all damage types were more prevalent in forests with greater tree densities where deer are more likely to find refuge from human disturbance. Bark stripping damage was more prevalent in mature forests with high tree diversity and ground level flora (e.g., bryophytes, herbs, and shrubs). Similarly, browsing damage was more prevalent in forests with greater tree richness but with understorey vegetation dominated by grass and ferns. Fraying damage was more common in mixed woodlands with understory dominated by bryophytes and grass. Crucially, we found that type and severity of forest damage were shaped by the interaction of multiple deer species occurring simultaneously, particularly at high densities, suggesting subtle inter-species competition and exclusion/partition dynamics that require further investigation to understand the ecological mechanism. Finally, we produce risk scenarios of forest damage by co-occurring deer species and precisely predict where damage is likely to occur on a national scale. We predict high levels of damage in sika and/or red deer hotspots, matching areas of highly concentrated deer distributions. This study highlights the ecological drivers and the role that co-occurring native and non-native deer species have on forest damage within a large spatial scale. By combining reliable species distribution models with the national forest inventory data, we can now provide a useful tool for practitioners to help alleviate and mitigate forest damage and human wildlife conflicts.

ecology↗

bioRxiv2021

Survey data on European organic multi-species livestock farms

While there is increasing evidence of the sustainability benefits of diversified systems in the organic cropping sector, this has been much less investigated with organic livestock farming. To fill this knowledge gap, we surveyed a sample of 128 European organic multi-species livestock farms located across seven countries - Austria, Belgium, France, Germany, Italy, Sweden and Switzerland - and covering a large range of livestock species combinations. We recorded 1574 variables as raw data out of which we calculated 107 indicators describing farm structure, management and several sustainability dimensions: resource use efficiency and conservation, animal, land and work productivities, animal and human welfare. After technical validation of the data, we withdrew 26 farms and the database covers 102 farms. This database is well suited to unveil relationships between various dimensions of organic multi-species livestock farm sustainability and their structure and management. It can help reveal sustainable strategies for organic multi-species livestock farming systems and understand levers or barriers to their development.

ecology↗

bioRxiv2017

Adaptive plasticity generates microclines in threespine stickleback male nuptial color

Adaptive phenotypic divergence is typically studied across relatively broad spatial scales (continents, archipelagos, river basins) because at these scales we expect environmental differences to be strong, and the homogenizing effect of gene flow to be weak. However, phenotypic plasticity and phenotype-dependent habitat choice are additional mechanisms that could also drive adaptation across spatially variable environments. We present evidence for apparently adaptive phenotypic variation across surprisingly small spatial scales (<2 vertical meters) in the threespine stickleback. We find that male breeding coloration varies as a function of the lakes optical-depth gradient, and these small-scale clines ( microclines) appear to be an adaptive response to ambient light gradients, as male color changes predictably in the opposite direction ( countergradient) to ambient light spectral shifts. Using visual models and field enclosure experiments, we show that these microclines result from phenotypic plasticity that maintains male conspicuousness. Our results show that adaptive phenotypic clines can exist across small spatial scales, because phenotypic plasticity rapidly generates repeatable trait-environment correlations despite the overwhelming opportunity for gene flow. Furthermore, these results provide strong evidence that phenotypic plasticity in nuptial coloration is an important mechanism for adjusting the conspicuousness of a visual signal to conspecifics.

evolutionary biology↗