Biology subjects

Aldridge, D. C.

Publications and source records attributed to Aldridge, D. C..

4 recordsLinked to original sources

bioRxiv2024

Variable responses of individual species to tropical forest degradation

The functional stability of ecosystems depends greatly on interspecific differences in responses to environmental perturbation. However, responses to perturbation are not necessarily invariant among populations of the same species, so intraspecific variation in responses might also contribute. Such inter-population response diversity has recently been shown to occur spatially across species ranges, but we lack estimates of the extent to which individual populations across an entire community might have perturbation responses that vary through time. We assess this using 524 taxa that have been repeatedly surveyed for the effects of tropical forest logging at a focal landscape in Sabah, Malaysia. Just 39 % of taxa - all with non-significant responses to forest degradation - had invariant responses. All other taxa (61 %) showed significantly different responses to the same forest degradation gradient across surveys, with 6 % of taxa responding to forest degradation in opposite directions across multiple surveys. Individual surveys had low power (< 80 %) to determine the correct direction of response to forest degradation for one-fifth of all taxa. Recurrent rounds of logging disturbance increased the prevalence of intra-population response diversity, while uncontrollable environmental variation and/or turnover of intraspecific phenotypes generated variable responses in at least 44 % of taxa. Our results show that the responses of individual species to local environmental perturbations are remarkably flexible, likely providing an unrealised boost to the stability of disturbed habitats such as logged tropical forests.

ecology↗

bioRxiv2022

European scenarios for future biological invasions

O_LIInvasive alien species are one of the major threats to global biodiversity, ecosystem integrity, natures contribution to people and human health. While scenarios about potential future developments have been available for other global change drivers for quite some time, we largely lack an understanding of how biological invasions might unfold in the future across spatial scales. C_LIO_LIBased on previous work on global invasion scenarios, we developed a workflow to downscale global scenarios to a regional and policy-relevant context. We applied this workflow at the European scale to create four European scenarios of biological invasions until 2050 that consider different environmental, socio-economic and socio-cultural trajectories, namely the European Alien Species Narratives (Eur-ASNs). C_LIO_LIWe compared the Eur-ASNs with their previously published global counterparts (Global-ASNs), assessing changes in 26 scenario variables. This assessment showed a high consistency between global and European scenarios in the logic and assumptions of the scenario variables. However, several discrepancies in scenario variable trends were detected that could be attributed to scale differences. This suggests that the workflow is able to capture scale-dependent differences across scenarios. C_LIO_LIWe also compared the Global- and Eur-ASNs with the widely used Global and European Shared Socioeconomic Pathways (SSPs), a set of scenarios developed in the context of climate change to capture different future socio-economic trends. Our comparison showed considerable divergences in the scenario space occupied by the different scenarios, with overall larger differences between the ASNs and SSPs than across scales (global vs. European) within the scenario initiatives. C_LIO_LIGiven the differences between the ASNs and SSPs, it seems that the SSPs do not adequately capture the scenario space relevant to understanding the complex future of biological invasions. This underlines the importance of developing independent, but complementary, scenarios focused on biological invasions. The downscaling workflow we presented and implemented here provides a tool to develop such scenarios across different regions and contexts. This is a major step towards an improved understanding of all major drivers of global change including biological invasions. C_LI

ecology↗

bioRxiv2022

A scenario-guided strategy for the future management of biological invasions

Future dynamics of biological invasions are highly uncertain because they depend on multiple environmental, societal and socio-economic drivers. We adopted a qualitative scenario approach to explore the future of invasive alien species (IAS) in Europe and created an overall strategy for their management that considers different plausible future developments. The scenarios and strategy were developed during two online workshops with a multidisciplinary team of experts. First, we downscaled four global scenarios of biological invasions to the European level. Second, we developed a management strategy structured into 19 goals that cover a broad array of IAS-related topics (i.e. policy, research, public awareness and biosecurity), and provided solutions for achieving these goals considering the European scenarios. Third, we identified four interrelated recommendations around which any long-term strategy for managing IAS in Europe can be structured: (i) a European biosecurity regime, (ii) a dedicated communication strategy, (iii) data standardization and management tools, and (iv) a monitoring and assessment system. Finally, we identified the feasibility of the IAS management strategy, finding strong differences among the four scenarios. High levels of technological development, public environmental awareness, and effectiveness of IAS policies facilitated the implementation of the overall management strategy. Together, our results indicate that it is time for a new management of biological invasions in Europe based on a more integrative perspective across sectors and countries to be better prepared for future challenges.

ecology↗

bioRxiv2018

Inter-basin water transfers and the expansion of aquatic invasive species

Inter-basin Water Transfers (IBWT) are recognized as one of the major pathways of freshwater invasion. They provide a direct link between previously isolated catchments and may modify the habitat conditions of the receiving waters such that they become more favourable for the establishment of invasive species. Combined, IBWT and invasive species will intensify the stress upon native species and ecosystems. Using the Severn and Thames Rivers-two of the largest river systems in Great Britain--as a case study, here we assess the potential influence of IBWT on the expansion of invasive species and thus their impact on biodiversity conservation. The Thames Valley is subject to extensive water abstraction, and an increasing population means that supplemented flow from the River Severn is being considered. Multi-scale Suitability Models, based on climate and water chemistry respectively, provided novel evidence that there is serious risk for further spread of invasive species in the focus area, particularly of the quagga mussel, a recent invader of the Thames River. Native freshwater mussels are particularly vulnerable to changing environmental conditions, and may suffer the decrease in alkalinity and increase in sedimentation associated with an IBWT from the lower Severn to the upper Thames. Regional models suggest considerable overlap between the areas suitable for three vulnerable native freshwater mussels and the expansion of invasive species that negatively impact upon the native mussels. This study illustrates the use of novel spatially-explicit techniques to help managers make informed decisions about the risks associated with introducing aquatic invasive species under different engineering scenarios. Such information may be especially important under new legislation (e.g. EU Invasive Species Regulation No 1143/2014) which increases the responsibility of water managers to contain and not transfer invasive species into new locations.

ecology↗