Steven L. Chown

Handbook of protocols for standardized measurement of terrestrial invertebrate functional traits

Summary n1. Trait-based approaches are increasingly being used to test mechanisms underlying species assemblages and biotic interactions across a wide range of organisms including terrestrial arthropods and to investigate consequences for ecosystem processes. Such an approach relies on the standardized measurement of functional traits that can be applied across taxa and regions. Currently, however, unified methods of trait measurements are lacking for terrestrial arthropods and related macroinvertebrates (terrestrial invertebrates hereafter). n2. Here, we present a comprehensive review and detailed protocol for a set of 29 traits known to be sensitive to global stressors and to affect ecosystem processes and services. We give rec- ommendations how to measure these traits under standardized conditions across various ter- restrial invertebrate taxonomic groups. n3. We provide considerations and approaches that apply to almost all traits described, such as the selection of species and individuals needed for the measurements, the importance of intraspecific trait variability, how many populations or communities to sample and over which spatial scales. 4. The approaches outlined here provide a means to improve the reliability and predictive power of functional traits to explain community assembly, species diversity patterns and ecosystem processes and services within and across taxa and trophic levels, allowing compar- ison of studies and running meta-analyses across regions and ecosystems. n5. This handbook is a crucial first step towards standardizing trait methodology across the most studied terrestrial invertebrate groups, and the protocols are aimed to balance general applicability and requirements for special cases or particular taxa. Therefore, we envision this handbook as a common platform to which researchers can further provide methodological input for additional special cases.

Antarctica's Protected Areas Are Inadequate, Unrepresentative, and at Risk

Global comparisons show that Antarcticas terrestrial biodiversity is poorly protected. Existing protected areas are inadequate, unrepresentative, and threatened by increasing human activity.

Polar lessons learned: Long-term management based on shared threats in Arctic and Antarctic environments

The Arctic and Antarctic polar regions are subject to multiple environmental threats, arising from both local and ex-situ human activities. We review the major threats to polar ecosystems including the principal stressor, climate change, which interacts with and exacerbates other threats such as pollution, fisheries overexploitation, and the establishment and spread of invasive species. Given the lack of progress in reducing global atmospheric greenhouse-gas emissions, we suggest that managing the threats that interact synergistically with climate change, and that are potentially more tractable, is all the more important in the short to medium term for polar conservation. We show how evidence-based lessons learned from scientific research can be shared between the poles on topics such as contaminant mitigation, biosecurity protocols to reduce species invasions, and the regulation of fisheries and marine environments. Applying these trans-polar lessons in tandem with expansion of international cooperation could substantially improve environmental management in both the Arctic and Antarctic.

Microclimate-based macrophysiology: implications for insects in a warming world

Understanding the influence of microclimates is an increasing focus of investigations of global change risks to insects. Here we review recent advances in this area in the context of macrophysiological forecasts of the impacts of warming. Some studies have suggested that risk estimates may be inaccurate owing to microclimate variation or behavioural responses. Using modelled microclimatic data we illustrate this problem, demonstrating that soil microclimates on the Australian continent will warm in concert with global climate change such that the upper thermal tolerance limits of many insects will be exceeded across much of the continent. Deeper microclimates will be cooler and more hospitable, emphasising the importance of behavioural adaptation and movement amongst microclimates as a response to environmental warming.

Interactions between rates of temperature change and acclimation affect latitudinal patterns of warming tolerance

Rates of temperature change and thermal acclimation can alter measures of temperature tolerance. Using new experimental data on springtails and data from the literature, we show that these factors interact and have consequences for estimates of organismal vulnerability to climate change at global scales.

Reconsidering connectivity in the sub‐Antarctic

Extreme and remote environments provide useful settings to test ideas about the ecological and evolutionary drivers of biological diversity. In the sub‐Antarctic, isolation by geographic, geological and glaciological processes has long been thought to underpin patterns in the regions terrestrial and marine diversity. Molecular studies using increasingly high‐resolution data are, however, challenging this perspective, demonstrating that many taxa disperse among distant sub‐Antarctic landmasses. Here, we reconsider connectivity in the sub‐Antarctic region, identifying which taxa are relatively isolated, which are well connected, and the scales across which this connectivity occurs in both terrestrial and marine systems. Although many organisms show evidence of occasional long‐distance, trans‐oceanic dispersal, these events are often insufficient to maintain gene flow across the region. Species that do show evidence of connectivity across large distances include both active dispersers and more sedentary species. Overall, connectivity patterns in the sub‐Antarctic at intra‐ and inter‐island scales are highly complex, influenced by life‐history traits and local dynamics such as relative dispersal capacity and propagule pressure, natal philopatry, feeding associations, the extent of human exploitation, past climate cycles, contemporary climate, and physical barriers to movement. An increasing use of molecular data – particularly genomic data sets that can reveal fine‐scale patterns – and more effective international collaboration and communication that facilitates integration of data from across the sub‐Antarctic, are providing fresh insights into the processes driving patterns of diversity in the region. These insights offer a platform for assessing the ways in which changing dispersal mechanisms, such as through increasing human activity and changes to wind and ocean circulation, may alter sub‐Antarctic biodiversity patterns in the future.

Urban warming favours C4 plants in temperate European cities

Summary nElucidating the mechanisms responsible for the structure of urban communities is a key aim of urban ecology, but one that is often confounded by the multitude of environmental changes that are caused by urbanization. We applied trait-based techniques to identify the specific environmental drivers that shape urban plant assemblages and predict how these drivers will further impact biotas with increasing urbanization and global environmental change. nUrbanized areas across temperate Europe have significantly higher abundance and richness of plants using the C4 photosynthetic pathway, relative to the total number and species richness of all plant records, than non-urban areas. nUrban warming, mediated by the contrasting physiological responses of C3 and C4 plants to warming, is the main driver of observed patterns of plant assemblage structure. This mirrors broadscale and historical distribution patterns of C3 and C4 plants. The increased relative abundance of C4 plants in cities demonstrated here may be indicative of more geographically widespread assemblage changes to be expected in temperate environments under continuing global climate change. nSynthesis. Applying a combined trait-based, ecoinformatic and remote-sensing approach provides new insight into the landscape-level consequences of urbanization. Specifically, we show that localized urban warming in cities across temperate Europe favours C4 plant species, which respond positively to increased temperatures. Urban plant assemblages are shaped by environmental warming and exhibit significant increases in C4 plant relative abundance compared to non-urban assemblages.

Basal resistance enhances warming tolerance of alien over indigenous species across latitude

Significance How climate change and biological invasions interact to affect biodiversity is of major concern to conservation. Quantitative evidence for the nature of climate change–invasion interactions is, however, limited. For the soil ecosystem fauna, such evidence is nonexistent. Yet across the globe, soil-dwelling animals regulate belowground functioning and have pronounced influences on aboveground dynamics. Using springtails as an exemplar taxon, widely known to have species-specific effects on below- and aboveground dynamics, we show that across a wide latitudinal span (16–54°S), alien species have greater ability to tolerate climate change-associated warming than do their indigenous counterparts. The consequences of such consistent differences are profound given globally significant invasions of soil systems by springtails. Soil systems are being increasingly exposed to the interactive effects of biological invasions and climate change, with rising temperatures expected to benefit alien over indigenous species. We assessed this expectation for an important soil-dwelling group, the springtails, by determining whether alien species show broader thermal tolerance limits and greater tolerance to climate warming than their indigenous counterparts. We found that, from the tropics to the sub-Antarctic, alien species have the broadest thermal tolerances and greatest tolerance to environmental warming. Both groups of species show little phenotypic plasticity or potential for evolutionary change in tolerance to high temperature. These trait differences between alien and indigenous species suggest that biological invasions will exacerbate the impacts of climate change on soil systems, with profound implications for terrestrial ecosystem functioning.

Choosing the future of Antarctica

We present two narratives on the future of Antarctica and the Southern Ocean, from the perspective of an observer looking back from 2070. In the first scenario, greenhouse gas emissions remained unchecked, the climate continued to warm, and the policy response was ineffective; this had large ramifications in Antarctica and the Southern Ocean, with worldwide impacts. In the second scenario, ambitious action was taken to limit greenhouse gas emissions and to establish policies that reduced anthropogenic pressure on the environment, slowing the rate of change in Antarctica. Choices made in the next decade will determine what trajectory is realized.The future of Antarctica and the Southern Ocean by 2070 is described under two scenarios, one in which action is taken to limit greenhouse gas emissions, and one in which no action is taken.

Climate change leads to increasing population density and impacts of a key island invader

The considerable threats of invasive rodents to island biodiversity are likely to be compounded by climate change. Forecasts for such interactions have been most pronounced for the Southern Ocean islands where ameliorating conditions are expected to decrease thermal and resource restrictions on rodents. Firm evidence for changing rodent populations in response to climate change, and demonstrations of associated impacts on the terrestrial environment, are nonetheless entirely absent for the region. Using data collected over three decades on sub-Antarctic Marion Island, we tested empirically whether mouse populations have changed through time and whether these changes can be associated significantly with changing abiotic conditions. Changes in invertebrate populations, which have previously been attributed to mouse predation, but with little explicit demographic analysis, were also examined to determine whether they can be associated with changing mouse populations. The total number of mice on the island at annual peak density increased by 430.0% between 1979-1980 and 2008-2011. This increase was due to an advanced breeding season, which was robustly related to the number of precipitation-free days during the non-breeding season. Mice directly reduced invertebrate densities, with biomass losses of up to two orders of magnitude in some habitats. Such invertebrate declines are expected to have significant consequences for ecosystem processes over the long term. Our results demonstrate that as climate change continues to create ameliorating conditions for invasive rodents on sub-Antarctic islands, the severity of their impacts will increase. They also emphasize the importance of rodent eradication for the restoration of invaded islands.