Invertebrates are the main components of faunal diversity in grasslands, playing substantial roles in ecosystem processes including nutrient cycling and pollination. Grassland invertebrate ...communities are heavily dependent on the plant diversity and production within a given system. Climate change models predict alterations in precipitation patterns, both in terms of the amount of total inputs and the frequency, seasonality and intensity with which these inputs occur, which will impact grassland productivity. Given the ecological, economic and biodiversity value of grasslands, and their importance globally as areas of carbon storage and agricultural development, it is in our interest to understand how predicted alterations in precipitation patterns will affect grasslands and the invertebrate communities they contain. Here, we review the findings from manipulative and observational studies which have examined invertebrate responses to altered rainfall, with a particular focus on large-scale field experiments employing precipitation manipulations. Given the tight associations between invertebrate communities and their underlying plant communities, invertebrate responses to altered precipitation generally mirror those of the plants in the system. However, there is evidence that species responses to future precipitation changes will be idiosyncratic and context dependent across trophic levels, challenging our ability to make reliable predictions about how grassland communities will respond to future climatic changes, without further investigation. Thus, moving forward, we recommend increased consideration of invertebrate communities in current and future rainfall manipulation platforms, as well as the adoption of new technologies to aid such studies.
Atmospheric carbon dioxide enrichment (eCO
) can enhance plant carbon uptake and growth
, thereby providing an important negative feedback to climate change by slowing the rate of increase of the ...atmospheric CO
concentration
. Although evidence gathered from young aggrading forests has generally indicated a strong CO
fertilization effect on biomass growth
, it is unclear whether mature forests respond to eCO
in a similar way. In mature trees and forest stands
, photosynthetic uptake has been found to increase under eCO
without any apparent accompanying growth response, leaving the fate of additional carbon fixed under eCO
unclear
. Here using data from the first ecosystem-scale Free-Air CO
Enrichment (FACE) experiment in a mature forest, we constructed a comprehensive ecosystem carbon budget to track the fate of carbon as the forest responded to four years of eCO
exposure. We show that, although the eCO
treatment of +150 parts per million (+38 per cent) above ambient levels induced a 12 per cent (+247 grams of carbon per square metre per year) increase in carbon uptake through gross primary production, this additional carbon uptake did not lead to increased carbon sequestration at the ecosystem level. Instead, the majority of the extra carbon was emitted back into the atmosphere via several respiratory fluxes, with increased soil respiration alone accounting for half of the total uptake surplus. Our results call into question the predominant thinking that the capacity of forests to act as carbon sinks will be generally enhanced under eCO
, and challenge the efficacy of climate mitigation strategies that rely on ubiquitous CO
fertilization as a driver of increased carbon sinks in global forests.
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FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Summary
Climate change models predict more extreme rainfall patterns, ranging from droughts to deluges, which will inevitably affect primary productivity in many terrestrial ecosystems. Insects ...within the ecosystem, living above‐ and below‐ground, may modify plant responses to water stress. For example, some functional groups improve soil conditions via resource provision, potentially alleviating water stress. Enhanced resource provision may, however, render plants more susceptible to herbivores and negate beneficial effects.
Using a model system, we tested how plants (Brassica oleracea) responded to drought, ambient and increased precipitation scenarios when interacting with both a soil conditioning ecosystem engineer (dung beetles; Bubas bison) and an above‐ground herbivore, the major crop pest diamondback moth (Plutella xylostella).
Dung beetles enhanced soil water retention by 10% and promoted growth in plants subjected to drought by 280%, relieving the impacts of water stress on plants. Under drought conditions, plants grown with dung beetles had c. 30% more leaves and were over twice as tall as those without dung beetles. Dung beetles produced a 2·7‐fold increase in nitrogen content and more than a threefold increase in carbon content of the shoots, though shoot concentrations of nitrogen and carbon were unchanged. Carbon concentrations in roots, however, were increased by dung beetles under both ambient and increased precipitation regimes.
Increased precipitation reduced root and shoot nitrogen concentrations by 16% and 30%, relative to plants under ambient regimes, respectively, most likely due to dilution effects of increased plant growth under increased precipitation. Soil carbon and nitrogen concentrations were largely unaffected.
While dung beetles enhanced plant growth and nitrogen content in plants experiencing drought, the anticipated increase in plant suitability to herbivores did not arise, possibly because shoot nitrogen concentrations and C:N ratio were unaffected.
To our knowledge, this is the first report of an insect ecosystem engineer alleviating the effects of predicted drought events on plants via physical manipulation of the soil matrix. Moreover, their effects did not change plant suitability to an above‐ground herbivore, pointing to potential beneficial role for insect ecosystem engineers in climate change adaptation and crop protection.
Lay Summary
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Abstract
Background
Climate change models predict changes in the amount, frequency and seasonality of precipitation events, all of which have the potential to affect the structure and function of ...grassland ecosystems. While previous studies have examined plant or herbivore responses to these perturbations, few have examined their interactions; even fewer have included belowground herbivores. Given the ecological, economic and biodiversity value of grasslands, and their importance globally for carbon storage and agriculture, this is an important knowledge gap. To address this, we conducted a precipitation manipulation experiment in a former mesic pasture grassland comprising a mixture of C
4
grasses and C
3
grasses and forbs, in southeast Australia. Rainfall treatments included a control ambient, reduced amount 50% ambient and reduced frequency ambient rainfall withheld for three weeks, then applied as a single deluge event manipulations, to simulate predicted changes in both the size and frequency of future rainfall events. In addition, half of all experimental plots were inoculated with adult root herbivores (Scarabaeidae beetles).
Results
We found strong seasonal dependence in plant community responses to both rainfall and root herbivore treatments. The largest effects were seen in the cool season with lower productivity, cover and diversity in rainfall-manipulated plots, while root herbivore inoculation increased the relative abundance of C
3
, compared to C
4
, plants.
Conclusions
This study highlights the importance of considering not only the seasonality of plant responses to altered rainfall, but also the important role of interactions between abiotic and biotic drivers of vegetation change when evaluating ecosystem-level responses to future shifts in climatic conditions.
Climate models predict shifts in the amount, frequency and seasonality of rainfall. Given close links between grassland productivity and rainfall, such changes are likely to have profound effects on ...the functioning of grassland ecosystems and modify species interactions. Here, we introduce a unique, new experimental platform - DRI-Grass (
rought and
oot Herbivore
nteractions in a
land) - that exposes a south-eastern Australian grassland to five rainfall regimes Ambient (AMB), increased amount (IA, +50%), reduced amount (RA, -50%), reduced frequency (RF, single rainfall event every 21 days, with total amount unchanged) and summer drought (SD, 12-14 weeks without water, December-March), and contrasting levels of root herbivory. Incorporation of a belowground herbivore (root-feeding scarabs) addition treatment allows novel investigation of ecological responses to the twin stresses of altered rainfall and root herbivory. We quantified effects of permanently installed rain shelters on microclimate by comparison with outside plots, identifying small shelter effects on air temperature (-0.19°C day, +0.26°C night), soil water content (SWC; -8%) and photosynthetically active radiation (PAR; -16%). Shelters were associated with modest increases in net primary productivity (NPP), particularly during the cool season. Rainfall treatments generated substantial differences in SWC, with the exception of IA; the latter is likely due to a combination of higher transpiration rates associated with greater plant biomass in IA and the low water-holding capacity of the well-drained, sandy soil. Growing season NPP was strongly reduced by SD, but did not respond to the other rainfall treatments. Addition of root herbivores did not affect plant biomass and there were no interactions between herbivory and rainfall treatments in the 1st year of study. Root herbivory did, however, induce foliar silicon-based defenses in
and
. Rapid recovery of NPP following resumption of watering in SD plots indicates high functional resilience at the site, and may reflect adaptation of the vegetation to historically high variability in rainfall, both within- and between years. DRI-Grass provides a unique platform for understanding how ecological interactions will be affected by changing rainfall regimes and, specifically, how belowground herbivory modifies grassland resistance and resilience to climate extremes.
Climate change is predicted to result in altered precipitation patterns, which may reshape many grassland ecosystems. Rainfall is expected to change in a number of different ways, ranging from ...periods of prolonged drought to extreme precipitation events, yet there are few community wide studies to accurately simulate future changes. We aimed to test how above- and below-ground grassland invertebrate populations were affected by contrasting future rainfall scenarios. We subjected a grassland community to potential future rainfall scenarios including ambient, increased amount (+50% of ambient), reduced amount (-50% of ambient), reduced frequency (no water for 21 days, followed by the total ambient rainfall applied in a single application) and summer drought (no rainfall for 13 weeks during the growing season). During Austral spring (September 2015), we sampled aboveground invertebrates, belowground macro invertebrates and nematodes. Aboveground communities showed a significant response to altered rainfall regime with the greatest effects observed in summer drought plots. This was mostly due to a large increase in sucking herbivores (658% higher than ambient plots). Plots experiencing summer droughts also had higher populations of parasitoids, chewing herbivores and detritivores. These plots had 92% more plant biomass suggesting that primary productivity increased rapidly following the end of the summer drought 5 months earlier. We interpret these results as supporting the plant vigor hypothesis (i.e., that rapid plant growth is beneficial to aboveground invertebrates). While belowground invertebrates were less responsive to altered precipitation, we observed a number of correlations between the abundances of above- and below-ground invertebrate groups under ambient rainfall that dissipated under altered rainfall regimes. Mechanisms underpinning these associations, and reasons for them to become decoupled under altered precipitation regimes (we term this 'climatic decoupling'), remain speculative, but they provide the basis for formulating hypotheses and future work. In conclusion, we predict that shifts in rainfall patterns, especially summer drought, will likely have large, but probably short-term, impacts on grassland invertebrate communities. In particular, sucking herbivores show sensitivity to precipitation changes, which have the potential to cascade through the food chain and affect higher trophic levels.
•We review effects of elevated temperature and CO2 on herbivore–enemy interactions.•Elevated CO2 will likely negatively affect herbivores via altered plant quality.•Elevated temperatures could alter ...species’ phenologies and distributions.•Enemies may be negatively affected by changes in host quality and phenology.•Climate and CO2, together, may upset species interactions and community structure.
Gaining a better understanding of climate and atmospheric change effects on species interactions is one of the great challenges facing modern ecology. Here, we review the literature concerning the responses of insect herbivores and their natural enemies to atmospheric and climate change, focusing specifically on elevated concentrations of atmospheric CO2 and air temperatures. We recommend that future work on the responses of systems to climate change incorporates as far as possible the trophic complexity inherent in ecosystems, and where feasible, considers the effects of interrelated climate factors in tandem. Such studies will produce more realistic insights into how species interactions may respond under future climates.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
Arthropod assemblages form a fundamental part of terrestrial ecosystems, underpinning ecosystem processes and services. Yet, little is known about how invertebrate communities, as a whole, respond to ...climatic and atmospheric changes, including predicted increases in carbon dioxide concentrations (CO2).
To date, woodland Free Air CO2 Enrichment (FACE) studies have focused entirely on northern hemisphere managed plantations. We manipulated atmospheric CO2 in a mature, native Eucalyptus woodland (0.15 ha, >32 000 m3) in Australia, using the Eucalyptus FACE (‘EucFACE’) facility. We used three complementary sampling methods (vacuum sampling, pitfall and sticky trapping) to record invertebrate abundances under ambient and elevated levels of CO2 (400 versus 550 ppm).
Based on the collection of over 83 000 invertebrates, we found significant declines in the overall abundance of ground‐dwelling (14.7%) and aerial (12.9%) arthropods under elevated CO2, with significant decreases in herbivore, omnivore, scavenger and parasitoid functional groups. Even though several groups showed varying declines in abundance, elevated CO2 did not measurably affect community composition.
The results of the present study indicate that atmospheric CO2 levels predicted within the next 35 years may cause declines in arthropod abundances in Eucalyptus woodland. Declines found in several functional groups suggest that elevated atmospheric CO2 has the potential to affect ecosystem processes, possibly including nutrient cycling by herbivores and omnivores, as well as biocontrol by parasitoids.
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BFBNIB, DOBA, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UILJ, UKNU, UL, UM, UPUK
Hedgerows provide an important habitat for wildlife including invertebrates, representing a large proportion of semi‐natural habitat patches in the modern agricultural landscapes of the UK and ...Europe. Around 40% of hedgerow length in England is managed under agri‐environment scheme (AES) options, which specify less frequent cutting and advise cutting in winter. Hedgerow management can alter habitat structure and quality, potentially influencing invertebrate community structure. We assessed the impacts of management treatments on moth communities and their parasitoids. Two treatments (‘cutting frequency’: once every 1, 2, or 3 years, and ‘cutting time’: autumn vs. winter) were applied to a long‐running hedgerow experiment, mimicking AES prescriptions. Moth larvae were collected from the hedgerows, identified and reared to determine parasitism. Hedgerow structure and foliar quality were quantified and related to changes in moth abundance, diversity, species richness, and parasitism. Hedgerow management did not significantly affect overall abundance of moth larvae, but did affect the abundance of certain feeding guilds and trophic interactions with parasitoids. Concealed moth larvae (mining, tentiform, and case bearing) were more abundant on hedgerows cut infrequently (every 2 or 3 years vs. annually). Parasitism rates were higher on hedgerows cut less often, when these were cut in autumn. There was a strong trend towards greater moth species richness and diversity on winter cut hedgerows. Agri‐environment scheme management can thus have complex effects on invertebrate communities. The abundance of some moths may be positively affected by AES hedgerow management and this can have knock‐on effects on parasitoid abundance.
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BFBNIB, FZAB, GIS, IJS, IZUM, KILJ, NLZOH, NUK, OILJ, PILJ, PNG, SAZU, SBCE, SBMB, UL, UM, UPUK
Bespoke (custom‐built) Raspberry Pi cameras are increasingly popular research tools in the fields of behavioral ecology and conservation, because of their comparative flexibility in programmable ...settings, ability to be paired with other sensors, and because they are typically cheaper than commercially built models.
Here, we describe a novel, Raspberry Pi‐based camera system that is fully portable and yet weatherproof—especially to humidity and salt spray. The camera was paired with a passive infrared sensor, to create a movement‐triggered camera capable of recording videos over a 24‐hr period. We describe an example deployment involving “retro‐fitting” these cameras into artificial nest boxes on Praia Islet, Azores archipelago, Portugal, to monitor the behaviors and interspecific interactions of two sympatric species of storm‐petrel (Monteiro's storm‐petrel Hydrobates monteiroi and Madeiran storm‐petrel Hydrobates castro) during their respective breeding seasons.
Of the 138 deployments, 70% of all deployments were deemed to be “Successful” (Successful was defined as continuous footage being recorded for more than one hour without an interruption), which equated to 87% of the individual 30‐s videos. The bespoke cameras proved to be easily portable between 54 different nests and reasonably weatherproof (~14% of deployments classed as “Partial” or “Failure” deployments were specifically due to the weather/humidity), and we make further trouble‐shooting suggestions to mitigate additional weather‐related failures.
Here, we have shown that this system is fully portable and capable of coping with salt spray and humidity, and consequently, the camera‐build methods and scripts could be applied easily to many different species that also utilize cavities, burrows, and artificial nests, and can potentially be adapted for other wildlife monitoring situations to provide novel insights into species‐specific daily cycles of behaviors and interspecies interactions.
We present a methodological paper focusing on a practical issue, describing a novel and easily constructed field camera system that has been designed (and rigorously tested) for deployment in remote locations with harsh conditions. We describe how the system can be easily adapted for diverse conservation/management and field ecology projects.
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FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
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