Contrasting Responses of Arbuscular Mycorrhizal Fungal Families to Simulated Climate Warming and Drying in A Semiarid Shrubland

We carried out a 4-year manipulative field experiment in a semiarid shrubland in Southeastern Spain to assess the impacts of experimental warming (W), rainfall reduction (RR) and their combination (W+RR) on the composition and diversity of arbuscular mycorrhizal fungal (AMF) communities in rhizosphere soil using singlemolecule real-time (SMRT) DNA sequencing. Across climate treatments, we encountered 109 AMF OTUs that were assigned to four families: Glomeraceae (93.94%), Gigasporaceae (2.19%), Claroideoglomeraceae (1.95%) and Diversisporaceae (1.92%). The AMF community composition and diversity indices at OTU level were unaffected by the climate manipulation treatments, except for a significant decrease in AMF richness in the W treatment relative to the control. In contrast, AMF family richness decreased significantly in all the climate manipulation treatments relative to the control treatment. Members of the Gigasporaceae and Diversisporaceae families appeared to be highly vulnerable to intensification of heat and drought stress, as their abundances decreased by 67% and 77% respectively, in the W+RR treatment relative to current ambient conditions. In contrast, the relative abundance and dominance of the Glomeraceae family within the AMF community increased significantly under the W+RR treatment, with Glomeraceae being indicator family for the W+RR treatment. The interaction between warming and rainfall reduction had a significant effect on AMF community structure at family level. These findings provide new insights into AM fungal community responses to climate warming and drying in dryland ecosystems.

Global change in the root zone: lessons from soil moisture dynamics in a multifactor climate manipulation experiment

<p>Assessing the future of water resources in terrestrial biomes is contingent on observations from climate-manipulation experiments. Global change in the Anthropocene could produce various permutations of warming, atmospheric carbon levels, and moisture availability; however the impact on ecosystem hydrology is largely studied individually (e.g., elevated CO<sub>2</sub> or temperature) rather than interactively. We sought to specify how various combinations of  drought, elevated CO<sub>2</sub> (+150 ppm, +300 ppm) and warming (+1.5°C and + 3°C) may alter the partitioning of soil moisture in the root zone of mountain grassland. Using spectral techniques, we transformed these high resolution data (i.e., 4 soil depths and every 15 min) into the frequency domain to study the interactive effects of climate change on sub-hourly to seasonal soil moisture signals. Diurnal moisture signals in heated plots (+3°C in air temperature) were up to 3x stronger (in amplitude) during summer drawdown compared to plots receiving heat and elevated CO<sub>2</sub> (+300 ppm). This preliminary analysis suggests that elevated atmospheric carbon may buffer heat-driven soil moisture losses in grassland root zones by reducing transpiration fluxes during seasonal dry periods.</p>

Cores for concern: Peatland carbon dynamics in a changing climate; a multidisciplinary approach.

<p>The effects of 21<sup>st</sup> century climate change are projected to be most severe in the northern hemisphere, where the majority of peatlands are located. Peatlands represent important long-term terrestrial stores of carbon (C), containing an estimated c.600-1055GT C, despite covering only 3% of total land area globally. In addition, pristine peatlands act as net sinks of atmospheric CO<sub>2</sub>, imparting a negative feedback mechanism cooling global climate, whilst simultaneously acting as sources of CO<sub>2</sub> and CH<sub>4</sub>. Peatlands remain net sinks of C as long as the rate of carbon sequestration exceeds that of decomposition. Projected changes in temperature, precipitation and other environmental variables threaten to disrupt this precarious balance, however, and the future direction of carbon feedback mechanisms are poorly understood, due to the complex nature of the peatland carbon cycle.</p><p> </p><p>Two methods are used in order to help understand future the carbon dynamics of peat bogs under climate change. These are experimental studies, which measure greenhouse gas fluxes under manipulated climatic and environmental conditions (warmer, drier), and palaeoecological studies, which examine the effects of past climate change upon carbon sequestration throughout the peat profile. However, both methods fundamentally contradict each other. Palaeoecological studies suggest that carbon accumulation increases during warming periods, whereas warming experiments observe greater carbon loss with increased temperature.</p><p> </p><p>The aim of this project is to link contemporary experimental and palaeoecological approaches to explain this discrepancy. This will be achieved by comparing greenhouse gas fluxes between plots which have been subjected to 10 years of passive warming and drought simulation at an experimental climate manipulation site on Cors Fochno, Ceredigion, Wales. Long term rates of carbon accumulation will be compared with net ecosystem contemporary carbon budgets from each plot. Surface samples from each plot will be analysed by a range of palaeoenvironmental proxies to test how well the climate manipulations are represented by each proxy. Finally, a high-resolution multi-proxy palaeoenvironmental reconstruction spanning the past 1000 years will be compared with reconstructions derived from short-cores from each plot covering the duration of the experiment from each treatment, to see how faithfully climate manipulation mirrors real periods of climate change.</p><p> </p><p>Understanding the future role of peatlands in future carbon sequestration and storage is of vital importance for modelling future climate change, in terms of both quantifying the potential ecosystem services peatlands may offer in mitigating the effects of climate change, as well as enhancing the predictive capabilities of global climate models. Currently, the uncertainty associated with peatland carbon cycling is such that peatlands are rarely included in global climate models.</p><p> </p>

Fast response of fungal and prokaryotic communities to climate change manipulation in two contrasting tundra soils

Background Climate models predict substantial changes in temperature and precipitation patterns across Arctic regions, including increased winter precipitation as snow in the near future. Soil microorganisms are considered key players in organic matter decomposition and regulation of biogeochemical cycles. However, current knowledge regarding their response to future climate changes is limited. Here, we explore the short-term effect of increased snow cover on soil fungal, bacterial and archaeal communities in two tundra sites with contrasting water regimes in Greenland. In order to assess seasonal variation of microbial communities, we collected soil samples four times during the plant-growing season. Results The analysis revealed that soil microbial communities from two tundra sites differed from each other due to contrasting soil chemical properties. Fungal communities showed higher richness at the dry site whereas richness of prokaryotes was higher at the wet tundra site. We demonstrated that fungal and bacterial communities at both sites were significantly affected by short-term increased snow cover manipulation. Our results showed that fungal community composition was more affected by deeper snow cover compared to prokaryotes. The fungal communities showed changes in both taxonomic and ecological groups in response to climate manipulation. However, the changes were not pronounced at all sampling times which points to the need of multiple sampling in ecosystems where environmental factors show seasonal variation. Further, we showed that effects of increased snow cover were manifested after snow had melted. Conclusions We demonstrated rapid response of soil fungal and bacterial communities to short-term climate manipulation simulating increased winter precipitation at two tundra sites. In particular, we provide evidence that fungal community composition was more affected by increased snow cover compared to prokaryotes indicating fast adaptability to changing environmental conditions. Since fungi are considered the main decomposers of complex organic matter in terrestrial ecosystems, the stronger response of fungal communities may have implications for organic matter turnover in tundra soils under future climate.

Tax climate manipulation on individual tax behavioural intentions

Purpose The purpose of this paper is to extend the slippery slope framework by exploring different dimensions of compliance quality and tax minimisation under different tax climate manipulation by groups. Design/methodology/approach The authors run a random assignment of tax climate manipulations through questionnaire with 301 usable data collected from the full-time postgraduate students, employed individuals and self-employed individuals. Manipulation check and results are generated via multivariate analysis of variance. Findings The results confirm the biggest impact of synergistic climate on voluntary compliance, and small to medium impact of antagonistic climate on tax evasion across three groups. Research limitations/implications The manipulation of this research is constrained with two treatments in addition to the common pitfall of social desired responses of self-report. Practical implications Theoretically, this study empirically explores tax minimisation dimensions and provides new insights that only illegal tax minimisation is at maximum under the prevailing negative antagonistic climate, but not for legal tax minimisation. Second, the effect of tax climate represented by trust and power on enforced compliance is minimal, as compared to the strong effect of positive synergistic climate on voluntary compliance. As for policy implications, possible guidelines and interventions are outlined to policy makers which would lead to a better quality of compliance behaviour. Originality/value This study operationalises and manipulates tax climate from perceptions of trust, legitimate power and coercive power. It also further affirms the prior inconsistent findings in respect of tax behavioural intentions due to sampling group and cultural differences.

Global warming reduces leaf-out and flowering synchrony among individuals

The temporal overlap of phenological stages, phenological synchrony, crucially influences ecosystem functioning. For flowering, among-individual synchrony influences gene flow. For leaf-out, it affects interactions with herbivores and competing plants. If individuals differ in their reaction to the ongoing change in global climate, this should affect population-level synchrony. Here, we use climate-manipulation experiments, Pan-European long-term (>15 years) observations, and common garden monitoring data on up to 72 woody and herbaceous species to study the effects of increasing temperatures on the extent of leaf-out and flowering synchrony within populations. Warmer temperatures reduce in situ leaf-out and flowering synchrony by up to 55%, and experiments on European beech provide a mechanism for how individual differences in day-length and/or chilling sensitivity may explain this finding. The rapid loss of reproductive and vegetative synchrony in European plants predicts changes in their gene flow and trophic interactions, but community-wide consequences remain largely unknown.Editorial note: This article has been through an editorial process in which the authors decide how to respond to the issues raised during peer review. The Reviewing Editor's assessment is that all the issues have been addressed (<xref ref-type="decision-letter" rid="SA1">see decision letter</xref>).

Loss of leaf-out and flowering synchrony under global warming

The temporal overlap of phenological stages, phenological synchrony, crucially influences ecosystem functioning. For flowering, among-individual synchrony influences gene flow. For leaf-out, it affects interactions with herbivores and competing plants. If individuals differ in their reaction to the ongoing change in global climate, this should affect population-level synchrony. Here, we use climate-manipulation experiments, Pan-European long-term (>15 years) observations, and common garden monitoring data on up to 72 woody and herbaceous species to study the effects of increasing temperatures on the extent of within-population leaf-out and flowering synchrony. Warmer temperatures reduce in situ leaf-out and flowering synchrony by up to 55%, and experiments on European beech provide a mechanism for how individual genetic differences may explain this finding. The rapid loss of reproductive and vegetative synchrony in European plants predicts changes in their gene flow and trophic interactions, but community-wide consequences remain largely unknown.