Three exciting new papers out in August!!

25-Aug-2020

Leaf manganese concentrations as a tool to assess belowground plant functioning in phosphorus-impoverished environments (Plant and Soil)

First cryo-scanning electron microscopy images and X-ray microanalysis of mucoromycotinian fine root endophytes in vascular plants (Frontiers in Microbiology)

The influence of soil age on ecosystem structure and function across biomes (Nature Communications)

New Postdoctoral Research Associate position at the University of Western Australia

3-Jul-2020

I have now begun my second postdoctoral position. A three year Research Associate position on an Australian Research Council (ARC) funded Discovery Project at the University of Western Australia. The project is titled "Plant nitrate restraint: Does constraining nitrate influx systems accompany high leaf phosphorus-use efficiency in a phosphorus-impoverished ecosystem?", and will be led by E/Prof Hans Lambers and Assoc/Prof Patrick Finnegan. I am very excited to be involved in this project and am looking forward to the new discoveries we will be sure to make.

Nature Ecology & Evolution article: Multiple elements of soil biodiversity drive ecosystem functions across biomes

9-Feb-2020

Delgado-Baquerizo, M., Reich, P.B., Trivedi, C., Eldridge, D.J., Abades, S., Alfaro, F.D., Bastida, F., Berhe, A.A., Cutler, N.A., Gallardo, A., García-Velázquez, L., Hart, S.C., Hayes, P.E., He, J.-Z., Hseu, Z.-Y., Hu, H.-W., Kirchmair, M., Neuhauser, S., Pérez, C.A., Reed, S.C., Santos, F., Sullivan, B.W., Trivedi, P., Wang, J.-T., Weber-Grullon, L., Williams, M.A., Singh, B.K., 2020. Multiple elements of soil biodiversity drive ecosystem functions across biomes. Nature Ecology & Evolution 4: 210–220 (https://doi.org/10.1038/s41559-019-1084-y) Link to free view

Abstract

The role of soil biodiversity in regulating multiple ecosystem functions is poorly understood, limiting our ability to predict how soil biodiversity loss might affect human wellbeing and ecosystem sustainability. Here, combining a global observational study with an experimental microcosm study, we provide evidence that soil biodiversity (bacteria, fungi, protists and invertebrates) is significantly and positively associated with multiple ecosystem functions. These functions include nutrient cycling, decomposition, plant production, and reduced potential for pathogenicity and belowground biological warfare. Our findings also reveal the context dependency of such relationships and the importance of the connectedness, biodiversity and nature of the globally distributed dominant phylotypes within the soil network in maintaining multiple functions. Moreover, our results suggest that the positive association between plant diversity and multifunctionality across biomes is indirectly driven by soil biodiversity. Together, our results provide insights into the importance of soil biodiversity for maintaining soil functionality locally and across biomes, as well as providing strong support for the inclusion of soil biodiversity in conservation and management programmes.

Presented at Microscopy and Microanalysis 2019: Analysing cell-level allocation of calcium and phosphorus in leaves of Proteaceae from south-western Australia

August 2019

Hayes, P.E., Clode, P.L., Pereira, C.G., Lambers, H., 2019. Analysing Cell-Level Allocation of Calcium and Phosphorus in Leaves of Proteaceae from South-Western Australia. Microscopy and Microanalysis 25: 1080–1081 (https://doi.org/10.1017/S1431927619006135)

Nature Communications article: Global ecological predictors of the soil priming effect

15-Aug-2019

Bastida, F., García, C., Fierer, N., Eldridge, D.J., Bowker, M.A., Abades, S., Alfaro, F.D., Asefaw Berhe, A., Cutler, N.A., Gallardo, A., García-Velázquez, L., Hart, S.C., Hayes, P.E., Hernández, T., Hseu, Z.-Y., Jehmlich, N., Kirchmair, M., Lambers, H., Neuhauser, S., Peña-Ramírez, V.M., Pérez, C.A., Reed, S.C., Santos, F., Siebe, C., Sullivan, B.W., Trivedi, P., Vera, A., Williams, M.A., Luis Moreno, J., Delgado-Baquerizo, M., 2019. Global ecological predictors of the soil priming effect. Nature Communications 10: 3481 (https://doi.org/10.1038/s41467-019-11472-7)

Abstract

Identifying the global drivers of soil priming is essential to understanding C cycling in terrestrial ecosystems. We conducted a survey of soils across 86 globally-distributed locations, spanning a wide range of climates, biotic communities, and soil conditions, and evaluated the apparent soil priming effect using 13C-glucose labeling. Here we show that the magnitude of the positive apparent priming effect (increase in CO2 release through accelerated microbial biomass turnover) was negatively associated with SOC content and microbial respiration rates. Our statistical modeling suggests that apparent priming effects tend to be negative in more mesic sites associated with higher SOC contents. In contrast, a single-input of labile C causes positive apparent priming effects in more arid locations with low SOC contents. Our results provide solid evidence that SOC content plays a critical role in regulating apparent priming effects, with important implications for the improvement of C cycling models under global change scenarios.

PNAS article: Changes in belowground biodiversity during ecosystem development

15-Aug-2019

Delgado-Baquerizo, M., Bardgett, R.D., Vitousek, P.M., Maestre, F.T., Williams, M.A., Eldridge, D.J., Lambers, H., Neuhauser, S., Gallardo, A., García-Velázquez, L., Sala, O.E., Abades, S.R., Alfaro, F.D., Berhe, A.A., Bowker, M.A., Currier, C.M., Cutler, N.A., Hart, S.C., Hayes, P.E., Hseu, Z.-Y., Kirchmair, M., Peña-Ramírez, V.M., Pérez, C.A., Reed, S.C., Santos, F., Siebe, C., Sullivan, B.W., Weber-Grullon, L., Fierer, N. 2019. Changes in belowground biodiversity during ecosystem development. Proceedings of the National Academy of Sciences 116: 6891–6896 (https://doi.org/10.1073/pnas.1818400116)

Abstract

Belowground organisms play critical roles in maintaining multiple ecosystem processes, including plant productivity, decomposition, and nutrient cycling. Despite their importance, however, we have a limited understanding of how and why belowground biodiversity (bacteria, fungi, protists, and invertebrates) may change as soils develop over centuries to millennia (pedogenesis). Moreover, it is unclear whether belowground biodiversity changes during pedogenesis are similar to the patterns observed for aboveground plant diversity. Here we evaluated the roles of resource availability, nutrient stoichiometry, and soil abiotic factors in driving belowground biodiversity across 16 soil chronosequences (from centuries to millennia) spanning a wide range of globally distributed ecosystem types. Changes in belowground biodiversity during pedogenesis followed two main patterns. In lower-productivity ecosystems (i.e., drier and colder), increases in belowground biodiversity tracked increases in plant cover. In more productive ecosystems (i.e., wetter and warmer), increased acidification during pedogenesis was associated with declines in belowground biodiversity. Changes in the diversity of bacteria, fungi, protists, and invertebrates with pedogenesis were strongly and positively correlated worldwide, highlighting that belowground biodiversity shares similar ecological drivers as soils and ecosystems develop. In general, temporal changes in aboveground plant diversity and belowground biodiversity were not correlated, challenging the common perception that belowground biodiversity should follow similar patterns to those of plant diversity during ecosystem development. Taken together, our findings provide evidence that ecological patterns in belowground biodiversity are predictable across major globally distributed ecosystem types and suggest that shifts in plant cover and soil acidification during ecosystem development are associated with changes in belowground biodiversity over centuries to millennia.

Research article published in the European Journal of Soil Science

28-Nov-2018

Turner, B.L., Hayes, P.E., Laliberté, E., 2018. A climosequence of chronosequences in southwestern Australia. European Journal of Soil Science 69, 69–85.

Link to Article 

Abstract

To examine how climate affects soil development and nutrient availability over long timescales, we studied a series of four long-term chronosequences along a climate gradient in southwestern Australia. Annual rainfall ranged from 533 to 1185mm (water balance from −900 to +52 mm) and each chronosequence included Holocene (≤6.5 ka), Middle Pleistocene (120–500 ka) and Early Pleistocene (∼2000 ka) dunes. Vegetation changed markedly along the climosequence, from shrubland at the driest site to Eucalyptus forest at the wettest. Soil pH was similar in the youngest soil of each chronosequence, although the carbonate and P contents of the parent sand declined from dry to wet along the climosequence, presumably linked to variation in offshore productivity. Despite this, soil development and associated nutrient status followed remarkably consistent patterns along the four chronosequences. Pedogenesis involved decalcification and secondary carbonate precipitation in Holocene soils and leaching of iron oxides fromMiddle Pleistocene soils, leading ultimately to bleached quartz sands in the oldest soils. Along all chronosequences soil pH and total P declined, whereas C:P and N:P ratios increased, which is consistent with the predicted change from N to P limitation of vegetation during ecosystem development. The expected unimodal pattern of leaf area index was most pronounced along wetter chronosequences, suggesting an effect of climate on the expression of retrogression. The four chronosequences do not appear to span a pedogenic climate threshold, defined as an abrupt change in soil properties across a relatively small change in climate, because exchangeable phosphate and base cations declined consistently during long-term pedogenesis. However, the proportion of total P in organic form was greater along wetter chronosequences. We conclude that soil and nutrient availability on the coastal sand plains of southwestern Australia change consistently during long-term pedogenesis, despite marked variation in modern vegetation and climate. The four chronosequences provide a rare soil-age X climate framework within which to study long-term ecosystem development.

Published the first chapter of my PhD thesis in Plant, Cell & Environment

Hayes, P.E., Clode, P.L., Oliveira, R.S., Lambers, H., 2018. Proteaceae from phosphorus-impoverished habitats preferentially allocate phosphorus to photosynthetic cells: an adaptation improving phosphorus-use efficiency. Plant, Cell and Environment 41: 605–619.

Link to Article

Abstract

Plants allocate nutrients to specific leaf cell types; eudicots are thought to predominantly allocate phosphorus (P) to epidermal/bundle sheath cells. However, three Proteaceae species have been shown to preferentially allocate P to mesophyll cells instead. These Proteaceae species are highly adapted to P‐impoverished habitats, with exceptionally high photosynthetic P‐use efficiencies (PPUE). We hypothesized that preferential allocation of P to photosynthetic mesophyll cells is an important trait in species adapted to extremely P‐impoverished habitats, contributing to their high PPUE. We used elemental X‐ray mapping to determine leaf cell‐specific nutrient concentrations for 12 Proteaceae species, from habitats of strongly contrasting soil P concentrations, in Australia, Brazil, and Chile. We found that only species from extremely P‐impoverished habitats preferentially allocated P to photosynthetic mesophyll cells, suggesting it has evolved as an adaptation to their extremely P‐impoverished habitat and that it is not a family‐wide trait. Our results highlight the possible role of soil P in driving the evolution of ecologically relevant nutrient allocation patterns and that these patterns cannot be generalized across families. Furthermore, preferential allocation of P to photosynthetic cells may provide new and exciting strategies to improve PPUE in crop species.

Co-authored a really nice project with Gang Huang; looking at P-acquisition in the Australian native Peppermint tree, which shifts its P-acquisition strategy with decreasing soil P availability, from mycorrhizal to mass flow

Huang, G., Hayes, P. E., Ryan, M. H., Pang, J., Lambers, H. 2017. Peppermint trees shift their phosphorus-acquisition strategy along a strong gradient of plant-available phosphorus by increasing their transpiration at very low phosphorus availability. Oecologia (in press)

Abstract

Some plant species use different strategies to acquire phosphorus (P) dependent on environmental conditions, but studies investigating the relative significance of P-acquisition strategies with changing P availability are rare. We combined a natural P availability gradient and a glasshouse study with 10 levels of P supplies to investigate the roles of rhizosphere carboxylates and transpiration-driven mass flow in P acquisition by Agonis flexuosa. Leaf P concentrations of A. flexuosa decreased and leaf manganese (Mn) concentrations increased with decreasing soil P concentration along a dune chronosequence. In the glasshouse, in response to decreasing P supply, shoot growth and root length decreased, leaf P and Mn concentrations decreased, rhizosphere carboxylates decreased, transpiration rate and transpiration ratio increased and the percentage of root length colonized by arbuscular mycorrhizal fungi was unchanged. Although it was proved leaf Mn concentration was a good proxy for rhizosphere carboxylate amounts in the glasshouse study, the enhanced plant P acquisition at low P supply was related to transpiration-induced mass flow rather than carboxylates. We deduced that the higher leaf Mn concentrations in low soil P availability of the field were likely a result of increased mass flow. In summary, as soil P availability declined, A. flexuosa can shift its P-acquisition strategy away from a mycorrhizal mode towards one involving increased mass flow.