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Johnson SN, Vandegeer RK, Borevitz JO, Hartley SE, Tissue DT, Hall CR. Climatic Drivers of Silicon Accumulation in a Model Grass Operate in Low- but Not High-Silicon Soils. PLANTS (BASEL, SWITZERLAND) 2023; 12:995. [PMID: 36903856 PMCID: PMC10005694 DOI: 10.3390/plants12050995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 02/14/2023] [Accepted: 02/15/2023] [Indexed: 06/18/2023]
Abstract
Grasses are hyper-accumulators of silicon (Si), which is known to alleviate diverse environmental stresses, prompting speculation that Si accumulation evolved in response to unfavourable climatic conditions, including seasonally arid environments. We conducted a common garden experiment using 57 accessions of the model grass Brachypodium distachyon, sourced from different Mediterranean locations, to test relationships between Si accumulation and 19 bioclimatic variables. Plants were grown in soil with either low or high (Si supplemented) levels of bioavailable Si. Si accumulation was negatively correlated with temperature variables (annual mean diurnal temperature range, temperature seasonality, annual temperature range) and precipitation seasonality. Si accumulation was positively correlated with precipitation variables (annual precipitation, precipitation of the driest month and quarter, and precipitation of the warmest quarter). These relationships, however, were only observed in low-Si soils and not in Si-supplemented soils. Our hypothesis that accessions of B. distachyon from seasonally arid conditions have higher Si accumulation was not supported. On the contrary, higher temperatures and lower precipitation regimes were associated with lower Si accumulation. These relationships were decoupled in high-Si soils. These exploratory results suggest that geographical origin and prevailing climatic conditions may play a role in predicting patterns of Si accumulation in grasses.
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Affiliation(s)
- Scott N. Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
| | - Rebecca K. Vandegeer
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
| | - Justin O. Borevitz
- Research School of Biology, Australian National University, Canberra, ACT 2601, Australia
| | - Susan E. Hartley
- School of Biosciences, University of Sheffield, Sheffield S10 2TN, UK
| | - David T. Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
| | - Casey R. Hall
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW 2751, Australia
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Johnson SN, Chen ZH, Rowe RC, Tissue DT. Field application of silicon alleviates drought stress and improves water use efficiency in wheat. FRONTIERS IN PLANT SCIENCE 2022; 13:1030620. [PMID: 36438110 PMCID: PMC9682199 DOI: 10.3389/fpls.2022.1030620] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Accepted: 10/17/2022] [Indexed: 06/16/2023]
Abstract
Detrimental impacts of drought on crop yield have tripled in the last 50 years with climate models predicting that the frequency of such droughts will intensify in the future. Silicon (Si) accumulation, especially in Poaceae crops such as wheat (Triticum aestivum L.), may alleviate the adverse impacts of drought. We have very limited information, however, about whether Si supplementation could alleviate the impacts of drought under field conditions and no studies have specifically manipulated rainfall. Using field-based rain exclusion shelters, we determined whether Si supplementation (equivalent to 39, 78 and 117 kg ha-1) affected T. aestivum growth, elemental chemistry [Si, carbon (C) and nitrogen (N)], physiology (rates of photosynthesis, transpiration, stomatal conductance, and water use efficiency) and yield (grain production) under ambient and drought (50% of ambient) rainfall scenarios. Averaged across Si treatments, drought reduced shoot mass by 21% and grain production by 18%. Si supplementation increased shoot mass by up to 43% and 73% in ambient and drought water treatments, respectively, and restored grain production in droughted plants to levels comparable with plants supplied with ambient rainfall. Si supplementation increased leaf-level water use efficiency by 32-74%, depending on Si supplementation rates. Water supply and Si supplementation did not alter concentrations of C and N, but Si supplementation increased shoot C content by 39% and 83% under ambient and drought conditions, respectively. This equates to an increase from 6.4 to 8.9 tonnes C ha-1 and from 4.03 to 7.35 tonnes C ha-1 under ambient and drought conditions, respectively. We conclude that Si supplementation ameliorated the negative impacts of drought on T. aestivum growth and grain yield, potentially through its beneficial impacts on water use efficiency. Moreover, the beneficial impacts of Si on plant growth and C storage may render Si supplementation a useful tool for both drought mitigation and C sequestration.
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Affiliation(s)
- Scott N. Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Zhong-Hua Chen
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
- School of Science, Western Sydney University, Penrith, NSW, Australia
| | - Rhiannon C. Rowe
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - David T. Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
- Global Centre for Land-Based Innovation, Western Sydney University, Richmond, NSW, Australia
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Chieppa J, Power SA, Nielsen UN, Tissue DT. Plant functional traits affect competitive vigor of pasture grasses during drought and following recovery. Ecosphere 2022. [DOI: 10.1002/ecs2.4156] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Jeff Chieppa
- Hawkesbury Institute for the Environment, Hawkesbury Campus Western Sydney University Richmond New South Wales Australia
- Department of Biological Sciences Texas Tech University Lubbock Texas USA
| | - Sally A. Power
- Hawkesbury Institute for the Environment, Hawkesbury Campus Western Sydney University Richmond New South Wales Australia
| | - Uffe N. Nielsen
- Hawkesbury Institute for the Environment, Hawkesbury Campus Western Sydney University Richmond New South Wales Australia
| | - David T. Tissue
- Hawkesbury Institute for the Environment, Hawkesbury Campus Western Sydney University Richmond New South Wales Australia
- Global Centre for Land‐based Innovation Western Sydney University, Hawkesbury Campus Richmond New South Wales Australia
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Churchill AC, Zhang H, Fuller KJ, Amiji B, Anderson IC, Barton CVM, Carrillo Y, Catunda KLM, Chandregowda MH, Igwenagu C, Jacob V, Kim GW, Macdonald CA, Medlyn BE, Moore BD, Pendall E, Plett JM, Post AK, Powell JR, Tissue DT, Tjoelker MG, Power SA. Pastures and Climate Extremes: Impacts of Cool Season Warming and Drought on the Productivity of Key Pasture Species in a Field Experiment. FRONTIERS IN PLANT SCIENCE 2022; 13:836968. [PMID: 35321443 PMCID: PMC8937038 DOI: 10.3389/fpls.2022.836968] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 02/09/2022] [Indexed: 06/14/2023]
Abstract
Shifts in the timing, intensity and/or frequency of climate extremes, such as severe drought and heatwaves, can generate sustained shifts in ecosystem function with important ecological and economic impacts for rangelands and managed pastures. The Pastures and Climate Extremes experiment (PACE) in Southeast Australia was designed to investigate the impacts of a severe winter/spring drought (60% rainfall reduction) and, for a subset of species, a factorial combination of drought and elevated temperature (ambient +3°C) on pasture productivity. The experiment included nine common pasture and Australian rangeland species from three plant functional groups (C3 grasses, C4 grasses and legumes) planted in monoculture. Winter/spring drought resulted in productivity declines of 45% on average and up to 74% for the most affected species (Digitaria eriantha) during the 6-month treatment period, with eight of the nine species exhibiting significant yield reductions. Despite considerable variation in species' sensitivity to drought, C4 grasses were more strongly affected by this treatment than C3 grasses or legumes. Warming also had negative effects on cool-season productivity, associated at least partially with exceedance of optimum growth temperatures in spring and indirect effects on soil water content. The combination of winter/spring drought and year-round warming resulted in the greatest yield reductions. We identified responses that were either additive (Festuca), or less-than-additive (Medicago), where warming reduced the magnitude of drought effects. Results from this study highlight the sensitivity of diverse pasture species to increases in winter and spring drought severity similar to those predicted for this region, and that anticipated benefits of cool-season warming are unlikely to be realized. Overall, the substantial negative impacts on productivity suggest that future, warmer, drier climates will result in shortfalls in cool-season forage availability, with profound implications for the livestock industry and natural grazer communities.
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Affiliation(s)
- Amber C. Churchill
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Haiyang Zhang
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Kathryn J. Fuller
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Burhan Amiji
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Ian C. Anderson
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Craig V. M. Barton
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Yolima Carrillo
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Karen L. M. Catunda
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | | | - Chioma Igwenagu
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Vinod Jacob
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Gil Won Kim
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
- Institute of Agriculture and Life Sciences, Gyeongsang National University, Jinju, South Korea
| | - Catriona A. Macdonald
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Belinda E. Medlyn
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Ben D. Moore
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Elise Pendall
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Jonathan M. Plett
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Alison K. Post
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
- The Center for Ecosystem Science and Society, Northern Arizona University, Flagstaff, AZ, United States
| | - Jeff R. Powell
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - David T. Tissue
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
- Global Centre for Land-Based Innovation, Western Sydney University, Hawkesbury Campus, Richmond, NSW, Australia
| | - Mark G. Tjoelker
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
| | - Sally A. Power
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW, Australia
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Barnett KL, Johnson SN, Facey SL, Gibson-Forty EVJ, Ochoa-Hueso R, Power SA. Altered precipitation and root herbivory affect the productivity and composition of a mesic grassland. BMC Ecol Evol 2021; 21:145. [PMID: 34266378 PMCID: PMC8283849 DOI: 10.1186/s12862-021-01871-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/23/2021] [Indexed: 11/10/2022] Open
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 C4 grasses and C3 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 C3, compared to C4, 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.
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Affiliation(s)
- Kirk L Barnett
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
| | - Scott N Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Sarah L Facey
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Eleanor V J Gibson-Forty
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Raul Ochoa-Hueso
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.,Department of Biology, University of Cádiz, Avenida República Árabe Saharaui, 11510, Puerto Real, Cádiz, Spain
| | - Sally A Power
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
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Brightly WH, Hartley SE, Osborne CP, Simpson KJ, Strömberg CAE. High silicon concentrations in grasses are linked to environmental conditions and not associated with C 4 photosynthesis. GLOBAL CHANGE BIOLOGY 2020; 26:7128-7143. [PMID: 32897634 DOI: 10.1111/gcb.15343] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2020] [Accepted: 08/03/2020] [Indexed: 06/11/2023]
Abstract
The uptake and deposition of silicon (Si) as silica phytoliths is common among land plants and is associated with a variety of functions. Among these, herbivore defense has received significant attention, particularly with regard to grasses and grasslands. Grasses are well known for their high silica content, a trait which has important implications ranging from defense to global Si cycling. Here, we test the classic hypothesis that C4 grasses evolved stronger mechanical defenses than C3 grasses through increased phytolith deposition, in response to extensive ungulate herbivory ("C4 -grazer hypothesis"). Despite mixed support, this hypothesis has received broad attention, even outside the realm of plant biology. Because C3 and C4 grasses typically dominate in different climates, with the latter more abundant in hot, dry regions, we also investigated the effects of water availability and temperature on Si deposition. We compiled a large dataset of grasses grown under controlled environmental conditions. Using phylogenetically informed generalized linear mixed models and character evolution models, we evaluated whether photosynthetic pathway or growth condition influenced Si concentration. We found that C4 grasses did not show consistently elevated Si concentrations compared with C3 grasses. High temperature treatments were associated with increased concentration, especially in taxa adapted to warm regions. Although the effect was less pronounced, reduced water treatment also promoted silica deposition, with slightly stronger response in dry habitat species. The evidence presented here rejects the "C4 -grazer hypothesis." Instead, we propose that the tendency for C4 grasses to outcompete C3 species under hot, dry conditions explains previous observations supporting this hypothesis. These findings also suggest a mechanism via which anthropogenic climate change may influence silica deposition in grasses and, by extension, alter the important ecological and geochemical processes it affects.
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Affiliation(s)
- William H Brightly
- Department of Biology and the Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, USA
| | - Sue E Hartley
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Colin P Osborne
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Kimberley J Simpson
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield, UK
| | - Caroline A E Strömberg
- Department of Biology and the Burke Museum of Natural History and Culture, University of Washington, Seattle, WA, USA
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Liu Y, Li Z. Effects of Water Addition on Reproductive Allocation of Dominant Plant Species in Inner Mongolia Steppe. FRONTIERS IN PLANT SCIENCE 2020; 11:555743. [PMID: 33304359 PMCID: PMC7701291 DOI: 10.3389/fpls.2020.555743] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/28/2020] [Accepted: 10/27/2020] [Indexed: 06/12/2023]
Abstract
Extreme events such as extreme drought and precipitation are expected to increase in intensity and/or duration in the face of climate change. Such changes significantly affect plant productivity and the biomass allocation between reproductive and vegetation organs (i.e., reproductive allocation). Our aims are to test the effects of water addition on the trade-offs in allocation of plant biomass and whether such effects are modified by species. A manipulative experiment was conducted from May 2000 to October 2001, where four dominant plant species (i.e., Leymus chinensis, Stipa grandis, Artemisia frigida, and Potentilla acaulis) in the Inner Mongolia steppe in China were treated with 8 levels of water addition. Results demonstrated that water addition significantly affected the reproductive allocation of plants, and such effects were modified by species. Specifically, with increasing water availability, L. chinensis was not impacted, while A. frigida allocated more biomass to reproductive organs than to vegetative organs, while such allocation in S. grandis and P. acaulis first decreased, and then increased after reaching a peak. Our results indicated that plant species can adjust their reproductive allocation patterns to deal with water availability gradients. Climatic factors such as rainfall and temperature usually co-appearing, thus future research should explore the joint effects of several climate change factors on grasslands in order to maintain the health and sustainability of grasslands.
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Affiliation(s)
- Yongjie Liu
- State Key Laboratory of Grassland Agro-ecosystems, Key Laboratory of Grassland Livestock Industry Innovation, Ministry of Agriculture and Rural Affairs, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
| | - Zhenqing Li
- State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
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Ochoa‐Hueso R, Arca V, Delgado‐Baquerizo M, Hamonts K, Piñeiro J, Serrano‐Grijalva L, Shawyer J, Power SA. Links between soil microbial communities, functioning, and plant nutrition under altered rainfall in Australian grassland. ECOL MONOGR 2020. [DOI: 10.1002/ecm.1424] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Affiliation(s)
- Raúl Ochoa‐Hueso
- Department of Biology IVAGROUniversity of Cádiz Campus de Excelencia Internacional Agroalimentario (ceiA3), Campus del Rio San Pedro Puerto Real Cádiz 11510 Spain
- Hawkesbury Institute for the EnvironmentWestern Sydney University Locked Bag 1797 Penrith New South Wales2751 Australia
| | - Valentina Arca
- Hawkesbury Institute for the EnvironmentWestern Sydney University Locked Bag 1797 Penrith New South Wales2751 Australia
| | - Manuel Delgado‐Baquerizo
- Hawkesbury Institute for the EnvironmentWestern Sydney University Locked Bag 1797 Penrith New South Wales2751 Australia
- Departamento de Sistemas Físicos, Químicos y Naturales Universidad Pablo de Olavide Sevilla 41013 Spain
| | - Kelly Hamonts
- Hawkesbury Institute for the EnvironmentWestern Sydney University Locked Bag 1797 Penrith New South Wales2751 Australia
| | - Juan Piñeiro
- Hawkesbury Institute for the EnvironmentWestern Sydney University Locked Bag 1797 Penrith New South Wales2751 Australia
- Division of Plant and Soil Sciences West Virginia University Morgantown West Virginia 26506 USA
| | - Lilia Serrano‐Grijalva
- Department of Biology IVAGROUniversity of Cádiz Campus de Excelencia Internacional Agroalimentario (ceiA3), Campus del Rio San Pedro Puerto Real Cádiz 11510 Spain
- Hawkesbury Institute for the EnvironmentWestern Sydney University Locked Bag 1797 Penrith New South Wales2751 Australia
| | - Julien Shawyer
- Hawkesbury Institute for the EnvironmentWestern Sydney University Locked Bag 1797 Penrith New South Wales2751 Australia
| | - Sally A. Power
- Hawkesbury Institute for the EnvironmentWestern Sydney University Locked Bag 1797 Penrith New South Wales2751 Australia
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Improvement and Application of Key Pasture Theory for the Evaluation of Forage–Livestock Balance in the Seasonal Grazing Regions of China’s Alpine Desert Grasslands. SUSTAINABILITY 2020. [DOI: 10.3390/su12176794] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The calculation of theoretical carrying capacity (TCC) is one of the most fundamental tasks for the evaluation of the forage–livestock balance on grassland pastures. At present, the main methods for calculating TCC are the traditional theory (TT) and key pasture theory (KPT), but they both have obvious limitations in practical applications for the seasonal grazing regions in the alpine desert grasslands of China. In this study, the pastures in Wulan County (PWC) were selected as the research area. The unique features of the research area as well as the faulty applications of TT and KPT were fully analyzed, and then a new method named dynamic key pasture theory (DKPT) was established for calculating TCC by improving KPT with the introduction of the two dynamic factors of the livestock slaughter rate (α) and coefficient of grassland productivity (β). TT, KPT and DKPT were respectively used to calculate the TCC of the PWC under different precipitation scenarios. The forage–livestock balance in the PWC determined using DKPT was assessed by the forage–livestock balance index (FLBI). The results showed that the natural processes of grassland supply and livestock demand were significantly imbalanced in time and space and formed a dynamic cycle with four subprocesses, which was the supporting basis of DKPT; DKPT effectively improved the rationality of TCC and offered greater guidance for the evaluation of the forage–livestock balance in the seasonal grazing regions of China’s alpine desert grasslands. In the PWC, the TCCs of different pastures calculated by DKPT were clearly different from those calculated by TT and KPT; the areas of the pastures divided were extremely imbalanced, with a huge surplus of more than 50% in cool-season pastures; in the representative year of 2016, the pastures in the Xisai Basin were underloaded (FLBI = −35.19%) on the whole, while the pastures in the Chaka Basin were overloaded (FLBI = 24.34%).
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10
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Deveautour C, Chieppa J, Nielsen UN, Boer MM, Mitchell C, Horn S, Power SA, Guillen A, Bennett AE, Powell JR. Biogeography of arbuscular mycorrhizal fungal spore traits along an aridity gradient, and responses to experimental rainfall manipulation. FUNGAL ECOL 2020. [DOI: 10.1016/j.funeco.2019.100899] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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11
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Johnson SN, Ryalls JMW, Barton CVM, Tjoelker MG, Wright IJ, Moore BD. Climate warming and plant biomechanical defences: Silicon addition contributes to herbivore suppression in a pasture grass. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13295] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Scott N. Johnson
- Hawkesbury Institute for the Environment Western Sydney University Sydney New South Wales Australia
| | - James M. W. Ryalls
- Hawkesbury Institute for the Environment Western Sydney University Sydney New South Wales Australia
| | - Craig V. M. Barton
- Hawkesbury Institute for the Environment Western Sydney University Sydney New South Wales Australia
| | - Mark G. Tjoelker
- Hawkesbury Institute for the Environment Western Sydney University Sydney New South Wales Australia
| | - Ian J. Wright
- Department of Biological Sciences Macquarie University Sydney New South Wales Australia
| | - Ben D. Moore
- Hawkesbury Institute for the Environment Western Sydney University Sydney New South Wales Australia
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12
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Ryalls JMW, Moore BD, Johnson SN. Silicon uptake by a pasture grass experiencing simulated grazing is greatest under elevated precipitation. BMC Ecol 2018; 18:53. [PMID: 30514265 PMCID: PMC6280423 DOI: 10.1186/s12898-018-0208-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 11/22/2018] [Indexed: 12/27/2022] Open
Abstract
BACKGROUND Grasses are hyper-accumulators of silicon (Si) and often up-regulate Si following herbivory. Positive correlations exist between Si and plant water content, yet the extent to which Si uptake responses can be mediated by changes in soil water availability has rarely been studied and never, to our knowledge, under field conditions. We used field-based rain-exclusion shelters to investigate how simulated grazing (shoot clipping) and altered rainfall patterns (drought and elevated precipitation, representing 50% and 150% of ambient precipitation levels, respectively) affected initial patterns of root- and shoot-Si uptake in a native Australian grass (Microlaena stipoides) in Si-supplemented and untreated soils. RESULTS Si supplementation increased soil water retention under ambient and elevated precipitation but not under drought, although this had little effect on Si uptake and growth (tiller numbers or root biomass) of M. stipoides. Changes in rainfall patterns and clipping had strong individual effects on plant growth and Si uptake and storage, whereby clipping increased Si uptake by M. stipoides under all rainfall treatments but to the greatest extent under elevated precipitation. Moreover, above-ground-below-ground Si distribution only changed following elevated precipitation by decreasing the ratio of root:shoot Si concentrations. CONCLUSIONS Results highlight the importance of soil water availability for Si uptake and suggest a role for both active and passive Si transport mechanisms. Such manipulative field studies may provide a more realistic insight into how grasses initially respond to herbivory in terms of Si-based defence under different environmental conditions.
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Affiliation(s)
- James M. W. Ryalls
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW Australia
- Centre for Agri-Environmental Research, School of Agriculture, Policy and Development, University of Reading, Reading, UK
| | - Ben D. Moore
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW Australia
| | - Scott N. Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Richmond, NSW Australia
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13
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Barnett KL, Johnson SN, Power SA. Drought negates growth stimulation due to root herbivory in pasture grasses. Oecologia 2018; 188:777-789. [PMID: 30099604 DOI: 10.1007/s00442-018-4244-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 08/04/2018] [Indexed: 10/28/2022]
Abstract
Predicted increases in extreme weather are likely to alter the interactions between organisms within ecosystems. Whilst many studies have investigated the impacts of climate change on aboveground plant-insect interactions, those belowground remain relatively unexplored. Root herbivores can be the dominant taxa in grasslands, potentially altering plant community dynamics. To better predict the impact of climate change on grasslands, we subjected four Australian pasture grasses (Cynodon dactylon, Paspalum dilatatum, Microlaena stipoides and Lolium perenne) to contrasting rainfall regimes [a press drought (i.e. sustained, moderate water stress), a pulse drought (water stress followed by periodic, infrequent deluge event) and a well-watered control], with and without root herbivores; a manual root cutting treatment was also included for comparison. Plant growth, rooting strategy, phenology and biochemistry were measured to evaluate above and belowground treatment responses. Watering treatments had a larger effect on plant productivity than root damage treatments: press drought and pulse drought treatments reduced biomass by 58% and 47%, respectively. Root herbivore damage effects were species dependent and were not always equivalent to root cutting. The combination of pulse drought and root herbivory resulted in increased root:shoot ratios for both P. dilatatum and L. perenne, as well as decreased biomass and delayed flowering time for P. dilatatum. Plant biomass responses to root damage were greatest under well-watered conditions; however, root damage also delayed or prevented investment in reproduction in at least one species. Our findings highlight the important role of soil-dwelling invertebrates for forecasting growth responses of grassland communities to future rainfall regime changes.
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Affiliation(s)
- Kirk L Barnett
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
| | - Scott N Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
| | - Sally A Power
- Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia
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14
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Ochoa-Hueso R, Collins SL, Delgado-Baquerizo M, Hamonts K, Pockman WT, Sinsabaugh RL, Smith MD, Knapp AK, Power SA. Drought consistently alters the composition of soil fungal and bacterial communities in grasslands from two continents. GLOBAL CHANGE BIOLOGY 2018; 24:2818-2827. [PMID: 29505170 DOI: 10.1111/gcb.14113] [Citation(s) in RCA: 115] [Impact Index Per Article: 19.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 01/15/2018] [Indexed: 06/08/2023]
Abstract
The effects of short-term drought on soil microbial communities remain largely unexplored, particularly at large scales and under field conditions. We used seven experimental sites from two continents (North America and Australia) to evaluate the impacts of imposed extreme drought on the abundance, community composition, richness, and function of soil bacterial and fungal communities. The sites encompassed different grassland ecosystems spanning a wide range of climatic and soil properties. Drought significantly altered the community composition of soil bacteria and, to a lesser extent, fungi in grasslands from two continents. The magnitude of the fungal community change was directly proportional to the precipitation gradient. This greater fungal sensitivity to drought at more mesic sites contrasts with the generally observed pattern of greater drought sensitivity of plant communities in more arid grasslands, suggesting that plant and microbial communities may respond differently along precipitation gradients. Actinobateria, and Chloroflexi, bacterial phyla typically dominant in dry environments, increased their relative abundance in response to drought, whereas Glomeromycetes, a fungal class regarded as widely symbiotic, decreased in relative abundance. The response of Chlamydiae and Tenericutes, two phyla of mostly pathogenic species, decreased and increased along the precipitation gradient, respectively. Soil enzyme activity consistently increased under drought, a response that was attributed to drought-induced changes in microbial community structure rather than to changes in abundance and diversity. Our results provide evidence that drought has a widespread effect on the assembly of microbial communities, one of the major drivers of soil function in terrestrial ecosystems. Such responses may have important implications for the provision of key ecosystem services, including nutrient cycling, and may result in the weakening of plant-microbial interactions and a greater incidence of certain soil-borne diseases.
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Affiliation(s)
- Raúl Ochoa-Hueso
- Department of Ecology, Autonomous University of Madrid, Madrid, Spain
| | - Scott L Collins
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | - Manuel Delgado-Baquerizo
- Cooperative Institute for Research in Environmental Sciences, University of Colorado, Boulder, CO, USA
| | - Kelly Hamonts
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
| | - William T Pockman
- Department of Biology, University of New Mexico, Albuquerque, NM, USA
| | | | - Melinda D Smith
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO, USA
| | - Alan K Knapp
- Department of Biology and Graduate Degree Program in Ecology, Colorado State University, Fort Collins, CO, USA
| | - Sally A Power
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, New South Wales, Australia
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15
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Collins L, Bradstock RA, Resco de Dios V, Duursma RA, Velasco S, Boer MM. Understorey productivity in temperate grassy woodland responds to soil water availability but not to elevated [CO 2 ]. GLOBAL CHANGE BIOLOGY 2018; 24:2366-2376. [PMID: 29316074 DOI: 10.1111/gcb.14038] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2017] [Accepted: 11/22/2017] [Indexed: 06/07/2023]
Abstract
Rising atmospheric [CO2 ] and associated climate change are expected to modify primary productivity across a range of ecosystems globally. Increasing aridity is predicted to reduce grassland productivity, although rising [CO2 ] and associated increases in plant water use efficiency may partially offset the effect of drying on growth. Difficulties arise in predicting the direction and magnitude of future changes in ecosystem productivity, due to limited field experimentation investigating climate and CO2 interactions. We use repeat near-surface digital photography to quantify the effects of water availability and experimentally manipulated elevated [CO2 ] (eCO2 ) on understorey live foliage cover and biomass over three growing seasons in a temperate grassy woodland in south-eastern Australia. We hypothesised that (i) understorey herbaceous productivity is dependent upon soil water availability, and (ii) that eCO2 will increase productivity, with greatest stimulation occurring under conditions of low water availability. Soil volumetric water content (VWC) determined foliage cover and growth rates over the length of the growing season (August to March), with low VWC (<0.1 m3 m-3 ) reducing productivity. However, eCO2 did not increase herbaceous cover and biomass over the duration of the experiment, or mitigate the effects of low water availability on understorey growth rates and cover. Our findings suggest that projected increases in aridity in temperate woodlands are likely to lead to reduced understorey productivity, with little scope for eCO2 to offset these changes.
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Affiliation(s)
- Luke Collins
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Ross A Bradstock
- Centre for Environmental Risk Management of Bushfires, University of Wollongong, Wollongong, NSW, Australia
| | - Victor Resco de Dios
- Department of Crop and Forest Sciences and AGROTECNIO Center, Universitat de Lleida, Lleida, Spain
| | - Remko A Duursma
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Sabrina Velasco
- Centre for Environmental Risk Management of Bushfires, University of Wollongong, Wollongong, NSW, Australia
| | - Matthias M Boer
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
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16
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Deveautour C, Donn S, Power SA, Bennett AE, Powell JR. Experimentally altered rainfall regimes and host root traits affect grassland arbuscular mycorrhizal fungal communities. Mol Ecol 2018; 27:2152-2163. [PMID: 29443420 DOI: 10.1111/mec.14536] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2017] [Revised: 02/04/2018] [Accepted: 02/07/2018] [Indexed: 11/27/2022]
Abstract
Future climate scenarios predict changes in rainfall regimes. These changes are expected to affect plants via effects on the expression of root traits associated with water and nutrient uptake. Associated microorganisms may also respond to these new precipitation regimes, either directly in response to changes in the soil environment or indirectly in response to altered root trait expression. We characterized arbuscular mycorrhizal (AM) fungal communities in an Australian grassland exposed to experimentally altered rainfall regimes. We used Illumina sequencing to assess the responses of AM fungal communities associated with four plant species sampled in different watering treatments and evaluated the extent to which shifts were associated with changes in root traits. We observed that altered rainfall regimes affected the composition but not the richness of the AM fungal communities, and we found distinctive communities in the increased rainfall treatment. We found no evidence of altered rainfall regime effects via changes in host physiology because none of the studied traits were affected by changes in rainfall. However, specific root length was observed to correlate with AM fungal richness, while concentrations of phosphorus and calcium in root tissue and the proportion of root length allocated to fine roots were correlated to community composition. Our study provides evidence that climate change and its effects on rainfall may influence AM fungal community assembly, as do plant traits related to plant nutrition and water uptake. We did not find evidence that host responses to altered rainfall drive AM fungal community assembly in this grassland ecosystem.
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Affiliation(s)
- Coline Deveautour
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Suzanne Donn
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Sally A Power
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
| | - Alison E Bennett
- Department of Evolution, Ecology, & Organismal Biology The Ohio State University, 318 W. 12th Ave., 300 Aronoff Laboratory, Columbus OH, 43210
| | - Jeff R Powell
- Hawkesbury Institute for the Environment, Western Sydney University, Penrith, NSW, Australia
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17
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Zhang B, Tan X, Wang S, Chen M, Chen S, Ren T, Xia J, Bai Y, Huang J, Han X. Asymmetric sensitivity of ecosystem carbon and water processes in response to precipitation change in a semi‐arid steppe. Funct Ecol 2017. [DOI: 10.1111/1365-2435.12836] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Affiliation(s)
- Bingwei Zhang
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
- University of Chinese Academy of Sciences Beijing100049 China
| | - Xingru Tan
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
- University of Chinese Academy of Sciences Beijing100049 China
| | - Shanshan Wang
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
- University of Chinese Academy of Sciences Beijing100049 China
| | - Minling Chen
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
- College of Chinese Language and Culture Jinan University Guangzhou510610 China
| | - Shiping Chen
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
| | - Tingting Ren
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
| | - Jianyang Xia
- Tiantong National Forest Ecosystem Observation and Research Station School of Ecological and Environmental Sciences East China Normal University Shanghai200062 China
| | - Yongfei Bai
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
| | - Jianhui Huang
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
| | - Xingguo Han
- State Key Laboratory of Vegetation and Environmental Change Institute of Botany Chinese Academy of Sciences Beijing100093 China
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18
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Moore BD, Johnson SN. Get Tough, Get Toxic, or Get a Bodyguard: Identifying Candidate Traits Conferring Belowground Resistance to Herbivores in Grasses. FRONTIERS IN PLANT SCIENCE 2017; 7:1925. [PMID: 28105030 PMCID: PMC5214545 DOI: 10.3389/fpls.2016.01925] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Accepted: 12/05/2016] [Indexed: 05/11/2023]
Abstract
Grasses (Poaceae) are the fifth-largest plant family by species and their uses for crops, forage, fiber, and fuel make them the most economically important. In grasslands, which broadly-defined cover 40% of the Earth's terrestrial surface outside of Greenland and Antarctica, 40-60% of net primary productivity and 70-98% of invertebrate biomass occurs belowground, providing extensive scope for interactions between roots and rhizosphere invertebrates. Grasses invest 50-70% of fixed carbon into root construction, which suggests roots are high value tissues that should be defended from herbivores, but we know relatively little about such defenses. In this article, we identify candidate grass root defenses, including physical (tough) and chemical (toxic) resistance traits, together with indirect defenses involving recruitment of root herbivores' natural enemies. We draw on relevant literature to establish whether these defenses are present in grasses, and specifically in grass roots, and which herbivores of grasses are affected by these defenses. Physical defenses could include structural macro-molecules such as lignin, cellulose, suberin, and callose in addition to silica and calcium oxalate. Root hairs and rhizosheaths, a structural adaptation unique to grasses, might also play defensive roles. To date, only lignin and silica have been shown to negatively affect root herbivores. In terms of chemical resistance traits, nitrate, oxalic acid, terpenoids, alkaloids, amino acids, cyanogenic glycosides, benzoxazinoids, phenolics, and proteinase inhibitors have the potential to negatively affect grass root herbivores. Several good examples demonstrate the existence of indirect defenses in grass roots, including maize, which can recruit entomopathogenic nematodes (EPNs) via emission of (E)-β-caryophyllene, and similar defenses are likely to be common. In producing this review, we aimed to equip researchers with candidate root defenses for further research.
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Affiliation(s)
- Ben D Moore
- Hawkesbury Institute for the Environment, Western Sydney University Richmond, NSW, Australia
| | - Scott N Johnson
- Hawkesbury Institute for the Environment, Western Sydney University Richmond, NSW, Australia
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19
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Torode MD, Barnett KL, Facey SL, Nielsen UN, Power SA, Johnson SN. Altered Precipitation Impacts on Above- and Below-Ground Grassland Invertebrates: Summer Drought Leads to Outbreaks in Spring. FRONTIERS IN PLANT SCIENCE 2016; 7:1468. [PMID: 27766101 PMCID: PMC5052266 DOI: 10.3389/fpls.2016.01468] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 09/15/2016] [Indexed: 05/09/2023]
Abstract
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.
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Affiliation(s)
- Marcel D. Torode
- School of Biosciences, Cardiff UniversityCardiff, UK
- Hawkesbury Institute for the Environment, Western Sydney University, RichmondNSW, Australia
| | - Kirk L. Barnett
- Hawkesbury Institute for the Environment, Western Sydney University, RichmondNSW, Australia
| | - Sarah L. Facey
- Hawkesbury Institute for the Environment, Western Sydney University, RichmondNSW, Australia
| | - Uffe N. Nielsen
- Hawkesbury Institute for the Environment, Western Sydney University, RichmondNSW, Australia
| | - Sally A. Power
- Hawkesbury Institute for the Environment, Western Sydney University, RichmondNSW, Australia
| | - Scott N. Johnson
- Hawkesbury Institute for the Environment, Western Sydney University, RichmondNSW, Australia
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