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Guasconi D, Manzoni S, Hugelius G. Climate-dependent responses of root and shoot biomass to drought duration and intensity in grasslands-a meta-analysis. Sci Total Environ 2023; 903:166209. [PMID: 37572920 DOI: 10.1016/j.scitotenv.2023.166209] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Revised: 08/08/2023] [Accepted: 08/08/2023] [Indexed: 08/14/2023]
Abstract
Understanding the effects of altered precipitation regimes on root biomass in grasslands is crucial for predicting grassland responses to climate change. Nonetheless, studies investigating the effects of drought on belowground vegetation have produced mixed results. In particular, root biomass under reduced precipitation may increase, decrease or show a delayed response compared to shoot biomass, highlighting a knowledge gap in the relationship between belowground net primary production and drought. To address this gap, we conducted a meta-analysis of nearly 100 field observations of grassland root and shoot biomass changes under experimental rainfall reduction to disentangle the main drivers behind grassland responses to drought. Using a response-ratio approach we tested the hypothesis that water scarcity would induce a decrease in total biomass, but an increase in belowground biomass allocation with increased drought length and intensity, and that climate (as defined by the aridity index of the study location) would be an additional predictor. As expected, meteorological drought decreased root and shoot biomass, but aboveground and belowground biomass exhibited contrasting responses to drought duration and intensity, and their interaction with climate. In particular, drought duration had negative effects on root biomass only in wet climates while more intense drought had negative effects on root biomass only in dry climates. Shoot biomass responded negatively to drought duration regardless of climate. These results show that long-term climate is an important modulator of belowground vegetation responses to drought, which might be a consequence of different drought tolerance and adaptation strategies. This variability in vegetation responses to drought suggests that physiological plasticity and community composition shifts may mediate how climate affects carbon allocation in grasslands, and thus ultimately carbon storage in soil.
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Affiliation(s)
- Daniela Guasconi
- Department of Physical Geography, Stockholm University, Stockholm, Sweden; Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden.
| | - Stefano Manzoni
- Department of Physical Geography, Stockholm University, Stockholm, Sweden; Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
| | - Gustaf Hugelius
- Department of Physical Geography, Stockholm University, Stockholm, Sweden; Bolin Centre for Climate Research, Stockholm University, Stockholm, Sweden
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Maisnam P, Jeffries TC, Szejgis J, Bristol D, Singh BK, Eldridge DJ, Horn S, Chieppa J, Nielsen UN. Severe Prolonged Drought Favours Stress-Tolerant Microbes in Australian Drylands. Microb Ecol 2023; 86:3097-3110. [PMID: 37878053 PMCID: PMC10640424 DOI: 10.1007/s00248-023-02303-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 09/15/2023] [Indexed: 10/26/2023]
Abstract
Drylands comprise one-third of Earth's terrestrial surface area and support over two billion people. Most drylands are projected to experience altered rainfall regimes, including changes in total amounts and fewer but larger rainfall events interspersed by longer periods without rain. This transition will have ecosystem-wide impacts but the long-term effects on microbial communities remain poorly quantified. We assessed belowground effects of altered rainfall regimes (+ 65% and -65% relative to ambient) at six sites in arid and semi-arid Australia over a period of three years (2016-2019) coinciding with a significant natural drought event (2017-2019). Microbial communities differed significantly among semi-arid and arid sites and across years associated with variation in abiotic factors, such as pH and carbon content, along with rainfall. Rainfall treatments induced shifts in microbial community composition only at a subset of the sites (Milparinka and Quilpie). However, differential abundance analyses revealed that several taxa, including Acidobacteria, TM7, Gemmatimonadates and Chytridiomycota, were more abundant in the wettest year (2016) and that their relative abundance decreased in drier years. By contrast, the relative abundance of oligotrophic taxa such as Actinobacteria, Alpha-proteobacteria, Planctomycetes, and Ascomycota and Basidiomycota, increased during the prolonged drought. Interestingly, fungi were shown to be more sensitive to the prolonged drought and to rainfall treatment than bacteria with Basidiomycota mostly dominant in the reduced rainfall treatment. Moreover, correlation network analyses showed more positive associations among stress-tolerant dominant taxa following the drought (i.e., 2019 compared with 2016). Our result indicates that such stress-tolerant taxa play an important role in how whole communities respond to changes in aridity. Such knowledge provides a better understanding of microbial responses to predicted increases in rainfall variability and the impact on the functioning of semi-arid and arid ecosystems.
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Affiliation(s)
- Premchand Maisnam
- Hawkesbury Institute of Environment, Western Sydney University, Penrith, NSW, Australia.
| | - Thomas C Jeffries
- Hawkesbury Institute of Environment, Western Sydney University, Penrith, NSW, Australia
- School of Science, Western Sydney University, Penrith, NSW, Australia
| | - Jerzy Szejgis
- Hawkesbury Institute of Environment, Western Sydney University, Penrith, NSW, Australia
| | - Dylan Bristol
- Hawkesbury Institute of Environment, Western Sydney University, Penrith, NSW, Australia
| | - Brajesh K Singh
- Hawkesbury Institute of Environment, Western Sydney University, Penrith, NSW, Australia
- Global Centre for Land Based Innovation, Western Sydney University, Penrith, NSW, Australia
| | - David J Eldridge
- Centre for Ecosystem Science, School of Biological, Earth and Environmental Sciences, University of New South Wales, Sydney, NSW, Australia
| | - Sebastian Horn
- Hawkesbury Institute of Environment, Western Sydney University, Penrith, NSW, Australia
| | - Jeff Chieppa
- Hawkesbury Institute of Environment, Western Sydney University, Penrith, NSW, Australia
| | - Uffe N Nielsen
- Hawkesbury Institute of Environment, Western Sydney University, Penrith, NSW, Australia
- Global Centre for Land Based Innovation, Western Sydney University, Penrith, NSW, Australia
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Heckman RW, Rueda A, Bonnette JE, Aspinwall MJ, Khasanova A, Hawkes CV, Juenger TE, Fay PA. Legacies of precipitation influence primary production in Panicum virgatum. Oecologia 2023; 201:269-278. [PMID: 36372830 DOI: 10.1007/s00442-022-05281-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2022] [Accepted: 10/31/2022] [Indexed: 11/15/2022]
Abstract
Precipitation is a key driver of primary production worldwide, but primary production does not always track year-to-year variation in precipitation linearly. Instead, plant responses to changes in precipitation may exhibit time lags, or legacies of past precipitation. Legacies can be driven by multiple mechanisms, including persistent changes in plant physiological and morphological traits and changes to the physical environment, such as plant access to soil water. We used three precipitation manipulation experiments in central Texas, USA to evaluate the magnitude, duration, and potential mechanisms driving precipitation legacies on aboveground primary production of the perennial C4 grass, Panicum virgatum. Specifically, we performed a rainout shelter study, where eight genotypes grew under different precipitation regimes; a transplant study, where plants that had previously grown in a rainout shelter under different precipitation regimes were moved to a common environment; and a mesocosm study, where the effect of swapping precipitation regime was examined with a single genotype. Across these experiments, plants previously grown under wet conditions generally performed better than expected when exposed to drought. Panicum virgatum exhibited stronger productivity legacies of past wet years on current-year responses to drought than of past dry years on current-year responses to wet conditions. Additionally, previous year tiller counts, a proxy for meristem availability, were important in determining legacy effects on aboveground production. As climate changes and precipitation extremes-both dry and wet-become more common, these results suggest that populations of P. virgatum may become less resilient.
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Affiliation(s)
- Robert W Heckman
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA.
- USDA Forest Service, Rocky Mountain Research Station, Cedar City, UT, 84721, USA.
| | - Austin Rueda
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
- PathogenDx, Tucson, AZ, 85714, USA
| | - Jason E Bonnette
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Michael J Aspinwall
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
- College of Forestry and Wildlife Sciences, Auburn University, Auburn, AL, 36849, USA
| | - Albina Khasanova
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
- Lawrence Berkeley National Laboratory, Berkeley, CA, 74720, USA
| | - Christine V Hawkes
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
- Department of Plant and Microbial Biology, North Carolina State University, Raleigh, NC, 27695, USA
| | - Thomas E Juenger
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, 78712, USA
| | - Philip A Fay
- Grassland Soil and Water Research Lab, USDA-ARS, Temple, TX, 76502, USA
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van Blerk JJ, West AG, Altwegg R, Hoffman MT. Post-fire summer rainfall differentially affects reseeder and resprouter population recovery in fire-prone shrublands of South Africa. Sci Total Environ 2021; 788:147699. [PMID: 34034189 DOI: 10.1016/j.scitotenv.2021.147699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 05/07/2021] [Accepted: 05/07/2021] [Indexed: 06/12/2023]
Abstract
Summer rainfall can have strong effects on post-fire mediterranean-type shrubland recovery patterns, with potentially long-lasting implications on communities. Our three-year field rainfall manipulation experiment tested post-fire survival and physiological responses of reseeders and resprouters to contrasting summer rainfall patterns in Fynbos and Renosterveld shrublands in South Africa. Climate projections are uncertain for this region but indicate that increased convective summer rainfall events could occur. We irrigated treatment plots during the hottest summer months (i.e. Jan, Feb, March) to contrast the naturally dry summer conditions. This allowed for assessments of the potential limiting effects of summer drought on post-fire vegetation recovery and the responsiveness of vegetation to moisture inputs during this time. Natural summer droughts led to leaf dehydration, reduced photosynthesis and reduced photosynthetic capacity. This had a particularly severe effect on reseeders during the first summer after fire leading to high mortality rates. Summer irrigations strongly reduced levels of reseeder stress and mortality. Resprouters in both vegetation types were physiologically less sensitive to rainfall patterns and showed little drought-related mortality. Comparisons of final population sizes with emergence and survival patterns showed that summer rainfall during the first summer after fire had the potential to strongly alter reseeder population sizes. The physiological sensitivity of plants to summer rainfall patterns was higher in shrubland communities occurring on fine-textured, moderately fertile soils (e.g. Renosterveld). Shrublands occurring on sandy, nutrient-poor soils (e.g. Fynbos) were remarkably insensitive to summer drought after the first summer with lower irrigation responses. Our study demonstrated the potential for variation in post-fire summer rainfall to strongly affect reseeder and resprouter population recovery patterns.
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Affiliation(s)
- J J van Blerk
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa.
| | - A G West
- Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
| | - R Altwegg
- Centre for Statistics in Ecology, Environment and Conservation, Department of Statistical Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
| | - M T Hoffman
- Plant Conservation Unit, Department of Biological Sciences, University of Cape Town, Private Bag X3, Rondebosch 7701, South Africa
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Parra A, Moreno JM. Drought differentially affects the post-fire dynamics of seeders and resprouters in a Mediterranean shrubland. Sci Total Environ 2018; 626:1219-1229. [PMID: 29898529 DOI: 10.1016/j.scitotenv.2018.01.174] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2017] [Revised: 01/17/2018] [Accepted: 01/17/2018] [Indexed: 06/08/2023]
Abstract
In fire-prone ecosystems, changes in rainfall after fire could differentially affect seeders and resprouters, thus leading to long-lasting impacts on the vegetation. Climate change in the Mediterranean region is projected to reduce precipitation, expand the summer drought and increase fire danger. Understanding the sensitivity to changes in rainfall during the post-fire regeneration stage is critical to anticipate the impacts of climate change on Mediterranean-type areas of the world. Here, we investigated how species differing in post-fire regeneration strategy (seeders vs resprouters) responded to rainfall changes in a Cistus-Erica shrubland of central Spain. Drought treatments were implemented using a system of automatic rainout shelters with an irrigation facility before (one season) and after (four years) burning a set of experimental plots. Treatments applied were: environmental control (natural rainfall), historical control (mimicking the long-term rainfall), moderate drought (-25% rainfall), and severe drought (-45% rainfall). Plant demography and vigour (main woody shrubs), as well as abundance (shrubs and herbs) were monitored during the first four years after fire. The first post-fire year was the key period for the recovery of seeders (Cistus ladanifer and Rosmarinus officinalis), and their recruitment, cover and size significantly decreased with drought. However, density four years after fire was larger than unburned and it was significantly correlated with emergence during the first year, indicating that population controls were more on emergence than on establishment. In contrast, resprouters (Erica arborea, Erica scoparia and Phillyrea angustifolia) were hardly affected by drought. Plant community dynamics in the burned control plots progressively converged with the unburned ones, while that in the drought-treated plots lagged behind them, maintaining a higher cover, richness and diversity of herbs. This post-fire "herbalization" due to drought might facilitate an untimely fire, before seeders would reach sexual maturity, which could have major implications for the maintenance of the community.
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Affiliation(s)
- Antonio Parra
- Universidad de Castilla-La Mancha, Departamento de Ciencias Ambientales, E-45071 Toledo, Spain.
| | - José M Moreno
- Universidad de Castilla-La Mancha, Departamento de Ciencias Ambientales, E-45071 Toledo, Spain.
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