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Asare MO, Midula P, Oravová L, Kuráň P, Hejcman M. Elemental composition of post-wildfire biomass ashes and partly burned woody species in Bohemian Switzerland National Park, Czech Republic. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2024:10.1007/s11356-024-34858-7. [PMID: 39215921 DOI: 10.1007/s11356-024-34858-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/06/2023] [Accepted: 08/26/2024] [Indexed: 09/04/2024]
Abstract
The study explored the post-wildfire elemental composition of parts (wood, bark, branch, cone, trunk, litter, twig, needle, sward, fallow, sapling, etc.) and by-products (biomass ashes, partly burnt parts, and char) of different woody species in the Bohemian Switzerland National Park, Czech Republic, and considered their effects on soils. Multi-elemental analysis of the fire by-products of the woody species was determined with inductively coupled plasma-optical emission spectrometry and mass spectrometry and compared with control biomass samples unaffected by wildfire. Most fire by-products were slightly alkaline, with acidic ashes obtained from blueberry wood. The by-products of the wildfire were characterized by varied total contents of macro (P, Ca, K, Mg, and S), micro (Na, Mn, Fe, Cu, and Zn), and other elements (B, Co, Mo, and V) vital to soil fertility and plant growth. The mean content of macro elements in the biomass ashes was up to 4.16 P, 23.5 Ca, 2.48 Mg, 63 K, and 5.57 S g kg-1. These values were comparatively lower than published data for ashes obtained under optimized conditions, e.g., those combusted in power generation facilities. Conversely, partly burnt parts-an indication of incomplete combustion-had higher 9.22 P, 79 Ca, and 5.99 Mg g kg-1 contents in spruce needles than in biomass ashes and the control. Variations in woody species and anthropogenic activities in areas of wildfires produced varied As, Cd, Cr, Ni, and Pb contents above EU fertilizer regulation. Caution in applying biomass ashes from wildfires on fields is required due to risk/toxic elements input from anthropogenic activities. Wildfire effects on the elemental composition of woody species can provide information on plant parts most suitable for biomass ashes for soil and ecosystem safety.
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Affiliation(s)
- Michael O Asare
- Faculty of Environment, Jan Evangelista Purkyně University in Ústí Nad Labem, Pasteurova 3544/1, Ústí Nad Labem, CZ400 96, Czech Republic.
- Department of Agroenvironmental Chemistry and Plant Nutrition, Faculty of Agrobiology, Food, and Natural Resources, Czech University of Life Sciences Prague, Kamýcká 129, 165 00, Prague 6, Czech Republic.
| | - Pavol Midula
- Faculty of Environment, Jan Evangelista Purkyně University in Ústí Nad Labem, Pasteurova 3544/1, Ústí Nad Labem, CZ400 96, Czech Republic
| | - Lucie Oravová
- Faculty of Environment, Jan Evangelista Purkyně University in Ústí Nad Labem, Pasteurova 3544/1, Ústí Nad Labem, CZ400 96, Czech Republic
| | - Pavel Kuráň
- Faculty of Environment, Jan Evangelista Purkyně University in Ústí Nad Labem, Pasteurova 3544/1, Ústí Nad Labem, CZ400 96, Czech Republic
| | - Michal Hejcman
- Faculty of Environment, Jan Evangelista Purkyně University in Ústí Nad Labem, Pasteurova 3544/1, Ústí Nad Labem, CZ400 96, Czech Republic
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Xu X, Zhao B, Shen B, Qi Z, Wang J, Cui H, Li B, Chen S, Wang G, Liu X. Using RNA-Seq Analysis to Select Key Genes Related to Seed Dormancy in ALS-Inhibiting Resistant Descurainia sophia with Pro-197-Thr Mutation. PLANTS (BASEL, SWITZERLAND) 2024; 13:2305. [PMID: 39204741 PMCID: PMC11360172 DOI: 10.3390/plants13162305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2024] [Revised: 07/26/2024] [Accepted: 08/07/2024] [Indexed: 09/04/2024]
Abstract
Flixweed (Descurainia sophia) is a weed that seriously affects wheat fields in China. Over the past 20 years, it has evolved resistance to the herbicide tribenuron-methyl. In the present study, a resistant D. sophia population with a Pro-197-Thr mutation of acetolactate synthetase (ALS) was found to have a resistance index of 457.37 for tribenuron-methyl. Under the same growth conditions, the seeds of resistant (R) and susceptible (S) populations exhibited similar vitality but the germination rates of R seeds were higher than those of S seeds. This result demonstrated that seed dormancy periods were shorter in the R seeds. RNA-Seq transcriptome analysis was then used to choose candidate genes that could regulate seed dormancy pathways in the R population. A total of 504,976,046 clean reads were selected from nine RNA-Seq libraries and assembled into 79,729 unigenes. Among these, 33,476 unigenes were assigned to 51 GO subgroups, and 26,117 unigenes were assigned to 20 KEGG secondary metabolic pathways. Next, 2473 differentially expressed genes (DEGs) were divided into three groups, as follows: G-24 h (germinating seeds) vs. D (dormant seeds); G-48 h (germinated seeds) vs. D; and G-48 h vs. G-24 h. From these 2473 DEGs, 8 were selected as candidate dormancy unigenes for the R population if their expression levels continuously decreased during the seed germination progress and their functional annotations were related to plant seed dormancy. One candidate unigene was annotated as CYP707A2; two unigenes were annotated as the transcription factors TGA4 and TGA2; one unigene was annotated as the cystathionine beta-synthase gene; and four unigenes could not be annotated as any gene listed in the six public databases. However, qRT-PCR-validated results showed that, during the germination of R seeds, the expression of the three candidate unigenes first decreased and then increased, indicating that they may have other growth-regulating functions in R populations. In brief, the dormancy function of the eight candidate dormancy unigenes needs to be further studied.
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Affiliation(s)
- Xian Xu
- Key Laboratory of Crop Cultivation Physiology and Green Production of Hebei Province, Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050035, China; (X.X.); (B.Z.); (B.S.); (Z.Q.); (J.W.); (H.C.); (B.L.)
| | - Bochui Zhao
- Key Laboratory of Crop Cultivation Physiology and Green Production of Hebei Province, Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050035, China; (X.X.); (B.Z.); (B.S.); (Z.Q.); (J.W.); (H.C.); (B.L.)
| | - Beibei Shen
- Key Laboratory of Crop Cultivation Physiology and Green Production of Hebei Province, Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050035, China; (X.X.); (B.Z.); (B.S.); (Z.Q.); (J.W.); (H.C.); (B.L.)
| | - Zhizun Qi
- Key Laboratory of Crop Cultivation Physiology and Green Production of Hebei Province, Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050035, China; (X.X.); (B.Z.); (B.S.); (Z.Q.); (J.W.); (H.C.); (B.L.)
| | - Jianping Wang
- Key Laboratory of Crop Cultivation Physiology and Green Production of Hebei Province, Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050035, China; (X.X.); (B.Z.); (B.S.); (Z.Q.); (J.W.); (H.C.); (B.L.)
| | - Haiyan Cui
- Key Laboratory of Crop Cultivation Physiology and Green Production of Hebei Province, Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050035, China; (X.X.); (B.Z.); (B.S.); (Z.Q.); (J.W.); (H.C.); (B.L.)
| | - Binghua Li
- Key Laboratory of Crop Cultivation Physiology and Green Production of Hebei Province, Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050035, China; (X.X.); (B.Z.); (B.S.); (Z.Q.); (J.W.); (H.C.); (B.L.)
| | - Silong Chen
- College of Food Science and Biology, Hebei University of Science and Technology, Shijiazhuang 050018, China
| | - Guiqi Wang
- Key Laboratory of Crop Cultivation Physiology and Green Production of Hebei Province, Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050035, China; (X.X.); (B.Z.); (B.S.); (Z.Q.); (J.W.); (H.C.); (B.L.)
| | - Xiaomin Liu
- Key Laboratory of Crop Cultivation Physiology and Green Production of Hebei Province, Institute of Cereal and Oil Crops, Hebei Academy of Agriculture and Forestry Sciences, Shijiazhuang 050035, China; (X.X.); (B.Z.); (B.S.); (Z.Q.); (J.W.); (H.C.); (B.L.)
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Pandey N, Nalla S, Dayal A, Rai P, Sahi VP. Smoke-water treatment of seeds, an ancient technique for increasing seed vigor. PROTOPLASMA 2024:10.1007/s00709-024-01975-6. [PMID: 39153082 DOI: 10.1007/s00709-024-01975-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Accepted: 07/28/2024] [Indexed: 08/19/2024]
Abstract
Germination is an essential phenomenon in the life cycle of plants, and a variety of external and internal factors influence it. Fire and the produced smoke have been vital environmental stimulants for the germination of seeds in many plant species, like Leucospermum cordifolium and Serruria florida. These plants do not germinate at all if fire and smoke are not present. This phenomenon of germination in plant species has existed in the ecosystem since ancient times. Various studies to study the response of seeds to smoke and its extracts have been undertaken for stimulation of germination by burning various plant materials and bubbling the smoke produced through water. The application of plant-derived smoke and smoke water is well known for promoting germination, breaking dormancy, and checking abiotic stress. This significantly indicates that plant-derived smoke contains some bioactive metabolites responsible for the physiological metabolism of seed germination and is involved in enhancing seed vigor. The present review deals with the ancient use of smoke and smoke extracts for seed priming, the cost-efficient method of its preparation, the mode of action of karrikins relating to its perception by plants, and its significant effects on various crops, including its ability to check biotic and abiotic stresses.
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Affiliation(s)
- Nidhi Pandey
- Sam Higginbottom University of Agriculture Technology and Sciences, Prayagraj, Uttar Pradesh, India
| | - Sandeep Nalla
- Sam Higginbottom University of Agriculture Technology and Sciences, Prayagraj, Uttar Pradesh, India
| | - Abhinav Dayal
- Sam Higginbottom University of Agriculture Technology and Sciences, Prayagraj, Uttar Pradesh, India
| | - Prashant Rai
- Sam Higginbottom University of Agriculture Technology and Sciences, Prayagraj, Uttar Pradesh, India
| | - Vaidurya Pratap Sahi
- Sam Higginbottom University of Agriculture Technology and Sciences, Prayagraj, Uttar Pradesh, India.
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Overton J, Ooi MKJ, Tangney R. Some like it hot: Seed thermal threshold variation in obligate seeding Acacia pulchella along a climate gradient. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 948:174929. [PMID: 39038678 DOI: 10.1016/j.scitotenv.2024.174929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2024] [Revised: 07/18/2024] [Accepted: 07/19/2024] [Indexed: 07/24/2024]
Abstract
Dormancy in seeds is a key persistence mechanism for many flowering plants. Physically dormant (PY) seeds have water impermeable seed coats, and in fire-prone systems a common mechanism for dormancy release is fire-induced soil heating. However, the thermal thresholds innate to seeds with PY may be influenced by vegetation, climate, and fire regimes, varying substantially between populations of the same species. To investigate intraspecific variation of thermal thresholds in PY seeds, we sampled obligate seeding Acacia pulchella (Fabaceae) which produces PY seeds. Sampling was undertaken from 13 populations across a climate gradient of rainfall and temperature, and between two vegetation communities in fire-prone Mediterranean-type ecosystems of south-west Western Australia. To test a range of weather and fire-induced soil heating dormancy-break scenarios, we conducted dry heat shock experiments between 40 and 140 °C for 10 min and scored germination for 16 weeks. We created population-specific thermal performance curves and extracted the dormancy release temperature at which 50 % of the seeds had germinated (DRT50), the optimum dormancy-breaking temperature to stimulate maximum germination (T0), and the lethal temperature at which 50 % of the seeds were killed (LT50). Generalised linear models were used to examine relationships between thermal thresholds and possible vegetation, climate, and fire regime drivers of intraspecific variation in seed traits. We found that thermal thresholds differed between vegetation communities, with thresholds consistently higher in forest-type ecosystems compared to open woodland, and the influence of climate varied significantly between the two communities. Seeds from Jarrah Forest populations had a DRT50 16.0 °C higher, a T0 9.7 °C higher, and LT50 7.8 °C higher than seeds from Banksia woodlands. A high rate of non-dormancy was identified in one population that had lost fire in its system and displayed significant germination after both summer and fire-related temperatures. The PY thermal thresholds modelled here provide insight into the strong influence of variable soil heating as a function of vegetation and fuel dynamics in fire-prone environments. Our findings highlight the significant intraspecific variation for this species and suggest that fire-induced soil heating generated by vegetation characteristics may be an overlooked element of fire regimes shaping seed traits.
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Affiliation(s)
- Jessica Overton
- Centre for Ecosystem Science, School of Biological Earth and Environmental Sciences, University of New South Wales, Kensington, NSW, Australia; Kings Park Science, Biodiversity and Conservation Science, Department of Biodiversity, Conservation, and Attractions, Kings Park, WA, Australia.
| | - Mark K J Ooi
- Centre for Ecosystem Science, School of Biological Earth and Environmental Sciences, University of New South Wales, Kensington, NSW, Australia
| | - Ryan Tangney
- Centre for Ecosystem Science, School of Biological Earth and Environmental Sciences, University of New South Wales, Kensington, NSW, Australia; Kings Park Science, Biodiversity and Conservation Science, Department of Biodiversity, Conservation, and Attractions, Kings Park, WA, Australia
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5
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Krawczyk R, Osyczka P, Siebielec G, Nobis M. Fires in the face of climate change: Indicators of fire disturbance in heath areas - Inference from military training lands. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 363:121373. [PMID: 38850907 DOI: 10.1016/j.jenvman.2024.121373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2024] [Revised: 05/20/2024] [Accepted: 06/01/2024] [Indexed: 06/10/2024]
Abstract
Global warming significantly affects the frequency and intensity of wildfires in many fire-prone areas of the world and fire disturbance regimes are changing rapidly. Alongside this, controlled burning is often considered or implemented as an alternative method for nature protection. Here, we studied the post-fire secondary succession in dry heath habitat located in military training grounds to recognise the impact of fire on the effectiveness and rate of ecosystem recovery. We focus particularly on identifying indicator species for a given successional phase of Central European dry heath habitats and assessing their value for dating the last fire disturbance. The research involved 60 vegetation patches (plots of 25 m2), which were assigned to four post-fire age classes, namely: 1-5 years (Class A), 6-10 years (Class B), 11-15 years (Class C), and >15 years (Class D). In each study plot, species diversity and coverage of lichens, bryophytes and vascular plants were examined in addition to the physicochemical properties of the soil substrate. Cryptogams and vascular plants clearly differ in terms of the secondary succession pattern; specific sets of cryptogams correspond well to particular post-fire classes and are therefore good determinants of the post-fire succession stage. Spontaneous succession of plant vegetation eventually leads to complete recovery of the heath in a relatively short time. Nevertheless, great vegetation dynamics in the first years after a fire disturbance may result in seemingly different directions of succession. Post-fire classes did not differ noticeably in terms of soil properties, it follows that the effects of fire on soil conditions are negligible; though, a significant upward trend was observed for exchangeable form of K throughout the succession process. Our results indicate that sporadic fires reduce the undesirable overgrowth of heathlands or psamophilous grasslands and generally have a little negative side-effect on the ecosystem. The revealed succession patterns and defined sets of species characteristic for subsequent post-fire age classes are applicable to dating fire disturbances, regardless of whether the fire was planned or spontaneous.
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Affiliation(s)
- Rafał Krawczyk
- Institute of Biological Sciences, Faculty of Biology and Biotechnology, University of Maria Curie-Skłodowska, Lublin, Poland.
| | - Piotr Osyczka
- Institute of Botany, Faculty of Biology, Jagiellonian University, Kraków, Poland.
| | - Grzegorz Siebielec
- Institute of Soil Science and Plant Cultivation, State Research Institute, Puławy, Poland
| | - Marcin Nobis
- Institute of Botany, Faculty of Biology, Jagiellonian University, Kraków, Poland
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6
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Pausas JG, Lamont BB, Keeley JE, Bond WJ. The need for mechanistic explanations in (seed) ecology. THE NEW PHYTOLOGIST 2024; 242:2394-2398. [PMID: 38643979 DOI: 10.1111/nph.19751] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2023] [Accepted: 03/25/2024] [Indexed: 04/23/2024]
Affiliation(s)
- Juli G Pausas
- CIDE-CSIC, Consejo Superior de Investigaciones Científicas, 46113 Montcada, Valencia, Spain
| | - Byron B Lamont
- Ecology Section, School of Life and Molecular Sciences, Curtin University, Perth, WA, 6845, Australia
| | - Jon E Keeley
- US Geological Survey, Western Ecological Research Center, Sequoia-Kings Canyon Field Station, Three Rivers, CA, 93271, USA
- Department of Ecology and Evolutionary Biology, University of California-Los Angeles, Los Angeles, CA, 90095, USA
| | - William J Bond
- Department of Biological Sciences, University of Cape Town, Cape Town, 7701, South Africa
- South African Environmental Observation Network, National Research Foundation, Claremont, 7735, South Africa
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Niu J, Xu M, Zong N, Sun J, Zhao L, Hui W. Ascorbic acid releases dormancy and promotes germination by an integrated regulation of abscisic acid and gibberellin in Pyrus betulifolia seeds. PHYSIOLOGIA PLANTARUM 2024; 176:e14271. [PMID: 38566130 DOI: 10.1111/ppl.14271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2023] [Revised: 02/28/2024] [Accepted: 03/08/2024] [Indexed: 04/04/2024]
Abstract
Seed dormancy is an important life history state in which intact viable seeds delay or prevent germination under suitable conditions. Ascorbic acid (AsA) acts as a small molecule antioxidant, and breaking seed dormancy and promoting subsequent growth are among its numerous functions. In this study, a germination test using Pyrus betulifolia seeds treated with exogenous AsA or AsA synthesis inhibitor lycorine (Lyc) and water absorption was conducted. The results indicated that AsA released dormancy and increased germination and 20 mmol L-1 AsA promoted cell division, whereas Lyc reduced germination. Seed germination showed typical three phases of water absorption; and seeds at five key time points were sampled for transcriptome analysis. It revealed that multiple pathways were involved in breaking dormancy and promoting germination through transcriptome data, and 12 differentially expressed genes (DEGs) related to the metabolism and signal transduction of abscisic acid (ABA) and gibberellins (GA) were verified by subsequent RT-qPCR. For metabolites, exogenous AsA increased endogenous AsA and GA3 but reduced ABA and the ABA/GA3 ratio. In addition, three genes regulating ABA synthesis were downregulated by AsA, while five genes mediating ABA degradation were upregulated. Taken together, AsA regulates the pathways associated with ABA and GA synthesis, catalysis, and signal transduction, with subsequent reduction in ABA and increase in GA and further the balance of ABA/GA, ultimately releasing dormancy and promoting germination.
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Affiliation(s)
- Junpeng Niu
- College of Life Sciences, Shaanxi Normal University, China
- College of Grassland Agriculture, Northwest A&F University, Yangling, China
| | - Mingzhen Xu
- College of Life Sciences, Shaanxi Normal University, China
| | - Na Zong
- College of Life Sciences, Shaanxi Normal University, China
| | - Jia Sun
- College of Life Sciences, Shaanxi Normal University, China
| | - Lei Zhao
- College of Life Sciences, Shaanxi Normal University, China
| | - Wei Hui
- College of Life Sciences, Shaanxi Normal University, China
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Cuena Lombraña A, Dessì L, Podda L, Fois M, Luna B, Porceddu M, Bacchetta G. The Effect of Heat Shock on Seed Dormancy Release and Germination in Two Rare and Endangered Astragalus L. Species (Fabaceae). PLANTS (BASEL, SWITZERLAND) 2024; 13:484. [PMID: 38498413 PMCID: PMC10892968 DOI: 10.3390/plants13040484] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 02/02/2024] [Accepted: 02/06/2024] [Indexed: 03/20/2024]
Abstract
Many Astragalus species exhibit seeds with physical dormancy (PY), but little is known about the ecological context of this dormancy. We focused on A. maritimus and A. verrucosus, two threatened Sardinian endemic species inside the subgenus Trimeniaeus Bunge. Fresh seeds collected from the only two respective known populations were used to investigate the effect of mechanical scarification, heat shock, and water imbibition processes on PY release and germination. PY can be overcome through mechanical scarification of the water-impermeable seed coats, while no dormancy break was detected, nor a subsequent increase in seed germination due to fire-induced heat. This suggests that fire does not trigger dormancy release and seed germination in these species. The seeds tolerate relatively high heat shock temperatures (up to 120 and 100 °C for A. verrucosus and A. maritimus, respectively), but after 120 °C for 10 min, the number of dead seeds increases in both species. These facts suggest the capacity to develop a soil seed bank that can persist after fires and delay germination until the occurrence of optimal conditions. As regards water imbibition, both Astragalus species did not show the typical triphasic pattern, as germination started without further water uptake. This study emphasizes the significance of understanding germination processes and dormancy in threatened species. In fire-prone ecosystems, PY dormancy plays a crucial role in soil seed bank persistence, and it may be selectively influenced by post-fire conditions. Understanding such adaptations provides useful insights into conservation strategies.
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Affiliation(s)
- Alba Cuena Lombraña
- Centre for Conservation of Biodiversity (CCB), Sardinian Germplasm Bank (BG-SAR), Department of Life and Environmental Sciences, University of Cagliari, Viale Sant’Ignazio da Laconi 9-13, 09123 Cagliari, Italy; (A.C.L.); (L.P.); (M.F.); (M.P.); (G.B.)
| | - Ludovica Dessì
- Centre for Conservation of Biodiversity (CCB), Sardinian Germplasm Bank (BG-SAR), Department of Life and Environmental Sciences, University of Cagliari, Viale Sant’Ignazio da Laconi 9-13, 09123 Cagliari, Italy; (A.C.L.); (L.P.); (M.F.); (M.P.); (G.B.)
| | - Lina Podda
- Centre for Conservation of Biodiversity (CCB), Sardinian Germplasm Bank (BG-SAR), Department of Life and Environmental Sciences, University of Cagliari, Viale Sant’Ignazio da Laconi 9-13, 09123 Cagliari, Italy; (A.C.L.); (L.P.); (M.F.); (M.P.); (G.B.)
| | - Mauro Fois
- Centre for Conservation of Biodiversity (CCB), Sardinian Germplasm Bank (BG-SAR), Department of Life and Environmental Sciences, University of Cagliari, Viale Sant’Ignazio da Laconi 9-13, 09123 Cagliari, Italy; (A.C.L.); (L.P.); (M.F.); (M.P.); (G.B.)
| | - Belén Luna
- Departamento de Ciencias Ambientales, Facultad de Ciencias Ambientales y Bioquímica, Universidad de Castilla-La Mancha, Av. Carlos III S/N, 45071 Toledo, Spain;
| | - Marco Porceddu
- Centre for Conservation of Biodiversity (CCB), Sardinian Germplasm Bank (BG-SAR), Department of Life and Environmental Sciences, University of Cagliari, Viale Sant’Ignazio da Laconi 9-13, 09123 Cagliari, Italy; (A.C.L.); (L.P.); (M.F.); (M.P.); (G.B.)
| | - Gianluigi Bacchetta
- Centre for Conservation of Biodiversity (CCB), Sardinian Germplasm Bank (BG-SAR), Department of Life and Environmental Sciences, University of Cagliari, Viale Sant’Ignazio da Laconi 9-13, 09123 Cagliari, Italy; (A.C.L.); (L.P.); (M.F.); (M.P.); (G.B.)
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9
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Wei P, Lamont B, He T, Xue W, Wang PC, Song W, Zhang R, Keyhani AB, Zhao S, Lu W, Dong F, Gao R, Yu J, Huang Y, Tang L, Lu K, Ma J, Xiong Z, Chen L, Wan N, Wang B, He W, Teng M, Dian Y, Wang Y, Zeng L, Lin C, Dai M, Zhou Z, Xiao W, Yan Z. Vegetation-fire feedbacks increase subtropical wildfire risk in scrubland and reduce it in forests. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 351:119726. [PMID: 38052142 DOI: 10.1016/j.jenvman.2023.119726] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 11/20/2023] [Accepted: 11/25/2023] [Indexed: 12/07/2023]
Abstract
Climate dictates wildfire activity around the world. But East and Southeast Asia are an apparent exception as fire-activity variation there is unrelated to climatic variables. In subtropical China, fire activity decreased by 80% between 2003 and 2020 amid increased fire risks globally. Here, we assessed the fire regime, vegetation structure, fuel flammability and their interactions across subtropical Hubei, China. We show that tree basal area (TBA) and fuel flammability explained 60% of fire-frequency variance. Fire frequency and fuel flammability, in turn, explained 90% of TBA variance. These results reveal a novel system of scrubland-forest stabilized by vegetation-fire feedbacks. Frequent fires promote the persistence of derelict scrubland through positive vegetation-fire feedbacks; in forest, vegetation-fire feedbacks are negative and suppress fire. Thus, we attribute the decrease in wildfire activity to reforestation programs that concurrently increase forest coverage and foster negative vegetation-fire feedbacks that suppress wildfire.
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Affiliation(s)
- P Wei
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - B Lamont
- Ecology Section, School of Molecular and Life Sciences, Curtin University, Perth, WA 6845, Australia.
| | - T He
- College of Science Engineering & Education, Murdoch University, Murdoch, WA 6150, Australia.
| | - W Xue
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - P C Wang
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - W Song
- College of Agronomy, Northwest Agriculture & Forestry University, Xianyang, 712100, China.
| | - R Zhang
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - A B Keyhani
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - S Zhao
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - W Lu
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - F Dong
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - R Gao
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - J Yu
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - Y Huang
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - L Tang
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - K Lu
- Hubei Forestry Survey and Design Institute, East Lake Science and Technology, District, Wuhan, 430074, Hubei, China.
| | - J Ma
- Hubei Forestry Survey and Design Institute, East Lake Science and Technology, District, Wuhan, 430074, Hubei, China.
| | - Z Xiong
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - L Chen
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - N Wan
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - B Wang
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - W He
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - M Teng
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - Y Dian
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - Y Wang
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - L Zeng
- Key Laboratory of Forest Ecology and Environment, Chinese Academy of Forestry, Beijing, 100091, China.
| | - C Lin
- Hubei Forestry Survey and Design Institute, East Lake Science and Technology, District, Wuhan, 430074, Hubei, China.
| | - M Dai
- Hubei Forestry Survey and Design Institute, East Lake Science and Technology, District, Wuhan, 430074, Hubei, China.
| | - Z Zhou
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
| | - W Xiao
- Key Laboratory of Forest Ecology and Environment, Chinese Academy of Forestry, Beijing, 100091, China.
| | - Z Yan
- Department of Forestry, College of Horticulture and Forestry, Huazhong Agricultural University, Wuhan, 430070, Hubei, China.
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Lamont BB. To burn, or not to burn: that is the question. Trends Ecol Evol 2023; 38:1119-1121. [PMID: 37777373 DOI: 10.1016/j.tree.2023.09.010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2023] [Revised: 09/10/2023] [Accepted: 09/12/2023] [Indexed: 10/02/2023]
Abstract
Recently, Zylstra et al. reported that wet sclerophyll forest left unburnt for 75 years experiences a marked decrease in flammability, requiring a radical rethink about fire management. This also highlights the vertical dimension of fires, with species conservation favored by a mosaic of fire types (high pyrodiversity).
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Affiliation(s)
- Byron B Lamont
- Ecology Section, School of Molecular and Life Sciences, Curtin University, Perth, WA 6003, Australia.
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11
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Fleming MB, Stanley L, Zallen R, Chansler MT, Brudvig LA, Lowry DB, Weber M, Telewski FW. The 141-year period for Dr. Beal's seed viability experiment: A hybrid surprise. AMERICAN JOURNAL OF BOTANY 2023; 110:e16250. [PMID: 37812737 DOI: 10.1002/ajb2.16250] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 09/27/2023] [Accepted: 09/29/2023] [Indexed: 10/11/2023]
Abstract
PREMISE In 1879, Dr. William Beal buried 20 glass bottles filled with seeds and sand at a single site at Michigan State University. The goal of the experiment was to understand seed longevity in the soil, a topic of general importance in ecology, restoration, conservation, and agriculture, by periodically assaying germinability of these seeds over 100 years. The interval between germination assays has been extended and the experiment will now end after 221 years, in 2100. METHODS We dug up the 16th bottle in April 2021 and attempted to germinate the 141-year-old seeds it contained. We grew germinants to maturity and identified these to species by vegetative and reproductive phenotypes. For the first time in the history of this experiment, genomic DNA was sequenced to confirm species identities. RESULTS Twenty seeds germinated over the 244-day assay. Eight germinated in the first 11 days. All 20 belonged to the Verbascum genus: Nineteen were V. blattaria according to phenotype and ITS2 genotype; and one had a hybrid V. blattaria × V. thapsus phenotype and ITS2 genotype. In total, 20/50 (40%) of the original Verbascum seeds in the bottle germinated in year 141. CONCLUSIONS While most species in the Beal experiment lost all seed viability in the first 60 years, a high percentage of Verbascum seeds can still germinate after 141 years in the soil. Long-term experiments such as this one are rare and invaluable for studying seed viability in natural soil conditions.
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Affiliation(s)
- Margaret B Fleming
- Department of Plant, Soil and Microbial Science, Michigan State University, East Lansing, Michigan, 48824, USA
| | - Lauren Stanley
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA
| | - Robyn Zallen
- Department of Plant, Soil and Microbial Science, Michigan State University, East Lansing, Michigan, 48824, USA
| | - Matthew T Chansler
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA
- MSU Herbarium, Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA
| | - Lars A Brudvig
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA
- Program in Ecology, Evolution, and Behavior, Michigan State University, East Lansing, Michigan, 48824, USA
| | - David B Lowry
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA
- Program in Ecology, Evolution, and Behavior, Michigan State University, East Lansing, Michigan, 48824, USA
- Plant Resilience Institute, Michigan State University, East Lansing, MI, 48824, USA
| | - Marjorie Weber
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA
- Program in Ecology, Evolution, and Behavior, Michigan State University, East Lansing, Michigan, 48824, USA
| | - Frank W Telewski
- Department of Plant Biology, Michigan State University, East Lansing, Michigan, 48824, USA
- W. J. Beal Botanical Garden and Campus Arboretum, Office of the Provost, Michigan State University, East Lansing, Michigan, 48824, USA
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12
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Rosbakh S, Carta A, Fernández-Pascual E, Phartyal SS, Dayrell RLC, Mattana E, Saatkamp A, Vandelook F, Baskin J, Baskin C. Global seed dormancy patterns are driven by macroclimate but not fire regime. THE NEW PHYTOLOGIST 2023; 240:555-564. [PMID: 37537732 DOI: 10.1111/nph.19173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Accepted: 07/05/2023] [Indexed: 08/05/2023]
Abstract
Seed dormancy maximizes plant recruitment in habitats with variation in environmental suitability for seedling establishment. Yet, we still lack a comprehensive synthesis of the macroecological drivers of nondormancy and the different classes of seed dormancy: physiological dormancy, morphophysiological dormancy and physical dormancy. We examined current geographic patterns and environmental correlates of global seed dormancy variation. Combining the most updated data set on seed dormancy classes for > 10 000 species with > 4 million georeferenced species occurrences covering all of the world's biomes, we test how this distribution is driven by climate and fire regime. Seed dormancy is prevalent in seasonally cold and dry climates. Physiological dormancy occurs in relatively dry climates with high temperature seasonality (e.g. temperate grasslands). Morphophysiological dormancy is more common in forest-dominated, cold biomes with comparatively high and evenly distributed precipitation. Physical dormancy is associated with dry climates with strong seasonal temperature and precipitation fluctuations (e.g. deserts and savannas). Nondormancy is associated with stable, warm and wetter climates (e.g. tropical rain forest). Pyroclimate had no significant effect on the distribution of seed dormancy. The environmental drivers considered in this study had a comparatively low predictive power, suggesting that macroclimate is just one of several global drivers of seed dormancy.
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Affiliation(s)
- Sergey Rosbakh
- Department of Plant and Environmental Sciences, University of Copenhagen, 1871, Frederiksberg, Denmark
- Ecology and Conservation Biology, University of Regensburg, 93040, Regensburg, Germany
| | - Angelino Carta
- Department of Biology, University of Pisa, 56126, Pisa, Italy
- CIRSEC - Centre for Climate Change Impact, University of Pisa, 56126, Pisa, Italy
| | - Eduardo Fernández-Pascual
- IMIB Biodiversity Research Institute (University of Oviedo-CSIC-Principality of Asturias), University of Oviedo, 33600, Mieres, Spain
| | - Shyam S Phartyal
- School of Ecology and Environment Studies, Nalanda University, Rajgir, 803116, India
| | - Roberta L C Dayrell
- Ecology and Conservation Biology, University of Regensburg, 93040, Regensburg, Germany
- Royal Botanic Gardens, Kew, Wakehurst, TH17 6TH, Ardingly, UK
| | - Efisio Mattana
- Royal Botanic Gardens, Kew, Wakehurst, TH17 6TH, Ardingly, UK
| | - Arne Saatkamp
- Aix Marseille Université, IMBE, Avignon Univ, CNRS, IRD, 13397, Marseille, France
| | | | - Jerry Baskin
- Department of Biology, University of Kentucky, Lexington, KY, 40506-022, USA
| | - Carol Baskin
- Department of Biology, University of Kentucky, Lexington, KY, 40506-022, USA
- Department of Plants and Soil Sciences, University of Kentucky, Lexington, KY, 40506-022, USA
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13
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Pausas JG, Keeley JE. Evolutionary fire ecology: An historical account and future directions. Bioscience 2023; 73:602-608. [PMID: 37680689 PMCID: PMC10481411 DOI: 10.1093/biosci/biad059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Revised: 06/08/2023] [Accepted: 06/14/2023] [Indexed: 09/09/2023] Open
Abstract
The idea that fire acts as an evolutionary force contributing to shaping species traits started a century ago, but had not been widely recognized until very recently. Among the first to realize this force were Edward B. Poulton, R. Dale Guthrie, and Edwin V. Komarek in animals and Willis L. Jepson, Walter W. Hough, Tom M. Harris, Philip V. Wells, and Robert W. Mutch in plants. They were all ahead of their time in their evolutionary thinking. Since then, evolutionary fire ecology has percolated very slowly into the mainstream ecology and evolutionary biology; in fact, this topic is still seldom mentioned in textbooks of ecology or evolution. Currently, there is plenty of evidence suggesting that we cannot understand the biodiversity of our planet without considering the key evolutionary role of fire. But there is still research to be done in order to fully understand fire's contribution to species evolution and to predicting species responses to rapid global changes.
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Affiliation(s)
- Juli G Pausas
- Centro de Investigaciones sobre Desertificación, Consejo Superior de Investigaciones Cientificas, Montcada, Spain
| | - Jon E Keeley
- Sequoia-Kings Canyon Field Station, at theWestern Ecological Research Center, US Geological Survey, Three Rivers, California, United States
- Department of Ecology and Evolutionary Biology at the University of California-Los Angeles, Los Angeles, California, United States
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14
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Née G, Krüger T. Dry side of the core: a meta-analysis addressing the original nature of the ABA signalosome at the onset of seed imbibition. FRONTIERS IN PLANT SCIENCE 2023; 14:1192652. [PMID: 37476171 PMCID: PMC10354442 DOI: 10.3389/fpls.2023.1192652] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Accepted: 06/08/2023] [Indexed: 07/22/2023]
Abstract
The timing of seedling emergence is a major agricultural and ecological fitness trait, and seed germination is controlled by a complex molecular network including phytohormone signalling. One such phytohormone, abscisic acid (ABA), controls a large array of stress and developmental processes, and researchers have long known it plays a crucial role in repressing germination. Although the main molecular components of the ABA signalling pathway have now been identified, the molecular mechanisms through which ABA elicits specific responses in distinct organs is still enigmatic. To address the fundamental characteristics of ABA signalling during germination, we performed a meta-analysis focusing on the Arabidopsis dry seed proteome as a reflexion basis. We combined cutting-edge proteome studies, comparative functional analyses, and protein interaction information with genetic and physiological data to redefine the singular composition and operation of the ABA core signalosome from the onset of seed imbibition. In addition, we performed a literature survey to integrate peripheral regulators present in seeds that directly regulate core component function. Although this may only be the tip of the iceberg, this extended model of ABA signalling in seeds already depicts a highly flexible system able to integrate a multitude of information to fine-tune the progression of germination.
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15
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Cao D, Baskin JM, Baskin CC, Li DZ. Burning lignin: overlooked cues for post-fire seed germination. TRENDS IN PLANT SCIENCE 2023; 28:386-389. [PMID: 36801194 DOI: 10.1016/j.tplants.2023.01.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 01/18/2023] [Accepted: 01/26/2023] [Indexed: 06/18/2023]
Abstract
Information about smoke cues for seed germination is fundamental to understanding fire adaptation. Recently, lignin-derived syringaldehyde (SAL) was identified as a new smoke cue for seed germination, which challenges the assumption that cellulose-derived karrikins are the primary smoke cues. We highlight the overlooked association between lignin and the fire adaptation of plants.
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Affiliation(s)
- Dechang Cao
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China
| | - Jerry M Baskin
- Department of Biology, University of Kentucky, Lexington, KY 40506-0225, USA
| | - Carol C Baskin
- Department of Biology, University of Kentucky, Lexington, KY 40506-0225, USA; Department of Plant and Soil Sciences, University of Kentucky, Lexington, KY 40546-0312, USA
| | - De-Zhu Li
- Germplasm Bank of Wild Species, Kunming Institute of Botany, Chinese Academy of Sciences, Kunming, Yunnan 650201, China.
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16
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Muscha JM, Vermeire LT, Angerer JP. Fire reduces Russian olive seed germination and seedling survival with increasing fuel load. Restor Ecol 2023. [DOI: 10.1111/rec.13904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/31/2023]
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17
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Crowe RE, Parker VT. The morphological and ecological variation of Arctostaphylos (Ericaceae) fruit: A link between plant ecology and animal foraging behavior. Ecol Evol 2023; 13:e9801. [PMID: 36937065 PMCID: PMC10017329 DOI: 10.1002/ece3.9801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2022] [Revised: 01/11/2023] [Accepted: 01/20/2023] [Indexed: 03/18/2023] Open
Abstract
Persistent soil seed banks are characteristic of Arctostaphylos (Ericaceae) species in the Mediterranean-climate California Floristic Province. While most species are obligate seeders, regeneration of stands of all Arctostaphylos species ultimately depends on post-fire seedling recruitment. Arctostaphylos seed banks are created, in large part, by scatter-hoarding rodents. Variation in fruit morphology, therefore, is expected to impact the Arctostaphylos-rodent interaction. Seeds produce sufficient rewards (nutritious mature embryo) to entice rodents to disperse and ultimately bury seeds in the soil. Hard seed coats increase the time required to extract the embryo, encouraging rodents to choose storage over immediate predation, and nutlets are frequently empty. We assessed the variation of fruit nutlet fusion and seed viability among 38 Arctostaphylos taxa. Factors such as latitude, elevation, life history, ploidy, and phylogenetic position were also analyzed. Generalized mixed-effects models were used to determine the factors contributing to variation in fruit nutlet fusion and seed viability. Our results indicate that fruit volume and shape are the most important variables affecting nutlet fusion and seed viability. Additionally, other potential influences only show a weak correlation and are not predicted to significantly impact nutlet fusion or seed viability. These findings provide insights into evolved strategies used by plants to increase reproductive success via scatter-hoarding rodents. Our study benefits the conservation and restoration of Arctostaphylos stands by emphasizing the importance of animal-mediated dispersal and providing estimates of seed viability for different species. With the anticipated effects of climate change, such as departures from historic fire regimes, the preservation of the relationship between plants and animal foragers is crucial for the continued survival of Arctostaphylos and California's evergreen chaparral.
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Affiliation(s)
- Rebecca E. Crowe
- San Francisco State UniversitySan FranciscoCaliforniaUSA
- UCI HerbariumUniversity of California, IrvineIrvineCaliforniaUSA
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18
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Lamont BB. Grass species with smoke-released seed dormancy: A response to climate and fire regime but not photosynthetic pathway. PLANT BIOLOGY (STUTTGART, GERMANY) 2023; 25:24-31. [PMID: 36250211 PMCID: PMC10099466 DOI: 10.1111/plb.13479] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
Both C3 and C4 photosynthetic pathways and smoke-released seed dormancy occur among grasses. C4 species evolved from C3 species as seasonality and fire frequency increased and might therefore imply that their smoke sensitivity increased. I searched the worldwide literature for reports on germination responses among grasses, whose photosynthetic pathway was known, to treatment by smoke. Data were obtained for 217 species and 126 genera. While subfamilies tended to be C3 (Pooideae), C4 (Chloridoideae) or a mixture (Panicoideae), a beneficial smoke response was independent of their photosynthetic pathway. The only exceptions were Danthonioideae (C3, non-smoke responsive) and Triodia (C4, smoke responsive). One third of both C3 and C4 genera were smoke responsive. Even within genera, 90% of species showed contrasting smoke responses, confirming that smoke sensitivity is rarely taxonomically constrained. Data on photosynthetic pathway, climate, fire regime and vegetation were compiled for 15 regions that formed four distinct groups: 1) In warm climates with aseasonal rainfall, C4 grasses are moderately better represented, with crown fires and limited smoke responses. 2) In cool regions, most species are C3, with surface-crown fires and lack smoke responses. 3) In warm regions with summer rain (savannas), most species are C4, with surface fires and lack smoke responses. 4) In Mediterranean-climate regions with summer drought, most species are C3, with crown fires and smoke-released dormancy. Thus, even though C3 and C4 grasses are equally capable of expressing smoke sensitivity, their response depends on the region's climate and fire regime that also dictate which photosynthetic pathway dominates.
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Affiliation(s)
- B. B. Lamont
- Ecology Section, School of Molecular and Life SciencesCurtin UniversityPerthWAAustralia
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19
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Lamont BB, Grey J. Extrafloral nectar as entrée and elaiosomes as main course for ant visitors to a fireprone, mediterranean-climate shrub. Ecol Evol 2022; 12:e9500. [PMID: 36381400 PMCID: PMC9643124 DOI: 10.1002/ece3.9500] [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: 08/19/2022] [Revised: 10/20/2022] [Accepted: 10/21/2022] [Indexed: 11/11/2022] Open
Abstract
Thousands of plants produce both extrafloral nectaries (EFNs) on their leaves and nutrient-rich appendages on their diaspores (elaiosomes). Although their individual ecology is well-known, any possible functional link between these structures has almost always been ignored. Here, we recognized their co-presence in the shrub, Adenanthos cygnorum (Proteaceae), and studied their function and interaction. We observed that the same ants frequently visit both structures, seeds are attractive to vertebrate granivores but are released into a leafy cup from where they are harvested by ants and taken to their nests, from which seeds, lacking elaiosomes, germinate after fire. We showed that juvenile plants do not produce EFNs and are not visited by ants. We conclude that EFNs are not just an indirect adaptation to minimize herbivory via aggressive ant visitors (the role of a minority) but specifically enhance reproductive success in two ways: First, by inducing ants to visit the plant as a reliable food source throughout the year. Second, by promoting discovery of the seasonally available, elaiosome-bearing seeds for transport to their nests (the majority of visitors), so avoiding the risk of granivory should seeds instead fall to the ground. Parasitoid wasps play a supporting role in controlling the main insect herbivore whose larvae devour the reproductive apices. Thus, the EFN-elaiosome relationship has three components that enhance species fitness: foliage protection, seed transport, and granivore escape. A similar system has been described only once before (in an unrelated biome) and, consistent with the objectives of ecology as an integrative science, deserves wider study.
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Affiliation(s)
- Byron B. Lamont
- Ecology Section, School of Life and Molecular SciencesCurtin UniversityPerthWestern AustraliaAustralia
| | - James Grey
- Ecology Section, School of Life and Molecular SciencesCurtin UniversityPerthWestern AustraliaAustralia
- Present address:
Assurance SystemsNorth SydneyNew South WalesAustralia
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20
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Pausas JG, Lamont BB, Keeley JE, Bond WJ. Bet-hedging and best-bet strategies shape seed dormancy. THE NEW PHYTOLOGIST 2022; 236:1232-1236. [PMID: 35975702 PMCID: PMC9825997 DOI: 10.1111/nph.18436] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/22/2022] [Accepted: 08/02/2022] [Indexed: 06/15/2023]
Affiliation(s)
- Juli G. Pausas
- CIDE‐CSIC, Consejo Superior de Investigaciones CientíficasMontcada46113ValenciaSpain
| | - Byron B. Lamont
- Ecology Section, School of Life and Molecular SciencesCurtin UniversityPerthWA6845Australia
| | - Jon E. Keeley
- US Geological Survey, Western Ecological Research CenterSequoia–Kings Canyon Field StationThree RiversCA93271USA
- Department of Ecology and Evolutionary BiologyUniversity of California–Los AngelesLos AngelesCA90095USA
| | - William J. Bond
- Department of Biological SciencesUniversity of Cape TownCape Town7701South Africa
- South African Environmental Observation NetworkNational Research FoundationClaremont7735South Africa
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21
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Zomer M, Moreira B, Pausas JG. Fire and summer temperatures interact to shape seed dormancy thresholds. ANNALS OF BOTANY 2022; 129:809-816. [PMID: 35390121 PMCID: PMC9292603 DOI: 10.1093/aob/mcac047] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 04/05/2022] [Indexed: 05/05/2023]
Abstract
BACKGROUND AND AIMS In Mediterranean ecosystems, the heat shock of wildfire disrupts physical seed dormancy in many plant species. This triggers germination in the post-fire environment where seedling establishment is optimal due to decreased competition and increased resource availability. However, to maintain the soil seed bank until a fire occurs, the minimum heat capable of breaking seed dormancy (i.e. the lower heat threshold) must be above the maximum temperatures typically observed in the soil during the summer. We therefore hypothesized that summer temperatures have shaped heat requirements for physical dormancy release. Specifically, we predicted that seeds from populations growing under warmer summers will have higher values of the lower heat threshold. METHODS To evaluate this prediction, we collected seeds from two Cistus species in 31 populations (20 Cistus albidus and 11 Cistus salviifolius) along a climate gradient of summer temperatures on the eastern coast of Spain. For each population, seeds were treated to 10 min heat shocks, from 30 to 120 °C in 5 °C increments (19 treatments), to simulate increasing heat doses from summer to fire-related temperatures. Seeds were then germinated in the lab. KEY RESULTS For all populations, maximum germination was observed when applying temperatures associated with fire. Lower heat thresholds varied among populations, with a positive relationship between summer temperatures at seed population origin and the heat dose required to break dormancy. CONCLUSIONS Our results suggest that fire drives maximum dormancy release for successful post-fire germination, while summer temperatures determine lower heat thresholds for ensuring inter-fire seed bank persistence. Significant among-population variation of thresholds also suggests that post-fire seeder species have some potential to modify their dormancy release requirements in response to changing climate.
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Affiliation(s)
- Maya Zomer
- Centro de Investigaciones sobre Desertificación (CIDE-CSIC), Ctra. Náquera Km. 4.5, Moncada, E-46113 Valencia, Spain
| | - Bruno Moreira
- Centro de Investigaciones sobre Desertificación (CIDE-CSIC), Ctra. Náquera Km. 4.5, Moncada, E-46113 Valencia, Spain
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22
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He T, Lamont BB. Ancient Rhamnaceae flowers impute an origin for flowering plants exceeding 250-million-years ago. iScience 2022; 25:104642. [PMID: 35800761 PMCID: PMC9254029 DOI: 10.1016/j.isci.2022.104642] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/28/2022] [Accepted: 06/14/2022] [Indexed: 12/01/2022] Open
Abstract
Setting the molecular clock to newly described 100-million-year-old flowering shoots of Phylica in Burmese amber enabled us to recalibrate the phylogenetic history of Rhamnaceae. We traced its origin to ∼260 million years ago (Ma) that can explain its migration within and beyond Gondwana since that time and implies an origin for flowering plants that stretches well beyond 290 Ma. Ancestral trait assignments also revealed that hard-seededness, fire-proneness, and to a lesser extent, heat-released seed dormancy, have a similarly long history in this clade. 100-million-year-old fossils of Phylica (Rhamnaceae) have recently been described Phylogenetic reconstruction using them reveals a crown age for Rhamnaceae at 259 Ma Ancestral trait reconstruction shows the associated vegetation was fire prone 259 Ma These are the oldest flowering-plant ages and fire-related traits obtained so far
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23
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Pausas JG, Lamont BB. Fire-released seed dormancy - a global synthesis. Biol Rev Camb Philos Soc 2022; 97:1612-1639. [PMID: 35384243 PMCID: PMC9540907 DOI: 10.1111/brv.12855] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2021] [Revised: 03/17/2022] [Accepted: 03/18/2022] [Indexed: 11/29/2022]
Abstract
Seed dormancy varies greatly between species, clades, communities, and regions. We propose that fireprone ecosystems create ideal conditions for the selection of seed dormancy as fire provides a mechanism for dormancy release and postfire conditions are optimal for germination. Thus, fire‐released seed dormancy should vary in type and abundance under different fire regimes. To test these predictions, we compiled data from a wide range of fire‐related germination experiments for species in different ecosystems across the globe. We identified four dormancy syndromes: heat‐released (physical) dormancy, smoke‐released (physiological) dormancy, non‐fire‐released dormancy, and non‐dormancy. In fireprone ecosystems, fire, in the form of heat and/or chemical by‐products (collectively termed ‘smoke’), are the predominant stimuli for dormancy release and subsequent germination, with climate (cold or warm stratification) and light sometimes playing important secondary roles. Fire (heat or smoke)‐released dormancy is best expressed where woody vegetation is dense and fires are intense, i.e. in crown‐fire ecosystems. In such environments, seed dormancy allows shade‐intolerant species to take advantage of vegetation gaps created by fire and synchronize germination with optimal recruitment conditions. In grassy fireprone ecosystems (e.g. savannas), where fires are less intense but more frequent, seed dormancy is less common and dormancy release is often not directly related to fire (non‐fire‐released dormancy). Rates of germination, whether controls or postfire, are twice as fast in savannas than in mediterranean ecosystems. Fire‐released dormancy is rare to absent in arid ecosystems and rainforests. The seeds of many species with fire‐released dormancy also possess elaiosomes that promote ant dispersal. Burial by ants increases insulation of seeds from fires and places them in a suitable location for fire‐released dormancy. The distribution of these dormancy syndromes across seed plants is not random – certain dormancy types are associated with particular lineages (phylogenetic conservatism). Heat‐released dormancy can be traced back to fireprone floras in the ‘fiery’ mid‐Cretaceous, followed by smoke‐released dormancy, with loss of fire‐related dormancy among recent events associated with the advent of open savannas and non‐fireprone habitats. Anthropogenic influences are now modifying dormancy‐release mechanisms, usually decreasing the role of fire as exaptive effects. We conclude that contrasting fire regimes are a key driver of the evolution and maintenance of diverse seed dormancy types in many of the world's natural ecosystems.
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Affiliation(s)
- Juli G Pausas
- CIDE-CSIC, Consejo Superior de Investigaciones Científicas, Montcada, Valencia, 46113, Spain
| | - Byron B Lamont
- Ecology Section, School of Life and Molecular Sciences, Curtin University, Perth, WA, 6845, Australia
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