1
|
Chakrawal A, Lindahl BD, Manzoni S. Modelling optimal ligninolytic activity during plant litter decomposition. THE NEW PHYTOLOGIST 2024; 243:866-880. [PMID: 38343140 DOI: 10.1111/nph.19572] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2023] [Accepted: 01/22/2024] [Indexed: 07/05/2024]
Abstract
A large fraction of plant litter comprises recalcitrant aromatic compounds (lignin and other phenolics). Quantifying the fate of aromatic compounds is difficult, because oxidative degradation of aromatic carbon (C) is a costly but necessary endeavor for microorganisms, and we do not know when gains from the decomposition of aromatic C outweigh energetic costs. To evaluate these tradeoffs, we developed a litter decomposition model in which the aromatic C decomposition rate is optimized dynamically to maximize microbial growth for the given costs of maintaining ligninolytic activity. We tested model performance against > 200 litter decomposition datasets collected from published literature and assessed the effects of climate and litter chemistry on litter decomposition. The model predicted a time-varying ligninolytic oxidation rate, which was used to calculate the lag time before the decomposition of aromatic C is initiated. Warmer conditions increased decomposition rates, shortened the lag time of aromatic C oxidation, and improved microbial C-use efficiency by decreasing the costs of oxidation. Moreover, a higher initial content of aromatic C promoted an earlier start of aromatic C decomposition under any climate. With this contribution, we highlight the application of eco-evolutionary approaches based on optimized microbial life strategies as an alternative parametrization scheme for litter decomposition models.
Collapse
Affiliation(s)
- Arjun Chakrawal
- Department of Physical Geography and Bolin Centre for Climate Research, Stockholm University, 10691, Stockholm, Sweden
| | - Björn D Lindahl
- Swedish University of Agricultural Sciences, Department of Soil and Environment, 75007, Uppsala, Sweden
| | - Stefano Manzoni
- Department of Physical Geography and Bolin Centre for Climate Research, Stockholm University, 10691, Stockholm, Sweden
| |
Collapse
|
2
|
Flo V, Joshi J, Sabot M, Sandoval D, Prentice IC. Incorporating photosynthetic acclimation improves stomatal optimisation models. PLANT, CELL & ENVIRONMENT 2024. [PMID: 38589983 DOI: 10.1111/pce.14891] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2023] [Revised: 03/04/2024] [Accepted: 03/08/2024] [Indexed: 04/10/2024]
Abstract
Stomatal opening in plant leaves is regulated through a balance of carbon and water exchange under different environmental conditions. Accurate estimation of stomatal regulation is crucial for understanding how plants respond to changing environmental conditions, particularly under climate change. A new generation of optimality-based modelling schemes determines instantaneous stomatal responses from a balance of trade-offs between carbon gains and hydraulic costs, but most such schemes do not account for biochemical acclimation in response to drought. Here, we compare the performance of six instantaneous stomatal optimisation models with and without accounting for photosynthetic acclimation. Using experimental data from 37 plant species, we found that accounting for photosynthetic acclimation improves the prediction of carbon assimilation in a majority of the tested models. Photosynthetic acclimation contributed significantly to the reduction of photosynthesis under drought conditions in all tested models. Drought effects on photosynthesis could not accurately be explained by the hydraulic impairment functions embedded in the stomatal models alone, indicating that photosynthetic acclimation must be considered to improve estimates of carbon assimilation during drought.
Collapse
Affiliation(s)
- Victor Flo
- Department of Life Sciences, Georgina Mace Centre for the Living Planet, Imperial College London, Silwood Park Campus, Ascot, UK
- Departament de Biologia Animal, Biologia Vegetal i Ecologia, Univ Autònoma de Barcelona, Cerdanyola del Vallès, Spain
| | - Jaideep Joshi
- Department of Geosciences, Institute of Geography, University of Bern, Bern, Switzerland
- Oeschger Centre for Climate Change Research, Faculty of Science, University of Bern, Bern, Switzerland
- Advancing Systems Analysis Program, International Institute for Applied Systems Analysis, Laxenburg, Austria
- Complexity Science and Evolution Unit, Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
| | - Manon Sabot
- ARC Centre of Excellence for Climate Extremes, Sydney, New South Wales, Australia
- Climate Change Research Centre, University of New South Wales, Sydney, New South Wales, Australia
- Department of Biogeochemical Signals, Max Planck Institute for Biogeochemistry, Jena, Germany
| | - David Sandoval
- Department of Life Sciences, Georgina Mace Centre for the Living Planet, Imperial College London, Silwood Park Campus, Ascot, UK
| | - Iain Colin Prentice
- Department of Life Sciences, Georgina Mace Centre for the Living Planet, Imperial College London, Silwood Park Campus, Ascot, UK
| |
Collapse
|
3
|
Potkay A, Feng X. Dynamically optimizing stomatal conductance for maximum turgor-driven growth over diel and seasonal cycles. AOB PLANTS 2023; 15:plad044. [PMID: 37899972 PMCID: PMC10601388 DOI: 10.1093/aobpla/plad044] [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: 12/22/2022] [Accepted: 07/04/2023] [Indexed: 10/31/2023]
Abstract
Stomata have recently been theorized to have evolved strategies that maximize turgor-driven growth over plants' lifetimes, finding support through steady-state solutions in which gas exchange, carbohydrate storage and growth have all reached equilibrium. However, plants do not operate near steady state as plant responses and environmental forcings vary diurnally and seasonally. It remains unclear how gas exchange, carbohydrate storage and growth should be dynamically coordinated for stomata to maximize growth. We simulated the gas exchange, carbohydrate storage and growth that dynamically maximize growth diurnally and annually. Additionally, we test whether the growth-optimization hypothesis explains nocturnal stomatal opening, particularly through diel changes in temperature, carbohydrate storage and demand. Year-long dynamic simulations captured realistic diurnal and seasonal patterns in gas exchange as well as realistic seasonal patterns in carbohydrate storage and growth, improving upon unrealistic carbohydrate responses in steady-state simulations. Diurnal patterns of carbohydrate storage and growth in day-long simulations were hindered by faulty modelling assumptions of cyclic carbohydrate storage over an individual day and synchronization of the expansive and hardening phases of growth, respectively. The growth-optimization hypothesis cannot currently explain nocturnal stomatal opening unless employing corrective 'fitness factors' or reframing the theory in a probabilistic manner, in which stomata adopt an inaccurate statistical 'memory' of night-time temperature. The growth-optimization hypothesis suggests that diurnal and seasonal patterns of stomatal conductance are driven by a dynamic carbon-use strategy that seeks to maintain homeostasis of carbohydrate reserves.
Collapse
Affiliation(s)
- Aaron Potkay
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Twin Cities, 500 Pillsbury Drive S.E., Minneapolis, MN 55455, USA
- Saint Anthony Falls Laboratory, University of Minnesota, Twin Cities, 23rd Ave SE, Minneapolis, MN 55414, USA
| | - Xue Feng
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Twin Cities, 500 Pillsbury Drive S.E., Minneapolis, MN 55455, USA
- Saint Anthony Falls Laboratory, University of Minnesota, Twin Cities, 23rd Ave SE, Minneapolis, MN 55414, USA
| |
Collapse
|
4
|
Blonder BW, Aparecido LMT, Hultine KR, Lombardozzi D, Michaletz ST, Posch BC, Slot M, Winter K. Plant water use theory should incorporate hypotheses about extreme environments, population ecology, and community ecology. THE NEW PHYTOLOGIST 2023; 238:2271-2283. [PMID: 36751903 DOI: 10.1111/nph.18800] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 01/30/2023] [Indexed: 05/19/2023]
Abstract
Plant water use theory has largely been developed within a plant-performance paradigm that conceptualizes water use in terms of value for carbon gain and that sits within a neoclassical economic framework. This theory works very well in many contexts but does not consider other values of water to plants that could impact their fitness. Here, we survey a range of alternative hypotheses for drivers of water use and stomatal regulation. These hypotheses are organized around relevance to extreme environments, population ecology, and community ecology. Most of these hypotheses are not yet empirically tested and some are controversial (e.g. requiring more agency and behavior than is commonly believed possible for plants). Some hypotheses, especially those focused around using water to avoid thermal stress, using water to promote reproduction instead of growth, and using water to hoard it, may be useful to incorporate into theory or to implement in Earth System Models.
Collapse
Affiliation(s)
- Benjamin Wong Blonder
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
| | - Luiza Maria Teophilo Aparecido
- School of Earth and Space Exploration, Arizona State University, Tempe, AZ, 85287, USA
- Department of Research, Conservation and Collections, Desert Botanical Garden, Phoenix, AZ, 85008, USA
| | - Kevin R Hultine
- Department of Research, Conservation and Collections, Desert Botanical Garden, Phoenix, AZ, 85008, USA
| | - Danica Lombardozzi
- Climate and Global Dynamics Laboratory, National Center for Atmospheric Research, Boulder, CO, 80305, USA
| | - Sean T Michaletz
- Department of Botany and Biodiversity Research Centre, University of British Columbia, Vancouver, BC, V6T 1Z4, Canada
| | - Bradley C Posch
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, 94720, USA
- Department of Research, Conservation and Collections, Desert Botanical Garden, Phoenix, AZ, 85008, USA
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, 79409, USA
| | - Martijn Slot
- Smithsonian Tropical Research Institute, Balboa, Ancón, 0843-03092, Panama
| | - Klaus Winter
- Smithsonian Tropical Research Institute, Balboa, Ancón, 0843-03092, Panama
| |
Collapse
|
5
|
Potkay A, Feng X. Do stomata optimize turgor-driven growth? A new framework for integrating stomata response with whole-plant hydraulics and carbon balance. THE NEW PHYTOLOGIST 2023; 238:506-528. [PMID: 36377138 DOI: 10.1111/nph.18620] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2022] [Accepted: 11/11/2022] [Indexed: 06/16/2023]
Abstract
Every existing optimal stomatal model uses photosynthetic carbon assimilation as a proxy for plant evolutionary fitness. However, assimilation and growth are often decoupled, making assimilation less ideal for representing fitness when optimizing stomatal conductance to water vapor and carbon dioxide. Instead, growth should be considered a closer proxy for fitness. We hypothesize stomata have evolved to maximize turgor-driven growth, instead of assimilation, over entire plants' lifetimes, improving their abilities to compete and reproduce. We develop a stomata model that dynamically maximizes whole-stem growth following principles from turgor-driven growth models. Stomata open to assimilate carbohydrates that supply growth and osmotically generate turgor, while stomata close to prevent losses of turgor and growth due to negative water potentials. In steady state, the growth optimization model captures realistic stomatal, growth, and carbohydrate responses to environmental cues, reconciles conflicting interpretations within existing stomatal optimization theories, and explains patterns of carbohydrate storage and xylem conductance observed during and after drought. Our growth optimization hypothesis introduces a new paradigm for stomatal optimization models, elevates the role of whole-plant carbon use and carbon storage in stomatal functioning, and has the potential to simultaneously predict gross productivity, net productivity, and plant mortality through a single, consistent modeling framework.
Collapse
Affiliation(s)
- Aaron Potkay
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, USA
- Saint Anthony Falls Laboratory, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, USA
| | - Xue Feng
- Department of Civil, Environmental, and Geo-Engineering, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, USA
- Saint Anthony Falls Laboratory, University of Minnesota, Twin Cities, Minneapolis, MN, 55455, USA
| |
Collapse
|
6
|
Manzoni S, Chakrawal A, Ledder G. Decomposition rate as an emergent property of optimal microbial foraging. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1094269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Decomposition kinetics are fundamental for quantifying carbon and nutrient cycling in terrestrial and aquatic ecosystems. Several theories have been proposed to construct process-based kinetics laws, but most of these theories do not consider that microbial decomposers can adapt to environmental conditions, thereby modulating decomposition. Starting from the assumption that a homogeneous microbial community maximizes its growth rate over the period of decomposition, we formalize decomposition as an optimal control problem where the decomposition rate is a control variable. When maintenance respiration is negligible, we find that the optimal decomposition kinetics scale as the square root of the substrate concentration, resulting in growth kinetics following a Hill function with exponent 1/2 (rather than the Monod growth function). When maintenance respiration is important, optimal decomposition is a more complex function of substrate concentration, which does not decrease to zero as the substrate is depleted. With this optimality-based formulation, a trade-off emerges between microbial carbon-use efficiency (ratio of growth rate over substrate uptake rate) and decomposition rate at the beginning of decomposition. In environments where carbon substrates are easily lost due to abiotic or biotic factors, microbes with higher uptake capacity and lower efficiency are selected, compared to environments where substrates remain available. The proposed optimization framework provides an alternative to purely empirical or process-based formulations for decomposition, allowing exploration of the effects of microbial adaptation on element cycling.
Collapse
|