scholarly journals Eco-evolutionary responses of plant communities to drought and rainfall variability

2021 ◽  
Author(s):  
Jaideep Joshi ◽  
Benjamin Stocker ◽  
Florian Hofhansl ◽  
Shuangxi Zhou ◽  
Åke Brännström ◽  
...  
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Functional Diversity ◽  
Plant Communities ◽  
Environmental Conditions ◽  
Photosynthetic Capacity ◽  
Rainfall Variability ◽  
Assimilation Rate ◽  
Functional Responses ◽  
Plant Photosynthesis

<p>The future Earth is projected to experience elevated rainfall variability, with more frequent and intense droughts, as well as high-rainfall events. Increasing CO<sub>2</sub> concentrations are expected to raise terrestrial gross primary productivity (GPP), whereas water stress is expected to lower GPP. Plant responses to water stress vary strongly with timescale, and plants adapted to different environmental conditions differ in their functional responses. Here, we embed a unified optimality-based theory of stomatal conductance and biochemical acclimation of leaves we have recently developed [Joshi, J. et al. (2020) Towards a unified theory of plant photosynthesis and hydraulics. bioRxiv 2020.12.17.423132] in an eco-evolutionary vegetation-modelling framework, with the goal to investigate emergent functional diversity and associated GPP impacts under different rainfall regimes.</p><p>The model of photosynthesis used here simultaneously predicts the stomatal responses and biochemical acclimation of leaves to atmospheric and soil-moisture conditions. Using three hydraulic traits and two cost parameters, it successfully predicts the simultaneous declines in CO<sub>2</sub> assimilation rate, stomatal conductance, and leaf photosynthetic capacity caused by drying soil. It also correctly predicts the responses of CO<sub>2</sub> assimilation rate, stomatal conductance, leaf water potential, and leaf photosynthetic capacity to vapour pressure deficit, temperature, ambient CO<sub>2</sub>, light intensity, and elevation. Our model therefore captures the synergistic effects of atmospheric and soil drought, as well as of atmospheric CO<sub>2</sub> changes, on plant photosynthesis and transpiration.</p><p>We embed this model of photosynthesis and transpiration in a trait-height-patch structured eco-evolutionary vegetation model. This model accounts for allometric carbon allocation, height-structured competition for light, patch-structured successional dynamics, and coevolution of plant functional traits. It predicts functional species mixtures and emergent ecosystem properties under different environmental conditions. Using this model, we investigate the evolution of plant hydraulic strategies under different regimes of drought and rainfall variability. Our approach provides an eco-evolutionarily consistent framework to scale up the responses of plant communities from individual plants to ecosystems to provide ecosystem-level predictions of functional diversity, primary production, and plant water use, and could thus be used for reliable projections of the global carbon and water cycles under future climate scenarios. </p>

scholarly journals Effect of leaf age and position on light-saturated CO2 assimilation rate, photosynthetic capacity, and stomatal conductance in rubber trees

2010 ◽  
Vol 48 (1) ◽  
pp. 67-78 ◽  
Author(s):  
B. Kositsup ◽  
P. Kasemsap ◽  
S. Thanisawanyangkura ◽  
N. Chairungsee ◽  
D. Satakhun ◽  
...  
Keyword(s):  
Stomatal Conductance ◽  
Photosynthetic Capacity ◽  
Leaf Age ◽  
Assimilation Rate

scholarly journals Towards a unified theory of plant photosynthesis and hydraulics

2020 ◽  
Author(s):  
Jaideep Joshi ◽  
Ulf Dieckmann ◽  
Iain Colin Prentice
Keyword(s):  
Water Stress ◽  
Stomatal Conductance ◽  
Water Potential ◽  
Soil Water ◽  
Soil Water Potential ◽  
Vapour Pressure Deficit ◽  
Plant Responses ◽  
Plant Hydraulics ◽  
Plant Photosynthesis ◽  
Embolism Resistance

<p>Increasing frequencies and intensities of droughts are projected for many regions of the Earth. Water stress leads to a decline in the gross primary productivity (GPP) of plants. Plant responses to water stress vary with timescale, and plants adapted to different environments differ in their responses. Here, we present a unified theory of plant photosynthesis and plant hydraulics, which explains a wide range of observed plant responses to developing water stress.</p><p>Our theory is based on the least-cost hypothesis of Prentice et al. (2014). By integrating plant hydraulics into the least-cost framework, we attempt to improve upon the model of GPP by Wang et al. (2017), which accurately predicts the responses of global GPP to temperature, elevation, and vapour pressure deficit, but overestimates GPP under water-stressed conditions. Our model has three key ingredients. (1) The aforementioned least-cost framework, in which optimal stomatal conductance minimizes the summed costs of maintaining transpiration, the photosynthetic machinery, and the hydraulic pathways, including the potential costs of repairing embolized xylem. We also test a closely related maximum-benefit framework, in which optimal stomatal conductance maximizes the net benefit from assimilation while accounting for these summed costs, and obtain comparable results. (2) A trait-dependent model of water flow through the plant stem, in which water flow is limited by the conductivity (K<sub>s</sub>) and embolism resistance (P<sub>50</sub>) of the hydraulic pathway. At the shortest timescale, water stress causes stomatal closure to an extent that the transpiration demand determined by the vapour pressure deficit at the leaf surface is matched by the water supply through the stem. (3) A short-term response of photosynthetic capacity (V<sub>cmax</sub>) to soil moisture, through which the potential V<sub>cmax</sub> acclimates to prevailing daytime conditions to equalize carboxylation-limited and electron-transport-limited photosynthesis rates (A<sub>c</sub> and A<sub>j</sub>), while the realized values of V<sub>cmax</sub>, A<sub>c</sub>, and A<sub>j</sub> are reduced from their potential values by a factor dependent on the leaf water potential and the leaf embolism resistance.</p><p>We estimate the parameters of our model using published data from short-term and long-term dry-down experiments. The key predictions of our model are as follows: (1) GPP declines with decreasing soil water potential and drops to zero soon after the soil water potential crosses P<sub>50</sub>; (2) soil-to-leaf water potential difference remains relatively constant under developing water stress; (3) functional forms describing the declines in stomatal conductance, V<sub>cmax</sub>, and GPP with soil water potential are consistent with observations; and (4) decreased photosynthetic capacity (V<sub>cmax</sub>) recovers (in the long term) if the plant increases its Huber value (e.g., by shedding leaves), increases its conductivity (e.g., by growing wider new vessels), or decreases its height growth (e.g., by reducing allocation to growth). Our theory provides a potential way of integrating trait-based responses of plants to water stress into global vegetation models, and should therefore help to improve predictions of the global carbon and water cycles in a changing environment.</p><p>References: [1] Prentice IC, et al. <em>Ecology letters</em> 17.1 (2014): 82-91.  [2] Wang H, et al. <em>Nature Plants</em> 3.9 (2017): 734.</p>

scholarly journals Hyperspectral sensing of photosynthesis, stomatal conductance, and transpiration for citrus tree under drought condition

2021 ◽  
Author(s):  
Jing-Jing Zhou ◽  
Ya-Hao Zhang ◽  
Ze-Min Han ◽  
Xiao-Yang Liu ◽  
Yong-Feng Jian ◽  
...  
Keyword(s):  
Machine Learning ◽  
Water Stress ◽  
Stomatal Conductance ◽  
Large Scale ◽  
Photosynthetic Capacity ◽  
Machine Learning Algorithms ◽  
Soil Drought ◽  
Photosynthetic Parameters ◽  
Hyperspectral Reflectance ◽  
Drought Period

AbstractObtaining variation in water use and photosynthetic capacity is a promising route toward yield increases, but it is still too laborious for large-scale rapid monitoring and prediction. We tested the application of hyperspectral reflectance as a high-throughput phenotyping approach for early identification of water stress and rapid assessment of leaf photosynthetic traits in citrus trees. To this end, photosynthetic CO2 assimilation rate (Pn), stomatal conductance (Cond) and transpiration rate (Trmmol) were measured with gas-exchange approaches alongside measurements of leaf hyperspectral reflectance from citrus grown across a gradient of soil drought levels. Water stress caused Pn, Cond and Trmmol rapid and continuous decreases in whole drought period. Upper layer was more sensitive to drought than middle and lower layers. Original reflectance spectra of three drought treatments were surprisingly of low diversity and could not track drought responses, whereas specific hyperspectral spectral vegetation indices (SVIs) and absorption features or wavelength position variables presented great potential. Performance of four machine learning algorithms were assessed and random forest (RF) algorithm yielded the highest predictive power for predicting photosynthetic parameters. Our results indicated that leaf hyperspectral reflectance was a reliable and stable method for monitoring water stress and yield increasing in large-scale orchards.HighlightAn efficient and stable methods using hyperspectral features for early and pre-visual identification of drought and machine learning techniques for predicting photosynthetic capacity.

Altitude of origin influences stomatal conductance and therefore maximum assimilation rate in Southern Beech, Nothofagus cunninghamii

2000 ◽  
Vol 27 (5) ◽  
pp. 451 ◽  
Author(s):  
Mark J. Hovenden ◽  
Tim Brodribb
Keyword(s):  
Stomatal Conductance ◽  
Stomatal Density ◽  
Carbon Assimilation ◽  
Co2 Concentration ◽  
Carboxylation Efficiency ◽  
Assimilation Rate ◽  
Carbon Assimilation Rate ◽  
Southern Beech ◽  
Maximum Stomatal Conductance ◽  
Leaf Biochemistry

Gas exchange measurements were made on saplings of Southern Beech, Nothofagus cunninghamii (Hook.) Oerst. collected from three altitudes (350, 780 and 1100 m above sea level) and grown in a common glasshouse trial. Plants were grown from cuttings taken 2 years earlier from a number of plants at each altitude in Mt Field National Park, Tasmania. Stomatal density increased with increasing altitude of origin, and stomatal con-ductance and carbon assimilation rate were linearly related across all samples. The altitude of origin influenced thestomatal conductance and therefore carbon assimilation rate, with plants from 780 m having a greater photosynthetic rate than those from 350 m. The intercellular concentration of CO2 as a ratio of external CO2 concentration (ci/ca) was similar in all plants despite the large variation in maximum stomatal conductance. Carboxylation efficiency was greater in plants from 780 m than in plants from 350 m. Altitude of origin has a strong influence on the photo-synthetic performance of N. cunninghamii plants even when grown under controlled conditions, and this influence is expressed in both leaf biochemistry (carboxylation efficiency) and leaf morphology (stomatal density).

scholarly journals Shifts in soil and plant functional diversity along an altitudinal gradient in the French Alps

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Alexia Stokes ◽  
Guillermo Angeles ◽  
Fabien Anthelme ◽  
Eduardo Aranda-Delgado ◽  
Isabelle Barois ◽  
...  
Keyword(s):  
Plant Community ◽  
Functional Diversity ◽  
Plant Communities ◽  
Species Abundance ◽  
Chemical Properties ◽  
Water Infiltration ◽  
Temperate Climate ◽  
Biophysical Properties ◽  
Tropical Zone ◽  
Soil Microbial

Abstract Objectives Altitude integrates changes in environmental conditions that determine shifts in vegetation, including temperature, precipitation, solar radiation and edaphogenetic processes. In turn, vegetation alters soil biophysical properties through litter input, root growth, microbial and macrofaunal interactions. The belowground traits of plant communities modify soil processes in different ways, but it is not known how root traits influence soil biota at the community level. We collected data to investigate how elevation affects belowground community traits and soil microbial and faunal communities. This dataset comprises data from a temperate climate in France and a twin study was performed in a tropical zone in Mexico. Data description The paper describes soil physical and chemical properties, climatic variables, plant community composition and species abundance, plant community traits, soil microbial functional diversity and macrofaunal abundance and diversity. Data are provided for six elevations (1400–2400 m) ranging from montane forest to alpine prairie. We focused on soil biophysical properties beneath three dominant plant species that structure local vegetation. These data are useful for understanding how shifts in vegetation communities affect belowground processes, such as water infiltration, soil aggregation and carbon storage. Data will also help researchers understand how plant communities adjust to a changing climate/environment.

scholarly journals Ozone damage, detoxification and the role of isoprenoids – new impetus for integrated models

2016 ◽  
Vol 43 (4) ◽  
pp. 324 ◽  
Author(s):  
Supriya Tiwari ◽  
Rüdiger Grote ◽  
Galina Churkina ◽  
Tim Butler
Keyword(s):  
Stomatal Conductance ◽  
Environmental Conditions ◽  
Economic Losses ◽  
Plant Responses ◽  
Damage Scenarios ◽  
Biochemical Processes ◽  
Wide Range ◽  
Defence Responses ◽  
High Concentrations ◽  
The Impact

High concentrations of ozone (O3) can have significant impacts on the health and productivity of agricultural and forest ecosystems, leading to significant economic losses. In order to estimate this impact under a wide range of environmental conditions, the mechanisms of O3 impacts on physiological and biochemical processes have been intensively investigated. This includes the impact on stomatal conductance, the formation of reactive oxygen species and their effects on enzymes and membranes, as well as several induced and constitutive defence responses. This review summarises these processes, discusses their importance for O3 damage scenarios and assesses to which degree this knowledge is currently used in ecosystem models which are applied for impact analyses. We found that even in highly sophisticated models, feedbacks affecting regulation, detoxification capacity and vulnerability are generally not considered. This implies that O3 inflicted alterations in carbon and water balances cannot be sufficiently well described to cover immediate plant responses under changing environmental conditions. Therefore, we suggest conceptual models that link the depicted feedbacks to available process-based descriptions of stomatal conductance, photosynthesis and isoprenoid formation, particularly the linkage to isoprenoid models opens up new options for describing biosphere-atmosphere interactions.

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