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- Kumarathunge, Dushan P., et al.
(författare)
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Acclimation and adaptation components of the temperature dependence of plant photosynthesis at the global scale
- 2019
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Ingår i: New Phytologist. - : John Wiley & Sons. - 0028-646X .- 1469-8137. ; 222:2, s. 768-784
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Tidskriftsartikel (refereegranskat)abstract
- The temperature response of photosynthesis is one of the key factors determining predicted responses to warming in global vegetation models (GVMs). The response may vary geographically, owing to genetic adaptation to climate, and temporally, as a result of acclimation to changes in ambient temperature. Our goal was to develop a robust quantitative global model representing acclimation and adaptation of photosynthetic temperature responses.We quantified and modelled key mechanisms responsible for photosynthetic temperature acclimation and adaptation using a global dataset of photosynthetic CO2 response curves, including data from 141 C3 species from tropical rainforest to Arctic tundra. We separated temperature acclimation and adaptation processes by considering seasonal and common-garden datasets, respectively.The observed global variation in the temperature optimum of photosynthesis was primarily explained by biochemical limitations to photosynthesis, rather than stomatal conductance or respiration. We found acclimation to growth temperature to be a stronger driver of this variation than adaptation to temperature at climate of origin.We developed a summary model to represent photosynthetic temperature responses and showed that it predicted the observed global variation in optimal temperatures with high accuracy. This novel algorithm should enable improved prediction of the function of global ecosystems in a warming climate.
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| 2. |
- Bartholomew, David, et al.
(författare)
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Differential nutrient limitation and tree height control leaf physiology, supporting niche partitioning in tropical dipterocarp forests
- 2022
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Ingår i: Functional Ecology. - : John Wiley & Sons. - 0269-8463 .- 1365-2435. ; 36:8, s. 2084-2103
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Tidskriftsartikel (refereegranskat)abstract
- 1. Revealing the mechanisms of environmental niche partitioning within lowland tropical forests is important for understanding the drivers of current species distributions and potential vulnerability to environmental change. Tropical forest structure and species composition change across edaphic gradients in Borneo over short distances. However, our understanding of how edaphic conditions affect tree physiology and whether these relationships drive niche partitioning within Bornean forests remains incomplete.2. This study evaluated how leaf physiological function changes with nutrient availability across a fine-scale edaphic gradient and whether these relationships vary according to tree height. Furthermore, we tested whether intraspecific leaf trait variation allows generalist species to populate a wider range of environments.3. We measured leaf traits of 218 trees ranging in height from 4 to 66 m from 13 dipterocarp species within four tropical forest types (alluvial, mudstone, sandstone and kerangas) occurring along an <5 km edaphic gradient in North Borneo. The traits measured included saturating photosynthesis (Asat), maximum photosynthetic capacity (Vcmax), leaf dark respiration (Rleaf), leaf mass per area (LMA), leaf thickness, minimum stomatal conductance (gdark) and leaf nutrient concentrations (N, P, Ca, K and Mg).4. Across all species, leaf traits varied consistently in response to soil nutrient availability across forest types except Rleaf_mass, [Mg]leaf and [Ca]leaf. Changes in photosynthesis and respiration rates were related to different leaf nutrients across forest types, with greater nutrient-use efficiency in more nutrient-poor environments. Generalist species partially or fully compensated reductions in mass-based photosynthesis through increasing LMA in more nutrient-poor environments.5. Leaf traits also varied with tree height, except Vcmax_mass, but only in response to height-related modifications of leaf morphology (LMA and leaf thickness). These height–trait relationships did not vary across the edaphic gradient, except for Asat, [N]leaf, [P]leaf and [K]leaf.6. Our results highlight that modification of leaf physiological function and morphology act as important adaptations for Bornean dipterocarps in response to edaphic and vertical environmental gradients. Meanwhile, multiple nutrients appear to contribute to niche partitioning and could drive species distributions and high biodiversity within Bornean forest landscapes. Read the free Plain Language Summary for this article on the Journal blog.
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| 3. |
- Oliver, Rebecca J., et al.
(författare)
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Large but decreasing effect of ozone on the European carbon sink
- 2018
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 15:13, s. 4245-4269
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Tidskriftsartikel (refereegranskat)abstract
- The capacity of the terrestrial biosphere to sequester carbon and mitigate climate change is governed by the ability of vegetation to remove emissions of CO2 through photosynthesis. Tropospheric O3, a globally abundant and potent greenhouse gas, is, however, known to damage plants, causing reductions in primary productivity. Despite emission control policies across Europe, background concentrations of tropospheric O3 have risen significantly over the last decades due to hemispheric-scale increases in O3 and its precursors. Therefore, plants are exposed to increasing background concentrations, at levels currently causing chronic damage. Studying the impact of O3 on European vegetation at the regional scale is important for gaining greater understanding of the impact of O3 on the land carbon sink at large spatial scales. In this work we take a regional approach and update the JULES land surface model using new measurements specifically for European vegetation. Given the importance of stomatal conductance in determining the flux of O3 into plants, we implement an alternative stomatal closure parameterisation and account for diurnal variations in O3 concentration in our simulations. We conduct our analysis specifically for the European region to quantify the impact of the interactive effects of tropospheric O3 and CO2 on gross primary productivity (GPP) and land carbon storage across Europe. A factorial set of model experiments showed that tropospheric O3 can suppress terrestrial carbon uptake across Europe over the period 1901 to 2050. By 2050, simulated GPP was reduced by 4 to 9 % due to plant O3 damage and land carbon storage was reduced by 3 to 7 %. The combined physiological effects of elevated future CO2 (acting to reduce stomatal opening) and reductions in O3 concentrations resulted in reduced O3 damage in the future. This alleviation of O3 damage by CO2-induced stomatal closure was around 1 to 2 % for both land carbon and GPP, depending on plant sensitivity to O3. Reduced land carbon storage resulted from diminished soil carbon stocks consistent with the reduction in GPP. Regional variations are identified with larger impacts shown for temperate Europe (GPP reduced by 10 to 20 %) compared to boreal regions (GPP reduced by 2 to 8 %). These results highlight that O3 damage needs to be considered when predicting GPP and land carbon, and that the effects of O3 on plant physiology need to be considered in regional land carbon cycle assessments.
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