{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T10:36:13Z","timestamp":1787567773065,"version":"build-2736575974"},"reference-count":47,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,20]],"date-time":"2026-08-20T00:00:00Z","timestamp":1787184000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Plants"],"abstract":"<jats:p>Photorespiration and drought-induced stomatal closure are two important physiological constraints that reduce carbon assimilation and productivity in C3 forest trees under Mediterranean climatic conditions. T\u00fcrkiye\u2019s two dominant commercial pine species, Pinus brutia Ten. (Calabrian pine) and Pinus nigra J.F. Arnold subsp. pallasiana (Anatolian black pine), together cover approximately 8.15 million hectares. This study integrated published gas-exchange measurements, radiation-use efficiency estimates from MODIS, official forest inventory data, and dendrochronological growth records into a counterfactual accounting framework and propagated parameter uncertainty by Monte Carlo simulation (N = 40,000 draws). The two constraints jointly reduced weighted-mean net primary productivity (NPP) from a radiation-limited potential of 5.61 to an actual 3.46 Mg C ha\u22121 yr\u22121, a reduction of 37.9% (95% CI 32.2\u201343.4%). Decomposition shows that 47.7% of this loss is the obligate metabolic cost of C3 carboxylation, which no silvicultural intervention can address, while 52.3%\u201420.1 of the 37.9 percentage points\u2014is drought-attributable. Nationally, the deficit corresponds to 64.3 Mt CO2 yr\u22121 of forgone sequestration (47.8\u201381.2) and 34.4 Mm3 yr\u22121 of forgone stemwood-volume equivalent (24.9\u201344.5), of which approximately 20.6 Mm3 would be merchantable, giving an annual economic deficit of USD 3.37 billion (2.40\u20136.48). Filtering the drought-attributable component for eligible area, recovery efficiency, additionality, leakage, and permanence yields approximately 1.0 Mt CO2 yr\u22121 of potentially issuable credits, fewer than two per cent of the headline figure. Eco-physiological suppression of this magnitude is currently invisible in national forest carbon accounting, and its recognition bears directly on dynamic baseline design and on the credibility of offsets generated from Mediterranean conifer forests.<\/jats:p>","DOI":"10.3390\/plants15162527","type":"journal-article","created":{"date-parts":[[2026,8,20]],"date-time":"2026-08-20T16:05:19Z","timestamp":1787241919000},"page":"2527","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Quantifying Carbon Losses Associated with Photorespiration and Drought Stress in Two Dominant Mediterranean Pine Species"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-0249-0798","authenticated-orcid":false,"given":"Emre","family":"Yazar","sequence":"first","affiliation":[{"name":"Department of Bioengineering and Sciences, Graduate School of Natural and Applied Sciences, Kahramanmara\u015f S\u00fct\u00e7\u00fc \u0130mam University, 46050 Kahramanmara\u015f, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8236-3280","authenticated-orcid":false,"given":"B\u00fclent","family":"Akg\u00fcn","sequence":"additional","affiliation":[{"name":"Department of Bioengineering and Sciences, Graduate School of Natural and Applied Sciences, Kahramanmara\u015f S\u00fct\u00e7\u00fc \u0130mam University, 46050 Kahramanmara\u015f, T\u00fcrkiye"},{"name":"Department of Forest Engineering, Faculty of Forestry, Kahramanmara\u015f S\u00fct\u00e7\u00fc \u0130mam University, 46050 Kahramanmara\u015f, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1776-3018","authenticated-orcid":false,"given":"Emre","family":"Babur","sequence":"additional","affiliation":[{"name":"Department of Forest Engineering, Faculty of Forestry, Kahramanmara\u015f S\u00fct\u00e7\u00fc \u0130mam University, 46050 Kahramanmara\u015f, T\u00fcrkiye"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,20]]},"reference":[{"key":"ref_1","unstructured":"OGM (2021). Annual Activity Report, General Directorate of Forestry."},{"key":"ref_2","unstructured":"OGM (2023). Annual Activity Report, General Directorate of Forestry."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"101","DOI":"10.1007\/s11676-015-0147-4","article-title":"Development of ecoregion-based merchantable volume systems for Pinus brutia Ten. and Pinus nigra Arnold. in southern Turkey","volume":"27","author":"Karatepe","year":"2016","journal-title":"J. For. Res."},{"key":"ref_4","unstructured":"FAO (2014). Global Forest Resources Assessment 2015\u2014Turkey Country Report, Food and Agriculture Organization of the United Nations."},{"key":"ref_5","first-page":"57","article-title":"Ecological factors restricting the regeneration of Pinus brutia in Turkey","volume":"13","author":"Eron","year":"1987","journal-title":"Ecol. Mediterr."},{"key":"ref_6","first-page":"55","article-title":"The silviculture of Pinus brutia in Turkey","volume":"86","author":"Gezer","year":"1986","journal-title":"Options Mediterr."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"169","DOI":"10.1515\/sg-2004-0031","article-title":"Genetic variation in Turkish red pine (Pinus brutia Ten.) seed stands as determined by RAPD markers","volume":"53","author":"Kandemir","year":"2004","journal-title":"Silvae Genet."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"691","DOI":"10.1007\/s00484-012-0595-x","article-title":"An improved reconstruction of May\u2013June precipitation using tree-ring data from western Turkey and its links to volcanic eruptions","volume":"57","author":"Akkemik","year":"2013","journal-title":"Int. J. Biometeorol."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"253","DOI":"10.1111\/j.1365-3040.2001.00668.x","article-title":"Improved temperature response functions for models of Rubisco-limited photosynthesis","volume":"24","author":"Bernacchi","year":"2001","journal-title":"Plant Cell Environ."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"32","DOI":"10.1111\/nph.15283","article-title":"Plant carbon metabolism and climate change: Elevated CO2 and temperature impacts on photosynthesis, photorespiration and respiration","volume":"221","author":"Dusenge","year":"2019","journal-title":"New Phytol."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"107","DOI":"10.1146\/annurev-arplant-043015-111709","article-title":"The costs of photorespiration to food production now and in the future","volume":"67","author":"Walker","year":"2016","journal-title":"Annu. Rev. Plant Biol."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"689","DOI":"10.1098\/rsbl.2011.1059","article-title":"Drought-induced forest decline: Causes, scope and implications","volume":"8","author":"Lloret","year":"2012","journal-title":"Biol. Lett."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1532","DOI":"10.1093\/treephys\/tpab141","article-title":"Diverging responses of water and carbon relations during and after heat and hot drought stress in Pinus sylvestris","volume":"42","author":"Rehschuh","year":"2022","journal-title":"Tree Physiol."},{"key":"ref_14","first-page":"coz012","article-title":"Drought-induced dieback of Pinus nigra: A tale of hydraulic failure and carbon starvation","volume":"7","author":"Savi","year":"2019","journal-title":"Conserv. Physiol."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"123614","DOI":"10.1016\/j.foreco.2026.123614","article-title":"Shaping gas exchange under drought: Seasonal and interspecific variation in photosynthetic traits of Pinus halepensis and Pinus brutia in Mediterranean forests","volume":"609","author":"Kiorapostolou","year":"2026","journal-title":"For. Ecol. Manag."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Sazeides, C.I., and Fyllas, N.M. (2025). Simulating net ecosystem productivity (NEP) in Mediterranean pine forests (Pinus brutia) during the 21st century: The effect of leaf area index and elevation. Plants, 14.","DOI":"10.3390\/plants14071090"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"41","DOI":"10.18182\/tjf.1404940","article-title":"A comparison of photosynthetic gas exchange parameters measured under in situ and in vitro conditions in Pinus nigra subsp. pallasiana and Pinus brutia trees","volume":"25","author":"Bayar","year":"2024","journal-title":"Turk. J. For."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"21","DOI":"10.1016\/j.foreco.2018.01.047","article-title":"Recent growth trends of black pine (Pinus nigra J.F. Arnold) in the eastern Mediterranean","volume":"412","author":"Janssen","year":"2018","journal-title":"For. Ecol. Manag."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"662","DOI":"10.1007\/s11629-021-6738-y","article-title":"Relationship between the productivity of Pinus brutia Ten. and site characters, the Taurus Mountains, Turkey","volume":"19","year":"2022","journal-title":"J. Mt. Sci."},{"key":"ref_20","first-page":"7079","article-title":"Above-ground biomass and carbon stock equations for Crimean pine stands in the Kastamonu region of Turkey","volume":"27","author":"Sakici","year":"2018","journal-title":"Fresenius Environ. Bull."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"1036","DOI":"10.1111\/nph.14258","article-title":"The sensitivity of photosynthesis to O2 and CO2 concentration identifies strong Rubisco control above the thermal optimum","volume":"213","author":"Busch","year":"2017","journal-title":"New Phytol."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"5067","DOI":"10.1093\/jxb\/erw267","article-title":"A compendium of temperature responses of Rubisco kinetic traits: Variability among and within photosynthetic groups and impacts on photosynthesis modelling","volume":"67","author":"Laanisto","year":"2016","journal-title":"J. Exp. Bot."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"637","DOI":"10.1093\/treephys\/tpr047","article-title":"Hydraulic adjustments underlying drought resistance of Pinus halepensis","volume":"31","author":"Klein","year":"2011","journal-title":"Tree Physiol."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"1285","DOI":"10.1038\/s41559-017-0248-x","article-title":"A multi-species synthesis of physiological mechanisms in drought-induced tree mortality","volume":"1","author":"Adams","year":"2017","journal-title":"Nat. Ecol. Evol."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1479","DOI":"10.1007\/s11676-018-00876-8","article-title":"Differences in physiological and biochemical responses to summer drought of Pinus nigra subsp. pallasiana and Pinus brutia in a natural mixed stand","volume":"31","author":"Cankara","year":"2020","journal-title":"J. For. Res."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"\u00d6z\u00e7elik, M.S. (2025). Dendrometer-based analysis of intra-annual growth and water status in two pine species in a Mediterranean forest stand under a semi-arid climate. Forests, 16.","DOI":"10.3390\/f16081229"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"78","DOI":"10.1007\/BF00386231","article-title":"A biochemical model of photosynthetic CO2 assimilation in leaves of C3 species","volume":"149","author":"Farquhar","year":"1980","journal-title":"Planta"},{"key":"ref_28","unstructured":"Running, S.W., and Zhao, M. (2019). User\u2019s Guide: MOD17A2H\/A2HGF\/A3H\u2014Daily and Annual GPP and NPP Products, NASA EOS MODIS Land Algorithm Theoretical Basis Document, Version 3.0, University of Montana."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"285","DOI":"10.1007\/s10661-018-6656-9","article-title":"Compatible above-ground biomass equations and carbon stock estimation for small-diameter Turkish pine (Pinus brutia Ten.)","volume":"190","author":"Sakici","year":"2018","journal-title":"Environ. Monit. Assess."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"394","DOI":"10.1080\/02827580903164471","article-title":"Carbon concentrations of tree components, forest floor and understorey in young Pinus sylvestris stands in north-western Turkey","volume":"24","author":"Tolunay","year":"2009","journal-title":"Scand. J. For. Res."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"92","DOI":"10.1080\/14693062.2025.2485196","article-title":"Carbon prices on the rise? Shedding light on the emerging second EU Emissions Trading System (EU ETS 2)","volume":"26","author":"Pahle","year":"2026","journal-title":"Clim. Policy"},{"key":"ref_32","first-page":"29455","article-title":"Carbon pricing and aggregate macroeconomic performance in the Eurozone: A contribution to the climate-policy debate using the EU ETS and the Macroeconomic Performance Index","volume":"31","year":"2024","journal-title":"Environ. Sci. Pollut. Res."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"2560","DOI":"10.1080\/01431161.2018.1430913","article-title":"A new approach to evaluate the MODIS annual NPP product (MOD17A3) using forest field data from Turkey","volume":"39","author":"Gulbeyaz","year":"2018","journal-title":"Int. J. Remote Sens."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"8409","DOI":"10.15376\/biores.18.4.8409-8431","article-title":"Carbon emissions-trading potential of Turkey\u2019s forests","volume":"18","year":"2023","journal-title":"BioResources"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"117533","DOI":"10.1016\/j.foreco.2019.117533","article-title":"Photosynthetic capacity, nutrient and water status following precommercial thinning in Anatolian black pine","volume":"451","author":"Bayar","year":"2019","journal-title":"For. Ecol. Manag."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1169","DOI":"10.1007\/s00468-020-01989-6","article-title":"Impacts of precommercial thinning on gas exchange, midday water potential, and chlorophyll content in Pinus nigra subsp. pallasiana stand from the semiarid region","volume":"34","author":"Bayar","year":"2020","journal-title":"Trees"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1016\/j.foreco.2016.07.046","article-title":"Potential of forest thinning to mitigate drought stress: A meta-analysis","volume":"380","author":"Sohn","year":"2016","journal-title":"For. Ecol. Manag."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"e064","DOI":"10.5424\/fs\/2016252-09290","article-title":"Effects of spacing on early growth rate and carbon sequestration in Pinus brutia Ten. plantations","volume":"25","author":"Erkan","year":"2016","journal-title":"For. Syst."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"977","DOI":"10.1007\/s00468-022-02264-6","article-title":"Genetic diversity and population structure of Pinus halepensis Mill. in Jordan revealed by simple sequence repeats","volume":"36","author":"Mustafa","year":"2022","journal-title":"Trees"},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"105576","DOI":"10.1016\/j.atmosres.2021.105576","article-title":"Intercomparison of the expected change in the temperature and the precipitation retrieved from CMIP6 and CMIP5 climate projections: A Mediterranean hot spot case, Turkey","volume":"256","author":"Yucel","year":"2021","journal-title":"Atmos. Res."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"321","DOI":"10.5194\/esd-13-321-2022","article-title":"The Mediterranean climate change hotspot in the CMIP5 and CMIP6 projections","volume":"13","author":"Cos","year":"2022","journal-title":"Earth Syst. Dyn."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"3311","DOI":"10.1007\/s00024-025-03757-4","article-title":"Prediction of future drought characteristics over the southwest of Turkey using CMIP6 models","volume":"182","author":"Davraz","year":"2025","journal-title":"Pure Appl. Geophys."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"711","DOI":"10.1111\/pbi.13750","article-title":"Alternative pathway to photorespiration protects growth and productivity at elevated temperatures in a model crop","volume":"20","author":"Cavanagh","year":"2022","journal-title":"Plant Biotechnol. J."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"1550","DOI":"10.1111\/nph.16485","article-title":"Plant responses to rising vapor pressure deficit","volume":"226","author":"Grossiord","year":"2020","journal-title":"New Phytol."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"672","DOI":"10.1126\/science.adf5041","article-title":"Global water-use efficiency saturation due to increased vapor pressure deficit","volume":"381","author":"Li","year":"2023","journal-title":"Science"},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"1433","DOI":"10.1111\/gcb.15943","article-title":"Systematic over-crediting in California\u2019s forest carbon offsets program","volume":"28","author":"Badgley","year":"2022","journal-title":"Glob. Change Biol."},{"key":"ref_47","doi-asserted-by":"crossref","first-page":"101809","DOI":"10.1016\/j.ecoser.2025.101809","article-title":"Quantifying and integrating ecosystem services in forest management planning: A Turkey case study","volume":"73","author":"Baskent","year":"2026","journal-title":"Ecosyst. Serv."}],"container-title":["Plants"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2223-7747\/15\/16\/2527\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,24]],"date-time":"2026-08-24T09:42:57Z","timestamp":1787564577000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2223-7747\/15\/16\/2527"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,20]]},"references-count":47,"journal-issue":{"issue":"16","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["plants15162527"],"URL":"https:\/\/doi.org\/10.3390\/plants15162527","relation":{},"ISSN":["2223-7747"],"issn-type":[{"value":"2223-7747","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,20]]}}}