Elevated CO₂ and Nutrient Limitations in Forest Ecosystems
Ivy Shum '29
Elevated carbon dioxide(eCO₂) and climate change have been important topics of discussion for the past few years. Since the industrial revolution, increasing daily carbon emissions and the urgency of climate change have been worrying and are desperately in need of an effective resolution. Simulations that calculate human activities and carbon impacts, such as EnRoads, have been created to help environmentalists find potential solutions for the endangering situation, and the UN has held multiple meetings to mitigate this issue with the objective of finding a common ground between commercial and environmental needs.
Recent studies show that “trees can temporarily store more CO₂ as atmospheric CO₂ levels rise” (Munich, 2026). Trees contribute to the process of photosynthesis, the process where “plants transform light energy into chemical energy,” using the presence of water and CO₂ to generate initial glucose and oxygen (Ekele, Jiata Ugwah et al., 2025). With sufficient CO2 stored in trees, they can begin the carboxylation process. The carboxylation process produces triose phosphates, which are “crucial carbon compounds for plant growth and development (Ekele, Jiata Ugwah et al., 2025). However, long-term immersion of trees in a CO₂-heavy atmosphere reduces the ability to store high amounts of CO₂ due to nutrient limitations of nutrients like Nitrogen (N) and Phosphorus (P) (Ekele, Jiata Ugwah et al., 2025). Both N and P are essential elements that contribute to plant nutrient absorption and growth. N isotopes are different forms of nitrogen that have different masses due to the variety of neutrons. There are two types of N isotopes: 15N and 14N. Both are stable isotopes that provide information of where nitrogen comes from and what process it went through, including transformation and nitrogen cycle (USGS -- Isotope Tracers -- Resources, 2026).
To have a control measurement of the Nitrogen isotopes sample collection, scientists “applied a grid of 250 square cells (50 × 50 km) over Sweden” to compile tree cores (Bassett et al., 2026). Using these tree cores, an autosampler provided data for the analysis of N isotopes by chopping a core slice that has removed CO₂ and water vapor. Core slices are samples of tree cores that represent 10-year segments. Climate parameters, annual temperature, atmospheric CO₂ concentrations, total basal area (the cross-sectional diameter of a single tree at breast height) , and stand age (forest age) are all measured (Basal Area: A Measure Made for Management - Alabama Cooperative Extension System, 2024)(Vangi et al., 2024). This condensed data on the core slice provides the average total N deposition (the process of which gas transforms into solid directly) of each sample based on geographic location. The total basal area is observed to analyze the influence of forest management and environmental change factors (Bassett et al., 2026).
Analyzing the sample collected from 1961-2018, the influx of “atmospheric CO₂ concentration generally stimulates terrestrial net primary productivity and consequently causes or aggravates nutrient limitation due to increasing nutrient demands for plant growth” (Du et al., 2023). More specifically, low temperature, heavy moisture, and high soil pH, all results from the accumulating CO₂, cause N limitations, as N accumulation in plant and litter during forest development further intensifies the N loss. P losses are mostly connected to extreme weather, including the increase of heat and erosion, and loss of materials (Steel et al., 2023). Without the needed nutrients to support photosynthesis, forests meet the maximum carbon source they can store, leading to a positive feedback loop of CO₂ where atmospheric carbon continues to increase at an exponential rate and the ability of forests to obtain that carbon declines. Additionally, over the past few centuries, “about 26% of total anthropogenic CO₂ emissions since the industrial revolution are attributable to deforestation” (Noormets et al., 2023). Even a small fraction of altered global deforestation patterns highly contributes to the uncontrollable trend of tree carbon sequestration.
In response to the influx of CO₂ emissions but lack of N and P supply, trees have developed adaptations that help them thrive in this intraspecific competitive situation. For example, Amazonian trees have developed an efficient internal cycle that allows them to gain “nutrients from their leaves before they drop them…[and utilize] organic matter decomposition on the ground” that further supply extra nutrients (Munich, 2026). Researchers have also used open-top chambers (chambers that study the impacts of rising temperature through vegetation in high latitude environments) to plan future solutions for increasing atmospheric CO₂. Open-top chambers can control the temperature around plants and take in natural rainfall. After two years, researchers found that “plants redistribute their root systems to extract more nutrients, particularly phosphorus,” with these chambers (Munich, 2026). Self-regulation of nutrients through the litter layer, the process where fallen leaves “release enzymes that decompose organic matter and [intake] phosphorus before it is transferred into the soil and may become resorbed,” is crucial for plants to obtain nutrient resources (Munich, 2026).
While there are strategies that increase carbon storage, they only temporarily buffer climate change and are eventually restricted by limited nutrient availability. The deteriorating ability of trees to sequester carbon because of lack of nutrient supply highlights the significance and vulnerability of forest ecosystems in the midst of accelerating climate change. Trees provide essential elements for humans, engaging in co-existence with human and other animal species. The rising CO₂ disrupts the normal regulations of trees, posing a threat to the whole ecosystem.
References
Bassett, K. R., Hupperts, S. F., Jämtgård, S., et al. (2026). Rising atmospheric CO2 reduces nitrogen availability in boreal forests [Rising atmospheric CO2 reduces nitrogen availability in boreal forests]. Nature Portfolio. https://doi.org/10.1038/s41586-025-10039-5
Du, E., Terrer, C., McNulty, et al. (2023). Nutrient limitation in global forests: current status and future trends. In S. G. McNulty (Ed.), Future Forests (pp. 65-74). https://doi.org/10.1016/C2020-0-01940-7
Ekele, J. U., Webster, R., Heredia, F. P. de, et al. (2025). Current impacts of elevated CO2 on crop nutritional quality: a review using wheat as a case study [Current impacts of elevated CO2 on crop nutritional quality: a review using wheat as a case study]. PubMed Central. https://doi.org/10.1007/s44154-025-00217-w
Elledge, J., & Barlow, B. (2018). Basal Area: A Measure Made for Management. The Alabama Cooperative Extension System. https://www.aces.edu/blog/topics/forestry/basal-area-a-measure-made-for-management/
Hollister, R. D., Elphinstone, C., Henry, G. H.R., et al. (2022). A review of open top chamber (OTC) performance across the ITEX Network. Arctic Science, 9(2). https://doi.org/10.1139/as-2022-0030
Noormets, A., Miao, G., Kim, D., et al. (2023). Mitigation potential of forests: challenges to carbon accrual in the ecosystem. In S. G. McNulty (Ed.), Future Forests (pp. 75-94). https://doi.org/10.1016/C2020-0-01940-7
Periodic Table--Nitrogen, H.R. Rep. (Jan., 2004). https://wwwrcamnl.wr.usgs.gov/isoig/period/n_iig.html?utm_source=openai
Steel, E. A., Hinckley, T. M., Richards, W. H., & D'Amore, D. V. (2023). Forests then and now: managing for ecosystem benefits, services to humans, and healthy forests across scales. In S. G. McNulty (Ed.), Future Forests (pp. 49-64). https://doi.org/10.1016/C2020-0-01940-7
Technical University Munich. (2026, April 28). Rainforests can buffer rising CO₂ in the short term—but this comes at a cost [Rainforests can buffer rising CO₂ in the short term—but this comes at a cost]. Science X. https://phys.org/news/2026-04-rainforests-buffer-short-term.html
Vangi, E., Dalmonech, D., Cioccolo, E., et al. (2024). Stand age diversity (and more than climate change) affects forests' resilience and stability, although unevenly. Journal of Environmental Management, 366(121822). https://doi.org/10.1016/j.jenvman.2024.121822