ecosystem importance: damage to nitrogen fixation (Introduction)

by David Turell , Monday, October 21, 2024, 20:22 (31 days ago) @ David Turell

From a new study:

https://www.sciencedaily.com/releases/2024/10/241018162550.htm

"Mississippi State University is part of a European-American collaboration studying how human activities, like fertilizer use and polluting, are impacting nitrogen-fixing plants which are crucial for maintaining healthy ecosystems by adding nitrogen to the soil.

"MSU Assistant Professor Ryan A. Folk of the Department of Biological Sciences co-authored a study published today [Oct. 18] in Science Advances, showing that increased nitrogen deposition from human activity is reducing the diversity and evolutionary distinctiveness of nitrogen-fixing plants.

"Lead author Pablo Moreno García, at the University of Arizona, said excessive nitrogen from agriculture and industry makes nitrogen fixers less competitive, leading to simplified plant communities with fewer species of nitrogen fixers.

"Folk said, "While others predicted climate change might benefit nitrogen fixers, our research shows this has not happened. Humans are changing Earth in multiple ways that affect nitrogen fixers, and nitrogen deposition is overwhelming as a harmful effect. Nitrogen, the first number listed on a bag of fertilizer, is often the most important plant macronutrient in natural and agricultural systems, so the loss of these plants threatens both biodiversity and ecosystem stability."

Abstract: https://www.science.org/doi/10.1126/sciadv.adp7953

"Biological nitrogen fixation is a fundamental part of ecosystem functioning. Anthropogenic nitrogen deposition and climate change may, however, limit the competitive advantage of nitrogen-fixing plants, leading to reduced relative diversity of nitrogen-fixing plants. Yet, assessments of changes of nitrogen-fixing plant long-term community diversity are rare. Here, we examine temporal trends in the diversity of nitrogen-fixing plants and their relationships with anthropogenic nitrogen deposition while accounting for changes in temperature and aridity. We used forest-floor vegetation resurveys of temperate forests in Europe and the United States spanning multiple decades. Nitrogen-fixer richness declined as nitrogen deposition increased over time but did not respond to changes in climate. Phylogenetic diversity also declined, as distinct lineages of N-fixers were lost between surveys, but the “winners” and “losers” among nitrogen-fixing lineages varied among study sites, suggesting that losses are context dependent. Anthropogenic nitrogen deposition reduces nitrogen-fixing plant diversity in ways that may strongly affect natural nitrogen fixation. (my bold)

***

"Nitrogen deposition is associated with long-term declines in the proportion of N-fixing plants across temperate forests of Europe and the US. Unexpectedly, changes in temperature and aridity did not contribute to the observed temporal changes in N-fixing diversity, likely reflecting the greater relative importance of N deposition for N-fixing plants. Given the effect of N deposition on N-fixer richness, we should be cautious about predicting future changes in N-fixers based solely on climatic changes without understanding the complex interplays with anthropogenically driven changes in soil nutrient conditions. Declines in N-fixer PD mostly reflect the loss of evolutionarily divergent species, leading to fewer distinct N-fixing lineages. However, no consistent clades of winner or loser species are found, indicating that the response of N-fixing plants to N deposition is driven by local environmental conditions (and possibly priority effects). Therefore, the strategic benefits of temperature and aridity increases for N-fixing species may be curtailed by N deposition, reducing N-fixing richness and their associated ecosystem services.

Comment: Any ecosystem that loses phylogenetic diversity is weakened. The Earth is covered by ecosystems that influence each other in important ways. Every oddity I present here is an important part of the overall system. Nothing is unimportant, which dhw should note when he derides something.