Photo of the Makahiku Falls in the Haleakala National Park Maui, Hawaii
The Makahiku Falls in the Haleakala National Park Maui, Hawaii. Credit: Zsuzsanna Balogh-Brunstad

Biogeochemical cycles describe the flow of elements in the Earth systems. They are strongly influenced by biological and anthropogenic activity and, in turn, influence other aspects of the Earth systems and human environment. Biogeochemical Cycles: Ecological Drivers and Environmental Impact, a book published by AGU, demonstrates how biogeochemical cycles developed over time and how they manifest in different environments, and presents new methodologies available to quantify and predict flow of the elements. Here the book’s editors give an overview of our understanding of biogeochemical cycles and summarize current challenges and opportunities for research.

What makes biogeochemical cycles such an interesting field of study?

The biogeochemical cycles of the elements influence most of the abiotic factors that govern life.

The biogeochemical cycles of the elements influence most of the abiotic factors that govern life. Studying biogeochemical cycles is important for understanding how natural ecosystems resist Anthropocene stresses, and also for anticipating and modeling the sustainable functioning of human-impacted ecosystems such as agricultural soils.

Example of isotope analysis application to elemental cycles. Credit: Nägler et al. [2020], Figure 8.7

 What is the interest of the Critical Zone concept in the study of biogeochemical cycles?

The Critical Zone is a porous skin of the Earth’s land surface extending from the top of the vegetation canopy to the lower limits of freely circulating groundwater (NRC, 2001). It is a useful concept in biogeochemistry because it brings together soils, vegetation, rocks, and water. Geologically speaking, it is a very thin layer, but it is the layer that shelters life, including humans.

Link between structure and function in critical zone. Credit: Moravec and Chorover [2020], Figure 6.1

What are some of the challenges in determining cause and effect relationships within biogeochemical cycles?

Earth systems are incredibly complex and interconnected meaning that one change can trigger multiple abiotic and biological responses and feedbacks. This, for example, can make studying effects of climate change on organic carbon preservation and cycling in soils challenging.

Structure of microbial decomposition models. Credit: Abs and Ferrière [2020], Figure 5.1, adapted from Georgiou et al. [2017]

How do human activities affect, and how are they affected by, biogeochemical cycles?

It is hard to name something in the environment that is not influenced by humans, including  biogeochemical cycles. Climate change is a big concern now and effects of climate change and feedbacks are particularly dramatic in the regions of the permafrost. Herndon et al. [2020] demonstrated influence of warming on the cycles of redox‐sensitive elements in permafrost‐affected ecosystems. One of the biggest concerns is positive feedback on the global warming due to the release of CO2 and methane, but many other elements, such as P, N, S, and Fe, are affected.

Why is there urgency in studying the interconnectedness of different ecosystems?

Earth is one system with numerous subsystems that are continuously interacting. Different ecosystems cannot be fully understood if they are studied in isolation because they are not closed systems.

Earth is one system with numerous subsystems such as the biosphere, hydrosphere, atmosphere, and the tectonic system that are continuously interacting. Different ecosystems cannot be fully understood if they are studied in isolation because they are not closed systems. There is a continuous exchange of materials, energy, and living matter among them and they are all connected through the biogeochemical cycles.

To understand complex relationships, processes and feedback loops within landscape evolutions we need to understand how different ecosystems are connected in space and time.

The urgency of studying the interconnectedness of different ecosystems is coming from seizing the current opportunities that are offered by the Critical Zone Exploration Network via providing locations for the studies and collaborations among various experts.

What are some of the major gaps in our understanding of biogeochemical cycles where additional research is needed?

Our book lists nine major gaps, of which the two most important are: quantification of the effects of biological weathering across scales, and application of biogeochemical knowledge to solve societal problems.

Spanning orders of magnitude in spatial and temporal scales of processes is challenging in geosciences and adding the connected biological processes makes understanding even more complex. The establishment of the Critical Zone Observatories and their Exploration Network provides opportunities to investigate processes are various scales at numerous locations.

Application and transformation of knowledge to solve societal problems are becoming more pressing and relevant as humans exert a significant influence on the environment, including biogeochemical cycles.

The interdisciplinarity of biogeochemistry and the existing uncertainties in the research findings make it challenging to directly influence decision making. Increased collaborations between fields of biogeochemistry, humanities, and social sciences can offer results and apply solutions for societal problems, such as sustainable food production, food security, carbon management, and sequestration.

Biogeochemical Cycles: Ecological Drivers and Environmental Impact, 2021, ISBN: 978-1-119-41331-8, list price $199.95 (print), $160.00 (ebook). AGU members receive 35 percent off all books at Wiley.com. Log in to your AGU member profile to access the discount code.

—Katerina Dontsova (dontsova@arizona.edu,  0000-0003-2177-8965),  University of Arizona, USA; Zsuzsanna Balogh‐Brunstad ( 0000-0002-5749-1213), Hartwick College, USA; and Gaël Le Roux ( 0000-0002-1579-0178), National Center for Scientific Research, France

Editor’s Note: It is the policy of AGU Publications to invite the authors or editors of newly published books to write a summary for Eos Editors’ Vox.

Citation:

Dontsova, K., Z. Balogh‐Brunstad, and G. Le Roux (2021), Evaluating the impact and reach of biogeochemical cycles, Eos, 102, https://doi.org/10.1029/2021EO163024. Published on 20 September 2021.

Text © 2021. The authors. CC BY-NC-ND 3.0
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