Evaluate the impact and scope of biogeochemical cycles


Biogeochemical cycles describe the flow of elements in earth systems. They are strongly influenced by biological and anthropogenic activity and, in turn, influence other aspects of earth systems and the human environment. Biogeochemical cycles: ecological factors and environmental impact, a book published by AGU, shows how biogeochemical cycles have developed over time and how they manifest in different environments, and presents new methodologies available to quantify and predict element flux. Here, the editors of the book provide an overview of our understanding of biogeochemical cycles and summarize current challenges and research opportunities.

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 study of biogeochemical cycles is important to understand how natural ecosystems resist the stresses of the Anthropocene, but also to anticipate and model the sustainable functioning of ecosystems impacted by humans such as agricultural soils.

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

What is the interest of the concept of critical zone in the study of biogeochemical cycles?

The critical zone is a porous skin of the Earth’s land surface that extends from the top of the canopy to the lower limits of free flowing 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 houses life, including man.

Diagram showing the links between structure and function in a critical area.
Link between structure and function in critical area. 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, which means that a change can trigger multiple abiotic and biological responses and feedbacks. This, for example, can make it difficult to study the effects of climate change on the preservation and cycling of organic carbon in soils.

Series of three figures showing the structure of microbial decomposition models.
Structure of microbial decomposition models. Credit: Abs et 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’s hard to name anything in the environment that isn’t influenced by humans, including biogeochemical cycles. Climate change is of great concern now and the effects of climate change and feedbacks are particularly dramatic in permafrost regions. Herndon et al. [2020] demonstrated the influence of warming on the cycles of redox-sensitive elements in ecosystems affected by permafrost. One of the biggest concerns is the positive feedback on 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 it urgent to study the interdependence of different ecosystems?

The Earth is a system with many subsystems such as the biosphere, hydrosphere, atmosphere and tectonic system that are constantly 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 between them and they are all connected through biogeochemical cycles.

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

The urgency to study the interdependence of different ecosystems comes to seize the current opportunities offered by the Critical Zone Exploration Network by providing locations for studies and collaborations between various experts.

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

Our book identifies nine major gaps, the two most important of which are: quantifying the effects of biological weathering at all scales and applying biogeochemical knowledge to solve societal problems.

Covering orders of magnitude in the spatial and temporal scales of processes is a challenge in geosciences and the addition of connected biological processes makes the understanding even more complex. The establishment of critical zone observatories and their exploration network offers opportunities to study processes at different scales in many places.

Cover of the book Biogeochemical Cycles: Ecological Drivers and Environmental ImpactThe application and transformation of knowledge to solve societal problems is becoming increasingly urgent and relevant as humans exert significant influence on the environment, including biogeochemical cycles.

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

Biogeochemical cycles: ecological factors and environmental impact, 2021, ISBN: 978-1-119-41331-8, list price $ 199.95 (print), $ 160.00 (ebook). AGU members receive 35% off all books at Wiley.com. Log in to your AGU member profile to access the discount code.

—Katerina Dontsova ([email protected], ORCIDE logo 0000-0003-2177-8965), University of Arizona, USA; Zsuzsanna Balogh ‐ Brunstad (ORCIDE logo 0000-0002-5749-1213), Hartwick College, USA; and Gaël Le Roux (ORCIDE logo 0000-0002-1579-0178), National Center for Scientific Research, France

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

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