Plant and soil elemental coupling in response to experimentally altered precipitation and root herbivory in an Australian grassland
Ochoa-Hueso, R., P Chatzopoulos, L Serrano-Grijalva, A. Forján, C. Caetano-Sánchez, K. L.Barnett, S. N. Johnson and S. A. Power . 2026.
Abstract
1. On planet Earth, all elemental cycles are interconnected through coupled biotic and
abiotic processes, including climate, water availability and variability, soil-forming
factors and plant-animal-microbial interactions. Variations in these factors, which
may be driven by anthropogenic factors such as climate change and community reorganizations, may affect the bioavailability and abundance of chemical elements,
17 of which are essential nutrients for plants. Differential responses among chemical elements may, in turn, lead to changes in their interrelationships, resulting in the
coupling or decoupling of elemental cycles across different ecosystem compartments (e.g. animals, plants and soils).
2. We analysed the impact of experimentally altered rainfallregimes (reduced amount
and frequency) and root herbivory (through the addition of scarab beetle larvae)
on the bioavailability, abundance and coupling of 11 soil and 14 plant elements in
an Eastern Australian grassland. We also examined how elemental coupling may be
influenced by the atomic properties of those elements, particularly atomic mass,
which is closely linked to each element's abundance, reactivity and mobility in soils
and plants.
3. Overall, plant elemental content was not significantly affected by the experimental manipulations, reflecting a high degree of homeostatic regulation. In contrast,
soil nutrient bioavailability responded more strongly to changes in rainfall, with
the bioavailability of potassium increasing and that of secondary macronutrients
such as calcium and magnesium and micronutrients such as manganese decreasing
under altered precipitation scenarios. Plant elements were generally more coupled than those in soil, reflecting stronger internal regulation (i.e. homeostasis), but
this coupling was significantly influenced by both experimentally altered rainfall
and root herbivory. Plant coupling was generally reduced in response to rainfall
manipulation, while the effects of herbivory were highly rainfall treatment- and year-dependent. Additionally, we found signals of a positive association between
elemental coupling and atomic mass in soils, whereas no such relationship was
detected in plants.
4. Synthesis. Our work provides novel experimental evidence on how chemical elements in plants and soils respond to changes in precipitation regimes and shifts
in plant-animal interactions (root herbivory), moving the focus from changes in
plant and soil elements to the way in which such elements are coordinated.
Key Words
climate extremes, early warning signals, elemental coupling, grasslands, plant-herbivore interactions, precipitation regimes
