“Plante to slip” – ADEME’s campaign is relevant to better understand life on the ground beneath our feet. However, it has its limits when it comes to understanding the recycling of organic matter, as a study just published in the journal Nature Ecology & Evolution has shown. The quality of organic matter (Organic matter (OM) is the carbonaceous matter generally produced by…), more diverse than cotton slips, and decomposers evolve in different climatic contexts. This spatial variability is essential for understanding the carbon cycle and the effects of climate change.
Photo on the left (© François-Xavier Joly): Bags of natural litter next to the standard material (paper and wooden sticks) in a test area in a German forest.
Graph on the right: Natural litter degradation rate as a function of standard material degradation rate in each of the studied plots (one point per plot) in different forests in Finland, Poland, Germany, Romania, Italy and Spain (solid color by country).
There is no relationship between the two measurements as indicated by the dotted line (the slight slope is not statistically significant). In other words, one cannot predict the degradation of natural litter produced in each plot based on the degradation of identical standard materials in all plots.
The diversity of organisms that live in the soil invisible to our eyes has long been ignored. These soil organisms live on essentially plant waste, such as carbon dioxide or carbonic acid, is a …) and nutrients, which are again available to the plants. This recycling of waste, so well mastered by nature and so poorly copied by human societies, is a major driving force in the planetary carbon cycle (A planetary denotes a moving mechanical unit representing the solar system…).
With about 60 gigatons of carbon emitted each year by all terrestrial ecosystems through decomposition into the atmosphere, six times more than through human activity, this key ecosystem process is the subject of extensive study by scientists. However, despite more than ten thousand existing studies on the subject, there are still major uncertainties as to the relative role of the various control factors (The word control can have several meanings. It can be used as a synonym for testing. of…) of decomposition. In particular, it has recently been suggested that the importance of regional climate – a key parameter for modeling the carbon cycle – has been grossly overestimated by ignoring the variability of environmental conditions on very small spatial scales.
A natural litter layer on the floor of a mixed oak and pine forest in a trial field in Spain.
© François-Xavier Joly
The FunDivEUROPE system and its network of more than 200 forest plots along a significant climate gradient from Finland to Spain was created as part of a large-scale European project involving 27 partners, including the Center for Functional Ecology (in mathematics, the term functional refers to to specific functions…) and evolutionary (CEFE – University (A university is a higher education institution whose objective is the…) Montpellier / CNRS / EPHE / IRD). It provides the ideal framework for studying the relative importance of different degradation control factors.
Using three parallel and concerted experiments, including one at the CEFE experimental field, the researchers hypothesized that the decomposability of the litter from all plots and in a common garden on one side, as well as the environmental factors specific to each plot, were determined on the other hand, are characterized by the in situ degradation of standard materials would make it possible to predict the in situ degradation of natural waste. However, this was not the case: the rate of decomposition of standard materials varies completely (complete or fully automatic or by Anglicism completion or…) independently of that of natural litter decomposing side by side in the plot forests across Europe. These parallel experiments were therefore able to show that the regional climate is indeed an important controlling factor, both directly and indirectly via vegetation (vegetation is the set of wild or cultivated plants (flora) that …) and soil organisms that adapt to it Conditions are adapted to climate.
Two important conclusions follow from this: First, the confirmation of the important role of regional climate is good news for modeling approaches aimed at better understanding the effects of climate change on the carbon cycle. Second, the results based on the use of standard materials – such as tea bags or slips – which are increasingly used in large-scale decomposition studies, must be treated with caution, since these materials are detached from the evolutionary context of both the plants and those attached to these resources adapted decomposers are found.
A test area in a mixed forest in Italy (left) and in a monospecific spruce forest in Finland.
© Stephan Hättenschwiler
Relation:
Resolving the intricate role of climate in litter decomposition by François-Xavier Joly, Michael Scherer-Lorenzen & Stephan Hattenschwiler, published in Nature Ecology & Evolution on January 9, 2023.
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