The size and age of plants has more of an impact on their productivity than temperature and precipitation, University of Arizona researchers have discovered
The size and age of plants has more of an impact on their productivity than temperature and precipitation, according to a landmark study by University of Arizona researchers.
Sean Michaletz (left) and Brian Enquist take a break from measuring trees in an old-growth forest in Oregon. The large tree behind them is an example of an old, large tree with a low growth rate, absorbing carbon from the atmosphere and making food for animals like squirrels and birds.
Credit: Irena Simova
UA professor Brian Enquist and postdoctoral researcher Sean Michaletz, along with collaborators Dongliang Cheng from Fujian Normal University in China and Drew Kerkhoff from Kenyon College in Gambier, Ohio, have combined a new mathematical theory with data from more than 1,000 forests across the world to show that climate has a relatively minor direct effect on net primary productivity, or the amount of biomass that plants produce by harvesting sunlight, water and carbon dioxide.
The findings will be available as an advance online publication by the journal Nature on July 20.
"A fundamental assumption of our models for understanding how climate influences the functioning of ecosystems is that temperature and precipitation directly influence how fast plants can take up and use carbon dioxide," said Enquist, a professor in the UA's Department of Ecology and Evolutionary Biology whose research lab led the study.
"Essentially, warm and wet environments are thought to allow plant metabolism to run fast, while cold and drier environments slow down metabolism and hence lower biomass production in ecosystems," he said. "This assumption makes sense, as we know from countless experiments that temperature and water control how fast plants can grow. However, when applied to a the scale of entire ecosystems, this assumption appears to not be correct."
To test the assumption on the scale of ecosystems, the team developed a new mathematical theory that assesses the relative importance of several hypothesized drivers of net primary productivity. That theory was then evaluated using a massive new dataset assembled from more than 1,000 different forest locations across the world.
The analysis revealed a new and general mathematical relationship that governs worldwide variation in terrestrial ecosystem net primary productivity. The team found that plant size and plant age control most of the variation in plant productivity, not temperature and precipitation as traditionally thought.
"This general relationship shows that climate doesn't influence productivity by changing the metabolic reaction rates underlying plant growth, but instead by determining how large plants can get and how long they can live for," said Sean Michaletz, lead author of the study and a postdoctoral researcher at the UA Department of Ecology and Evolutionary Biology. "This means that plants in warm, wet environments can grow more because their larger size and longer growing season enable them to capture more resources, not because climate increases the speed of their metabolism."
The finding does not, however, mean that climate is unimportant for plant productivity, the researchers said.
"Climate is still an important factor," said Michaletz, "but our understanding of how it influences ecosystem functioning has now changed."
The team's new findings suggest that mathematical models used for predicting the effects of global climate change can be improved by accounting for the effects of plant size and plant age on net primary productivity.
"Understanding exactly how climate controls net primary production is important for understanding the plant-atmosphere feedbacks that control climate change," said Michaletz.
Enquist said: "In other words, to better predict how ecosystems will change with climate, we need to understand what influences the amount of plant biomass in a given area as well as its age."
The study was funded through an NSF MacroSystems award (1065861), a fellowship from the Aspen Center for Environmental Studies, and through support by the National Natural Science Foundation of China (31170374 and 31370589) and the Fujian Natural Science Fund for Distinguished Young Scholars (2013J06009).
The DOI for the above paper will be10.1038/nature13470. Once the paper is published electronically, the DOI can be used to retrieve the abstract and full text from the Nature website by adding it to the following url: http://dx.doi.org/.
An animated visualization of net primary productivity across the globe is available on NASA's Earth Observatory website: http://eoimages.gsfc.nasa.gov/images/globalmaps/data/mov/MOD17A2_M_PSN.mov
Shelley Littin | University of Arizona
Conservationists are sounding the alarm: parrots much more threatened than assumed
15.09.2017 | Justus-Liebig-Universität Gießen
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
Plants and algae use the enzyme Rubisco to fix carbon dioxide, removing it from the atmosphere and converting it into biomass. Algae have figured out a way to increase the efficiency of carbon fixation. They gather most of their Rubisco into a ball-shaped microcompartment called the pyrenoid, which they flood with a high local concentration of carbon dioxide. A team of scientists at Princeton University, the Carnegie Institution for Science, Stanford University and the Max Plank Institute of Biochemistry have unravelled the mysteries of how the pyrenoid is assembled. These insights can help to engineer crops that remove more carbon dioxide from the atmosphere while producing more food.
A warming planet
Our brains house extremely complex neuronal circuits, whose detailed structures are still largely unknown. This is especially true for the so-called cerebral cortex of mammals, where among other things vision, thoughts or spatial orientation are being computed. Here the rules by which nerve cells are connected to each other are only partly understood. A team of scientists around Moritz Helmstaedter at the Frankfiurt Max Planck Institute for Brain Research and Helene Schmidt (Humboldt University in Berlin) have now discovered a surprisingly precise nerve cell connectivity pattern in the part of the cerebral cortex that is responsible for orienting the individual animal or human in space.
The researchers report online in Nature (Schmidt et al., 2017. Axonal synapse sorting in medial entorhinal cortex, DOI: 10.1038/nature24005) that synapses in...
Whispering gallery mode (WGM) resonators are used to make tiny micro-lasers, sensors, switches, routers and other devices. These tiny structures rely on a...
Using ultrafast flashes of laser and x-ray radiation, scientists at the Max Planck Institute of Quantum Optics (Garching, Germany) took snapshots of the briefest electron motion inside a solid material to date. The electron motion lasted only 750 billionths of the billionth of a second before it fainted, setting a new record of human capability to capture ultrafast processes inside solids!
When x-rays shine onto solid materials or large molecules, an electron is pushed away from its original place near the nucleus of the atom, leaving a hole...
For the first time, physicists have successfully imaged spiral magnetic ordering in a multiferroic material. These materials are considered highly promising candidates for future data storage media. The researchers were able to prove their findings using unique quantum sensors that were developed at Basel University and that can analyze electromagnetic fields on the nanometer scale. The results – obtained by scientists from the University of Basel’s Department of Physics, the Swiss Nanoscience Institute, the University of Montpellier and several laboratories from University Paris-Saclay – were recently published in the journal Nature.
Multiferroics are materials that simultaneously react to electric and magnetic fields. These two properties are rarely found together, and their combined...
19.09.2017 | Event News
12.09.2017 | Event News
06.09.2017 | Event News
22.09.2017 | Life Sciences
22.09.2017 | Medical Engineering
22.09.2017 | Physics and Astronomy