Forest ecologists have long wondered why forests decline in the absence of catastrophic disturbances. A new study, in part funded by the British Ecological Society, and published in this week’s Science, has shed new light on this problem.
This study investigated natural forested stands across each of six ’chronosequences’ or sequences of soils of different ages since the most recent major disturbance. These sequences were located in a range of climatic zones, including northern Sweden (a series of forested islands near Arjeplog), Alaska, Hawaii, eastern Australia and two locations in southern New Zealand. All sequences consisted of forest stands on soils ranging in age from those formed very recently to those at least several thousand years old; the oldest soils studied were 4.1 million years old in Hawaii.
For all six sequences, forest biomass (mass of trees per unit area) increased initially as soil fertility increased. However, after thousands to tens of thousands of years, forest biomass declined sharply for all sequences, to a level where some sites could no longer support trees. The researchers found that this decline in all cases was due to reduced levels of plant-available phosphorus relative to nitrogen in the soil. As soils age, phosphorus becomes increasingly limiting for trees because it is not biologically renewable in the ecosystem. Conversely, nitrogen is biologically renewable (because atmospheric nitrogen can be converted by soil bacteria into forms of nitrogen that trees can use), so nitrogen limitation does not contribute to forest decline in these systems, contrary to popular views. There was also evidence from this study that phosphorous limitation during stage of forest decline negatively affected soil organisms, and therefore reduced their potential to release nutrients from the soil for maintaining tree growth.
Becky Allen | alfa
Litter is present throughout the world’s oceans: 1,220 species affected
27.03.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung
International network connects experimental research in European waters
21.03.2017 | Leibniz-Institut für Gewässerökologie und Binnenfischerei (IGB)
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
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