Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

The Fall And Rise Of Forest Ecosystems

23.07.2004


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.



These results have several implications. First they show that major disturbances are necessary for rejuvenating forest ecosystems. Disturbances which rejuvenate the system vary for different forests, but can include for example wildfire, glaciation, or volcanic activity. In the absences of these disturbances productive forests do not perpetuate indefinitely; eventually phosphorous becomes sufficiently limiting that forests with a high standing biomass can no longer be maintained. Second, they reveal that high biomass forest stands represent a transitional phase in the long term (in the order of thousands to tens of thousands of years) and if left without major disturbances will then decline. Finally they show that very similar patterns of decline, and mechanisms behind this decline, occur for very different types of forest throughout the world, spanning the boreal, temperate and tropical climatic zones.

The study was conducted by David Wardle from the Swedish University of Agricultural Sciences (Sweden) and Landcare Research (New Zealand), Richard Bardgett from Lancaster University (U.K.) and Lawrence Walker from the University of Nevada (USA).

Becky Allen | alfa
Further information:
http://www.britishecologicalsociety.org

More articles from Ecology, The Environment and Conservation:

nachricht Bioinvasion on the rise
15.02.2017 | Universität Konstanz

nachricht Litter Levels in the Depths of the Arctic are On the Rise
10.02.2017 | Alfred-Wegener-Institut, Helmholtz-Zentrum für Polar- und Meeresforschung

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Breakthrough with a chain of gold atoms

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

In the field of nanoscience, an international team of physicists with participants from Konstanz has achieved a breakthrough in understanding heat transport

Im Focus: DNA repair: a new letter in the cell alphabet

Results reveal how discoveries may be hidden in scientific “blind spots”

Cells need to repair damaged DNA in our genes to prevent the development of cancer and other diseases. Our cells therefore activate and send “repair-proteins”...

Im Focus: Dresdner scientists print tomorrow’s world

The Fraunhofer IWS Dresden and Technische Universität Dresden inaugurated their jointly operated Center for Additive Manufacturing Dresden (AMCD) with a festive ceremony on February 7, 2017. Scientists from various disciplines perform research on materials, additive manufacturing processes and innovative technologies, which build up components in a layer by layer process. This technology opens up new horizons for component design and combinations of functions. For example during fabrication, electrical conductors and sensors are already able to be additively manufactured into components. They provide information about stress conditions of a product during operation.

The 3D-printing technology, or additive manufacturing as it is often called, has long made the step out of scientific research laboratories into industrial...

Im Focus: Mimicking nature's cellular architectures via 3-D printing

Research offers new level of control over the structure of 3-D printed materials

Nature does amazing things with limited design materials. Grass, for example, can support its own weight, resist strong wind loads, and recover after being...

Im Focus: Three Magnetic States for Each Hole

Nanometer-scale magnetic perforated grids could create new possibilities for computing. Together with international colleagues, scientists from the Helmholtz Zentrum Dresden-Rossendorf (HZDR) have shown how a cobalt grid can be reliably programmed at room temperature. In addition they discovered that for every hole ("antidot") three magnetic states can be configured. The results have been published in the journal "Scientific Reports".

Physicist Dr. Rantej Bali from the HZDR, together with scientists from Singapore and Australia, designed a special grid structure in a thin layer of cobalt in...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Booth and panel discussion – The Lindau Nobel Laureate Meetings at the AAAS 2017 Annual Meeting

13.02.2017 | Event News

Complex Loading versus Hidden Reserves

10.02.2017 | Event News

International Conference on Crystal Growth in Freiburg

09.02.2017 | Event News

 
Latest News

Biocompatible 3-D tracking system has potential to improve robot-assisted surgery

17.02.2017 | Medical Engineering

Real-time MRI analysis powered by supercomputers

17.02.2017 | Medical Engineering

Antibiotic effective against drug-resistant bacteria in pediatric skin infections

17.02.2017 | Health and Medicine

VideoLinks
B2B-VideoLinks
More VideoLinks >>>