Many types of vegetation have more or less ground cover and recruitment of new individuals often occurs only in temporarily empty patches or gaps. Ever since Watt’s (1947) Presidential address to the BES, the Journal of Ecology has been publishing the results of investigations into the importance of processes in such gaps in the determination of community structure. Three recent papers from Norway, the UK and the USA (Vandvik 2004, Turnbull et al. 2004 and Ewanchuk and Bertness, 2004, respectively - all in volume 92, issue 1), report different approaches to addressing this issue.
Working in salt marches in New England, USA, Ewanchuk and Bertness show that the recolonisation of gaps generated by ice scour is slow and driven by competitive processes. Parts of these marshes consist of patches of sparse, but species-rich, vegetation dominated by non-grassy herbaceous plants (forbs). These areas were found to be inhospitable to plants which grew well nearby, suggesting physical limitation at the local scale, while the forbs were restricted to these patches by interspecific competition.
Vandvik showed that revegetation of gaps in subalpine grassland in Norway depended upon gap size and grassland age along a gradient of secondary succession. The degree to which individual species depended on gaps for regeneration changed as the disturbance regime altered during succession, with such gap phase processes being important for a majority (74%) of species in the system. Taking a more mechanistic and small-scale approach, Turnbull et al. also found that most species of annuals in a limestone grassland showed a preference for colonizing unvegetated patches. Through a series of exacting and careful measurements of individual plants and neighbourhood modeling they derived individual-level competition coefficients for seven annuals. Seed size was found to be a key trait determining both competitive and colonizing ability.
Becky Allen | alfa
A new indicator for marine ecosystem changes: the diatom/dinoflagellate index
21.08.2017 | Leibniz-Institut für Ostseeforschung Warnemünde
Value from wastewater
16.08.2017 | Hochschule Landshut
Whether you call it effervescent, fizzy, or sparkling, carbonated water is making a comeback as a beverage. Aside from quenching thirst, researchers at the University of Illinois at Urbana-Champaign have discovered a new use for these "bubbly" concoctions that will have major impact on the manufacturer of the world's thinnest, flattest, and one most useful materials -- graphene.
As graphene's popularity grows as an advanced "wonder" material, the speed and quality at which it can be manufactured will be paramount. With that in mind,...
Physicists at the University of Bonn have managed to create optical hollows and more complex patterns into which the light of a Bose-Einstein condensate flows. The creation of such highly low-loss structures for light is a prerequisite for complex light circuits, such as for quantum information processing for a new generation of computers. The researchers are now presenting their results in the journal Nature Photonics.
Light particles (photons) occur as tiny, indivisible portions. Many thousands of these light portions can be merged to form a single super-photon if they are...
For the first time, scientists have shown that circular RNA is linked to brain function. When a RNA molecule called Cdr1as was deleted from the genome of mice, the animals had problems filtering out unnecessary information – like patients suffering from neuropsychiatric disorders.
While hundreds of circular RNAs (circRNAs) are abundant in mammalian brains, one big question has remained unanswered: What are they actually good for? In the...
An experimental small satellite has successfully collected and delivered data on a key measurement for predicting changes in Earth's climate.
The Radiometer Assessment using Vertically Aligned Nanotubes (RAVAN) CubeSat was launched into low-Earth orbit on Nov. 11, 2016, in order to test new...
A study led by scientists of the Max Planck Institute for the Structure and Dynamics of Matter (MPSD) at the Center for Free-Electron Laser Science in Hamburg presents evidence of the coexistence of superconductivity and “charge-density-waves” in compounds of the poorly-studied family of bismuthates. This observation opens up new perspectives for a deeper understanding of the phenomenon of high-temperature superconductivity, a topic which is at the core of condensed matter research since more than 30 years. The paper by Nicoletti et al has been published in the PNAS.
Since the beginning of the 20th century, superconductivity had been observed in some metals at temperatures only a few degrees above the absolute zero (minus...
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