Biotic interactions as a structuring force in soil communities: evidence from the micro-arthropods of an Antarctic moss model system

first_imgCurrent meta-community theories postulate that the structure of local communities depends on dispersal, environmental filtering, and biotic interactions. However, disentangling the relative effects of these factors in the field and for diverse assemblages is a major challenge. A solution is to address natural but simple communities (i.e. with low numbers of species in few trophic levels), wherein one of these factors is predominant. Here, we analyse the micro-arthropod community of a moss-turf habitat typical of the Antarctic Peninsula region, and test the widely accepted hypothesis that this system is abiotically driven. In the austral summers 2006/7 and 2007/8, we sampled nearly 80 units of moss from four islands in the Argentine Islands. Using variance partitioning, we quantified the relative contribution of: (1) multiple scale spatio-temporal autocorrelation; (2) environmental effects; (3) the island effect. Little variance (1 %) was accounted for by sources 1 (1 %, significant) and 2 (<1 %, not significant). The island effect significantly accounted for the largest amount of variation (8 %). There was a relatively large effect of spatially structured environmental variation (7 %). Null models demonstrated that species co-occurred less frequently than expected by chance, suggesting the prevalence of negative interactions. Our data support the novel hypothesis that negative biotic interactions are the most important structuring force of this micro-arthropod community. The analysed system is a good proxy for more complex communities in terms of taxonomic composition and the functional groups present. Thus, biotic interaction might be a predominant factor in soil meta-community dynamics.last_img read more

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Bakery chains line up to bag Ainsleys shops

There has been an “encouraging show of interest” in Ainsleys of Leeds, after the business was forced to call in the adminis-trators earlier this month, with Greggs and Cooplands (Doncaster) among the interested parties.Joint administrator Joe McLean, a partner at Grant Thornton in Leeds, told British Baker the business was “running as normal”. He said it had been an encouraging week, and that staff in Ainsleys’ bakery and shops had taken the news with great resilience, despite hundreds of jobs being at risk. “We are in discussions with some parties… it’s still early, but we are hopeful we might find a buyer.”Greggs said it would be “very interested” in looking at a number of Ainsleys shops. “We could offer a future to somewhere in the region of one in three Ainsleys shops, if the administrators would consider those coming over to Greggs,” said chief executive Ken McMeikan. “Our sadness at the moment is to see other another baker in trouble. We want to see the bakery industry thriving.” Chris Peck, chairman of Cooplands, confirmed that the 75-strong bakery chain was also interested in Ainsleys, but said that it was “early days” in terms of a deal. “Ainsleys has a good name and, geographically, it is within our logistical capabilities, so it would be relatively painless to absorb the company.”The 29-shop firm went into administration on Friday 6 November, after earlier attempts to find a buyer failed. McLean said Ainsleys had been trading in difficult circumstances for some time, with declining retail sales and increased market competition.Ainsleys employs 263 full- and part-time staff, and around 30 temporary workers, across its shops and bakery in Sheepscar, Leeds, and in its van sales operation. General manager James Ainsley said that, along with the Ainsley family and company directors, he wished to acknowledge the hard work and loyalty of the staff, “particularly through the recent challenging times”. read more

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