Wissenschaft: Biokrusten schützen vor dem Zahn der Zeit - nicht entfernen!

 

Fotos: scinexx.de

(cnn) Ökologen Ayurella Horn-Muller, Matthew Bowker, Bo Xiao) haben herausgefunden, dass Teile der Chinesischen Mauer durch Erosion gefährdet sind, aber eine ungewöhnliche "lebende Haut" von Organismen, genannt Biokrusten, trägt dazu bei, diese Strukturen zu schützen. Stampflehmteile der Mauer gelten als Schwachstelle, aber eine neue Studie zeigt, dass diese Bereiche eine natürliche Verteidigungslinie gegen Verfall entwickelt haben. Die Bodenoberflächen sind von Biokrusten bedeckt, die aus winzigen wurzellosen Pflanzen und Mikroorganismen bestehen. Diese Biokrusten, bestehend aus Cyanobakterien und Moos, erhöhen tatsächlich die Stabilität der Mauer und verbessern ihre Widerstandsfähigkeit gegen Erosion. Frühere Studien hatten gezeigt, dass ähnliche Biokrusten bei modernen Steinstrukturen Erosion verursachen können, aber bei der Chinesischen Mauer haben sie eine positive Wirkung und sind eine Quelle für das Durchhaltevermögen des Kulturerbes.

25 % der 15-Jährigen hängen OECD-weit bei schulischen Aufgaben durch

Jeder vierte 15-Jährige in der OECD versagt bei leichten Aufgaben, so eine Pisa-Studie. Hilfe für die schwachen und schwächsten Schüler zeige unmittelbare Wirkung auf Gesellschaft und Wirtschaft und sei dringend empfehlenswert.

Die Rechnung ist ganz einfach, die 15-Jährigen werden älter und die wenigsten haben ihre Defizite ausgebügelt. Die 25 % zeigen sich stabil in der deutschen 20-Mio-Gruppe der Schlecht-, Schwach- und Schwächer-Verdiener.

Den gesamten Wortlaut auf Deutsch gibt es zum Beispiel hier:
13 Millionen Jugendliche scheitern an einfachsten Aufgaben

In Englisch:

Helping the weakest students essential for society and the economy, says OECD

Most countries have made little progress helping their weakest students improve their performance in reading, mathematics and science over the past decade. This means too many young people are still leaving school without the basic skills needed in today’s society and workplace, hurting their futures and long-term economic growth, according to a new OECD report.

“Low Performing Students: Why they fall behind and how to help them succeed” says that around 4.5 million 15-year-olds in OECD countries, equivalent to more than one in four, fail to achieve the most basic level of proficiency in reading, mathematics and/or science. In other countries, the share is often much larger. 

Analysing results from the OECD PISA survey between 2003 and 2012 reveals that few countries have seen improvements among low performers and nearly as many have seen their share of low performers increase.  

But countries as economically and culturally diverse as Brazil, Germany, Italy, Mexico, Poland, Portugal, Russian Federation, Tunisia and Turkey reduced their share of low performers in mathematics between 2003 and 2012. This shows that reducing the share of low performers is possible anywhere, given the right policies and the will to implement them, says the OECD.

“The social and economic gains from tackling low performance dwarf any conceivable cost of improvement,” said Andreas Schleicher, OECD Director for Education and Skills. “Education policy and practice can help overcome this issue. It needs to be made a priority and given the necessary resources so that every child can succeed at school.”

Low performers also tend to have less perseverance, motivation and self-confidence in maths, and skip classes or days at school more often than better performers. Students at schools where teachers are more supportive and with higher morale are less likely to be low performers, while students whose teachers have low expectations for them and are absent more often are more likely to be low performers. 

Click here to download data in Excel for all countries

In countries where educational resources are distributed more equitably across schools, there is less incidence of low performance in maths, and a larger share of top performers, even when comparing school systems whose educational resources are of similar quality.

Analysis also shows that the degree to which advantaged and disadvantaged students attend the same school is more strongly related to smaller proportions of low performers than to larger proportions of top performers. This suggests that systems that distribute both educational resources and students more equitably across schools would benefit low performers without undermining better-performing students.

To break the cycle of disengagement and low performance, the report outlines a series of recommendations. These include:

• Identify low performers and design a tailored policy strategy;

• Reduce inequalities in access to early education;

• Provide remedial support as early as possible;

• Encourage the involvement of parents and local communities;

• Provide targeted support to disadvantaged schools or families;

• Offer special programmes for immigrant, minority-language and rural students;