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StillnessDryland ecology fact

Biological soil crusts are living communities of cyanobacteria, lichens, fungi, mosses and algae that bind dryland soil and influence water and nutrient cycles.

Biological soil crust

NatureBiologyClimateScience

The story behind the card

Scientists often call these crusts biocrusts. The cyanobacterium Microcoleus vaginatus is usually among the first to settle: its sticky filaments glue sand grains together and prepare the ground for the lichens, mosses and algae that follow. Some crust organisms also fix nitrogen, taking it from the air and turning it into a form plants can use, which matters in poor desert soils. Growth is slow in dry ground, so a crushed crust can take years to regain its first layer and decades or even centuries to rebuild fully. In US national parks on the Colorado Plateau, such as Arches and Canyonlands, signs ask visitors to stay on the trails with the slogan 'Don't bust the crust'.

Türkçe oku
Biyolojik toprak kabukları siyanobakteri, liken, mantar, kara yosunu ve alglerin oluşturduğu canlı topluluklardır. Kurak bölgelerde toprağı bir arada tutar, suyun ve besinlerin döngüsünü etkilerler.

Bilim insanları bu kabuklara kısaca “biyokabuk” der. İlk yerleşenler arasında genellikle Microcoleus vaginatus adlı siyanobakteri bulunur: yapışkan iplikleri kum tanelerini birbirine bağlar, ardından gelecek liken, kara yosunu ve alglere zemin hazırlar. Kabuktaki bazı canlılar havadaki azotu bitkilerin kullanabileceği bir biçime de çevirir; çölün yoksul topraklarında bu büyük fark yaratır. Kurak toprakta her şey yavaş büyüdüğü için ezilen bir kabuğun ilk katmanı ancak yıllar içinde, tamamı ise on yıllarda, hatta yüzyıllarda yeniden oluşur. ABD'nin Colorado Platosu'ndaki Arches ve Canyonlands gibi millî parklarda tabelalar, ziyaretçilerden kabuğu ezmemek için patikadan çıkmamalarını ister.

Sources and further reading

Background reading: Biological soil crust
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