International year of light and international year of soils (soil crusts) 2015

Prospekt Gea, Intresting facts

Photo 1. Detail of overgrown soil crusts at Punta Križa on Cres Island (Photo by Marko Randić)


We recently came across some fine, and unusually diverse, examples of soil crusts while on a field trip on the peninsula of Punta Križa on Cres Island. We found soil crusts along the seashore and in the interior of the peninsula. The ones on the seashore were distinct types, exposed to both direct salination caused by the spraying of sea foam and to eolic salt sediments (deposited by the powerful bora wind). The soil crusts deeper inland have various types of multi-coloured lichens, both crusty and leafy, growing in and on them, as well as certain types of moss, the most abundant of which is a type of yellowish-orange moss. In places the mosses create carpets and are intertwined with other types of crusts and the occasional flowering plant. These specialised organisms receive their distinctive colouring from surface structures of particular optical features and from special natural pigments, in a wide variety of shades and colours, some variegated and some plain. Their job is probably to protect against excessive drying, strong solar radiation, wind gusts and other adverse effects in this extremely “photophilic” and arid habitat. Imagine how many different chemical compounds there are in only a few centimetres of surface soil and how tenacious life is there! Who knows what undiscovered and untapped resources might be lying right beneath our feet in those unsightly and crunchy crusts?

Photo 2. The green tiger beetle (Cicindella campestris) at Punta Križa, Cres Island (photo by Patrik Krstinić)

We found a diverse world of insects and other tiny animals living on the sparse and thin soils covered in crusts, where stones of various sizes and patches of sandy soil protrude from under the crunchy „sheath“. One of the most impressive insects among the beetles is the green tiger beetle, a fast-moving insect, related to the ground beetle. The green tiger beetle tirelessly scrambles among the crusts and rock debris. Its larvae dig holes in the surface of the soil, where they wait to ambush their prey, usually some other type of insect that carelessly comes too close.

Unfortunately, even in this harsh landscape, detached from civilisation, but which we biologists find so fascinating, we have come across examples of humankind’s irresponsible (to say the least) relationship with the millennia-old, inherited assets that soils provide. We use the occasion of the International Year of Soils and the International Year of Light to once again call attention to the immense value and uniqueness of soil crusts, yet another of Nature’s peculiarities and rarities in which our region is so generously blessed.

Categories: Interesting features of nature, Gaea, soil, International Year of Light, International Year of Soils

Key words: soil crusts, Cres Island, green tiger beetle Cicindella campestris, protection of natural assets

Links to related topics posted on the Web pages of PI “Priroda”:

  2. WAXCAPS – rare and threatened fungi of grassland habitats / WAXCAPS (Hygrocybe)

Marko Randić. M.Sc. and Patrik Krstinić, biology professor