Research on the 

Ecosystem Effects of Cryptobiotic Crusts


What Are Cryptobiotic Crusts ?

            Thin biological crusts which cover the ground surface are a common feature of pristine areas in alpine tundra, cold desert shrub-steppe, and high latitude polar ecosystems.  These cryptobiotic crusts (also known as "cryptogamic" or "microbiotic" crusts) vary in thickness from just a few millimeters to more than a few centimeters.  They are composed of varying proportions of lichens, mosses, cyanobacteria, and fungi, depending upon the environment and degree of crust development.  Cryptobiotic crusts reach their greatest development in cold and often seasonally-dry locations where the cover of vascular plants is sparse to moderate.  Complex plant communities of patchy low shrubs, forbs and grasses reside in the cryptobiotic matrix.  The crusts are highly susceptible to damage and destruction from physical disturbance.  For instance, the impact of human tread can compress and dislodge sections of crust, with recovery proceeding very slowly, if it occurs at all.   Despite its fragility and common occurrence in these ecosystems, little is known about the functional importance of these crusts.  We do know a great deal about the composition of crusts in some ecosystems and some of their functional attributes in laboratory settings.  Only recently have a number of functional questions been addressed in the field. How do they affect the development and maintenance of the dominant vascular plants in these areas?  Do they have significant roles in major ecosystem properties such as mineral nutrient and carbon cycling?  What might be the ecosystem significance of substantial disturbance to these crusts?


Publications on Crusts

Gold, WG, Glew KA, and LG Dickson (2001) Functional Influences of Cryptobiotic Surface Crusts in an Alpine Tundra Basin of the Olympic Mountains, Washington, U.S.A. Northwest Science 75(3): 315-326.

Bliss, LC, Gold WG (1999) Seed production, seedling survival and establishment in a High Arctic polar desert. Canadian Journal of Botany 77: 623-636.

Gold WG (1998) The influence of cryptogamic crusts on the thermal environment and temperature relations of plants in a high arctic polar desert, Devon Island, N.W.T., Canada. Arctic &  Alpine Research 30(2): 108-120.

Gold WG, Bliss LC (1995) Water limitations and plant community development in a polar desert. Ecology 76:1558-1568.

Gold WG, Bliss LC (1995) The nature of water limitations for plants in a high arctic polar desert. In: T Callaghan (ed) Global Change and Arctic Terrestrial Ecosystems. Ecosystems Research Report 10. Directorate-General Science, Research and Development; European Commission. pp. 149-155.

Bliss LC, Gold WG (1994) The patterning of plant communities and edaphic factors along a high arctic coastline: implications for succession. Canadian Journal of Botany 72:1095-1107.

Study Sites

Devon Island, N.W.T., Canada

Buckhorn Cirque, Olympic Mountains, Washington