IV. DESERT ALGAE, LICHENS, AND FUNGI
203
seemed to be no distinct differences between floras of different rock types
or geographic areas.
B. ECOLOGY OF DESERT ALGAE
Friedmann (1972) discussed the ecology of endolithic and chasmolithic
algal habitats. Field measurements in the Sonoran Desert of Mexico
demonstrated the extreme microclimate of the rock surface. In granite
with chasmolithic algal growth, the temperature of the rock at the surface
and at a depth of 2 cm below the surface and the temperature and relative
humidity of the air close to the surface and 1 meter above the rock were
monitored over a period of 24 hours.
Cameron (1971) and Horowitz, Cameron, and Hubbard (1972) discuss the microbial ecology of Antarctic deserts and offer data relevant to
soil algae, fungi, and lichens in cold deserts.
Novichkova-Ivanova (1972) gives interesting data about soil algae in
Central Asian deserts. The number of taxa (species and forms) of soil
algae in the arid regions of the U.S.S.R. is more than 400. There are 147
algal taxa known from the takyrs and only 30 from sand deserts. In the
Kakakum sand desert, the number of algal cells in soil was found to be
correlated with soil moisture content. According to earlier measurements
quoted by Novichkova-Ivanova, the dry organic matter formed by algae
in Southwestern Turkmenian takyrs amounts from 0.5 t to 1.4 t/ha (50
gm — 140 gm/m
2
) or more.
The biomass of endolithic and chasmolithic algae in Middle Eastern and
North American desert rocks was estimated from chlorophyll fluorescence
as between 2.1 gm and 62.0 gm dry weight/m
2
rock surface while total
organic matter, based on N analysis, ranged from 20.5 to 207.4 gm dry
weight/m
2
(E. I. Friedmann and R. C. Ocampo, unpublished).
C. FLORISTICS AND ECOLOGY OF DESERT LICHENS
Garty (1972) and Galun and Garty (1972) report 51 lichen species
from the North and Central Sinai Desert. The species composition of the
main habitats are described and the ecology of the lichen-substrate relationship is discussed.
Lange and Evenari (1971) found that the annual growth rate of Caloplaca awram/tf(Pers.)Hellb. in the Negev Desert was within the range
of other crustose lichens living in nondesert climates.
ACKNOWLEDGMENT
This work was supported, in part, by Grant No. GB-27521 from the National
Science Foundation to E. I. Friedmann.
203
seemed to be no distinct differences between floras of different rock types
or geographic areas.
B. ECOLOGY OF DESERT ALGAE
Friedmann (1972) discussed the ecology of endolithic and chasmolithic
algal habitats. Field measurements in the Sonoran Desert of Mexico
demonstrated the extreme microclimate of the rock surface. In granite
with chasmolithic algal growth, the temperature of the rock at the surface
and at a depth of 2 cm below the surface and the temperature and relative
humidity of the air close to the surface and 1 meter above the rock were
monitored over a period of 24 hours.
Cameron (1971) and Horowitz, Cameron, and Hubbard (1972) discuss the microbial ecology of Antarctic deserts and offer data relevant to
soil algae, fungi, and lichens in cold deserts.
Novichkova-Ivanova (1972) gives interesting data about soil algae in
Central Asian deserts. The number of taxa (species and forms) of soil
algae in the arid regions of the U.S.S.R. is more than 400. There are 147
algal taxa known from the takyrs and only 30 from sand deserts. In the
Kakakum sand desert, the number of algal cells in soil was found to be
correlated with soil moisture content. According to earlier measurements
quoted by Novichkova-Ivanova, the dry organic matter formed by algae
in Southwestern Turkmenian takyrs amounts from 0.5 t to 1.4 t/ha (50
gm — 140 gm/m
2
) or more.
The biomass of endolithic and chasmolithic algae in Middle Eastern and
North American desert rocks was estimated from chlorophyll fluorescence
as between 2.1 gm and 62.0 gm dry weight/m
2
rock surface while total
organic matter, based on N analysis, ranged from 20.5 to 207.4 gm dry
weight/m
2
(E. I. Friedmann and R. C. Ocampo, unpublished).
C. FLORISTICS AND ECOLOGY OF DESERT LICHENS
Garty (1972) and Galun and Garty (1972) report 51 lichen species
from the North and Central Sinai Desert. The species composition of the
main habitats are described and the ecology of the lichen-substrate relationship is discussed.
Lange and Evenari (1971) found that the annual growth rate of Caloplaca awram/tf(Pers.)Hellb. in the Negev Desert was within the range
of other crustose lichens living in nondesert climates.
ACKNOWLEDGMENT
This work was supported, in part, by Grant No. GB-27521 from the National
Science Foundation to E. I. Friedmann.