desertification was, however, often rather disappointing, e.g. at the Fourth and Fifth
Conferences of the Parties to the Convention to Combat Desertification (CCD-COP4
[held in Bonn] and CCD-COP5 [held in Geneva]). So, such political activities lasted
only a few years. Then the European Desert☼Net was founded elsewhere, but it
seems now just to be one among many other not especially creative or innovative
organizations. Scientific desert ecology is more attractive and an important background for applications.
5.1 Negev (Nizzana Sand Dunes)
How do plants survive in deserts? Water availability is reduced in all deserts, but
there are many different types of deserts, and generalizations are often misleading.
Several projects concerning desert ecology were undertaken. The Namib was studied
only randomly [three diploma theses (Veste and Mohr 2005)].
The Atacama had been visited during a 3-month stay in Chile, including study of
several salares (salt flats) and halophytic sites, and checking of salinity gradients;
however, before the return to Germany, all material, notes and samples – about
30 coloured films from all vegetation types between Arica and Chiloe – were lost
after being stolen in Santiago just in front of the university library. It happens.
Certainly it was not as tragic as the loss of Alfred Russel Wallace’s collection. He
was in Amazonia, charting the Rio Negro for 4 years, collecting specimens and
making notes on the peoples and languages he encountered, as well as the geography,
flora and fauna. The ship’s cargo caught fire, and the crew was forced to abandon the
ship in August 1852 on the Atlantic Ocean. All of the specimens Wallace had on the
ship, mostly collected during the last two – and most interesting – years of his trip,
were lost. He managed to save a few notes and pencil sketches, and little else (Raby
2002, note by Lüttge).
The special longitudinal sand dune system of the western Negev, near Nizzana,
was studied by a large joint project (Fig. 20b). The area is characterized by an arid
typical desert climate with rather strong variability from year to year (Fig. 21). A
synthesis of all studied topics was given by Breckle et al. (2008). Those longitudinal
dunes were an ideal study system. The very regular ecotopic mosaic of dunes is
characterized by the formation of a microbiotic crust (Fig. 22a) (Veste and Breckle
2003; Littmann and Veste 2005; Veste et al. 2011) despite the very arid climate.
Within a few years, even on mobile sand (totally protected by the military close to
the Egyptian border), it has a rather thick, strong appearance. This organic crust of
cyanobacteria, lichens and mosses (Fig. 22b) greatly reduces the infiltration of the
scarce rains in winter (Fig. 21) and results in a new pattern of water availability and a
vegetation mosaic on formerly mobile sand dunes. This mosaic strongly influences
the establishment of seed plants and is also a source of atmospheric nitrogen binding
(Russow et al. 2008). The thickness and chlorophyll content along the gradient are
shown in Fig. 23. Crust development strongly depends on the water regime, but dew
and fog often are the main water sources. Here, just 20–25 fogs per year is one water
Vegetation, Climate and Soil: 50 Years of Global Ecology
21
Conferences of the Parties to the Convention to Combat Desertification (CCD-COP4
[held in Bonn] and CCD-COP5 [held in Geneva]). So, such political activities lasted
only a few years. Then the European Desert☼Net was founded elsewhere, but it
seems now just to be one among many other not especially creative or innovative
organizations. Scientific desert ecology is more attractive and an important background for applications.
5.1 Negev (Nizzana Sand Dunes)
How do plants survive in deserts? Water availability is reduced in all deserts, but
there are many different types of deserts, and generalizations are often misleading.
Several projects concerning desert ecology were undertaken. The Namib was studied
only randomly [three diploma theses (Veste and Mohr 2005)].
The Atacama had been visited during a 3-month stay in Chile, including study of
several salares (salt flats) and halophytic sites, and checking of salinity gradients;
however, before the return to Germany, all material, notes and samples – about
30 coloured films from all vegetation types between Arica and Chiloe – were lost
after being stolen in Santiago just in front of the university library. It happens.
Certainly it was not as tragic as the loss of Alfred Russel Wallace’s collection. He
was in Amazonia, charting the Rio Negro for 4 years, collecting specimens and
making notes on the peoples and languages he encountered, as well as the geography,
flora and fauna. The ship’s cargo caught fire, and the crew was forced to abandon the
ship in August 1852 on the Atlantic Ocean. All of the specimens Wallace had on the
ship, mostly collected during the last two – and most interesting – years of his trip,
were lost. He managed to save a few notes and pencil sketches, and little else (Raby
2002, note by Lüttge).
The special longitudinal sand dune system of the western Negev, near Nizzana,
was studied by a large joint project (Fig. 20b). The area is characterized by an arid
typical desert climate with rather strong variability from year to year (Fig. 21). A
synthesis of all studied topics was given by Breckle et al. (2008). Those longitudinal
dunes were an ideal study system. The very regular ecotopic mosaic of dunes is
characterized by the formation of a microbiotic crust (Fig. 22a) (Veste and Breckle
2003; Littmann and Veste 2005; Veste et al. 2011) despite the very arid climate.
Within a few years, even on mobile sand (totally protected by the military close to
the Egyptian border), it has a rather thick, strong appearance. This organic crust of
cyanobacteria, lichens and mosses (Fig. 22b) greatly reduces the infiltration of the
scarce rains in winter (Fig. 21) and results in a new pattern of water availability and a
vegetation mosaic on formerly mobile sand dunes. This mosaic strongly influences
the establishment of seed plants and is also a source of atmospheric nitrogen binding
(Russow et al. 2008). The thickness and chlorophyll content along the gradient are
shown in Fig. 23. Crust development strongly depends on the water regime, but dew
and fog often are the main water sources. Here, just 20–25 fogs per year is one water
Vegetation, Climate and Soil: 50 Years of Global Ecology
21