1956] 
Christiansen — Collembola 
121 
ture of a sufficiently high level to support a more or less 
permanent population. Such refugia occur along the banks 
of rivers, in the moist beds of dry streams, or the edges 
of ponds and lakes. Most commonly they are found around 
the borders of the numerous springs of the mountainous 
regions. In extreme desert regions only a few xerophilic 
species can be found far from the limits of these refugia. 
The swamps or lake shore refugia frequently show an 
impoverishment of collembolan fauna, possibly due to 
their periodic inundation. Almost all of the Lebanese 
and Syrian level arable land is under heavy cultivation. 
Most of the species occurring in such areas are migrants 
or agriculture-tolerant forms. On the whole the fauna in 
this region is impoverished', although an occasional wood 
lot or hedge-row may be quite rich in some forms. 
The lower slopes of the Lebanese Mountains are largely 
covered by small xerophytic brush and a few strands of 
hardy grass. Wherever enough soil and enterprise remain, 
terraces are built and fruit, wheat and other crops are 
grown. A few planted and more or less carefully parked 
pine forests exist in a few regions, especially in southern 
Lebanon. All of these habitats have extremely limited 
collembolan faunas, although a large percentage of in- 
digenous forms occurs. The richest faunas occur in the 
high Lebanese Mountains. These areas were probably 
one time entirely forested, with spruce forests in the 
northern areas, and cedar in the central and southern 
regions. At the present time only four forests of any size 
are left, the remainder of the slopes being kept in a barren 
rocky condition with poor herb grass-low shrub cover- 
ing. The existing forests are: a large spruce forest in 
the Hrlba region of northern Lebanon; the Hadeth, Ain 
Zahlte, and Barouk cedar forests in central and southern 
Lebanon. All of these forests are growing on limestone 
substrates mostly on or near mountain peaks. The forest 
soil consists generally of a thin layer of duff, beneath 
which is a shallow black or gray humus. Below this layer 
limestone appears, frequently as bedrock. The forests tend 
to be open, with undergrowth limited to the edges and 
cleared central valleys. The spruce forest was largely cut 
