yy having 
al points 
lages can 
| seepage 
The TIR 
r normal 
ter flood 
State of 
11, Delft 
., 2002. 
aused by 
M data. 
8(3), pp. 
Remote 
Dienst, 
ent dam 
nd image 
\R-based 
ersity of 
pal and 
eohazard 
37-78. 
s), 1988. 
efences), 
CUR, 
s), 1991. 
feinema, 
S), 1994. 
IAPRS & SIS, Vol.34, Part 7, “Resource and Environmental Monitoring”, Hyderabad, India, 2002 
A REMOTE SENSING STUDY OF TWO-PHASE INVASION OF THE ALIEN SPECIES 
ACACIA SALIGNA WITHIN COASTAL SAND DUNE HABITATS IN ISRAEL 
Maxim Shoshany 1,3 , Oded Cohen 3 , Pua Kutiel 2 , and Merav Shub 3 
1 Geodetic Engineering Division, Faculty of Civil Engineering , Technion, Israel 
Institute of Technology, Haifa , 32000 Israel, maxim sh@hotmail.com 
  
2 Department of Geography and Environmental Development, Ben-Gurion University 
of the Negev, Beer Sheva 84150, Israel 
3 Environmental Information Laboratory , Bar-Ilan University, Ramat Gan 52900, Israel 
Commission VI/WGVII 
KEYWORDS: Biological Invasion, Coastal Dynamics, Remote Sensing, Air Photographs, GIS 
ABSTRACT: 
The coastal zone of Israel is undergoing major environmental changes as a result of a decrease in sand transport along the shoreline, 
the slowing down of dunes’ migration rate and human disturbance to the natural processes. À significant increase in the Dunes’ 
vegetation cover is partly attributed to these changes, and also related to a massive invasion of mainly Acacia saligna.. Invasion 
models usually distinguish between four stages, however, remote sensing study using historical air- photographs in the study area of 
Nizanim (southern section of the Israeli coastline) indicated the existence of two separate phases of invasion. During the first phase 
the Acacia saligna spreads into disturbed sand areas, and in the second phase it invades into areas already covered by indigenous 
vegetation. 
1. INTRODUCTION 
This research is part of ongoing uncoordinated attempts made 
by various individuals and groups to improve the understanding 
of processes taken place in the coastal zone of Israel and to 
contribute toward better management of resources in this 
environmentally sensitive zone (e.g. Shoshany et al, 1996; 
Barzilay et al., 1998: Kutiel et. Al, 2000). Recent research had 
indicated that there is decrease in the volume of sand 
transported along the coastline (Golik et al., 1997), decrease in 
the rates of volumetric (Arnold, 2002) and planimetric changes 
in the coastal dunes (Barzilay et al., 1998), and a prominent 
increase in their vegetation cover (Cohen, 2002). One of the 
areas of scientific debate concerns the question whether the 
slow down of the sand dunes dynamics is a result or cause of 
this rapid spread of the dunes’ vegetation. 
However, it is widely accepted, that the introduction of the 
Acacia saligna and other plants into the dunes’ area during the 
British Mandate in this region (1921 to 1948) is one of the 
primary reasons for these changes. Despite the importance of 
the environmental changes which had been noticed by many, 
there was no monitoring scheme established and rates and 
modes of ecological modifications taken place were left 
unknown. This reported study had aimed to contribute to the 
understanding of the processes undergoing by mapping land- 
cover and volumetric sand changes using historical air 
photographs based on experience gathered in monitoring coastal 
dynamics (Shoshany et. Al., 2002) and landscape changes in 
semi-natural Mediterranean environments (Shoshany, 2002; 
Shoshany and Goldshlager, 2002). The study area selected for 
this research consist of the Dunes Park of Nizanim located in 
the southern section of the Israeli coastline. This area represent 
various types of human disturbances while having a most 
dynamic sand dunes fields until recent years. 
2. ACACIA SALIGNA INVASION - BIOLOGICAL 
AND HISTORICAL PERSPECTIVE 
The biological invasion phenomenon encompasses all of the 
biogeographic regions of the world and has long-term 
implications, usually negative ones, for the structure and 
functioning of natural ecological systems (e.g., Lowry 1999; 
Goldberg 1999). Coastal dune systems, in particular, have been 
identified as susceptible to invasion (Baker 1986) by virtue of 
their inherent ‘instability’, which necessitated stabilization in 
order to protect infrastructures and agricultural areas using 
plants capable of survival in such conditions. The alien specie 
Acacia saligna is a dense, spreading shrub or single-stemmed 
tree that grows up to nine meters in height. A. saligna grows in 
a wide range of ecological conditions - particularly those 
considered harsh for other plants - barren slopes, sand dunes, 
and abandoned cultivated lands. Thus, it is considered one of 
the best woody species for stabilizing shifting sands. The 
Acacia saligna was brought to Israel as early as the beginning 
of the 20^ century by the British Government and the first 
Jewish settlers. It was brought for afforestation and soil 
conservation purposes on precipitous slopes, and for the 
stabilization of shifting sands for protecting transportation 
arteries, agricultural lands, and residential areas (report of the 
British Department of Agriculture and Forests for the years 
1927-1946). 
3. REMOTE SENSING STUDY 
Historical air photographs were selected for the Nizanim study 
area from those available at the archive of the Israel Mapping 
Center (Former Survey of Israel). The photographs of scale 
between 1:9,000 to 1:18,000 were scanned in high resolution. 
These photographs undergone relative geometric and 
radiometric corrections (Shoshany, 1992 ; Shoshany et al, 1996; 
2002), emphasizing their relative adjustments (Fig. 1). Visual 
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