ometer was used 
les of each of the 
' was specifically 
ls that correspond 
dicated in Table 7. 
d with TM from 
> 
iD 
; 
  
NIR | NR 
(middle) |(high) 
  
840 nm R90 nm 
  
  
  
  
e from Landsat in 
indsat would have 
) that of a Landsat 
rea with the 
rdaan, 2011) 
es for all four the 
Ocess, two images 
in Figure 9. Note 
mass) in the later 
r lying Marakele 
actly with the area 
tion type (Mucina 
vonden February 2005 
  
  
  
d 2005. 
ne using a change 
' the newer image 
compared to the 
  
corresponding pixels in the old image (before elephant impact 
image = 1995). The comparison is based on a 25% change in 
the NDVI value per pixel and if the was a change of more than 
25% the relevant pixel is green (if there was an increase) and 
red (if there was a decrease). 
À similar process was done on the digital numbers of the 
spectral bands of the satellite images directly (Landsat bands 2, 
3 and 4 were used) and again if a change of more than 25% was 
detected per corresponding pixel, it was coloured green for an 
upwards increase in value and red if the was a decrease. Figure 
10 shows the changes detected using Landsat band 4 as NIR 
was found to be the most predominant indicator of vegetation. 
Figure 10 illustrates the changes detected (25% or more per 
pixel) when the two NDVI images were compared and also 
when the two satellite images using spectral band 4 were 
compared. 
Change 1995-2005 using NDVI 
  
(Change 1995-2005 using spectral signatures 
  
  
  
  
  
  
Legend Scale 
  
Kilormeters 
Class_Names 
Fa Decreased 
  
Increased 
  
  
  
Figure 10: Changes by NDVI versus Changes by reflectance 
value 
Marakele National Park does not show much change with 
exception to some uniform black areas (figure 9) that may 
indicate fire events rather than a decrease in vegetation. 
Welgevonden, Tembe and Ithala also indicated patches of 
darker area but these are not likely to be fire related as it is not 
uniform. These darker areas are suspected to be caused by 
elephant browsing. Overall the later image (figure 9) appears 
lighter which would indicate an increase in vegetation over the 
area rather than a decrease. Rainfall data indicated both years to 
have been relatively dry but the preceding year has been a 
relatively wet year for Welgevonden. As commonly understood 
NDVI is used indicator of biomass and of vegetation production 
which is directly linked to rainfall, so the rainfall figures for the 
areas surrounding the four reserves were scrutinized to 
determine possible NDVI increases. 
5 DISCUSSION 
Wessels et al. (1999) indicates that the relationship between 
remotely sensed measures of landscape and biological diversity 
15 valuable in terms of biodiversity assessments and is 
beginning to be used as an important tool in integrated 
approaches to biodiversity assessment and conservation. The 
use of remote sensing has been found to be a successful method 
of determining vegetation change over time while also 
providing reliable information on vegetation composition (Liu 
et dl, , 2008, Brink & Eva, 2008 and 2005 Akasheh et al.). 
However the results from this study initially appear 
inconclusive. The change detection image generated suggests 
that the vegetation in Welgevonden has decreased over a ten 
year period, but there has been little change in Marakele. 
Change detection for Tembe indicates changes in the Coastal 
bushveld and shrubveld but very little in the threatened ‘Sand 
Forest’. Ithala however has had severe changes but this can be 
contributed to their dedicated fire regime (Bigwood, T. personal 
communication, December 04, 2010) 
A similar study done by Guldemond & Van Aarde (2007) who 
conducted a study looking at what they classified ‘Woodlands’ 
(basically ‘Tembe Sandy Bushveld’ and ‘Sand Forest’) 
comparing these woodlands inside ‘Tembe Elephant Park’ and 
at intact vegetation communities outside the Park. Three 
representative sampling sites were selected inside and outside 
the Park where quadrants (16*16 m) were used to record the 
number, species and structure of vegetation. Their study 
concluded that the elephants in Tembe Elephant Park fed on 
seven main species (Acacia burkei, Afzelia quanzensis, Albizia 
adianthifolia, | Dialium schlechteri, Maniklara discolour, 
Sapium integerrimum and Spirostachys africanum). These 
species occur at low numbers within the Sand Forest and are 
more common in ‘Tembe Sandy Bushveld’. Using remote 
sensing alone as instrument to determine elephant impact can 
also be misleading in that at Tembe the elephant do not impact 
severely on the endangered Sand Forest but they do create 
openings for the smaller antelopes such as Nyala (Nyala angasi) 
and Kudu (Tragelaphus strepsiceros). (Mathews, W. personal 
communication, April 2009). These antelopes then destroy the 
undergrowth and lower branches but not the larger trees and tree 
canopy. Therefore there is little immediate change to the 
vegetation but in the long run there is no succession as al the 
seedlings have been foraged by the antelopes. 
This study indicates (1) the value of NDVI variability as an 
indicator of landscape heterogeneity and biological diversity, 
and (2) the potential of integrating vegetation data from 
vegetation maps with the NDVI information to indicate 
landscape patterns of biological diversity. 
At an annual increase of 7% the populations in the four reserves 
would have a density of +2.15 elephants per km?. This would 
lead to huge losses in biomass and likely diversity as well, as 
shown in Sengwa Wildlife Research Area where there was a 
reduction of 45% in biomass of woodland species over a five 
year period (Cumming 1981) when the elephant population 
density was at a similar level to what the population could be in 
the four reserves by 2020, if the elephant population grows at 
7% per annum. 
Management of the four reserves used in the study, in particular 
but all reserves conserving elephants, will need to decide 
whether they want to manage according to biodiversity or 
whether they want to manage to the elephants needs. Various 
management actions could include culling, contraception of 
female elephants or possible vasectomies of elephant bulls (this 
has been done successfully at Welgevonden Private Nature 
Reserve). 
6 REFERENCES 
Akasheh, O.Z., Neale, C.M.U. and Jayanthi, H., 2008. Detailed 
Mapping of Riparian Vegetation in the Middle Rio Grande 
River using High Resolution Multi-Spectral Airbourne Remote 
Sensing. Journal of Arid Environments, 72, 1734-1744. 
Bigwood, T. 2010. Personal communication, 04 December 
2010,