Walia Special Edition on the Bale Mountains (2011) - Zoologische ...

Discussion
Although fire can have positive impacts on ecosystems, when unmanaged or overexploited it can
have negative effects on the environment such as increasing soil erosion (Pardini et al. 2004) or
altering species composition (Levine et. al. 1999) Ethiopia has lost 87.5% of its forest within the
past century, the majority of which is as a result of wild fire (MOA 2000). Bale Mountains National
Park is a park which is frequently burnt, often to a great extent. This has led to identifying the
development of a fire management plan for the park as a key objective in the ecological management
programme of the parks GMP (OARDB 2007). As a first step in developing this fire management
plan, understanding factors influencing the occurrence of fire, and identifying fire hotspots within
the park is important. This study applied GIS and Remote Sensing Technologies to map the extent
and frequency and the possible influencing factors of fire in the park.
Between 1999-2008 a total of 142 fires burning 38,150 ha occurred in the park. The general
trend shows that large fires are generally succeeded by low fire incidence, however in more recent
years it can be seen that the number of fires is increasing continuously, with few seasons where few
fires occur preventing the area from recuperating. A continuous pattern of burning with no chance
for recovery and especially with the increased grazing (FZS unpublished data) can have detrimental
effects on vegetation. Dry seasons (January-March) account for 63.3% of fires through out the
period, with highest number of fires and burned area occurring in March and January.
The highest number of fires occurred in woodland, montane forest and Erica shrub,
respectively, however a greater extent was burnt in montane forest and Erica shrub than in woodland
habitat type. Interestingly despite the high number and large extent of fires occurring in woodland
and montane forest, woodland vegetation type is burnt as expected given its total area but lower
than expected for montane forest. Erica shrub however has been burnt more than expected given
its available area in the park. This suggests that people are showing a preference for burning Erica
vegetation type over other vegetation types in the park and perhaps an avoidance of burning in
montane forest. A recent study identified that a primary reason for burning Erica was for the purpose
of facilitating grazing (Belayneh and Yohanis 2008).
Proportionally, woodland (125.7%) followed by Erica shrub (34.3%) and grassland (24.8%)
have the total area burnt given their actual area available in 2000. Whereas this proportion has
changed to 26.5%, 31.1%, and 14.3% respectively, given their respective area in 2008. The drastic
increase in the size of woodland (hence decrease in proportion of burnt area) could be attributed to
increasing trend of new clearings for agriculture in the montane forest.
It is not surprising that Chromic Luvisols and Pellic vertisols are shown to be the dominant
soil types burnt both in number and frequency, since they are the dominant soil types for Erica
shrub and montane forest, respectively. From these it is only Chromic Luvisols that are shown
to be generally burnt more than expected given their available area. Again confirming a distinct
preference for burning in areas where Erica shrub occurs.
The highest attitudinal belt was shown to have the most and greatest extent of fires occurring
(35001-4300 m a.s.l.). However, none of the altitudinal belts appeared to be burnt more frequently
<strong>Walia</strong>-<strong>Special</strong> <strong>Edition</strong> on the Bale Mountains 154