Patch-Mosaic Burn in Etosha National Park

Prepared By: Mr. Marthin K. Kasaona
Conservation Scientist [Etosha National Park]
Namibia National Focal Point for Fire [AMESD]
Ministry of Environment and Tourism

(Etosha National Park is a beneficiary of the AMESD SADC Fire Receiving Station)

 
Patch-Mosaic Burn in Etosha National Park (05-15 June 2012)

Introduction

Africa is regarded as the fire continent due to the role fire plays in shaping the savanna landscape. Fire management practices within conservation areas have been hotly debated for many decades. Conservation managers realize the importance and necessity of fire as a management tool in conservation areas. There are numerous practical fire management methods available to managers which necessitates ongoing research on a learning-while doing operating principle.

Patch-Mosaic Burning - Etosha, Namibia

Patch-Mosaic Burning - Etosha, Namibia

In Etosha, the present fire management practice of suppressing all fires is ineffective. Most of the fires occur during the hot, dry months which lead to large areas being burnt by homogenous and intensely hot fires which are detrimental to the vegetation of Etosha in the long-term. This called for a re-evaluation of the application of this burning management practice in Etosha.

The Mission statement for Etosha includes “ideals” such as “the maintenance of biodiversity”. On the basis of this objective, a new approach to using fire as a tool for management purposes in Etosha was adopted in this trial period.

This trial was based on the latest approaches adopted by large conservation areas in Africa. The approach is based on producing a flexible and variable fire regime with different intensities across several months which depending on rainfall, could start in April and end in August. The extent of areas burnt would vary widely, allowing for a patch-mosaic burn pattern with different intensities over different areas and under different conditions. It is expected that such a policy will:

  • result in the maintenance of biodiversity
  • provide a practical solution to the occurrence of wildfires in the hot, dry season by breaking up the fuel load;
  • allow lightning fires to occur naturally

This trial was intended to implement the patch-mosaic burn approach in Etosha, gauge its effectiveness and adapt implement a burning strategy suitable to the needs of Etosha.

Fire zones

Etosha Fire Zones

Fig 1: Etosha Fire Zones

Etosha has now been subdivided into 7 fire zones which replace the previously used 26 fire blocks. The zones are demarcated mainly on soil and vegetation characteristics. Additionally, each zone is accessible through a network of roads and firebreaks (access roads).

Zone 7 includes Kaross and Khoabendes which are the special species protection areas. This zone will be excluded from the fire implementation strategy for the larger Etosha.

Methodology for trial 1

  1. Four ignition points were lit at distances 3, 6, 9, 13km north of Okondeka on the 5th June 2012 (Fig 2).
  2. The points were ignited late afternoon during a time with almost no wind. The timing was chosen to reduce/minimize risks associated with implemented fires.
  3. Weather forecasts obtained from Oshakati and Hosea Kutako International predicted slight easterly and north-easterly winds.
  4. The spread of the fire was monitored through remote sensing techniques at the Etosha Ecological Institute, as well as two private planes.
  5. The farmers and Councillors were informed prior to the implementation of the fire.

 

Ignition Points

Figure 2. Ignition points indicated by arrows

 

Results

  1. The two ignition points indicated by the arrows were successfully ignited. The other two points did not contribute to the fire in Etosha.
  2. The sequence of the spread of the fire is illustrated in a series of maps (Figs 3 – 12).
  3. From the 5th till the 9th June, the fire spread into northerly, north-easterly and easterly directions (Figs 3-7).
  4. On the 9th June, a strong easterly wind accelerated the spread of the fire westwards.
  5. Late on the 9th June, the fire crossed the M’Bari/Narawandu road despite attempts to contain it with a responsible/limited back-burn.
  6. On the 10th June, the fire progressed rapidly in a westerly/south-westerly area, crossing the 19th latitude gravel road at Sonderkop.
  7. The decision was then made to put active measures in place to contain the fire at the Tobiroen firebreak south of the 19th latitude.
  8. From the 11th till the 17th June, the fire was contained at the Tobiroen fire break as well as a portion of the southern boundary. It was confirmed that no active fires were present in Etosha on the 17th June.
  9. The fire contributed to a patch-mosaic burn in Zones 3, 4, 5 and 6. Table 1 illustrates the relative percentages of burnt vs unburnt areas in the respective zones. It should be noted that the unburnt areas are under-represented and that the use of better remote sensing technology should clear this up.
    Zone number total size (km²) Burnt area (km²) % of total area
    1 900 0 0
    2 4541 0 0
    3 3922 324 8.3
    4 1986 1007 50.7
    5 2910 732 25.2
    6 3826 1036 27.1
    7 142 0 0
    18227 3099 17
  10. In all zones, except zone 4, the percentage of the burnt areas were within the allocated quotas (+-30%). In fact, the percentage burnt area of zone 3 should be increased within the next month. The large percentage of zone 4 could be attributed by the extensive grasslands occurring in this zone, which facilitates quick and large fires.
  11. No mortalities of game were evident either from the road or aerial surveillance.
  12. Except for an area adjacent to the northern boundary, the fire was contained within Etosha during the entire period. The area outside Etosha encompassed 3000 hectares, and ENP staff extinguished this fire to stop it from spreading.
  13. The spatial extent of this fire would lead to a substantial reduction in the spread of fires during the hot, dry season.
Extent of fire on the 6th June

Fig 3. Extent of fire on the 6th June

Extent of fire on the 7th June

Fig 4. Extent of fire on the 7th June

Extent of fire on the 8th June

Fig 5. Extent of fire on the 8th June (am)

Extent of fire on the 8th June

Fig 6. Extent of fire on the 8th June (pm)

Extent of fire on the 9th June

Fig 7. Extent of fire on the 9th June

Extent of fire on the 10th June

Fig 8. Extent of fire on the 10th June

Extent of fire on the 11th June

Fig 9. Extent of fire on the 11th June

Extent of fire on the 13th June

Fig 10. Extent of fire on the 13th June

Extent of fire on the 15th June

Fig 11. Extent of fire on the 15th June

Extent of fire on the 17th June

Fig 12. Extent of fire on the 17th June

 

Recommendations

  1. Zone 4 to be merged with zone 3 to set more realistic annual targets.
  2. Ignition burning to commence at the end of the growing season. This period depends on rainfall and will be flexible on an annual basis. An assessment of the vegetation biomass and dryness will precede the ignition. The application of patch fires will then continue till the season preceding the lightning season.
  3. With a high, dry biomass ignition points need to be chosen with care and in areas where the grading of the internal firebreaks have been completed.
  4. All fires caused by lightning should be allowed to burn and not be contained.
  5. All fires caused by other sources (charcoal burning etc) should be allowed to burn and not be contained.
  6. All fires will be contained if human life and infrastructure are threatened.
  7. The role and responsibilities of neighbours to secure their boundaries by means of grading needs to clarified and defined. This will improve Park-neighbour relations.