ENDELEO
 
 
 
 
 
 
CASE STUDY 1 : Forest fires in Eastern Mau forest, March 2009


The Mau Complex is the largest remaining closed canopy forest in Eastern Africa. It forms the upper catchments of most rivers that drain west of the Rift Valley, including Nzoia, Yala, Nyando, Sondu and Mara. It is also the main catchment of critical lakes and wetlands in the Rift Valley, including lakes Baringo, Nakuru, Naivasha, Natron and Turkana. The forests of the Mau Complex are very rich in flora and fauna.

In March 2009 several fires occurred in the Mau Complex and surrounding forests.  Some of the worst affected areas are Eastern Mau Forest and Mount Longonot.


Location of Eastern MauForest

The ENDELEO monitoring tool can be applied to monitor vegetation conditions in forests and surrounding areas. By comparing vegetation condition for a certain area with situation in other years or previous months, we can get an indication of the vulnerability to fire. As an example, we will have a closer look at the vegetation trends in Easter Mau forest in March 2009.

In normal years March corresponds with the start of a rainy season which will result in an increase of the ’vegetation health and density’. However, in March 2009, lack of rains resulted in a decrease of ’vegetation health and density’.

Tip: Information on estimated rainfall amounts in Kenya can be accessed from FAO’s Global Information and Early Warning System.

In the images showing the ‘vegetation health & density’ for the beginning, middle, and end of March 2008, we can clearly observe an increase in ‘vegetation health & density’ in Eastern Mau forest as large areas evolve from ‘Normal’ to ‘Good’. When looking at the images of March 2009, the opposite trend can be observed.

 
Vegetation health & density in March 2008: beginning of March (left image) – middle of March (middle image) – end of March (right image) - taken from ’image viewer’

 
Vegetation health & density in March 2009: beginning of March (left image) – middle of March (middle image) – end of March (right image) - taken from ’image viewer’


Based on the previous images, it can be concluded that in March 2009 the condition of the vegetation evolved different compared to 2008. In order to know to which extent the ‘Vegetation health & density’ in March 2009 differs from the previous year, we can select ‘comparison last year’ in the ‘Type’ menu. It can be observed that in the beginning and in the middle of March 2009, the vegetation condition is similar compared to the previous year. However, in the end of March the vegetation condition in large parts of the image are inferior to the previous year.      

 
Vegetation health & density in March 2009 compared with previous year: beginning of March (left image) – middle of March (middle image) – end of March (right image) - taken from ’image viewer’


In order to get a better idea how about vegetation trends in March 2009 we can look at the difference in ‘Vegetation health & density’ compared to the previous 10 days. From the beginning of March to the middle, the situation is stable or slightly better. From the middle to the end, there is a decrease in vegetation health & density.

 
Vegetation health & density in compared to last 10 days: middle of March compared to beginning of March (left image)- end of March compared to middle of March (right image) - taken from ’image viewer’


The vegetation indices calculated from MODIS give similar information, but at a higher spatial resolution (250 meters compared to 1000 meters for SPOT-VEGETATION). However, no comparison with the previous year or the average situation can be made as only recent data is available.

 
Vegetation health & density images for March 2009: based on SPOT-VEGEATION (left image) – based on MODIS (right image) - taken from ’image viewer’


High spatial resolution data can be used to observe the affected areas with higher spatial detail. Below, a Landsat ETM+ SWIR colour composite image of March 24th 2009 is compared with a Landsat ETM+ SWIR colour composite image of March 5th 2008. In these images forest can be clearly distinguished as they appear green. In the 2009 image, the yellow arrows point towards the areas affected by fire. The burnt areas appear black or dark blue. These areas were not affected in 2008. Note that in the 2008 image dark regions appear as well. However, these are shadows resulting from clouds (appearing white).   


Landsat ETM+ image of 05.03.2008 (left image) and 24.03.2009 (right image)

 

The image below shows the vegetation health & density for the last ten days of March 2009 compared with previous year. The image extent is the same as the Landsat ETM+ images above.  In large parts of the image the vegetation health & density is inferior compared to the previous year, but in the areas covered by forests (as observed on the Landsat ETM+ image) vegetation health & density is mostly similar to the previous year. This is because forests have a large buffering capacity against droughts. Only in the forest areas affected by fire, we observe inferior vegetation health & density compared to 2008 (yellow arrows).


Vegetation health & density at the end of March 2009 compared with previous year

 

The ‘Graph’ tool can be applied to investigate how the vegetation health & density evolves within a certain land cover class. The graphs below show the vegetation health & density, indicated by the Normalized Difference Vegetation Index (NDVI), for the closed woody land cover class within Eastern Mau forest boundaries. The blue graph shows the average values and the red graphs shows the values for the year we want to investigate. It can be clearly observed that in March 2009, the vegetation health & density of the closed woody land cover class within eastern Mau forest is much below the average situation. When looking at the situation of Kakamega forest we see a much more positive trend with the vegetation health & density being above the average situation for the end of March 2009.  


Vegetation health & density for closed woody land cover type in Eastern Mau forest for 2009 and for average year


Vegetation health & density for closed woody land cover type in Kakamega forest for 2009 and for average year



The ‘Table tool’ can be applied to get an overview of the vegetation health & density for all land cover classes within a spatial unit for a certain month within the current year. For each land cover class the difference in NDVI between the selected month of the current year and the average for that month for the period 1998 – 2009 is calculated. From the table below we can see that for Eastern Mau forest the vegetation health & density in March 2009 is 9 % lower than average for the closed woody land cover class. We can see that the open woody and open shrubs land cover classes are most affected with a vegetation health & density 23 % lower than average.

Vegetation Class

2009 Month: 03
compared to same month in:
Average (1998-2009)(%)

Total Area

-14

Built up

-9

Closed Woody

-9

Open Woody

-23

Open to very open areas

-18

Open Shrubs

-23

Sparse Shrubs

-13

Herbaceous with shrubs

-13

Herbaceous

-11

Tree Crops

-19

Rainfed herbaceous crops

-17

Difference in vegetation health & density between March 2009 and the average situation (in percentage) for the different land cover classes within Eastern Mau forest boundaries

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