In Depth Coverage

Assessment of Damage Caused by the Tree Locust to the Gum Arabic Tree

It is the application of Space technology in monitoring and early detection of the effect of tree locust pest on gum tree (hashab) through integration of ground data, imagery data and GIS.  Here the location of different infestation levels (both natural and artificial) is determined (with ground control points) using the GPS.  Both supervised and unsupervised classification will be done.  Having done this, the area of insect infestation, crowding and swarming can be easily determined, hence strategic control measure can immediately be  adopted to save and conserve the environment from the devastating effect of this dangerous insect.  

• Link With Climate Change

  Open

  Climatic change especially rainfall, relative humidity, wind direction and speed affect the distribution and appearance of tree locust pest. Suitable climatic conditions favour the pest status and result in outbreak.  Hence heavy damage and great defoliation of the “hashab” tree will take place and result in a great reduction of gum production.  The “hashab” tree a multi-purpose leguminous tree species, suitable for arid and semi-arid environment; it produces the best quality of Gum Arabic, good fodder for livestock, fuel wood charcoal, poles for building purpose and fence posts. It is useful for environmental protection and conservation especially in sandy soils (Goz). It fixes sand dunes and protects the sand from wind and water erosion.  In addition, it fixes nitrogen (Ballal, 2002).

• Objectives

  Open

  Owen et al., (1990) estimated the annual fixation to be less than 20 Kg nitrogen per ha. It is an integral part of the agro-forestry practices widely known in Sudan as bush fallow cultivation, where agricultural crops are grown in a time sequence with the trees. 
  The Gum Arabic Belt is one of the most important forests in Sudan, which lies within the low-rainfall savannah zone. The Belt is considered as an important area because it accommodates around one fifth of the population of the Sudan and two thirds of its livestock population. The Belt acts as a natural barrier to protect more than 50% of the total area of Sudan from desert encroachment (Ballal, 2002).
   
  Gum Arabic contributes significantly to increasing revenue for local communities and to Sudan exports where it constitutes a major source of foreign exchange earning. Gum has multiple uses in industrial products such as foodstuffs, pharmaceutical industries, beverages, ink, textile, paints, lithography, adhesive and a wide range of additional industrial products (Ballal, 1991).                    
  Gum Arabic is one of the main crops produced in the traditional rain-fed agricultural sub-sector. It is a non-timber forest product provided by Acacia; namely A. Senegal (L.), locally called ‘hashab’ tree. The majority of Gum Arabic produced in Sudan is obtained from this species. It contributes to the backbone of the gum trade in quality and quantity and represents 90% of the total value of exported gum (GAC, 2000).         /nbsp]                                                 /nbsp]     
  Gum Arabic provides an average of 12% of the gross domestic products (GDP) of the country and accounts for about 15.3 % and 10% of the household income of the gum producers and other farmers in the gum belt across the Sudan, respectively (Taha, 2000).
  Moreover, Gum Arabic is a key issue of the ecological, cultural and economical development of Africa, as it is often the main source of revenue for semi-nomadic African people who gather it from wild, untended plants (Ballal, 2002).
  
  - Objectives:
  o To review and highlight the role of remote sensing and field observation :  in early detection of gum tree damage / defoliation due to tree locust attack with some emphasis on future prospect in making use of the data obtained in better management of the insect.             
  o To quantify and qualify the extent of damage by different levels of tree locust infestation as well as artificial defoliation in term of gum yield and quality.                                       
  o To provide a database to help in the prediction and forecast of future infestations of Gum Arabic plantations by tree locusts.
  o To identify the areas of swarm formation and carry out ground truthing to pinpoint habitat for development of swarm.                                                                                            
   

• Work plan

  Open

  NA

• Schedule

  Open
  1. Duration Budget Remarks:Seasonal occurrence of adult and hopper tree locusts January up to September 2007 and 2008 Observed and assessed during field surveys
      
  2. Assessment of the effect of natural and artificial defoliation on the quantity and quality of gum production January up to September 2007 and 2008 Implementing of experiments in four blocks in the two sites of the study area
      
  3. Assessment of daily food-intake for adult and hopper tree locusts.
     July up to October 2007 and 2008
      
  4. Remote Sensing Data (data acquisition) July and August 2007 and 2008
     Image processing and analysis to be carried out in 2009
      

• Technical and Scientific Approach & Methods Proposed

  Open

  Materials and Methods:
  The study is carried out at Acacia Project, Sheikan locality, Kordofan State.  The project lies Southeast of Elobeid city and extends Eastwards.  The study area extend is shown below with long/lat projection:
  
  - the lower corner is X 30.397   Y   12.864
  - the upper corner    X 30.637   Y   12 .993
  
  The total area of the project is 28000 feddan. It was regenerated and planted by hashab seeds and seedling in 1997. The inter-rows spacing is 3m and the intra-row spacing is 5m. The soil of the project is “gurdud” soil (hard crust). Field survey is conducted to estimate the seasonal occurrence of adult and hopper tree locusts in relation to rainfall and humidity, also experiments on assessment of damage and estimation of quantitative and qualitative loss in gum production due to natural defoliation by tree locust and artificial defoliation was conducted within the study area in two locations (Elrahad and Nawa) through using conventional method of assessment. The modern method (satellite image) will be used to assess the damage and to estimate the loss in gum production, in addition, an experiment was conducted to assess the daily food-intake for both hopper and adult tree locusts.

• Results

  Open

  The outcome of this study will provide accurate data which can help in modeling programmes that can achieve better pests status and early detection of plant damage/ defoliation, and potentially allow the agricultural industry to respond to damage resulting from insect infestation and disease. It includes Maps showing the status of Gum tree, healthy/damaged (variation of leaf Chlorophyll) and biomass. 

• Deliverables

  Open

  The outcome of this study will provide accurate data which can help in modeling programmes that can achieve better pests status and early detection of plant damage/ defoliation, and potentially allow the agricultural industry to respond to damage resulting from insect infestation and disease. It includes Maps showing the status of Gum tree, healthy/damaged (variation of leaf Chlorophyll) and biomass

• Use of Satellite Imagery and GIS Solutions

  Open

  Remote Sensing Data (data acquisition):
  The remotely sensed data will be acquired during the peak of greenness for optimal interpretation of the vegetation. However the image prior to the peak is required to assess the status prior to locust damage. Remotely sensed data that will be used for this study are collected from one of the two sensors:

  1. SPOT as first option and highly recommended due to its high spatial resolution and suitability to the case study.
  2. Landsat ETM+sensor:
     Two sets of data is required (two SPOT scenes in each set)
     
     • The first set to be acquired during July 2007 and 2008 (1-15 July 2007 and 1-15 July 2008)
     • The second set to be acquired during August 2007 and August 2008 (1- 20 August 2007 and (1- 20 August 2008)

  ERDAS imagine and Arc GIS software will be used:

  1. The necessary image enhancement will be performed
  2. Image transformations will be carried out to ensure better image visualization and interpretation.
  3. Image ratio transformation will be applied (NDVI) to assess tree locust damage
  4. Unsupervised classification will be carried in which image data is grouped into spectral classes (cluster), based on statistical properties of all pixels values to train pixels in sample set (it was done automatically).
  5. Supervised classification will be carried, where it is a decision phase, each pixel was assigned a class name, if the spectral values of that pixel are similar enough to a class of training pixels
  6. Examining of the ratio of reflected infrared to red wavelengths will be done to measure tree health, i.e. calculation of the normalized differential vegetation index (NDVI) to assess the tree locust damage.
  7. Data Analysis: all images, field data, climatic data, and other relevant information will be integrated in a GIS for further analysis.
  8. GIS methods and ARCMap will be used to for maps production (Layout)
      

• Local Actions

  Open
  • Assessment of the effect of natural and artificial defoliation on the quantity and quality of gum production.
  • Tapping and gum production.

   

• Region Name

  Open
  Kordofan State

• Partners involved in project

  Open
  Project Leader :
  Remote Sensing Authority, National Center for Research
  
  Organisations and team involved in the project:
  o University of Khartoum
  o University of Kordofan