African elephants are a big direction policy concern in sub-Saharan African states. The survey was aimed at measuring the impact of elephants on the immediate milieus of wired irrigating holes in Botswana ‘s Chobe National Park. Picture imaging package was used to heighten and tag images taken by pupils from Kings College London in 1995, 1996, 2001 and 2006 in the park. Findingss suggest that about 32.4 % of the trees were lost by 2006. It besides concluded that elephants have a negative impact on flora and supports the demand for joint elephant culling attempts in the Chobe River riparian provinces.
Cardinal words: Chobe, pumped pans, human-elephant struggle
1. Introduction AND LITERATURE REVIEW
Elephant ( Loxodonta africana ) populations are a big direction policy concern for forest preservation in most of Sub-saharan African states ( Coe et al. , 1976 ) like Botswana. Coupled with relentless drouth and high frequence of fires, elephants have contributed significantly to loss in flora due to over-browsing ( Ben-Shahar, 1996 ) .
As protected species under the Convention on International Trade in Endangered Species understanding [ CITES ] , elephants are a major tourer attractive force ; conveying in foreign exchange to the part. Interestingly, approximately 17 % of Botswana ‘s land country is within a designated National Park or Game Reserve with a important figure of people populating in the designated militias. Elephants are hence an indispensable stuff resource for the native people populating in the appellations ( IUCN/ CBNRM Support Programme, 2002 ) .The deduction is that the devastation caused to vegetation straight or indirectly affects worlds.
1.1 Chobe National Park ( NP )
Chobe NP is located in northern Botswana and covers an country of about 10,566 km2. It is located in the passage country between the arid/ nutrient-rich Savannah of the Kalahari of Botswana and moist/ nutrient-poor Savannah of South-western Zambia ( Huntley & A ; Walker, 1982 ; Kamuhuza et Al. 1997 ) ,
The chief beginning of H2O supply in the park is the Chobe River, which supports evergreen woody workss and brush every bit good as flood plain grass home grounds. Chobe NP has the largest elephant population in Africa ( Skarpe, et al. , 2004 ) . Aerial studies indicate that the population was 120,000 ( dry season estimation ) in 2000 with an one-year growing rate of 5.7 % ( IUCN/ CBNRM Support Programme, 2002 ) .
Chobe NP has an norm of 400 millimeters [ in the south ] 650 millimeter [ in the north east ] of rainfall per annum that preponderantly occurs between November and March ( Mosugelo et al. , 2002 ) . It was designated a National Park in 1967 in direct response to worsening elephant population.
Three chief factors have been identified as responsible for the diminution in the elephant Numberss. First, eruption of diseases [ cattle plague and splenic fever ] led to the decease of many elephants. Second, rampant poaching fed the tusk trade in the early nineteenth century. Although poaching by and large declined since 1989, illegal tusk trade still exists. Last, relentless drouths have resulted in farther diminution in the population. These factors non merely necessitated the appellation of Chobe as a National Park, but besides the demand to protect the elephants.
1.2 Specific Study Site
There are both natural [ non-pumped ] and unreal [ pumped ] pans in the Chobe NP. Pumped pans were established by the Botswana ‘s Department of Wildlife and National Parks [ DWNP ] to supply H2O supplies following terrible drought periods in Botswana.
For this survey, images of flora around the wired pans [ Tambiko, Nogatsaa, Tchinga, Kabunga and Poha ] that lie South of the Chobe River in the Nogatshaa part of Chobe NP were reviewed.
2 ELEPHANT CHARACTERISTICS AND BEHAVIOUR
African elephants are gregarious big herbivorous animate beings of the household Elephantidae. Female and male grownup elephants measure up to 3 m and 3.6 m, severally, at the shoulder. Elephants live in households of 10 persons but can congregate into kins of 6-70 members led by a big female ( WWF, 2009 ) .
Elephant densenesss near to H2O beginnings can be every bit high as 7-10 persons km?? particularly towards the terminal of the dry season, but this is much lower for the desiccant mopane parts ( Ben-Shahar, 1996 ) . The motion of elephants is linked to the handiness of nutrient and which in bend is linked to handiness of H2O, related to rainfall the part receives. During the rainy season, the forage niche becomes big and densenesss can drop to every bit few as 0.5 persons km-2 ( Gibson et al. , 1998 ) . Elephants are basically grazers in the moisture season and bend to shoping in the dry season ( Stokke & A ; du Toit, 2000 ) . The mean ingestion of an grownup bull elephant is between 100 kilograms and 300 kilogram ( Nelleman et al. , 2002 ) .
Elephants use their ivories for excavation, depriving tree bark and supporting themselves against marauders. Therefore, the separating index of elephant harm to maturate woody workss is the tallness which corresponds with the mean crest of the shoulder blade ( Stokke & A ; du Toit, 2000 ) .
2.1 Vegetation in Chobe NP
There are three chief woody flora types in Chobe NP, viz. ; Acacia erioloba [ camel irritant ] , Biakiaea plurijuga [ Zambezi teak ] and Colophospermum mopane [ mopane ] . The prolific elephant population in the park have resulted in high use rates of mopane as a nutrient beginning in most of Southern Africa. This has resulted in the change of the flora construction and diminution of species diverseness ( Ben-Shahar & A ; Macdonald, 2002 ) .
2.2 Elephants in the Park
Emphasis has been placed on the function of the elephant on the unstable province of the savannah eco-system ( Caughley, 1976 ) . Several surveies have shown that the increasing figure of elephants can hold a pronounced impact on mature woody species as the grownup bull will eat the unpalatable woody flora that the grownup female elephants and calves, and smaller hoofed mammals do non ( Van de Koppel & A ; Prins, 1998 ) . This suggests that elephants can potentially do maximal harm to their home grounds.
Elephant harm is identified by the characteristic knocking over and up-rooting of trees every bit good as denudation of tree subdivisions. Depriving consequences in the decrease of the flora biomass. Figure 3 below shows the characteristic effects of elephant harm caused to woody flora.
Against this background, struggles have arisen as to whether or non the Savannah forest can prolong the increasing elephant population in Chobe NP and whether intercession is necessary.
Some argue that land users like pastoral husbandmans have had their grain shops, harvests and H2O supplies damaged by elephants in hunt of nutrient and H2O. The policy prescription, hence, is to command the elephant population. Others argue that intercession is unneeded as the herbivore-plant theoretical account would automatically modulate elephant populations to manageable Numberss ( Caughley 1976 ) . Yet others dismiss the nexus between elephant populations and flora loss ( Kalwij et al. , 2008 ) suggesting more rigorous steps of raising the elephants into the CITES I category like in Kenya and India. Such rigorous policy steps would potentially endanger the support of the local people ( IUCN/ CBRNM Support Programme, 2002 ) . An effort at deciding this struggle underpins the intent of this survey.
3 AIM OF STUDY
The chief intent of the survey was to measure the impact of elephants on the immediate milieus of wired irrigating holes. The findings of the survey contribute to the argument about whether or non a culling exercising in the Chobe NP is necessary. The premise of survey was that the trees that were no longer there had been knocked over or uprooted by elephants.
4 METHODOLOGY AND STUDY DESIGN
4.1 Imagery and Aerial Surveys
Imagery and aerial studies are established methods used in several surveies of elephant population and their consequence on flora. For illustration, Yang and Prince ( 1998 ) used satellite imagination to analyze spacial flora screen in Zambia. Verlinden and Masogo ( 1997 ) besides used the method to analyze suitableness of home ground in the Kalahari for hoofed mammals and ostriches. Gibson et Al. ( 1998 ) used aerial studies to set up the tendencies of elephant populations in northern Botswana. Although effectual, these methods are really expensive.
4.2 Procedure Adopted
In order to accomplish the declared purpose of the survey, a desk reappraisal of images [ images ] was conducted. The survey comprised reexamining images of the flora around the wired pans. The images used were taken by Kings College London pupils in 1995, 1996, 2001 and 2006. Pictures were taken in January [ rainy season ] , August and September [ dry seasons ] .
Picture- redacting package [ IrfanView ] was used to heighten, adjust and grade mention trees. Fifty catalogued images [ 1995-2001 ] were examined and matched with non-catalogued images from 2006. Images at different focal lengths were used in order to compare as many angles and landmarks as possible.
Tendencies in tree Numberss for the four central points [ north, E, South and west ] of each pan were recorded and compiled to supervise alterations in the flora around the pans over clip.
Processing of the informations included fiting the non-catalogued [ 2006 ] with the catalogued images [ 1995, 1996, 2001 ] and numeration trees that were decidedly there [ V ] , likely non there [ ? ] , and decidedly non there [ X ] by 2006, utilizing different coloring materials markers for each tree in clip, as shown in figure 4 below.
5 RESULTS AND DISCUSSION
A sum of 136 mention trees were counted for all sites from all central points at the beginning of the survey period in 1995. Table 1 below shows the entire figure of braid counted in the images reviewed at the pans for the continuance of the study. It besides shows the tendency of trees Numberss between 1995 and 2006 for each site.
The figure shows that the elephant copiousness is non unvarying throughout the Park [ outlined in xanthous ] . Poha [ 18 & A ; deg ; 24’46.41 ” S, 24 & A ; deg ; 54’44.72 ” E ] is more likely to lie within the country with a dry season elephant copiousness of 0.27 ; whilst Tambiko [ 18 & A ; deg ; 16’32.36 ” S, 25 & A ; deg ; 1’26.44 ” E ] , for illustration would more likely have a chance of 0.54 dry season copiousness. The possible forage niche for elephants varies with clip and this is strongly correlated with the sum of rainfall the country receives ( Gibbons, 2007 & A ; Nelleman et al. , 2002 ) . These surveies besides confirmed that elephant migration is mostly a map of handiness of H2O and good quality eatage.
During the rainy season, elephants will potentially scatter over a larger forage niche and during the desiccant seasons will congregate in hunt of H2O stoping up at wired pans. This will ensue in a similar form of flora loss as is seen at the Chobe River forepart.
The interaction between the elephant populations and the Savannah ecosystem has been described as complex with multiple stable provinces ( Van de Koppel & A ; Prins, 1998 ; Skarpe et Al. 2004 ) . The addition in elephant-numbers consequences in the loss of woody flora. The Savannah turns into grassland province ; restricting the Numberss of big herbivores it can back up. When grasslands prove unattractive home grounds for them, they will migrate to more suited home grounds and smaller hoofed mammals will take over the home ground until the forest province can be restored. The elephants will do similar harm to new home grounds and the rhythm of devastation continues.
There is hence a clear nexus between the elephant population and the devastation to trees in the immediate milieus of the wired pans contrary to statements advanced by Kalwij et Al. ( 2008 ) . These consequences would propose that there is a demand for a culling attempt in the park. One would reason, sing the herbivore-vegetation theoretical account ( Caughley, 1998 ) , that the strongest statement for culling is to decide the human-elephant struggle. The implicit in ground for back uping this statement is that when herbivores damage flora in one country, they migrate to other countries ( including other states ) . This allows the flora in old home grounds to retrieve. Therefore, culling should non be an ecological necessity.
Given that elephants that cause harm to flora in Chobe NP, migrate and are hence likely to do similar harm in other states ; culling should be carried out as a joint attempt among the riparian provinces of the Chobe River between which these elephants migrate. The caution should be that as a CITES II protected animate being ; culling should be steadfastly guided by the international regulations.
The chief restrictions of the survey were that the images used were captured in different seasons of the twelvemonth. This had the obvious consequence of altering the visual aspect of mention trees. It besides made the landmarks in the foreground expression different. Further, marker nogs were removed by elephants ensuing in fluctuations in the angles and distances from which images were captured over clip.
6 CONCLUSIONS AND RECOMMENDATIONS
The survey revealed grounds of devastation to corner around the wired lacrimation holes. The trees were either non there or diminished in size by the terminal of the survey period. One can reason that the elephant population is holding a negative impact on the flora. This determination supports the statement that culling is imperative, as a manner to decide the human-elephant struggle instead than an ecological direction necessity. The culling should be a joint attempt among the riparian provinces of the Chobe River, between which the elephants migrate and should be within international regulations.
The method used in this survey, though holding some restrictions, is scientifically sound to use in measuring the consequence of the elephants to vegetation around wired lacrimation holes.
For more consistent consequences, future surveies would profit from capturing images for the dry season when the harm is clearly apparent and browsing impact of the elephant is at its highest due to the reduced forage niche.
Surveies would besides profit from utilizing a Global Positioning System ( GPS ) to guarantee consistence of place and distances from which images are captured over clip.
Comparative surveies should be conducted in riparian provinces between which the elephants migrate to set up whether they cause similar harm to the environment in those states.
I would wish to thank Mark Van de Vaal and Jonathan Hardings for the images that were used during this survey. I besides thank Dr. Nicholas Drake for his helpful way and remarks on the survey design.
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