Digital vegetation charting technique for monitoring rangeland condition at local scale | Protocols, Manuals and Standards (Protocols & Software)
Insub-Saharan Africa, rangelands cover 494.2 million hectares. This vast area ischaracterised by harsh conditions with low and erratic rainfall. Historically,these rangelands have diverse plant communities, productive and well adapted tosustain grazing pressure. Nowadays, the ability of the rangelands to performtheir functions is declining, and their biodiversity is threatened. Furthermore,there are several indications that rangeland resources continue to decline inboth productivity and quality (more annual, less palatable and more unpalatablespecies). Thus, it is imperative that these degraded lands are rehabilitatedand better managed.
The first step before engaging in any rangelandrehabilitation and management project should be centred on mapping andassessing current rangeland conditions. Yet, ecologists and managers have beenchallenged to develop cost-effective methods of measuring changes in vegetationthat are reliable and repeatable. Several studies were conducted tocharacterise natural vegetation at the national or regional scales. However,lack of qualified staff and substantial financial resources do not allowexhaustive assessments of the results. There is an urgent need for reliablerapid mapping and monitoring techniques for assessing rangeland condition, andestimating their productivity at the farm/community level. User-friendly toolsthat can rapidly assess the occurrence and causes of land-degradation processeshave to be developed and field-tested.
With theadvances in technology, large areas can be mapped and monitored rapidly.Combining information from low-altitude sensors and geo-spatial data appears tooffer an optimal path for developing a practical system for cost-effective,databased, rangeland monitoring and assessment. If an inventory of rangeresources is established, priority areas with the greatest potential forimprovement can be identified. In collaboration with Oregon State University,the ICARDA Rangeland Ecology & Management Unit (REMU) has been developingquantitative methods to estimate cover using globally positioned digitalimaging coupled with image analysis for several years. The unit has developedsoftware and protocols that are repeatable and technician independent. Theseprotocols use a continuously recording global positioning system (GPS) device,digital camera, and a computer to acquire and manage information. REMU plans todisseminate the technique to all countries in sub- Saharan Africa (Annex 1 is auser guide and provides more information on application of this technique).
One ofthe most important indicators of rangeland condition and health is thepercentage of the soil that is covered and protected from raindrops by plantsand litter. Sequential measurements of cover at seasonal or yearly intervalscan indicate range trend. Unfortunately, plant foliar and litter cover isgenerally not measured. Rather, technicians estimate it using the quadratmethod because quantitative measurement via intercept or point methods istedious and time consuming. Differences in experience and judgment lead tosubstantial differences in cover estimates between technicians and from onesampling period to the next.
Scaling up approaches
Theinnovation is useful to a wide range of users. These are: national agriculturalresearch and development agencies; non-governmental organisations; developmentinstitutions; agricultural universities; and policy makers.
Severaldissemination methods were used to reach the users of the innovations. Thesewere: training (degree training, on-the-job training, group or individualtraining) and conducting research trials using the proposed techniques.
Thefactors essential for successful promotion and wider adoption of the technologyor innovation include: motivation and interest of research partners especiallyyoung scientists; and enabling policies (commitment of the governments insupport of this work). Continuous feedback would be important for fine-tuningthe protocol and for ease of use of the technology.
Challengesencountered in efforts to further disseminate the innovation and to promote itsadoption and scaling up/out include: funds to purchase necessary equipment(hand-held GPS units, digital cameras, specialised/customised software); use ofGPS receivers; availability and access to existing GIS data themes; lack ofenabling policies and effective institutions; and ensuring participation ofyoung scientists.
Recommendationsto address the challenges include: motivation of research partners; commitmentof governments in support of the innovation; strengthening capacity of existinginstitutions; and facilitating establishment of effective institutions.
Lessons learnt about the best ways to get technologiesor innovations used by the largest number of people: integrating technical,policy and institutional options can help to get stakeholders to apply thistechnology.
Name and address of key scientist:
ICARDA,Rangeland Ecology & Management Unit;
P. O.Box 5466,
Tel:+963-21 221 3433;
Fax:+963-21 221 3490
Name and address of key scientistsinvolved in generation of the innovation:
Prof DrDouglas E. Johnson,
OregonState University, Department of Rangeland Ecology & Management,
202Strand Agricultural Hall, Corvallis,
Telephone:(541) 737-1624; Fax: (541) 737-0504
ICARDAand its collaborators on this work have been developing quantitative methodsfor estimating cover using globally positioned digital imaging coupled withimage analysis for several years and have developed software and protocols thatare repeatable and technician independent. These protocols use a continuouslyrecording global positioning system (GPS) device, digital camera, and acomputer to acquire and manage information. Specialised software links an imageof the ground to a specific location, rotates and scales the image andprocesses it into meaningful classes such as foliar cover, litter and bareground. Original images, processed images, track logs and photo locations arestored on the computer or a DVD for reference and archiving. Because bothpositioned and processed images are tagged with GPS coordinates, they can beviewed in a geographic information system (GIS).
Materials and methods
Thistechnique requires a staff-mounted digital camera that is positioned to take adigital photograph vertically downward from a fixed height when the platformholding the camera is level (Figure 3.1). It consists of a Bogen Manfrotto 676BMonopod and a Bogen Manfrotto 3025/056 3D Junior Head to which a 5 by 8 inch(13 by 20 cm) platform has been mounted (Booth et al. 2004, Johnson et al.2008). Attached to the platform is a bubble level, magnetic compass,continuously recording GPS unit, and the digital camera. The camera head may bemounted on either a pole of a fixed height or a variable height monopod, aslong as the height does not change during a photo shoot (Figure 3.2).
Image processing using VegMeasuresoftware
VegMeasureis a computerised vegetation measurement program. It is the result of work doneon a series of projects by the Department of Rangeland Ecology and Managementat Oregon State University (USA) that measured and monitored vegetation onrangelands, agronomic fields and riparian areas.
Figure 3.1: Apparatus used to obtain digitalimages of quadrats.