Contents & Foreword, Characterizing And ... - IRRI books

subecosystems were recognized within the rainfed lowland and four within the upland.Subsequent efforts have attempted to sharpen the classes and provide betterestimates of their overall extent.Four distinct levels of ecosystems analysis, in terms of geographic scope andmapping scale, were recognized later (IRRI 1992): mega, macro, meso, and micro.Table 2 gives the indicative objectives and activities associated with work at each ofthese levels. Many technical problems still arise in ecosystems analysis and they aredue to the difficulties of working at different mapping scales and transferring informationacross scales.Table 3 presents some of the methods that have been commonly used in evaluatingthe parameters of rice ecosystems and Table 4 lists the parameters that havebeen used for characterization at different scales. These methods have a wide rangeand flexibility in their application and accordingly provide various outputs: from simpledescriptions to semi- or fully quantitative measurements, and computer-simulatedestimates. The techniques employed range from informal and formal interviews andsurveys including reconnaissance, rapid rural appraisals, field visits, and farm/householdsurveys to simple accounting and bookkeeping, application of procedures forspecific field and laboratory measurements, remotely sensed image and aerial photographinterpretation, applications of detailed simulation models of crop growth, andthe use of geographic information systems (GIS). Examples of the tools used arestructured and unstructured questionnaires, field books, specific instruments, and datarecorders. However, the tools and techniques in characterization cannot be separated.They are very closely linked, as a tool is basically an instrument and the applicationof it is a technique. The parameters or factors in the context of characterization arethose properties, obtained from primary and/or secondary sources, that can help describesufficiently the unit (site/system) in terms of its properties, thereby enhancingthe understanding of the system and serving as a diagnostic criterion to differentiate itinto its subclasses.While the field surveys provide ground truth as well as other needed ancillaryinformation, the advent of remote sensing and GIS has greatly enhanced characterizationand mapping capabilities. However, these methods are not fixed for any givenlevel of analysis and can also be used at other levels. For example, methods 1 and 2 inTable 3 can also be used at the micro and other levels.Mega-level analysisWhen IRRI restructured its research programs (IRRI 1989a) to explicitly address therice ecosystems, decision criteria for allocating funds on an ecosystem basis becamemore explicit. The rice area and production in each ecosystem were fundamentalinformation in applying a resource allocation model.Aggregate data and maps on the rice area by cultural type have been standardizedfor about two decades (Huke 1982, Huke and Huke 1997) on the basis of judiciousestimates. The accuracy of mega-level data on the amount of rice land in thefour major ecosystems is still uncertain, except in a few countries, because the na-6 Singh et al