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Shane Cridland
The maintenance of the perennial cover is critical to ecological functioning in rangeland systems. At the end of the dry season, it can be assumed that almost all the green material is in the perennial cover. The lowest Normalised Difference Vegetation Index (NDVI) was used to estimate the lowest amount of green perennial cover during the dry season (termed 'base'). The base values were compared with the range of base values from past years and new high or low values highlighted as indicating areas of possible change. The base values were then analysed, using standard regression procedures, for trends. Areas showing apparent trends were highlighted as areas of possible change.
The stability of an ecosystem's ability to convert rainfall to vegetation is
also critical to ecosystem functioning in rangeland systems. This parameter
(new green growth per unit of rainfall) was estimated by integrating 'NDVI above
the base' and rainfall over the growing season and calculating the transfer
quotient. The transfer quotient values were then analysed, using standard regression
procedures, for trends. Areas showing apparent trends were highlighted as areas
of possible change.
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