Effects of Biological Soil Crusts on the Grazing Gradient Patterns
Biological Soil Crusts (BSC) are distributed over three quarters of Australia with a 20 to 40% variation in cover. In most of the previous remote sensing studies, which were conducted in the areas in which BSC occur, they were either neglected all together or were considered as one or two groups. Previous remotely-sensed studies on the areas in which BSC are common were conducted when BSC was dry. These studies reported that there is high similarity between the spectra of BSC and dry bare soil thus leading to potential misinterpretation. From the remote sensing perspective there is large variation between individual BSC components, particularly from criterion of colour. There are few attempts in Australia to map land cover components by including BSC as one, or a maximum of two groups. This study, by developing 5 ground-based models, examined the effects of BSC components with different possibilities using Normalized Difference Vegetation Index (NDVI) on grazing gradient patterns, with an aim to investigate and model the neglecting of BSC, assuming them to be in one group (including major morphological/functional groups). The study also developed a possible model for the detection of these components by the use of a multi-temporal remote sensing technique. Results showed that there are large cover value differences among different models through the inclusion of BSC as one group, six groups or by neglecting them all together. This leads to serious image misinterpretation when images are acquired in both dry and wet conditions.