Pressurised pastoralism in South Gobi, Mongolia: what is the role of drought?

The desert-steppe region of southern Mongolia is susceptible to drought and extreme winter weather ( dzud ) that in combination form Mongolia's worst natural hazard. Low precipitation and high climatic variability in this dryland environment impact the landscape and affect pastoralism, the dominant rural lifestyle. Using the Standardised Precipitation Index (SPI), this paper identifies drought occurrence in South Gobi Province, Mongolia. It then examines the relationship of drought with climate factors, interaction with vegetation (derived from Normalised Difference Vegetation Index - NDVI - data), and local human and livestock populations, and the dzuds of 1999–2001. Results show that drought is recurrent in the region, reaching extreme intensity most recently in 2005–2006. In contrast with the prevailing concept of drought impacting dzuds , the study did not find a connection between drought and dzud in South Gobi Province. Though repeated events, these natural hazards occur independently in the region. Climatic variables show increasing temperatures (>1°C), fluctuating precipitation patterns and a decline in vegetation cover. The principal long-term correlation of drought is with human population rather than natural factors, dzud or livestock numbers.     

Assessment of Relationships Between Precipitation and Satellite Derived Vegetation Condition Within South Australia

The normalised difference vegetation index (NDVI) has evolved as a primary tool for monitoring continental‐scale vegetation changes and interpreting the impact of short to long‐term climatic events on the biosphere. The objective of this research was to assess the nature of relationships between precipitation and vegetation condition, as measured by the satellite‐derived NDVI within South Australia. The correlation, timing and magnitude of the NDVI response to precipitation were examined for different vegetation formations within the State (forest, scrubland, shrubland, woodland and grassland). Results from this study indicate that there are strong relationships between precipitation and NDVI both spatially and temporally within South Australia. Differences in the timing of the NDVI response to precipitation were evident among the five vegetation formations. The most significant relationship between rainfall and NDVI was within the forest formation. Negative correlations between NDVI and precipitation events indicated that vegetation green‐up is a result of seasonal patterns in precipitation. Spatial patterns in the average NDVI over the study period closely resembled the boundaries of the five classified vegetation formations within South Australia. Spatial variability within the NDVI data set over the study period differed greatly between and within the vegetation formations examined depending on the location within the state. ACRONYMS AVHRR Advanced Very High Resolution Radiometer ENVSAEnvironments of South Australia EOS Terra‐Earth Observing System EVIEnhanced Vegetation Index MODIS Moderate Resolution Imaging Spectro‐radiometer MVC Maximum Value Composite NDVINormalised Difference Vegetation Index NIRNear Infra‐Red NOAANational Oceanic and Atmospheric Administration SPOT Systeme Pour l’Observation de la Terre