Chowilla icon site - floodplain vegetation monitoring 2016 interim report.
Abstract
The aim of this study was to monitor and assess vegetation condition at the Chowilla Icon Site in South Australia against the objectives and associated TLM site specific ecological targets. A network of vegetation survey sites was established in areas of herbland and grassland in 2006. These sites were monitored to provide baseline data in 2006, and have been resurveyed on an annual basis to monitor medium-term vegetation changes and assess the aforementioned site specific ecological objectives. Between 2013 and 2016, an additional 58 sites in temporary wetlands that were part of a previous intervention monitoring program were added to the network to gain a better understanding of floodplain and temporary wetland condition at Chowilla. The 11th annual floodplain vegetation condition monitoring survey was undertaken in February 2016. A total of 21 taxa, from 10 families (12 from the Chenopodiaceae) were detected across the 69 original (established 2006) floodplain sites surveyed. With the inclusion of the additional temporary wetland sites surveyed in 2016, species richness across the Chowilla Floodplain increased to 57 taxa from 23 families (13 from the Chenopodiaceae and ten from the Asteraceae) across the 121 temporary wetland and floodplain sites surveyed. In 2016, there was a decrease in species richness at the original floodplain sites (1-85) compared to 2015 to levels similar to those during the Millennium Drought. However, when the temporary wetland sites are included (1-143) species richness is largely unchanged compared to 2015. In 2016, there was a decrease in the proportion of observations of bare soil at sites 1 to 85 despite it being the most abundant taxon recorded. The proportion of salt tolerant and terrestrial taxa was similar to 2015 but there was an increase in flood dependent species. Across all sites, there was an increase in the proportion of amphibious and flood dependent species and decrease in all other functional groups compared to 2015 (due to an increase in the number of temporary wetland sites surveyed in 2016). Current management practices (i.e., site-scale watering and regulator operation) and natural flooding have resulted in three out of the five targets for native understorey floodplain vegetation being achieved over the previous ten years.