Christmas Island National Park Island-wide Vegetation Survey of Key Species that Play a Role in Yellow Crazy Ant Scale Insect Mutualism 

In 2013 the scope of the Island-wide Survey was expanded to gather data at each survey site about scale insect assemblages. This involves a vegetation survey of twelve key tree species that play a role in YCA-scale insect mutualism. These tree species are an effective proxy for the scale species present in an area. The dataset contains vegetation transect survey data on the target twelve key tree species that play a role in YCA-scale insect mutualism, collected during the Island-wide Survey. 

We at TERN acknowledge the Traditional Owners and Custodians throughout Australia, New Zealand and all nations. We honour their profound connections to land, water, biodiversity and culture and pay our respects to their Elders past, present and emerging. 

The Australian territory of Christmas Island lies in the Indian Ocean, 2,600 km northwest of Perth and 500 km south of the Indonesian capital, Jakarta. Christmas Island National Park (CINP) is 85 km2 in size and makes up almost two thirds of Christmas Island. Introduced sap sucking scale insects, such as Tachardina aurantiaca and Pulvinaria urbicola, produce carbohydrate rich honey dew as a waste product which is consumed by Yellow Crazy Ant (YCA) colonies. YCAs will farm these scale insects and provide them with protection in order to access this honey dew. Large amounts of carbohydrates in the system allow YCA to form into supercolonies. The objectives of the vegetation survey are to: gather data at each survey site about scale insect assemblages; gather data on diversity of tree species and YCA activity/tree traffic across each tree species; provide an understanding of YCA-scale-tree dynamics at each site; provide information about potential sites where scale insects might colonise in the future, and therefore where new YCA infestations may occur; and inform selection of sites for future release of scale biological control agents. The introduced Yellow Crazy Ant (YCA) (Anoplolepis gracilipes) is considered the most significant threat to Christmas Islands biodiversity. The YCA was accidentally introduced to Christmas Island sometime between 1915 and 1934 and numbers remained low and had no obvious impact on the islands biota until 1989, when the first high density supercolony was discovered. YCA supercolonies can rapidly change forest structure and composition, alter ecosystem processes, and pose a threat to many endemic species, including listed threatened and endangered species. In 2001, as a part of the Action Plan for research and management of YCAs, a survey design was developed by La Trobe and Monash University for an Island-Wide Survey (IWS) to determine the extent of supercolony formation and impact of YCAs on Christmas Island, to guide control and management programs while assessing the impact of YCA on Red Crabs. The survey is now undertaken biennially and has been refined since its inception to assess the distribution of a number of native and introduced flora and fauna species including crabs, reptiles, land birds, sea birds and mammals. 

Data not provided.