Pk Bricher

Mapping sub-Antarctic cushion plants using random forests to combine very high resolution satellite imagery and terrain modelling

Monitoring changes in the distribution and density of plant species often requires accurate and high-resolution baseline maps of those species. Detecting such change at the landscape scale is often problematic, particularly in remote areas. We examine a new technique to improve accuracy and objectivity in mapping vegetation, combining species distribution modelling and satellite image classification on a remote sub-Antarctic island. In this study, we combine spectral data from very high resolution WorldView-2 satellite imagery and terrain variables from a high resolution digital elevation model to improve mapping accuracy, in both pixel- and object-based classifications. Random forest classification was used to explore the effectiveness of these approaches on mapping the distribution of the critically endangered cushion plant Azorella macquariensis Orchard (Apiaceae) on sub-Antarctic Macquarie Island. Both pixel- and object-based classifications of the distribution of Azorella achieved very high overall validation accuracies (91.6–96.3%, κ = 0.849–0.924). Both two-class and three-class classifications were able to accurately and consistently identify the areas where Azorella was absent, indicating that these maps provide a suitable baseline for monitoring expected change in the distribution of the cushion plants. Detecting such change is critical given the threats this species is currently facing under altering environmental conditions. The method presented here has applications to monitoring a range of species, particularly in remote and isolated environments.

Moving towards implementation of a Southern Ocean Observing System

The Global Ocean Observing System (GOOS) is deploying a holistic system to monitor the worlds ocean; however, a major challenge is many regions are chronically under-sampled. One such region is the Southern Ocean, which is remote and a harsh region to sample. The importance of improving holistic sampling in this region is clear, given its disproportionate significance to Earth and the fact that the area is exhibiting rapid change. As the Southern Ocean is beyond the capability of any single nation, the international Southern Ocean research community recognized a need for improved international coordination, strategic planning, and eventual implementation of a Southern Ocean Observing System (SOOS). The focus of SOOS is on (1) designing a sustainable system that provides data for determining the status and change of the Southern Ocean, (2) standardizing measurements across national efforts, (3) providing a forum for opportunities to guide future investments, (4) developing a portal for open transparent access to data, and (5) supporting grassroots discussion to identify/design expeditions and technology development. This manuscript highlights current SOOS strategies to meet those needs. Critical lessons emphasize the need for providing value to users who are contributing content/strategy as volunteers and sustain a dedicated office to coordinate those efforts while providing documented value to those contributing time and expertise.