Assessment of Coastal Saltmarsh TEC on NSW Crown Forest Estate

The operational map for Coastal Saltmarsh was constructed to resolve long-standing issues surrounding its identification, location and extent within the NSW State Forest estate covered by the eastern Regional Forest Agreements. The project’s Threatened Ecological Community Reference Panel (the Panel) reviewed the determination for Coastal Saltmarsh and agreed upon a set of diagnostic parameters for its identification. \r\nWe identified that any treeless saline and sub saline native vegetation found in the intertidal zone had the potential to be Coastal Saltmarsh. We estimated the extent of the intertidal zone by using a fine scale digital elevation model to determine the highest astronomical tideline (HAT). We then mapped potential Coastal Saltmarsh by analysing recent fine scale three dimensional aerial imagery to identify any native vegetation that comprised of low-growing treeless communities and was located within the HAT and on the landward side of mangroves. Mapping criteria used a tree cover tolerance of up to 30% to include areas that had a mixed cover of mangrove, paperbark or casuarina species with a saltmarsh understorey. Exposed mudflats and banks were also mapped when they were visible.\r\nOur mapping covered 1.4 million hectares of State Forest within the south, central and north coast regions of NSW. We identified a total of 111.9 hectares of Coastal Saltmarsh within 14 State Forests along the east coast. The most extensive areas are located in Bermagui and Mogo State Forests on the south coast and in Wallaroo State Forests on the north coast. \r\nWe validated our map of coastal saltmarsh using an existing independent map of estuarine habitats (Creese et al 2009). Our mapping consistently identified almost twice as much coastal saltmarsh as Creese et al (2009), but this was attributable to differences in the mapping criteria rather than any error.\r\n\r\nOperational TEC Mapping have been derived by API at a viewing scale between 1-4000 using ADS40 50 cm pixel imagery and 1 m derived LIDAR DEM grids for floodplain EECs.\r\n为解决东部区域森林协议覆盖的新南威尔士州（NSW）州立森林权属范围内，海岸盐沼（Coastal Saltmarsh）的识别、分布定位与覆盖范围长期存在的争议问题，本研究构建了海岸盐沼业务化制图成果。本项目的受威胁生态群落（Threatened Ecological Community）咨询专家组对海岸盐沼的认定标准进行了审议，并敲定了一套用于其识别的诊断参数。 研究认定，潮间带内所有无树的盐生及低盐生本土植被，均具备被归类为海岸盐沼的潜质。本研究通过高精度数字高程模型确定最高天文潮位线（Highest Astronomical Tideline, HAT），以此估算潮间带的范围。随后，通过分析近期高精度三维航空影像，对位于最高天文潮位线范围内且处于红树林向陆一侧的低矮无树本土植被群落进行识别，进而绘制潜在海岸盐沼分布图。本次制图采用的判定标准允许最高30%的树木覆盖度，以纳入那些以盐沼为下层植被、混生红树林、白千层或木麻黄物种的区域。裸露潮滩与岸堤在可见的情况下，也被纳入制图范围。 本次制图覆盖了新南威尔士州南、中、北海岸区域共计140万公顷的州立森林。研究在东海岸沿线的14处州立森林内，共识别出111.9公顷的海岸盐沼。其中分布规模最大的区域分别位于南海岸的伯马圭（Bermagui）州立森林、莫戈（Mogo）州立森林，以及北海岸的沃拉鲁（Wallaroo）州立森林。 本研究采用已发布的独立河口生境地图（Creese等人，2009年）对海岸盐沼识别地图进行了验证。本研究识别出的海岸盐沼面积约为Creese等人（2009）研究成果的两倍，但该差异源于制图标准的不同，而非制图误差。 受威胁生态群落（Threatened Ecological Community, TEC）业务化制图成果由API针对泛滥平原濒危生态群落（Endangered Ecological Community, EECs）制作，制图采用ADS40 50厘米像素航空影像与1米分辨率激光雷达（LIDAR）数字高程模型（DEM）格网数据，浏览尺度设定为1:4000。