Assessment of White Gum Moist Forest on NSW Crown Forest Estate

An indicative map for White Gum Moist Forest (WGMF) 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. \r\nThe determination of WGMF was reviewed by the project’s Threatened Ecological Community (TEC) Reference Panel (the Panel), and a set of diagnostic parameters for identifying the WGMF TEC was agreed. \r\nOur mapping process relied upon the occurrence of E.dunnii to diagnose the presence of WGMF. \r\n\r\nWe reviewed existing vegetation maps, predictive models and observation records of E.dunnii to identify State Forests that are known or likely to include stands of the species. We then attempted several different approaches to sampling and mapping E.dunnii using ground based surveys, predictive modelling and aerial photograph interpretation (API). We used API assessment of known E.dunnii stands to identify image patterns and signatures that indicated the presence of E.dunnii. We used our findings to examine un-surveyed areas of relevant state forests via API, and then we mapped any areas which appeared to be dominated or co-dominated by E.dunnii. We also developed a Random Forest presence-absence model and used it to predict the distribution of WGMF across its range.\r\nWe constructed an indicative map of WGMF using the combined results of our API mapping and our predictive model. In total, we mapped approximately 980 hectares of forest likely to be dominated or co-dominated by E.dunnii across 16 State Forests. Two thirds of the mapped area is associated with the northern populations of E.dunnii – the largest areas were in Beaury, Donaldson and Yabbra State Forests. In the southern area, Kangaroo River State Forest includes the largest representation of E.dunnii in State Forest. \r\nOur conclusions from this exercise is that our API interpretation is capable of separating E.dunnii from other related eucalypts but only where it is supported by field reconnaissance. Therefore, further work is required to increase API confidence throughout its range before our maps are suitable for operational applications. Nonetheless, our indicative map is still useful for providing a list of State Forests that include mapped areas of E.dunnii and identifying the areas that have corroborating field based evidence of E.dunnii.\r\nAs our indicative map stands at present, we consider that it overestimates the extent of E.dunnii and its dominance, however, it is unlikely that extensive stands exist outside our mapped areas. We also conclude that existing mapping (including both forest type mapping and OEH (2012) mapping) significantly underestimates the likely true extent).\r\n\r\nIndicative TEC Mapping have been generated from best available composite environmental data layers - standardised to 30 m pixels.

本研究针对白胶湿润林（White Gum Moist Forest, WGMF）制作了一张指示性地图，以解决长期以来困扰人们的、关于东部区域森林协议覆盖的新南威尔士州（NSW）州立森林辖区内该植被类型的识别、分布位置与范围的争议问题。
本项目的濒危生态群落（Threatened Ecological Community, TEC）咨询专家组（以下简称“专家组”）对WGMF的界定标准进行了审议，并就识别该濒危生态群落的一套诊断参数达成共识。
本次制图流程以邓恩桉（Eucalyptus dunnii, E. dunnii）的存在作为判定WGMF存在的依据。

我们首先梳理了现有植被地图、邓恩桉预测模型及观测记录，以确定已知或潜在分布有该物种林分的州立森林。随后，我们尝试采用地面调查、预测建模与航空影像解译（Aerial Photograph Interpretation, API）三种不同方法开展邓恩桉的采样与制图工作：通过对已知邓恩桉林分的航空影像解译，识别出可指示邓恩桉存在的影像特征与标识；利用上述识别结果，通过航空影像解译对相关州立森林的未调查区域进行排查，并勾绘出以邓恩桉为优势种或共优势种的区域；此外，我们还构建了随机森林（Random Forest）存在-不存在模型，用于预测WGMF在其分布范围内的空间分布。
我们结合航空影像解译制图与预测模型的结果，制作了WGMF的指示性地图。最终，我们在16处州立森林中勾绘出约980公顷、大概率以邓恩桉为优势种或共优势种的森林区域。其中三分之二的制图区域与邓恩桉的北部种群相关，面积最大的区域分布在比奥里（Beaury）、唐纳森（Donaldson）及亚布拉（Yabbra）州立森林内；在南部区域，袋鼠河（Kangaroo River）州立森林拥有州立森林中面积最大的邓恩桉分布区。
本研究得出的结论为：仅在实地踏勘验证的前提下，航空影像解译可有效区分邓恩桉与其他近缘桉属物种。因此，在本地图可用于业务应用前，仍需开展进一步工作以提升全分布范围内航空影像解译的可信度。尽管如此，本指示性地图仍具有实用价值：可用于梳理包含邓恩桉制图区域的州立森林清单，以及识别存在实地佐证证据的邓恩桉分布区域。
就当前版本的指示性地图而言，我们认为其高估了邓恩桉的分布范围及其优势度，但在我们勾绘的区域之外，不太可能存在大面积的邓恩桉林分。同时我们还发现，现有制图成果（包括森林类型图及2012年新南威尔士州环境与遗产办公室（Office of Environment and Heritage, OEH）发布的地图）均大幅低估了邓恩桉的实际潜在分布范围。

本濒危生态群落指示性地图基于当前可获取的最优复合环境数据图层生成，所有图层均统一分辨率为30米像素。