Extant Native Vegetation of Boorowa Shire and surrounds VIS_ID 1624

"Extant Native Vegetation of Boorowa Shire and surrounds.;\r\nVegetation map based on classified vegetation survey data, and modelling layers, derived from a 25 metre Digital Elevation Model, and a composite geology map derived from Department of Minerals geology data. Data derived from the following sources: Digital elevation model in integer format, 25 m grid cells, produced 1997, Land Information Centre; Catchment variables derived from DEM, using Arcview 3.2; Geology data from 1:250 K Geology Map, Department of Mineral Resources of NSW; Derived Elevation, Slope Steepness, Drainage from DEM; Combined Geology and sub-catchments within Boorowa Shire; Derivation of individual grid layers for each map unit; Compilation of individual map units, using merge request function in Arcview 3.2; Derivation of vegetation mask, using Landsat ETM band 5 to create a native forest/woodland cover map; Intersection of pre-european vegetation map with M305 native woody vegetation map to produce extant layer.;\r\n;\r\nMethod used was based on expert modelling of vegetation types, based on consultant EcoGIS's (Nic Gellie) knowledge of distribution of similar vegetation types in relation to lithology and broad landscape variables. To reduce possible error in expert models, modelling zones based on a combination of lithology classes and sub-catchments were produced from expert examination of the spread and patterns of each vegetation group. The modelling zones helped to reduce the number of vegetation groups to be modelled down to 2-3 groups;\r\nCareful inspection of sites within each vegetation group helped to determine the broad environmental niche of each vegetation group. A table of possible relationships between vegetation groups and environmental variables was drawn up to help with the modelling process. It was clear that the patterns of vegetation in the study area were more influenced by geochemistry of the lithology classes and topographic position in the landscape, rather than the conventional aspect and moisture relationships found in coastal higher rainfall environments. This conclusion helped to determine the development of terrain variables that could separate vegetation groups that occurred predominantly on ridges and hillslopes from those vegetation groups that occurred in valley bottoms. A neighbourhood variable, using stream pattern derived from the watershed models within Arcview, helped to distinguish hillslopes from valley bottoms.;\r\n;\r\nThe modelling process enabled a complete audit of all vegetation types mapped in the study area and allowed a transparent and flexible process of mapping to be documented. In the event that detailed inspection of the results of the model or field validation resulted in possible changes to the map, individual modelling zones could be remodelled with the new knowledge, or new site data. This approach also prevented grid layers from spreading to areas where the vegetation groups would logically not occur in. When all modelling zones had been modelled, the resultant grid layers were then compiled into a single Arcview view. The data layers were then sorted into an agreed order of precedence that enabled each grid layer to be displayed on the final vegetation map. Reclassification and merge request functions within Arcview Spatial Analyst then produced a pre-European vegetation map. The final pre-European vegetation map was then masked with an extant vegetation cover to produce an extant vegetation map.";\r\n;\r\nVIS_ID 1624;\r\n;\r\nANZLIC: ANZNS0208000217

布尔瓦郡及周边地区现存原生植被。
本植被地图基于分类植被调查数据与建模图层制作，建模图层源自25米分辨率数字高程模型（Digital Elevation Model, DEM），以及由矿产资源部门地质数据生成的综合地质图。
数据来源如下：
1. 整数格式25米格网数字高程模型，1997年由土地信息中心（Land Information Centre）制作；
2. 利用ArcView 3.2从DEM中提取的流域变量；
3. 新南威尔士州矿产资源部（Department of Mineral Resources of NSW）1:25万地质图提供的地质数据；
4. 从DEM中提取的高程、坡度、水系信息；
5. 布尔瓦郡范围内的综合地质图层与子流域图层；
6. 为每个地图单元生成的独立格网图层；
7. 利用ArcView 3.2的合并请求功能完成各独立地图单元的拼接；
8. 利用陆地卫星增强型专题制图仪（Landsat ETM）第5波段生成原生林/灌丛覆盖图，进而提取植被掩膜；
9. 将欧洲殖民前植被地图与M305原生木本植被地图进行空间叠加分析，生成现存原生植被图层。

本研究采用的建模方法基于专家经验，由EcoGIS咨询公司的尼克·吉利（Nic Gellie）依据其对相似植被类型分布与岩性、宏观景观变量关系的认知开展植被类型专家建模。为降低专家建模的潜在误差，研究人员基于岩性类别与子流域的组合划分建模分区，通过对各植被组的分布范围与格局进行专家研判生成该分区。该建模分区可将待建模的植被组数量缩减至2-3组。

对每个植被组内的样点进行细致核查，可确定各植被组的宽泛环境生态位。研究人员梳理了植被组与环境变量间的潜在关联关系表，以辅助建模流程。研究发现，研究区域内的植被格局主要受岩性类别的地球化学特征与景观地形位置影响，而非沿海高降水环境中常见的坡向与湿度关联关系。该结论为地形变量的开发提供了依据，可用于区分主要分布在山脊与山坡的植被组，以及分布在谷底的植被组。利用ArcView中流域模型生成的水系格局邻域变量，可有效区分山坡与谷底区域。

该建模流程可对研究区域内所有已绘制的植被类型进行完整审计，并形成透明且灵活的成图文档。若对模型结果的详细核查或野外验证发现地图存在需要调整的内容，可结合新的认知或实地样点数据对单个建模分区进行重新建模。该方法还可避免格网图层扩展至植被组理论上不应分布的区域。完成所有建模分区的建模后，将生成的格网图层整合至单个ArcView视图中。随后按照约定的优先级顺序对数据图层进行排序，使各格网图层可在最终植被地图上正确显示。利用ArcView空间分析模块的重分类与合并请求功能，生成欧洲殖民前植被地图。最后，利用现存植被覆盖层对最终欧洲殖民前植被地图进行掩膜处理，得到现存原生植被地图。

VIS编号：1624

澳新土地信息委员会（ANZLIC）编号：ANZNS0208000217