California Tiger Salamander (SON DPS) Predicted Habitat - CWHR A001b [ds3318]

CWHR Predicted Habitat Models represent areas of predicted suitable habitat for each species within its range. These models are built from the following principal inputs: 1) a statewide, best-available vegetation map (FVEG); 2) GIS data representing a species’ range; 3) the CWHR database of habitat suitability values for over 700 terrestrial vertebrate species. Habitat suitability ranks of Low (non-zero values less than 0.34), Medium (0.34-0.66), and High (greater than 0.66) are based on the maximum suitability value across the 3 species life requisites: reproduction, feeding, and cover. Note that previous versions of these Predicted Habitat Models used an average across the 3 life requisites in order to obtain an overall suitability score for each habitat type and stage class. Habitat suitability scores were developed based on habitat patch sizes greater than 40 acres in size and are best interpreted for habitat patches greater than 200 acres in size. The FVEG landcover dataset is an aggregation of multiple statewide landcover and regional vegetation mapping efforts, conducted at different points in time (approximately 1990 up to time of publishing) and at various resolutions, compiled by the California Department of Forestry and Fire Protection (CALFIRE). FVEG uses the most current and consistent data available for each region of the state. Decision rules were developed that controlled which layers were given priority in areas of overlap. Crosswalks were used to attribute the various data sources according to the CWHR habitat-type classification system. Attributing FVEG with CWHR habitat types allows for the extraction of areas with non-zero suitability values for each species within the bounds of its range, creating a series of maps of predicted suitable habitat which are species-specific. Because FVEG is an amalgam of disparate landcover assessment efforts across the state, the predictive power for determining suitable habitat will vary between species, and possibly even regionally for species which are widely distributed. While these maps represent CDFW’s best estimate of the presence of suitable habitat for any given species in the CWHR system, these maps are also limited by several factors: 1) the accuracy and resolution of vegetation maps in a given region; 2) the dynamic nature of the landscape in which fire and other disturbance events alter conditions at a greater frequency than mapping efforts can track; 3) the currency of expert knowledge, particularly as species adapt to changing land and climate conditions and the shifting of other species’ ranges; 4) the frequency of species-specific surveys across a representative sample of a species’ entire range; 5) metapopulation dynamics, which describes the shifting of populations within their environment as result of numerous types of interactions and responses. CWHR GIS data representing predicted suitable habitat should not be used to indicate the presence or absence of a particular species at any specific site. CWHR predicted habitat models are named according to the 4-character alpha-numeric CWHR ID assigned to each species (5 characters in the case of subspecies or other sub-taxa). There is also a “CWHR Revision Tracking Table” containing a record for each species, its CWHR ID, scientific name, common name, and range and habitat model data revision history. CWHR species range models, predicted habitat models, and GIS data of the statewide distribution of all CWHR habitat types, along with the CWHR revision tracking table, are available for download at https://www.wildlife.ca.gov/Data/CWHR.CWHR预测栖息地模型指代各物种种群分布范围内的潜在适宜栖息地区域。该类模型的构建主要基于以下三类核心输入：1）全州范围的最优可用植被图（FVEG）；2）表征物种种群分布范围的地理信息系统（Geographic Information System）数据；3）涵盖700余种陆生脊椎动物栖息地适宜性分值的CWHR数据库。 栖息地适宜性等级分为低（非零分值小于0.34）、中（0.34至0.66）、高（大于0.66）三级，其划分依据为物种三大生存必需条件——繁殖、觅食与隐蔽——对应的适宜性分值最大值。需注意，此前版本的该预测栖息地模型曾通过计算三大生存必需条件的平均分值，以获取各栖息地类型与阶段类别的综合适宜性评分。 栖息地适宜性分值的生成以面积大于40英亩的栖息地斑块为基准，其解读最优适配面积大于200英亩的栖息地斑块。FVEG土地覆盖数据集由加州林业与消防局（CALFIRE）整合多项全州及区域植被测绘项目成果编制而成，这些项目的实施时间跨度约为1990年至发布当日，且采用了不同的空间分辨率。FVEG针对全州各区域采用了当前可获取的最新且一致的数据，研究人员制定了决策规则以确定重叠区域内各数据图层的优先级，并通过交叉对照表依据CWHR栖息地类型分类体系为各类数据源赋予属性信息。 为FVEG数据集赋予CWHR栖息地类型属性后，即可提取各物种种群分布范围内具有非零适宜性分值的区域，进而生成一系列针对单一物种的预测适宜栖息地地图。由于FVEG是全州各类土地覆盖评估项目的整合成果，其判定适宜栖息地的预测能力会因物种而异，对于分布范围广泛的物种，甚至可能因区域不同而存在差异。 尽管上述地图代表了CWHR体系内针对任一物种的适宜栖息地存在情况的最优估算结果，但该类地图仍受以下若干因素限制：1）特定区域内植被图的精度与空间分辨率；2）景观的动态性：火灾与其他干扰事件改变栖息地条件的频率高于测绘项目的更新频率；3）专家知识的时效性：尤其当物种适应不断变化的土地与气候条件，以及其他物种种群分布发生迁移时；4）物种特异性调查的开展频率不足：未针对物种种群全分布范围的代表性样点开展足够频率的调查；5）集合种群动态：即种群在环境中因各类交互作用与响应而发生的分布偏移。 CWHR预测适宜栖息地的地理信息系统数据不得用于判定任一特定地点是否存在某一物种。CWHR预测栖息地模型的命名依据为分配给各物种的4位字母数字组合CWHR标识符（亚种或其他亚类群的标识符为5位）。此外还设有“CWHR修订追踪表”，其中包含各物种的相关记录，包括其CWHR标识符、学名、俗名，以及种群分布与栖息地模型数据的修订历史。 CWHR物种种群分布模型、预测栖息地模型、涵盖全州所有CWHR栖息地类型分布的地理信息系统数据，以及CWHR修订追踪表，均可通过https://www.wildlife.ca.gov/Data/CWHR下载获取。