Lesser Slender Salamander Predicted Habitat - CWHR A058 [ds2016]

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预测生境模型（CWHR Predicted Habitat Models）指各物种种群分布范围内的潜在适宜生境区域。该类模型基于以下核心输入构建：1）全州最优可用植被图（FVEG）；2）表征物种种群分布范围的GIS数据；3）收录700余种陆生脊椎动物生境适宜性分值的CWHR数据库。生境适宜性等级分为低（非零值小于0.34）、中（0.34~0.66）与高（大于0.66），其判定依据为物种繁殖、觅食与隐蔽3项生存必需条件对应的最大适宜性分值。值得注意的是，此前版本的预测生境模型采用这3项生存必需条件的平均值，计算每种生境类型与阶段类别的总体适宜性得分。生境适宜性分值基于面积大于40英亩的生境斑块开发，其适用最优场景为面积大于200英亩的生境斑块。 FVEG土地覆盖数据集整合了多次全州土地覆盖与区域植被制图工作的成果，这些工作于不同时期（大致1990年至本数据集发布时）完成，分辨率各异，由加州林业与消防局（California Department of Forestry and Fire Protection, CALFIRE）编制。FVEG采用该州各区域当前最精准且一致的可用数据，制定了决策规则以处理重叠区域的图层优先级问题，并通过跨参考对照表（Crosswalks）依据CWHR生境类型分类系统为各类数据源赋予属性。将FVEG与CWHR生境类型完成属性匹配后，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，从而生成一系列物种专属的潜在适宜生境地图。 由于FVEG是全州各类土地覆盖评估成果的整合集合，因此适宜生境判定的预测能力会因物种而异，对于分布广泛的物种甚至可能因区域不同而存在差异。尽管此类地图代表了加州鱼类与野生动物局（California Department of Fish and Wildlife, CDFW）对特定物种适宜生境存在情况的最佳估算，但它们仍受以下若干因素限制：1）特定区域植被图的精度与分辨率；2）景观的动态特性：火灾及其他干扰事件改变生境条件的频率高于制图更新的频率；3）专家知识的时效性，尤其是在物种适应土地与气候变化、其他物种种群分布发生转移的背景下；4）针对物种种群全分布范围的代表性样地开展物种专属调查的频率；5）集合种群动态（Metapopulation Dynamics）：即种群因各类相互作用与环境响应而在其栖息环境中发生的迁移变化。 CWHR用于表征潜在适宜生境的GIS数据不得用于判定任意特定地点是否存在某一物种。CWHR预测生境模型按照为每个物种分配的4位字母数字型CWHR ID命名（亚种或其他次级分类单元的ID为5位）。此外还设有"CWHR修订跟踪表"，其中包含每个物种的相关记录，包括其CWHR ID、学名、通用名、种群分布与生境模型数据的修订历史。 CWHR物种种群分布模型、预测生境模型、涵盖所有CWHR生境类型全州分布的GIS数据，以及"CWHR修订跟踪表"，均可在https://www.wildlife.ca.gov/Data/CWHR 下载。