Foothill Yellow-Legged Frog (Feather River DPS) Predicted Habitat - CWHR A043b [ds3351]

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）指在物种种群分布范围内，针对各物种预测得到的适宜生境分布区域。该模型的构建主要依托三类核心输入数据：1）全州范围内的最优可用植被图（FVEG）；2）表征物种种群分布范围的地理信息系统（GIS）数据；3）涵盖700余种陆生脊椎动物生境适宜性分值的CWHR数据库。生境适宜性等级划分为低（非零分值小于0.34）、中（0.34~0.66）与高（大于0.66），其划分依据为物种三大生存必需条件——繁殖、觅食与隐蔽——对应的最大生境适宜性分值。需注意，早期版本的预测生境模型采用三大生存必需条件的平均分值，来计算各类生境类型与阶段类别的整体适宜性得分。本数据集的生境适宜性分值基于面积大于40英亩的生境斑块开发，其最佳解读场景为面积大于200英亩的生境斑块。FVEG土地覆盖数据集由加州林业与消防局（CALFIRE）整合多项全州土地覆盖及区域植被测绘项目成果编制而成，这些测绘工作于不同时期（大致覆盖1990年至本数据集发布之时）以各异的分辨率开展，且针对州内各区域采用了当前可得的最新且一致的数据源。针对数据重叠区域，团队制定了决策规则以确定各图层的优先级，并通过属性映射表将各类数据源按照CWHR生境类型分类系统完成属性赋值。为FVEG数据集赋予CWHR生境类型标签后，即可提取物种种群分布范围内具备非零适宜性分值的区域，进而生成一系列物种专属的适宜生境预测地图。由于FVEG是全州多项不同土地覆盖评估工作的整合成果，适宜生境判定的预测能力会因物种而异，对于分布范围广泛的物种，甚至可能在不同区域存在差异。尽管本系列地图代表了加州鱼类与野生动物局（CDFW，California Department of Fish and Wildlife）针对CWHR体系内各物种的适宜生境存在情况所做出的最优估计，但该类地图仍受多项因素限制：1）特定区域植被图的精度与分辨率；2）景观的动态性：火灾及其他干扰事件改变生境条件的频率高于测绘更新的频率；3）专家知识的时效性：尤其在物种适应土地与气候条件变化、其他物种种群分布发生迁移的背景下；4）物种全分布范围内代表性采样点的专项调查频率；5）集合种群动态：即种群在环境中因各类相互作用与响应发生的迁移变化。CWHR预测生境的GIS数据不得用于指示特定地点是否存在某一物种。CWHR预测生境模型以分配给各物种的4位字母数字CWHR ID命名，亚种或其他亚分类单元对应的模型则使用5位ID。此外还设有“CWHR修订跟踪表”，其中包含每个物种的相关记录，涵盖其CWHR ID、学名、俗名、分布范围及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、全州所有CWHR生境类型分布的GIS数据，以及“CWHR修订跟踪表”，均可通过https://www.wildlife.ca.gov/Data/CWHR下载获取。