Pronghorn Predicted Habitat - CWHR M182 [ds2626]

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预测生境模型用于表征各物种在其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项构建：1）全州范围内可获取的最优植被图（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数值的CWHR数据库。生境适宜性等级划分为低（非零数值小于0.34）、中（0.34~0.66）与高（大于0.66），等级划分依据物种三大生存必需条件——繁殖、觅食与隐蔽——的最大适宜性数值确定。需注意，此前版本的预测生境模型曾通过计算三大生存必需条件的平均值，来获取各生境类型与阶段类别的整体适宜性评分。生境适宜性评分基于面积大于40英亩的生境斑块制定，其解读结果在生境斑块面积大于200英亩时最为准确。 FVEG土地覆盖数据集由加州林业与消防局（CALFIRE）整合多项全州尺度土地覆盖与区域植被制图项目成果编制而成，这些项目于不同时间（大致为1990年至发布时）开展，分辨率亦各不相同。FVEG采用加州各区域当前可获取的最新且一致的数据集。研究人员制定了决策规则，用于在图层重叠区域确定优先采用的数据源图层。依据CWHR生境类型分类系统，通过分类转换对照表对各类数据源进行属性赋值。将CWHR生境类型属性赋予FVEG数据集后，即可提取各物种分布范围内具有非零适宜性数值的区域，从而生成一系列针对单一物种的预测适宜生境地图。 由于FVEG整合了全州范围内多种不同的土地覆盖评估项目成果，其判定适宜生境的预测能力会因物种而异，对于分布范围广泛的物种，其预测能力甚至可能因区域不同而存在差异。 尽管这些地图代表了加州鱼类与野生动物局（CDFW）针对CWHR体系内各物种的适宜生境分布所作出的最优估算，但该类地图仍受多项因素限制：1）特定区域内植被图的精度与分辨率；2）景观的动态特性——火灾与其他干扰事件改变生境条件的频率高于制图项目的更新频率；3）专家知识的时效性——尤其是在物种适应土地与气候条件变化、其他物种分布范围发生转移的背景下；4）针对物种整个分布范围的代表性样区开展物种专项调查的频率；5）集合种群动态——即种群因各类相互作用与响应在环境中发生的位置转移。 请勿将表征预测适宜生境的CWHR GIS数据用于判定某一特定地点是否存在目标物种。 CWHR预测生境模型的命名依据为各物种分配的4位字母数字混合CWHR标识符（亚种或其他亚分类单元则采用5位标识符）。 另有一份“CWHR修订追踪表”，其中记录了各物种的CWHR标识符、学名、通用名，以及其分布范围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、覆盖全州所有CWHR生境类型分布的GIS数据，以及“CWHR修订追踪表”均可从https://www.wildlife.ca.gov/Data/CWHR下载获取。