California Spotted Owl Predicted Habitat - CWHR B270b [ds3342]

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）指代各物种种群分布范围内的潜在适宜生境区域。此类模型基于以下核心输入构建：1）全州范围内可获取的最优植被地图（FVEG）；2）表征物种种群分布范围的地理信息系统（Geographic Information System, 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。 生境适宜性等级分为低（非零数值小于0.34）、中（0.34~0.66）与高（大于0.66），其划分依据为物种3类生存必需条件——繁殖、觅食与隐蔽——对应的适宜性数值的最大值。需注意，此前版本的该预测生境模型曾基于3类生存必需条件的平均值，来计算每种生境类型与演替阶段的综合适宜性得分。 生境适宜性得分的测算基于面积大于40英亩的生境斑块，其解读最优适配面积大于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（California Department of Forestry and Fire Protection, CALFIRE）整合而成，整合了多套全州及区域植被测绘成果，这些测绘工作于不同时段（大致为1990年至发布当日）完成，且分辨率各异。FVEG会采用加州各区域当前可获取的最一致的数据。研究人员制定了决策规则，用于在数据图层重叠区域确定优先采用的图层。各类数据源依据CWHR生境类型分类体系，通过交叉映射表（Crosswalks）完成属性赋值。将CWHR生境类型赋值至FVEG数据集后，即可提取各物种种群分布范围内具有非零适宜性数值的区域，进而生成一系列物种专属的潜在适宜生境地图。 由于FVEG整合了全州范围内多套不同的土地覆盖评估成果，因此其在判定适宜生境时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。尽管这些地图代表了加州鱼类与野生动物部（California Department of Fish and Wildlife, CDFW）针对CWHR体系内各物种适宜生境存在情况的最优估算结果，但该类地图仍受多项因素限制：1）特定区域内植被地图的精度与分辨率；2）景观的动态性：火灾与其他干扰事件改变生境条件的频率高于测绘工作的更新频率；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范围发生迁移时；4）物种专属调查的开展频率：调查需覆盖物种种群全分布范围的代表性样本；5）集合种群动态：该概念指种群在环境中因各类相互作用与响应而发生的分布迁移。 不得将表征潜在适宜生境的CWHR地理信息系统数据，用于判定某一特定地点是否存在特定物种。CWHR预测生境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（若为亚种或其他亚类群，则采用5位标识符）。此外还有一份CWHR修订追踪表（CWHR Revision Tracking Table），其中包含各物种的相关记录，包括其CWHR标识符、学名、通用名，以及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、涵盖全州所有CWHR生境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。