Osprey Predicted Habitat - CWHR B110 [ds2084]

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预测栖息地模型指各物种种群分布范围内的预测适宜栖息地区域。此类模型基于以下核心输入构建：1）全州最优可用植被地图（FVEG）；2）代表物种种群分布范围的地理信息系统（GIS）数据；3）涵盖700余种陆生脊椎动物栖息地适宜性值的CWHR数据库。栖息地适宜性等级分为低（非零值小于0.34）、中（0.34~0.66）和高（大于0.66），划分依据为三类物种生存必需条件（繁殖、觅食、隐蔽）的最大适宜性值。需注意，此前版本的预测栖息地模型通过计算三类生存必需条件的平均值，以获取每种栖息地类型与阶段类群的整体适宜性得分。栖息地适宜性得分基于面积大于40英亩的栖息地斑块生成，其最佳解读场景为面积大于200英亩的栖息地斑块。 FVEG土地覆盖数据集整合了多项全州土地覆盖及区域植被测绘项目，这些项目于不同时段（大致为1990年至发布之时）以不同分辨率开展，由加州林业与消防局（CALFIRE）汇编完成。FVEG采用该州各区域当前可获取的最一致数据。研究人员制定了决策规则，用于管控重叠区域中各数据层的优先级，并通过交叉映射表（Crosswalks）依据CWHR栖息地类型分类系统对各类数据源进行属性赋值。将FVEG数据赋予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值的区域，从而生成一系列针对特定物种的预测适宜栖息地地图。 由于FVEG是全州范围内多项不同土地覆盖评估项目的整合成果，因此其在确定适宜栖息地方面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和野生动物部（CDFW）对CWHR系统中任一物种适宜栖息地存在情况的最优评估，但仍受多项因素限制：1）特定区域内植被地图的精度与分辨率；2）景观的动态特性：火灾及其他干扰事件改变栖息地条件的频率高于测绘工作的追踪更新速度；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）针对物种种群全分布范围的代表性样地开展物种专项调查的频率；5）复合种群动态：即种群在环境中因各类相互作用与响应而发生的迁移变化。 不得将CWHR预测适宜栖息地的GIS数据用于判定某一特定地点是否存在某一特定物种。CWHR预测栖息地模型的命名依据为分配给各物种的4位字母数字混合CWHR标识符（亚种或其他亚分类单元的标识符为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、通用名，以及分布范围与栖息地模型数据的修订历史。CWHR物种种群分布范围模型、预测栖息地模型、覆盖全州所有CWHR栖息地类型分布的GIS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。