Deer Mouse Predicted Habitat - CWHR M117 [ds2571]

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（CWHR Predicted Habitat Models）代表了各物种在其分布范围内的潜在适宜栖息地区域。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）代表物种种群分布的地理信息系统（Geographic Information System, GIS）数据；3）涵盖700余种陆地脊椎动物物种的栖息地适宜性值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）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——的最大适宜性分值。需注意，此前版本的预测栖息地模型采用三大生存必需条件的平均值，来计算每种栖息地类型及阶段类别的整体适宜性得分。 栖息地适宜性分值基于面积大于40英亩的栖息地斑块制定，其最优适用场景为面积大于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成果，这些成果于不同时期（大致为1990年至发布时）以不同分辨率完成，由加州林业与消防局（California Department of Forestry and Fire Protection, CALFIRE）汇编而成。FVEG采用加州各区域当前可获取的最新且一致的数据，并制定决策规则以确定重叠区域中各图层的优先级。同时通过交叉对照表，将各类数据源按照CWHR栖息地类型分类系统进行属性赋值。 将CWHR栖息地类型属性赋予FVEG数据集后，即可在物种种群分布范围内提取各物种的非零适宜性值区域，进而生成一系列针对特定物种的潜在适宜栖息地地图。 由于FVEG是全州各地不同土地覆盖评估成果的整合集合，因此适宜栖息地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系统内任意给定物种的适宜栖息地存在情况的最优估算结果，但此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）景观的动态特性——火灾及其他干扰事件改变环境的频率高于测绘工作的追踪更新频率；3）专家知识的时效性，尤其是在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发生转移的背景下；4）针对物种种群完整分布范围的代表性样本开展物种专属调查的频率；5）集合种群动态——即各类交互与响应导致种群在其生存环境中发生转移的现象。 CWHR地理信息系统数据（即预测适宜栖息地数据）不得用于判定某一特定地点是否存在某一物种。 CWHR预测栖息地模型以分配给各物种的4位字母数字组合CWHR标识符命名（亚种或其他亚分类单元则为5位）。此外还有一份"CWHR修订跟踪表"，其中包含各物种的相关记录，包括其CWHR标识符、学名、通用名，以及种群分布与栖息地模型数据的修订历史。 CWHR物种种群分布模型、预测栖息地模型、全州所有CWHR栖息地类型分布的地理信息系统数据，以及"CWHR修订跟踪表"，均可从https://www.wildlife.ca.gov/Data/CWHR 下载获取。