Cactus Mouse Predicted Habitat - CWHR M115 [ds2569]

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）指在物种分布范围内预测得到的适宜栖息地区域。该类模型基于以下核心输入数据构建：1）全州最佳可用植被地图（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余种陆生脊椎动物栖息地适宜性值的CWHR数据库。 栖息地适宜性等级分为低等级（非零值小于0.34）、中等级（0.34至0.66）与高等级（大于0.66），其划分基于物种3项生存必需条件——繁殖、觅食与隐蔽——的最大适宜性值计算得到。需注意，过往版本的该预测栖息地模型曾以3项生存必需条件的平均值，来计算每种栖息地类型与阶段类别的综合适宜性得分。 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，且其解读结果最适用于面积大于200英亩的栖息地斑块。 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）整合多项全州土地覆盖与区域植被测绘项目而成，这些项目于不同时段（约1990年至发布之时）开展，分辨率各异。FVEG采用加州各区域可获取的最新且一致的数据集。研究人员制定了决策规则，用于管控重叠区域中各数据图层的优先级；同时通过交叉映射对照表，按照CWHR栖息地类型分类系统为各类数据源赋予属性。 将FVEG数据赋予CWHR栖息地类型后，即可提取各物种分布范围内适宜性值非零的区域，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是全州多项不同土地覆盖评估项目的整合结果，其确定适宜栖息地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）对CWHR系统内任意物种适宜栖息地存在情况的最佳估算，但该类地图仍受多项因素限制：1）特定区域植被地图的精度与分辨率；2）景观的动态特性——火灾与其他干扰事件改变栖息地条件的频率高于测绘工作的追踪能力；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）针对物种全分布范围的代表性样本开展物种特异性调查的频率；5）集合种群动态——即种群在环境中因多种交互作用与响应而发生的位置转移。 CWHR预测适宜栖息地的地理信息系统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（亚种或其他亚分类群的标识符为5位）。 此外还有一份“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、分布范围及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、涵盖全州所有CWHR栖息地类型分布的地理信息系统数据，以及CWHR修订追踪表，均可从https://www.wildlife.ca.gov/Data/CWHR下载获取。