Merriam's Chipmunk Predicted Habitat - CWHR M060 [ds2518]

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）表征各物种在其分布范围内的潜在适宜生境分布区域。此类模型基于以下三类核心输入参数构建：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分值的CWHR数据库。 生境适宜性等级划分为低（非零分值小于0.34）、中（0.34~0.66）与高（大于0.66），该等级划分基于物种3类生存必需条件——繁殖、觅食与隐蔽——的最大适宜性分值。请注意，此前版本的CWHR预测生境模型采用3类生存必需条件的平均分值，以生成每种生境类型与演替阶段类别的整体适宜性评分。 本次生境适宜性分值的制定基于面积大于40英亩的生境斑块，其适用场景最优为面积大于200英亩的生境斑块。 FVEG土地覆盖数据集（FVEG）由加州林业与消防保护局（CALFIRE）汇编，整合了多项全州土地覆盖与区域植被制图成果——这些成果于1990年前后至本数据集发布的不同时段，以不同分辨率完成。FVEG采用加州各区域当前可获取的最一致、最新的数据，并制定了决策规则以明确重叠区域内各图层的优先级。同时通过分类转换对照表（Crosswalks），依据CWHR生境类型分类系统为各类数据源赋予对应属性。将FVEG数据与CWHR生境类型进行属性关联后，即可提取各物种分布范围内具有非零适宜性分值的区域，进而生成一系列针对特定物种的预测适宜生境地图。 由于FVEG整合了全州范围内各类不同的土地覆盖评估成果，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，甚至不同区域的预测能力也可能存在差异。 尽管此类地图代表了加州鱼类与野生动物部（CDFW）对CWHR系统中任意物种适宜生境存在情况的最优估计，但它们仍受多项因素限制：1）特定区域内植被图的精度与分辨率；2）景观的动态变化特性：火灾与其他干扰事件改变生境条件的频率高于制图工作的更新频率；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以及其他物种种群分布范围转移的背景下；4）针对物种种群完整分布范围的代表性样本开展物种特异性调查的频率；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移。 CWHR预测生境GIS数据不得用于判定某一特定地点是否存在某一物种。CWHR预测生境模型的命名采用为各物种分配的4位字母数字混合CWHR编号（亚种或其他亚分类单元的编号为5位）。此外还设有“CWHR修订跟踪表”，其中包含各物种的相关记录，包括其CWHR编号、学名、通用名、分布范围及生境模型数据的修订历史。 CWHR物种种群分布范围模型、预测生境模型、涵盖全州所有CWHR生境类型分布的GIS数据，以及CWHR修订跟踪表，均可从https://www.wildlife.ca.gov/Data/CWHR下载获取。