Vegetation - Knoxville Wildlife Area [ds2812]

The California Department of Fish and Wildlife (Department) Vegetation Classification and Mapping Program (VegCAMP) created a fine-scale vegetation classification and map of the southern addition to the Departments Knoxville Wildlife Area (WA), Napa County, California following State Vegetation Survey, Federal Geographic Data Committee (FGDC), and National Vegetation Classification (NVC) Standards (Grossman et al 1998). The vegetation classification was derived from data collected in the field following the Combined Rapid Assessment and Relevé Protocol during the periods November 18–20, 2013 and April 28–May 1, 2014. Vegetation polygons were drawn using heads-up manual digitizing using the 2011 Napa County 30-cm resolution color infrared (CIR) imagery as the base imagery. Supplemental imagery included National Agricultural Imagery Program (NAIP) true color and CIR 1-meter resolution data from 2009–2012, BING imagery, and current and historical imagery from Google Earth. The minimum mapping unit (MMU) is 1 acre, with the exception of wetland types, which have an MMU of 1/2 acre. Ponds, riparian types, and the one vernal pool on the WA that were visible on the imagery were mapped regardless of size, and streams were generally mapped if greater than 10 m wide (narrower portions may have been mapped to maintain the continuity of the streams). Mapping is to the NVC hierarchy association, alliance, or group level based on the ability of the photointerpreters to distinguish types based on all imagery available and on the field data. Both the existing (northern) and new addition (southern) portions of the Knoxville WA were mapped in 2002 as part of the Napa County vegetation map (https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=14660). The 2002 map is at a coarse thematic resolution (alliance through macrogroup level) and vegetation in portions of the WA has changed since the 2004 Rumsey Fire, necessitating this map update. We have produced an updated version of the KWA portion of the 2002 map layer that uses the same spatial data, but added a crosswalk to the current classification and the upper levels of the current hierarchy. This map layer is included in the downloaded dataset for this map and an expanded metadata report for that crosswalk can be found at https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=164825.加利福尼亚州鱼类与野生动物部（California Department of Fish and Wildlife，以下简称“该部”）下属植被分类与制图项目（Vegetation Classification and Mapping Program, VegCAMP），遵循州植被调查规范、联邦地理数据委员会（Federal Geographic Data Committee, FGDC）及国家植被分类系统（National Vegetation Classification, NVC）标准（Grossman等，1998），完成了加利福尼亚州纳帕县诺克斯维尔野生动物保护区（Knoxville Wildlife Area, WA）南部新增区域的精细尺度植被分类与制图工作。本次植被分类的数据源为2013年11月18日至20日、2014年4月28日至5月1日期间，采用组合快速评估与样方调查协议（Combined Rapid Assessment and Relevé Protocol）采集的野外调查数据。研究以2011年纳帕县30厘米分辨率彩色红外（Color Infrared, CIR）影像作为基础底图，通过目视屏幕手动数字化（heads-up manual digitizing）绘制植被矢量斑块。补充制图影像包括2009至2012年美国农业部国家农业影像计划（National Agricultural Imagery Program, NAIP）的真彩色与1米分辨率彩色红外影像、必应（BING）影像，以及谷歌地球的当前与历史影像。本次制图的最小制图单元（Minimum Mapping Unit, MMU）为1英亩，湿地类型除外，其最小制图单元为0.5英亩。影像上可见的池塘、河岸植被类型以及保护区内的1处季节性水池（vernal pool），无论面积大小均完成了制图；宽度大于10米的溪流通常均予以制图，较窄区段亦可纳入以保证溪流的连续性。制图精度将匹配至国家植被分类系统的群丛（association）、联盟（alliance）或群组（group）层级，匹配依据为影像解译人员结合所有可用影像与野外数据区分植被类型的能力。诺克斯维尔野生动物保护区的原有（北部）与新增（南部）区域，曾于2002年作为纳帕县植被制图项目的一部分完成制图（数据源链接：https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=14660）。2002年的制图主题分辨率较为粗糙，制图层级覆盖联盟至宏群组；且自2004年拉姆西火灾（Rumsey Fire）发生以来，保护区部分区域的植被已发生显著变化，因此亟需对该图层进行更新。本次研究生成了2002年制图图层中诺克斯维尔野生动物保护区部分的更新版本，该版本沿用了原有的空间数据，但新增了与当前植被分类系统及当前分类层级上层级的分类对应对照表（crosswalk）。该制图图层已包含在本次制图的下载数据集中，关于该分类对应对照表的扩展元数据报告可通过以下链接获取：https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=164825。