Vegetation Classification for the Nature Reserve of Orange County

The ultimate goal of this project is to create an updated fine‐scale vegetation map for about 58,000 acres of Orange County, consisting of the 37,000‐acre Orange County Central and Coastal Subregions Natural Community Conservation Plan (NCCP)/Habitat Conservation Plan (HCP) Habitat Reserve System; approximately 9,500 acres of associated NCCP/HCP Special Linkages, Existing Use Areas, and Non‐Reserve Open Space; and approximately 11,000 acres of adjoining conserved open space (study area). The project consisted of three phases. Phase 1: To update vegetation mapping, the Natural Reserve of Orange County (NROC) proposes to use Manual of California Vegetation (MCV) methods (2009), which will be implemented in two stages: Stage 1 – Development of a vegetation classification system for the Central and Coastal Subregions of Orange County that is consistent with the MCV. Stage 2 – Application of the vegetation classification system to create a vegetation map through photointerpretation of available aerial imagery and ground reconnaissance. The MCV methods were developed by the California Department of Fish and Game (CDFG) Vegetation Classification and Mapping Program in collaboration with the California Native Plant Society (CNPS). This approach relies on the collection of quantifiable environmental data to identify and classify biological associations that repeat across the landscape. For areas where documentation is lacking to effectively define all of the vegetation patterns found in California, CDFG and CNPS developed the Vegetation Rapid Assessment Protocol. This protocol guides data collection and analysis to refine vegetation classifications that are consistent with CDFG and MCV standards. Based on an earlier classification by Gray and Bramlet (1992), Orange County is expected to have vegetation types not yet described in the MCV. Using the MCV approach, Rapid Assessment (RA) data was collected throughout the study area and analyzed to characterize these new vegetation types or show concurrence with existing MCV types. Phase 2: Aerial Information Systems, Inc. (AIS) was contracted by the Nature Reserve of Orange County (NROC) to create an updated fine-scale regional vegetation map consistent with the California Department of Fish & Wildlife (CDFW) classification methodology and mapping standards. The mapping area covers approximately 86,000 acres of open space and adjacent urban and agricultural lands including habitat located in both the Central and Coastal Subregions of Orange County. The map was prepared over a baseline digital image created in 2012 by the US Department of Agriculture – Farm Service Agency's National Agricultural Imagery Program (NAIP). Vegetation units were mapped using the National Vegetation Classification System (NVCS) to the Alliance level as depicted in the second edition of the Manual of California Vegetation (MCV2). One of the most important data layers used to guide the conservation planning process for the 1996 Orange County Central & Coastal Subregion Natural Community Conservation Plan/Habitat Conservation Plan (NCCP/HCP) was the regional vegetation map created in the early 1990s by Dave Bramlett & Jones & Stokes Associates, Inc. (Jones & Stokes Associates, Inc. 1993). Up until now, this same map continues to be used to direct monitoring and management efforts in the NCCP/HCP Habitat Reserve. An updated map is necessary in order to address changes in vegetation makeup due to widespread and multiple burns in the mapping area, urban expansion, and broadly occurring vegetation succession that has occurred over the past 20 years since the original map was created. This update is further necessary in order to conform to the current NVCS, which is supported by the extensive acquisition of ground based field data and subsequent analysis that has ensued in those same 20 years over the region and adjacent similar habitats in the coastal and mountain foothills of Southern California. Vegetative and cartographic comparisons between the newly created 2012 image-based map and the original 1990s era vegetation map are documented in a separate report produced by the California Native Plant Society at the end of 2014. Phase 3: The California Native Plant Society (CNPS) Vegetation Program conducted an independent accuracy assessment of a new vegetation map completed for the natural lands of Orange County in collaboration with Aerial Information Systems (AIS), the California Department of Fish and Wildlife (CDFW), and the Nature Reserve of Orange County (NROC). This report provides a summary of the accuracy assessment allocation, field sampling methods, and analysis results; it also provides an in-depth crosswalk and comparison between the new map and the existing 1992 vegetation map. California state standards (CDFW 2007) require that a vegetation map should achieve an overall accuracy of 80%. After final scoring, the new Orange County vegetation map received an overall user's accuracy of 87%. The new fine-scale vegetation map and supporting field survey data provide baseline information for long-term land management and conservation within the remaining natural lands of Orange County. Data made available in the OC Data Portal in partnership with UCI Libraries.本项目的终极目标是为奥兰治县（Orange County）约5.8万英亩的区域制作更新后的精细植被地图，该区域包含3.7万英亩的奥兰治县中部与沿海次区域自然群落保护计划（Natural Community Conservation Plan, NCCP）/栖息地保护计划（Habitat Conservation Plan, HCP）栖息地保护区系统；约9500英亩的相关NCCP/HCP特殊连接区、现有使用区域及非保护区开放空间；以及约1.1万英亩的毗邻保护开放空间（即本研究区域）。 本项目共分为三个阶段： 第一阶段：为更新植被地图，奥兰治县自然保护区（Nature Reserve of Orange County, NROC）拟采用《加州植被手册（Manual of California Vegetation, MCV）》2009版方法，该方法分两阶段实施：第一阶段——构建与MCV标准一致的奥兰治县中部与沿海次区域植被分类体系；第二阶段——通过对现有航空影像的目视解译与地面踏勘，应用该分类体系制作植被地图。MCV方法由加州鱼类与狩猎局（California Department of Fish and Game, CDFG）植被分类与制图项目联合加州本土植物学会（California Native Plant Society, CNPS）开发。该方法依托可量化环境数据的采集，以识别并分类在景观中重复出现的生物群落。针对加州境内缺乏足够文档以有效界定所有植被类型的区域，CDFG与CNPS制定了《植被快速评估规程（Vegetation Rapid Assessment Protocol）》，该规程指导数据采集与分析工作，以细化符合CDFG与MCV标准的植被分类体系。基于Gray与Bramlet于1992年提出的早期分类体系，奥兰治县存在MCV尚未收录的植被类型。本研究采用MCV方法，在整个研究区域内收集快速评估（Rapid Assessment, RA）数据并开展分析，以明确这些新型植被类型，或验证其与现有MCV类型的一致性。 第二阶段：奥兰治县自然保护区（NROC）委托航空信息系统公司（Aerial Information Systems, Inc., AIS）制作符合加州鱼类与野生动物局（California Department of Fish & Wildlife, CDFW）分类方法与制图标准的更新版精细区域植被地图。制图区域覆盖约8.6万英亩的开放空间及毗邻的城市与农业用地，包括奥兰治县中部与沿海次区域内的栖息地。本次制图以美国农业部农场服务局2012年国家农业影像项目（National Agricultural Imagery Program, NAIP）生成的基准数字影像为基础。植被单元按照《加州植被手册（第二版）（Manual of California Vegetation 2nd Edition, MCV2）》中的分类，采用国家植被分类系统（National Vegetation Classification System, NVCS）绘制至联盟级（Alliance level）。1996年奥兰治县中部与沿海次区域自然群落保护计划/栖息地保护计划（NCCP/HCP）的保护规划流程中，最重要的参考数据层之一是Dave Bramlett与Jones & Stokes联合公司（Jones & Stokes Associates, Inc.）于1990年代初制作的区域植被地图（Jones & Stokes Associates, Inc., 1993）。直至今日，该地图仍用于指导NCCP/HCP栖息地保护区内的监测与管理工作。由于制图区域内广泛发生多起火灾、城市扩张，以及自原地图制作以来20年间普遍出现的植被演替，导致植被组成发生变化，因此亟需更新该地图。此外，为符合当前的NVCS标准，也需要开展本次更新——过去20年间，该区域及南加州沿海与山地丘陵地带的同类栖息地已完成大量地面实地数据采集与后续分析，为NVCS提供了支撑。2014年底，加州本土植物学会（CNPS）发布了一份独立报告，详细记录了2012年版基于影像的新植被地图与1990年代原版植被地图之间的植被与制图学对比情况。 第三阶段：加州本土植物学会（CNPS）植被项目联合航空信息系统公司（AIS）、加州鱼类与野生动物局（CDFW）及奥兰治县自然保护区（NROC），对奥兰治县自然用地的新版植被地图开展了独立精度评估。本报告总结了精度评估的抽样设计、野外采样方法与分析结果，同时深入对比了新地图与1992年版旧植被地图，并提供了对应转换表。根据加州标准（CDFW 2007），植被地图的总体精度需达到80%。最终评分显示，新版奥兰治县植被地图的总体用户精度达到87%。该新版精细植被地图及配套的实地调查数据，为奥兰治县剩余自然用地的长期土地管理与保护工作提供了基准信息。本数据集已通过与加州大学欧文分校图书馆合作的奥兰治县数据门户（OC Data Portal）对外开放。