GRSM_GRTS_SAMPLE_AREA

The GRSM Vegetation and Soil monitoring plot locations were chosen through a GRTS design (Generalized Random Tessellation Stratified). In order to implement GRTS, a sampling frame of all possible sampling areas is needed. This layer serves as that sampling frame. General sampling area& non-target masking The sample area was selected from within the 6 Vital Signs primary watersheds, which are Abrams Creek, Cataloochee Creek, Deep Creek, Hazel Creek, Little Pigeon River/Porters Creek, and Little River/Goshen Prong. Within these watersheds, the sampling area was masked to remove areas with slope >70%, as well as areas mapped as heath balds (these are considered non-forested, and so fall outside of our protocol for forest monitoring). Also, all area within 30 meters of a road, trail, social trail, or maintained front-country area was masked out. Accounting for feasibility of access Based on experiences of previous monitoring efforts and the 2015 pilot project for this protocol, a decision was made to limit sampling area based on feasibility of access. Several algorithms for determining feasible area were tested, and the one chosen uses a combination of modeled Total travel time to the plot location from our office, and the portion of that time that was modeled as being off-trail. The general rule is that the more time it takes to reach a plot location, the less amount of time we are willing to commit to off trail travel. This method of feasibility modeling created a sampling area that is both feasible and creates higher crew safety by not committing to long off-trail hikes once in the backcountry of the park. The feasibility design limits the sampling area to the following categories:1. Areas < 2 hours from Twin Creeks Science Center, and up to 90 minutes off trail2. Areas between 2-3 hours from Twin Creeks Science Center, and up to 60 minutes off trail3. Areas between 3 and 8 hours from Twin Creeks Science Center, and up to 30 minutes off trail. of Elevation The last step in the sampling area creation was to stratified the area based on both watershed and elevation. The area was divided into watersheds, then again into elevational strata of Low, Medium and High:Low Elevation Band: Less than 800m (2624')Mid Elevation Band: 800m - 1300m (2624' - 4265')High Elevation Band: Greater than 1300/ (4265')These chosen elevation bands produce 18 Watershed X Elevation strata. Of these, 2 strata were of too small area to be considered for sampling, and so were removed (Cataloochee Creek - Low Elevation, and Abrams Creek - High Elevation). The corresponding Integration of Resource Management Applications (IRMA) NPS Data Store reference is Great Smoky Mountains National Park GRTS Sample Area.大烟山（GRSM, Great Smoky Mountains）国家公园植被与土壤监测样地的点位选取采用了广义随机镶嵌分层抽样（GRTS, Generalized Random Tessellation Stratified）设计。开展GRTS抽样需构建覆盖所有潜在抽样区域的抽样框，本图层即承担该抽样框的功能。 通用抽样区域划定与非目标区域掩膜 样本区域选自6个核心生命流域，分别为艾布拉姆斯溪（Abrams Creek）、卡托奇溪（Cataloochee Creek）、迪普溪（Deep Creek）、黑兹尔溪（Hazel Creek）、小鸽子河/波特溪（Little Pigeon River/Porters Creek）以及小河/戈申普朗克（Little River/Goshen Prong）。在上述流域范围内，需对坡度大于70%的区域、被标注为石楠秃地的区域（该类区域属于非林地，不在本森林监测规程的适用范围内）进行掩膜剔除。同时，距道路、步道、社会步道或维护完善的前区区域30米以内的所有区域也需予以掩膜排除。 可达性适配调整 结合既往监测工作经验与本规程2015年试点项目的实践经验，团队决定基于可达性限制抽样区域的范围。经测试多种可行区域判定算法后，最终选用的方案综合了从本单位办公室前往样地的模拟总行程时间，以及其中非步道行程的占比。其通用原则为：抵达样地的行程耗时越长，允许的非步道行程时长越短。该可达性建模方法既保障了抽样区域具备实际作业可行性，同时通过规避偏远区域的长距离非步道徒步，提升了野外作业人员的安全水平。本次可达性设计将抽样区域划分为以下三类： 1. 距双溪科学中心（Twin Creeks Science Center）耗时小于2小时，且非步道行程上限为90分钟的区域； 2. 距双溪科学中心耗时2至3小时，且非步道行程上限为60分钟的区域； 3. 距双溪科学中心耗时3至8小时，且非步道行程上限为30分钟的区域。 海拔分层与最终筛选 抽样区域构建的最后一步为基于流域与海拔进行分层。首先按流域划分区域，再进一步划分为低、中、高三个海拔层级： - 低海拔带：海拔低于800米（2624英尺） - 中海拔带：海拔800米至1300米（2624英尺至4265英尺） - 高海拔带：海拔高于1300米（4265英尺） 上述海拔层级与流域组合后共生成18个“流域×海拔”分层单元。其中2个分层单元因面积过小不适用于抽样，予以剔除（卡托奇溪-低海拔层与艾布拉姆斯溪-高海拔层）。本数据集对应的资源管理集成应用（IRMA, Integration of Resource Management Applications）美国国家公园管理局数据存储参考条目为：大烟山国家公园GRTS抽样区域。