Niwot Ridge saddle 1:500 integrated terrain unit map (ITUM).

A 350 x 500 m integrated terrain unit map (ITUM) was produced at 1:500 scale inside the 350 x 500 m saddle grid, and the 1:500 digital elevation model (DEM). Vegetation was mapped using Komarkova's (1979) classification system (Braun-Blanquet) units. All map units were mapped to 1g8-inch minimum map-polygon-size resolution. The map is part of the Saddle grid geographic information system (GIS). Many GIS projects use an approach in which existing mapped information is digitized into the GIS database directly from the original sources. The maps may have different map scale, map-unit resolutions, dates of data collection, and classification systems. When these different sources are combined in a GIS, artifacts may arise due to boundary mismatches and scale incompatibility (Dangermond and Harnden 1990). Integrated geobotanical mapping can minimize many of these problems. This method simultaneously maps vegetation and other terrain features that are interpreted on a common air-photo base (Everett et al. 1978, Walker et al. 1980). We use the term geobotany in its traditional European sense to refer to the study of plant communities and their relationships to geology, landforms, and soils (Braun-Blanquet 1932). Terrain geomorphic boundaries are used to guide the delineation on aerial photographs of most major vegetation boundaries similiar to the landscape-guided vegetation mapping approach developed in Europe (Zonneveld 1988) and the integrated terrain unit mapping approach developed by the Environmental System Research Institute in Redlands, CA (Dangermond and Harnden 1990). Additional information concerning the Niwot Ridge LTER GIS can be found in Walker et al. (1993).

研究团队在350×500米的鞍状网格区域内，制作了比例尺为1:500的综合地形单元图（integrated terrain unit map, ITUM）与1:500分辨率的数字高程模型（digital elevation model, DEM）。植被制图采用科马罗娃（Komarkova）1979年提出的布劳恩-布朗凯（Braun-Blanquet）分类体系的植被单元。所有地图单元的最小制图多边形分辨率设定为1/8英寸（原文疑似"1g8-inch"为"1/8-inch"笔误）。该地图属于鞍状网格地理信息系统（Saddle grid geographic information system, GIS）的组成部分。诸多地理信息系统项目采用直接从原始数据源将现有制图信息数字化并导入GIS数据库的工作流程。此类地图可能存在比例尺、制图单元分辨率、数据采集日期与分类体系各不相同的问题。当将这些不同来源的数据整合至GIS中时，可能会因边界不匹配与比例尺不兼容产生数据伪影（Dangermond与Harnden，1990）。综合地植物学制图能够有效减少上述诸多问题。该方法可基于统一的航空摄影底图，同时完成植被与其他地形要素的制图（Everett等，1978；Walker等，1980）。本文采用欧洲传统语境下的地植物学概念，指代植物群落及其与地质、地貌和土壤之间关系的研究（Braun-Blanquet，1932）。地形地貌边界被用于指导航空影像上多数主要植被边界的勾绘，该方法与欧洲开发的景观导向型植被制图法（Zonneveld，1988）以及加利福尼亚州雷德兰兹市环境系统研究所提出的综合地形单元制图法思路相似（Dangermond与Harnden，1990）。有关尼沃特岭长期生态研究（Long-Term Ecological Research, LTER）地理信息系统的更多细节，可参阅Walker等（1993）的研究成果。