Vegetation Cover Data for 1953-1966, 1970 for USFS Study FSRM 1706-12

The file contains perennial grass basal cover and shrub foliar cover data collected for USFS Study FSRM 1706-12. A copy of the Study Plan may be downloaded from the web site. Measurements were taken on 20 randomly located permanent 100-ft. line transects in each of five pastures. The pastures had been grazed yearlong by cow-calf herds since 1915; utilization ranged from 47-60%. Two changes in grazing management were instituted at the start of the study period: 1) The utilization objective was lowered to 40%, and 2) Summer deferment (July-Sept) in alternate years began in 1958 in two pastures and in 1959 in the other two. Pasture 9 continued to be grazed yearlong and was measured in 1958 and 1963-1966 for comparative purposes. Data from pasture 9 were not included in published analyses. Mesquites (Prosopis velutina) in pastures 1 and 7 were killed with diesel oil between 1954 and 1957. Mesquites in pastures 8, 9, and 10 were left untreated. Cover was measured annually in late summer from 1957-1966 (except 1960) in units of 0.01 ft. Perennial grass was recorded as basal intercept; i.e., length of live root crown portion of tuft at ground level. Shrub cover was recorded as the entire live crown intercept excluding conspicuous openings or areas of dead crown. Taxa were recorded separately to the species level in most cases and sometimes to the genus level only. The OTHERPG code refers to unidentified perennial grass species; OTHSHRUB to unidentified shrub species. Sources of data were the original field data sheets except: Sources for pasture 1 in 1961-1966 were handwritten summaries that had been compiled from the field data sheets. A value of -9999 in a field means that no data were available because a reading was not made for that date.

本数据集包含美国林务局（USFS）FSRM 1706-12号研究采集的多年生草本基部盖度与灌木叶盖度数据，研究方案副本可从指定网站下载。研究在5个牧场各布设20条随机定位的永久性100英尺线样带开展测量；自1915年起，上述牧场便由肉牛母牛-犊牛群全年放牧，牧草利用率介于47%至60%之间。本研究启动时实施了两项放牧管理调整：其一，将牧草利用率目标下调至40%；其二，自1958年起，其中2个牧场开始实施隔年夏季休牧（7月至9月），另外2个牧场则于1959年启动该项休牧措施。牧场9仍保持全年放牧模式，分别于1958年及1963年至1966年开展测量以作对照，但其数据未纳入已发表的分析内容。1954年至1957年间，牧场1和7中的牧豆树（Prosopis velutina）采用柴油灭杀处理，而牧场8、9、10中的牧豆树未做任何处理。盖度测量于每年夏末开展，覆盖1957年至1966年（1960年除外），测量单位为0.01英尺；其中多年生草本盖度采用基部截距法记录，即记录地面处丛生株活根冠部分的长度，灌木盖度则记录为完整的活冠截距，需剔除明显的空隙或枯冠区域。绝大多数情况下，分类单元记录至物种水平，部分情况仅记录至属水平；其中OTHERPG代码指代未鉴定的多年生草本物种，OTHSHRUB代码指代未鉴定的灌木物种。数据原始来源为野外原始记录表，但以下情况除外：1961年至1966年牧场1的数据来源于根据野外记录表汇编的手写汇总表。字段中取值为-9999表示该日期未开展测量，无对应有效数据。