Developing Techniques to Quantify Phenological Development of Smooth Brome (Bromus inermis Leyss.): Sampling Variability

Management of invasive grasses such as smooth brome (Bromus inermis Leyss.) and Kentucky bluegrass (Poa pratensis L.) is a critical issue for land managers in the Northern Great Plains. Recent surveys of US Fish and Wildlife Service (USFWS) grasslands revealed fragments of native prairie and widespread invasion of two exotic cool-season grasses, smooth brome and Kentucky bluegrass. Understanding and identifying phenological stages of these grasses provides information necessary to effectively administer defoliation or other management treatments. I developed a method for USFWS staff to quickly estimate phenological leaf stage of smooth brome. My objectives were to develop training materials to allow others to correctly identify smooth brome leaf stage and to investigate observer variation in estimating leaf stage. I tested 11 observers with 15 samples for efficacy in using our training material. I also had three observers sample 42 sites on USFWS lands across North Dakota, South Dakota, and Minnesota. Sampling was conducted between 19 May and 04 July, 2013, during the period when cool season grasses were actively growing. Results indicated that my training material was highly effective in helping field workers identify phenological stages. I found no significant differences in identification of phenological stage among multiple observers after they were trained with our phenology guide. With proper training, personnel can quickly become proficient at estimating phenology and leaf stage of smooth brome, thereby allowing managers to precisely time treatments for improvement of grassland health and restoration or maintenance of biological integrity in native prairie systems