Limitations to Estimating Production on Rangelands

Abstract

“Each ranch is different from every other ranch, each pasture is different from every other pasture, each pasture is different every year, and the pasture changes throughout the year.” - Larry Howery, UA Cooperative Extension Rangeland Management Extension Specialist (retired) Rangeland management is a difficult venture requiring decision-makers to use various ecological data and assessments to evaluate continually changing conditions. Estimating aboveground net primary production (ANPP) is a frequently used tool for rangeland management and monitoring. ANPP, or production, is the amount of aboveground plant biomass accumulated over a specific time period (Byrne et al. 2011). Rangeland or forage production is typically measured annually after the growing season and is often used to calculate or re-evaluate carrying capacity, stocking rates, or as an indicator of ecological condition, etc. There are various methods to collect production data ranging from direct methods, indirect methods, and non-destructive methods such as remote sensing. Traditional ground-based methods are often labor-intensive and insufficient to collect reliable estimates because vegetation growth is highly variable and can exceed 40% variation on an interannual basis (Reeves et al. 2019). Despite the popularity of collecting production data for range management purposes, inaccuracy and sampling errors from each method should be carefully considered before implementing management decisions based on production data alone. Range managers and producers should be aware of the limitations of using production data to inform management decisions.