Ground truthing protocols for biomass estimation in rangeland environments

Abstract

Remote sensing for the assessment and mapping of total standing biomass relies on accurate ground data for calibration and validation. The spatial heterogeneity of rangelands pose challenges in sampling methodologies, demanding a large number of replicate measurements that are expensive and labour demanding when working on the scale of pastoral stations. In this paper we present a ground truthing protocol that can be used for biomass estimation in heterogeneous rangeland environments, important for the development of assessments based on remote sensing or growth modelling. The protocol is based on a combination of visual estimates, crop circle NDVI, and disk-plate meter height recordings. Relationships between these indirect measurements and biomass were specific for either season or vegetation type. A combination of these measurements in a multivariate regression provided an accurate alternative, while strongly reducing the number of cuts required.

Evaluation of vegetation indices for rangeland biomass estimation in the Kimberley area of Western Australia

“…The independent variables are the derived vegetation indices while the dependent variables are the total or green biomass. Sampling sites were further merged into three main groups according to the vegetation type; Open plains (6 sites), Bunch grasses (9 sites) and Spinifex (5 sites) (Mundava et al, 2013). Open plains refer to sites in areas with periodic flooding with mostly annual grasses, Bunch grasses include mostly perennial grasses and cover sandy Pindan country and other higher terrain while Spinifex sites were dominated by hard or soft spinifex (Triodia spp).…”