Multi-temp oral estimation of forage biomass in heterogeneous pastures using static and mobile ultrasonic and hyperspectral measurements

摘要

Efficient feed production from grassland, including grazing and harvesting for forage conservation, requires constant monitoring of total farm grasslands to ensure consistent animal production. Ground based remote sensing technologies have been recognised as a practical methodology to estimate various vegetation parameters at the field scale. Particularly, the combined use of e.g. spectral sensors and ultrasonic sensors might be of interest for the prediction of vegetation biomass in heterogenous pastures. The aim of this study was to evaluate the applicability of ultrasonic and hyperspectral mobile measurements to map spatial and temporal yield variation, over two consecutive years, in heterogeneous pastures. Field measurements were conducted at five sampling dates between April 2013 and May 2014 in three pastures with different grazing intensities (extensive, lenient, very lenient). Multivariate regression methods and Kriging interpolation were used to develop prediction models for fresh matter yield for every sampling date and grazing intensity. The results suggest that mobile multisensory systems can produce acceptable accuracies for forage quantity assessment in extremely heterogeneous grasslands. However, the prediction error increased towards the late successional stages due to the increasing cover of dead material. Mobile systems may facilitate mapping of larger grassland areas at high spatial position accuracy, allowing the identification of nested structures within the pastures.