[en] Georeferencing field plots by means of GPS/GLONASS techniques is becoming compulsory for many applications concerning forest management and inventory. True coordinates obtained in a total station traverse were compared against GPS/GLONASS occupations computed from one navigation-grade and three survey-grade receivers. Records were taken under a high Pinus sylvestris L. forest canopy situated in a mountainous area in central Spain. The horizontal component of the absolute error was a better descriptor of the performance of GPS/GLONASS receivers compared to the precision computed by the proprietary software. The vertical component of absolute error also failed to show the effects revealed when the horizontal one was studied. These differences might be critical for applications involving high-demanding surveys, in which a comparison against a terrestrially surveyed ground truth is still mandatory for accuracy assessment in forested mountainous areas. Moreover, a comparison of diverse Differential GPS/GLONASS techniques showed that the effect of lengthening the baseline and lowering the logging rate was not significant in this study. Differences among methods and receivers were only observed for recording periods between 5 and 15 minutes. The hand-held receiver was inappropriate for plot establishment due to its inaccuracy and a low rate of fixed solutions, though it may be used for forest campaigns tolerating low precision or permitting the employment of periods of 20 minutes or longer for plot mensuration.

[es] La georreferenciaci&oacute;n de trabajos de campo por medio de GPS/GLONASS es cada vez m&aacute;s necesaria para muchas aplicaciones en la gesti&oacute;n e inventario forestal. Se compararon coordenadas reales levantadas con estaci&oacute;n total con las obtenidas por un navegador y tres equipos de calidad topogr&aacute;fica. Los registros se efectuaron bajo una masa de Pinus sylvestris L. del Sistema Central, Espa&ntilde;a. La componente horizontal del error absoluto result&oacute; ser un mejor descriptor de la calidad de las mediciones de los receptores GPS/GLONASS que los valores de precisi&oacute;n proporcionados por el software de los equipos. La componente vertical del error absoluto no mostr&oacute; los efectos revelados por la componente horizontal. Estas diferencias pueden ser cr&iacute;ticas para trabajos que requieran levantamientos topogr&aacute;ficos de precisi&oacute;n, en los cu&aacute;les un contraste con itinerarios de validaci&oacute;n sobre el terreno sigue siendo indispensable para calcular la exactitud en &aacute;reas forestales monta&ntilde;osas. Por otro lado, la comparaci&oacute;n de diversas t&eacute;cnicas de GPS/GLONASS diferencial mostr&oacute; que los cambios en la longitud de la l&iacute;nea base y de la tasa de registros no fueron significativos en este estudio. S&oacute;lo se observaron diferencias ente los m&eacute;todos y receptores para tiempos de registro de 5 a 15 minutos. El navegador no result&oacute; adecuado para el establecimiento de parcelas debido a la inexactitud y baja tasa de soluciones fijadas, pero puede ser utilizado en campa&ntilde;as que toleren bajas precisiones y permitan tiempos de registro iguales o superiores a 20 minutos para las medias forestales.