A Capacitance Meter for Estimating Forage Weight

Fletcher, Joel E.; Robinson, Max E.

doi:10.2307/3894559

Cited by 33 publications

(21 citation statements)

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“…However, it is negatively influenced by rain or trampling (Castle ) and not applicable on steeper slopes or in structurally diverse vegetation. Another device, an electrical capacitance meter (Fletcher & Robinson ; Vickery et al. ), has received strong criticism because the actual moisture content influences the obtained values (Catchpole & Wheeler ).…”

Section: Introductionmentioning

confidence: 99%

Estimation of herbaceous biomass from species composition and cover

Axmanová

Tichý

Fajmonová

et al. 2012

Applied Vegetation Science

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Questions Biomass is an important ecological property, but its measurement is destructive and time‐consuming and therefore generally missing for historical vegetation plots. Here we propose and test indirect estimation of herbaceous biomass using models based on easily obtainable variables, namely plant height and cover. We compare these models with Ellenberg indicator values for nutrients (EIVs Nutrients), which are sometimes used as an alternative measure of productivity. Location Czech Republic, western Slovakia. Methods Above‐ground biomass (dry weight; g·m−2) was regressed against the following explanatory variables: (1) Cover E1, total percentage cover of the herb layer visually estimated in the field; (2) Biomass estimate‐raw, ‐adjusted and ‐median, calculated from plant covers and heights (according to a local flora); and (3) mean EIVs Nutrients calculated per plot. For the analyses, we used four data sets containing a total of 469 plots from different vegetation types: ‘Wet meadows’, ‘Dry grasslands’, ‘Fen–dry grassland transects’ and ‘Forest herb layer’. To test the applicability of different biomass estimates we chose an example of a species richness–productivity relationship in the ‘Wet meadows’ data set and describe differences in resulting patterns. Results Both cover of herb layer and calculated ‘biomass volumes’ were more accurate in predicting biomass dry weight than EIVs Nutrients. The best results were obtained from the Biomass estimate‐median model that combines median stand height and total cover of the herb layer. Cover E1 showed relatively tight correlations with biomass, particularly in sparse vegetation, but was a rather poor predictor when cover values were high. This was especially noticeable in application of the Cover E1 model in analysis of the species richness–productivity relationship. Conclusions In contrast to biomass, cover of the herb layer has a fixed upper limit (100%), which may lead to misinterpretations in dense, structurally diverse vegetation. Most promising is the Biomass estimate‐median method, which can be applied both to already sampled plots by calculating median height from average species heights according to local floras and to newly sampled plots using the median of plant heights measured in the field. Therefore, we propose it as a rapid, non‐destructive alternative to biomass harvest.

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Section: Introductionmentioning

confidence: 99%

Estimation of herbaceous biomass from species composition and cover

Axmanová

Tichý

Fajmonová

et al. 2012

Applied Vegetation Science

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“…A model of the electronic instrument for estimating pasture yield in situ, suggested by Fletcher and Robinson (4) and developed by Campbell, Phillips and O'Reilly (3) in New Zealand, was built at the Grassland Research Institute in 1963. The instrument consists of two units, a measuring head or probe, which is placed in the herbage, and a meter unit carried by the observer.…”

Section: Introductionmentioning

confidence: 99%

An Evaluation of an Electronic Instrument for Pasture Yield Estimation

Back

1968

Grass and Forage Science

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A model of the electronic instrument described by Campbell et al. (3) was built at the Grassland Research Institute and was found to behave in a very similar way to their New Zealand model. A considerable amount of field work was undertaken with it in 1964 and this demonstrated that no general relationship of acceptable accuracy had yet been found; nor could it be sufficiently improved by the inclusion of the meteorological and botanical factors recorded. This forces one to a consideration of double‐sampling techniques, which appear worth while; they will be discussed in Part 2 of this paper.

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“…With increasing frequency, capacitance decreased and conductance increased over the range tested. After considering the sensitivity of the instrument and sources of error, they compromised on a frequency of 3 MHz which was comparable to other meters (4,7,13).…”

Section: The University College Of North Wales Metermentioning

confidence: 63%

Uses and Capabilities of Electronic Capacitance Instruments for Estimating Standing Herbage

Neal

Neal²

1973

Grass and Forage Science

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A meter nsing electronic capacitance to estimate weight of standing regetation was first tested in 1949. It proved to be faster and more accurate than most indirect methods of measurement. Since then, other similar instruments have been built and several problems have become apparent. Short or dry vegetation, non-homogeneous distribution of vegetation, non-homogeneous phenology, and electronic circuit instability were the major problems. Tbe chief steps in the development of capacitance instruments for estimating vegetation weight are discussed. The significance of each of the major problems has been greatly reduced by improvements in instrumentation. Ilie technique of using electronic capacitance has now proved iteelf useful nnder a wide variety of range conditions.

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A Capacitance Meter for Estimating Forage Weight

Cited by 33 publications

References 0 publications

Estimation of herbaceous biomass from species composition and cover

Estimation of herbaceous biomass from species composition and cover

An Evaluation of an Electronic Instrument for Pasture Yield Estimation

Uses and Capabilities of Electronic Capacitance Instruments for Estimating Standing Herbage

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