Ground-truthing of remotely sensed within-field variability in a cv. Barbera plot for improving vineyard management

Tropical landscapes are, in general, a mosaic of pasture, agriculture, and forest undergoing various stages of succession. Forest succession is comprised of continuous structural changes over time and results in increases in aboveground biomass (AGB). New remote sensing methods, including sensors, image processing, statistical methods, and uncertainty evaluations, are constantly being developed to estimate biophysical forest changes. We review 318 peer-reviewed studies related to the use of remotely sensed AGB estimations in tropical forest succession studies and summarize their geographic distribution, sensors and methods used, and their most frequent ecological inferences. Remotely sensed AGB is broadly used in forest management studies, conservation status evaluations, carbon source and sink investigations, and for studies of the relationships between environmental conditions and forest structure. Uncertainties in AGB estimations were found to be heterogeneous with biases related to sensor type, processing methodology, ground truthing availability, and forest characteristics. Remotely sensed AGB of successional forests is more reliable for the study of spatial patterns of forest succession and over large time scales than that of individual stands. Remote sensing of temporal patterns in biomass requires further study, in particular, as it is critical for understanding forest regrowth at scales useful for regional or global analyses.

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Ground truthing groundwater-recharge estimates derived from remotely sensed evapotranspiration: a case in South Australia

Hydrogeology Journal ◽

10.1007/s10040-014-1200-7 ◽

2014 ◽

Vol 23 (2) ◽

pp. 335-350 ◽

Cited By ~ 21

Author(s):

Russell S. Crosbie ◽

Phil Davies ◽

Nikki Harrington ◽

Sebastien Lamontagne

Keyword(s):

Groundwater Recharge ◽

South Australia ◽

Remotely Sensed ◽

Ground Truthing

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Underwater photographic reconnaissance and habitat data collection in the Florida Keys—A procedure for ground truthing remotely sensed bathymetric data

Open-File Report ◽

10.3133/ofr20201118 ◽

2020 ◽

Author(s):

Zachery W. Fehr ◽

Kimberly K. Yates

Keyword(s):

Data Collection ◽

Florida Keys ◽

Remotely Sensed ◽

Bathymetric Data ◽

Ground Truthing

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Objective stratification and sampling-effort allocation of ground-truthing in benthic-mapping surveys

ICES Journal of Marine Science ◽

10.1093/icesjms/fsp280 ◽

2009 ◽

Vol 67 (4) ◽

pp. 628-637 ◽

Cited By ~ 12

Author(s):

Annika J. Clements ◽

James A. Strong ◽

Clare Flanagan ◽

Matthew Service

Keyword(s):

Resource Constraints ◽

Slope Angle ◽

Calculated Data ◽

Remotely Sensed ◽

Irish Sea ◽

Sampling Effort ◽

Remotely Sensed Data ◽

Sediment Grain Size ◽

Effort Allocation ◽

Ground Truthing

Abstract Clements, A. J., Strong, J. A., Flanagan, C., and Service, M. 2010. Objective stratification and sampling-effort allocation of ground-truthing in benthic-mapping surveys. – ICES Journal of Marine Science, 67: 628–637. The application of statistical procedures for objective stratification of sampling effort during map ground-truthing is presented. Marine benthic mapping is usually undertaken in two stages: a remotely sensed acoustic survey followed by ground-truthing to confirm ground-type and habitat classification. The objective of this study was to assess the application of optimum allocation analysis (OAA) through the use of remotely sensed data to direct expensive ground-truthing sampling effort. At an offshore site in the Irish Sea, classification of remotely sensed data, namely bathymetry and slope angle, generated six predicted ground-types. Calculated data variances within each ground-type were assumed to be a predictor of substratum heterogeneity, and these were used in an OAA to apportion ground-truthing effort objectively within each ground-type in order to achieve a set level of sampling precision. The sampling effort recommended by the OAA was realistic and practical with regard to video footage, but the collection of grabs was limited by resource constraints. The coefficient of variation (CV) of the video ground-truthing data matched that estimated by OAA, but the inability to collect all the recommended grabs resulted in CVs greater than expected for sediment grain-size parameters. The efficient identification of substratum classes using OAA represents a first stage whereby this method could direct ground-truthing that could ultimately be used for habitat mapping.

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Ground Truthing and Physiological Validation of Vis-NIR Spectral Indices for Early Diagnosis of Nitrogen Deficiency in cv. Barbera (Vitis vinifera L.) Grapevines

Agronomy ◽

10.3390/agronomy9120864 ◽

2019 ◽

Vol 9 (12) ◽

pp. 864

Author(s):

Cecilia Squeri ◽

Matteo Gatti ◽

Alessandra Garavani ◽

Alberto Vercesi ◽

Marta Buzzi ◽

...

Keyword(s):

Leaf Gas Exchange ◽

Nitrogen Deficiency ◽

Vitis Vinifera L ◽

N Availability ◽

Spectral Indices ◽

Leaf Level ◽

Ground Truthing ◽

Cv Barbera ◽

Relative Change ◽

Non Destructive

Several narrow or broadband spectral indices can be calculated at varying spatial and spectral resolution, which can then be correlated with the physiological and nutritional status of the leaves. In a three-year trial carried out on fruiting, potted cv. Barbera grapevines subjected to full (N+) or no (N0) nitrogen supply, seasonal evolution of different leaf spectral indices were correlated with non-destructive chlorophyll readings (Minolta SPAD meter), leaf gas exchange, and vine performance. Throughout the entire trial, N starvation resulted in greater-than-proportional limitation of vine yield as compared to vegetative growth (55% compared to 26% less than values measured on N+). Indices calculated within the red-edge spectral domain had highest sensitivity to relative change between N+ and N0, also indicating that the promptest response was recorded at the median shoot zone level. Twelve broadband indices were linearly correlated with leaf blade N concentration at veraison, indicating that N values ≤ 1.8% of dry matter identify a limiting N status. Any of these indices collected at the leaf level can be reliably used as a non-destructive predictor of N availability, albeit due to significant between-year variation in their absolute values at a given N level, readings should always include a well-supplied N treatment.

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