canopy sampling Articles
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Traceflux: a small-scale tracer experiment at a forested site
Results from four successful tracer experiments carried out in a dense forest canopy are presented. For each experiment, sulphur hexafluoride SF6 was released from a point source in trunk space and air samples were collected at 19 horizontally distributed locations in the canopy. Meteorological measurements include fast-response turbulence data recorded at several locations in and above the ...
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No persistent changes in pasture vegetation or seed bank composition after fallowing
The practice of fallowing pastures during the growing season is intended to increase plant diversity and allow natural reseeding of forage grasses. Fallowing delivers these benefits in New Zealand, but has been adopted on rotationally stocked farms in the northeastern United States with little or no quantitative assessment. Allowing the pasture to remain ungrazed may allow weedy species to ...
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Soybean yield and soybean cyst nematode densities related to soil ph, soil carbonate concentrations, and alkalinity stress index
Soybean [Glycine max (L.) Merr.] grown on high pH, calcareous soils often suffer yield loss due to unavailability of Fe. Further yield decline can occur due to infestations by soybean cyst nematodes (Heterodera glycines Ichinohe; SCN) that are often present in greater numbers in high-pH soils. An observational study was conducted from 2001 to 2005 in Iowa to examine the relationships among: pH; ...
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Soybean yield and soybean cyst Nematode densities related to soil ph, soil carbonate concentrations, and alkalinity stress index
Soybean [Glycine max (L.) Merr.] grown on high pH, calcareous soils often suffer yield loss due to unavailability of Fe. Further yield decline can occur due to infestations by soybean cyst nematodes (Heterodera glycines Ichinohe; SCN) that are often present in greater numbers in high-pH soils. An observational study was conducted from 2001 to 2005 in Iowa to examine the relationships among: pH; ...
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Spatial analysis of early wheat canopy normalized difference vegetative index
Efficient use of real-time canopy sensors requires knowledge of the scale (resolution) of variation in the measured canopy property. Knowing the amount of needed optical data requires estimation of the optimal combination of physical sensor density (number of sensors along the applicator boom) and sensor output density (sensor readings per unit distance along the travel path). The objective of ...
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Herb layer productivity under different light gaps in the forests of Western Ghats of Karnataka, India
A productivity estimation of tree, shrub and herb layer biomass was undertaken in Uttara Kannada, a Western Ghats district in Karnataka in differentially managed forests. In addition to biomass, light gap in these sample sites was also estimated to understand the relationship between the light interception pattern at different canopy layers and their productivity. The studies indicate that tree ...
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Spatial analysis of early wheat canopy normalized difference vegetative index: determining appropriate observation scale
Efficient use of real-time canopy sensors requires knowledge of the scale (resolution) of variation in the measured canopy property. Knowing the amount of needed optical data requires estimation of the optimal combination of physical sensor density (number of sensors along the applicator boom) and sensor output density (sensor readings per unit distance along the travel path). The objective of ...
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Canopy gas exchange measurements of cotton in an open system
A portable, open transparent chamber system for measuring canopy gas exchanges was developed and tested. Differentials between incoming and outgoing atmospheric H2O and CO2 concentrations were used to calculate canopy transpiration (E) and net assimilation (A) at 10-s intervals using solenoid valve actuated sample lines connected to an infrared gas analyzer. A programmable data logger controlled ...
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