Ground level photosynthetically active radiation dynamics in stands of Acacia mearnsii De Wild

ABSTRACTThe objective is to study the dynamics of photosynthetic radiation reaching the soil surface in stands of Acacia mearnsii De Wild and its influence on height growth in stands. This fact gives rise to the formulation of the following hypothesis for this study: "The reduction of the incidence of light inside the stand of black wattle will cause the inflection point in its height growth when this reaches 4 to 5 m in height, i.e. when the stand is between 2 and 3 years of age". The study was conducted in stands in the state of Rio Grande do Sul, Brazil, where diameters at breast height, total height and photosynthetically active radiation available at ground level were measured. The frequency tended to be more intense when the age of the stands increases. It was evident that a reduction of light incidence inside the forest occurred, caused by canopy closure. Consequently, closed canopy propitiated the competition of plants. This has affected the conditions for growth in diameter and height of this species, reason why it becomes possible to conceive the occurrence of an inflection point in the growth of these two variables, confirming the formulated hypothesis.

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Photosynthetically Active Radiation Environment, Patch Dynamics and Architecture in a Tropical Rainforest in Sumatra

Functional Plant Biology ◽

10.1071/pp9880327 ◽

1988 ◽

Vol 15 (2) ◽

pp. 327 ◽

Cited By ~ 25

Author(s):

EF Torquebiau

Keyword(s):

Photosynthetically Active Radiation ◽

Forest Dynamics ◽

Tropical Rainforest ◽

Lower Layer ◽

Ground Level ◽

Radiation Environment ◽

Horizontal Gradient ◽

Active Radiation ◽

Mature Forest ◽

Treefall Gap

The photosynthetically active radiation (PAR) environments of three sites within a tropical rainforest in Sumatra were characterised. The sites and sensor locations were chosen according to a previous study of forest dynamics based on forest mosaic maps and an analysis of forest architecture by means of detailed profile diagrams. Two sites were located in mature forest patches: one showed a layered architecture while the other had a continuous vertical distribution of foliage. A third site represented a 320 m� treefall gap. Vertical gradients of PAR from above canopy to ground level were studied in the mature forest zones, while a horizontal gradient of PAR at ground level was studied across a gap-mature forest boundary. Daily total PAR at ground level in the mature forest sites was 0.78% and 0.57% of incident radiation above the forest. The decrease of radiation from above canopy downwards was strikingly different between the sites: the layered site showed a 'PAR inversion' between successive layers, the amount of radiation under a given layer being less than at the top of the next lower layer. The non-layered site did not show such an inversion. The treefall gap radiation received was approximately 20% of the radiation recorded above the canopy. The spatial distribution of PAR in the forest is highly variable but can be usefully analysed against a framework of forest dynamics and architecture. Temporal distribution of PAR is also highly variable, and both distributions need to be analysed to understand photosynthetic responses and growth rates of rainforest species.

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Potential use of bialaphos, a microbially produced phytotoxin, to control red raspberry in forest plantations and its effect on black spruce

Canadian Journal of Forest Research ◽

10.1139/x91-066 ◽

1991 ◽

Vol 21 (4) ◽

pp. 489-497 ◽

Cited By ~ 13

Author(s):

Robert Jobidon

Keyword(s):

Active Ingredient ◽

Photosynthetically Active Radiation ◽

Black Spruce ◽

Growth Increment ◽

Height Growth ◽

First Year ◽

Quadratic Relation ◽

Foliar Injury ◽

Red Raspberry ◽

Active Radiation

Bialaphos foliar sprays were tested in eastern Quebec for control of red raspberry (Rubusidaeus L.), and the tolerance of planted black spruce (Piceamariana (Mill.) B.S.P.) seedlings was determined. Approximately 3 weeks after bialaphos was applied in July, August, or September, virtually all raspberry plants were killed. Efficiency of the June application, however, was much reduced. Spruce current-year foliage was more affected than older foliage. Foliar injury was more pronounced for bialaphos applications in June and July than for applications in August. First-year spruce survival was not affected by the treatments. Second-year evaluations revealed a significant quadratic relation of (i) month of application × bialaphos rate on raspberry density and (ii) bialaphos rate on raspberry height growth. Reduction in raspberry density and height growth was greater with the 2.0 and 2.5 kg active ingredient per hectare rates applied in August. As part of the evaluation of treatment efficiency, photosynthetically active radiation reaching spruce seedlings was measured using a portable integrating radiometer. Raspberry density and height growth were both negatively correlated with photosynthetically active radiation reaching spruce seedlings. A significant quadratic relation was found between bialaphos rate and 2nd-year spruce survival, which reached 95%, regardless of month and rate of application. A significant quadratic relation was found between spruce diameter growth increment and bialaphos rate. Except for calcium, 2nd-year spruce foliar mineral content was not affected by the treatments. Bialaphos treatments in August, with rates ranging from 1.0 to 2.0 kg active ingredient per hectare, had only slight or no adverse effects on spruce survival, foliar injury, and growth increment. Selective control of red raspberry in young black spruce plantations is a function of bialaphos rate and month of application.

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Deriving Photosynthetically Active Radiation at ground level in cloud-free conditions from Copernicus Atmospheric Monitoring Service (CAMS) products

10.5194/bg-2017-512 ◽

2018 ◽

Author(s):

William Wandji Nyamsi ◽

Phillipe Blanc ◽

John A. Augustine ◽

Antti Arola ◽

Lucien Wald

Keyword(s):

Photosynthetically Active Radiation ◽

Ground Level ◽

Photosynthetic Photon Flux Density ◽

Surface Radiation ◽

Coefficient Of Determination ◽

Photon Flux ◽

Photon Flux Density ◽

Distribution Method ◽

Active Radiation ◽

Monitoring Service

Abstract. A method is described that estimates the photosynthetically active radiation (PAR) at ground level in cloud-free conditions. It uses a fast approximation of the libRadtran radiative transfer numerical model, known as the k-distribution method and the correlated-k approximation of Kato et al. (1999). LibRadtran provides irradiances aggregated over several fixed spectral bands and a spectral resampling is proposed followed by an aggregation in the range [400, 700] nm. The Copernicus Atmosphere Monitoring Service (CAMS) produces daily estimates of the aerosol properties, and total column contents in water vapor and ozone that are input to the method. A comparison of the results is performed against instantaneous measurements of global Photosynthetic Photon Flux Density (PPFD) on a horizontal plane made in cloud-free conditions at seven sites of the Surface Radiation network (SURFRAD) in the USA in various climates. The bias ranges between −12 µmol m−2 s−1 (−1 % of the mean value at Desert Rock) and +61 µmol m−2 s−1 (+5 % at Penn. State Univ). The root mean square error ranges from 37 µmol m−2 s−1 (3 %) to 82 µmol m−2 s−1 (6 %). The coefficient of determination R2 ranges between 0.97 and 0.99. This work demonstrates the quality of the proposed method combined with the CAMS products.

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Incident photosynthetically active radiation as a basis for integrated management of purple nutsedge (Cyperus rotundus)

Weed Science ◽

10.1017/s0043174500088962 ◽

1997 ◽

Vol 45 (6) ◽

pp. 777-783 ◽

Cited By ~ 10

Author(s):

Christophe Neeser ◽

Renan Aguero ◽

Clarence J. Swanton

Keyword(s):

Costa Rica ◽

Photosynthetically Active Radiation ◽

Integrated Management ◽

Soil Surface ◽

Cyperus Rotundus ◽

Purple Nutsedge ◽

Active Radiation ◽

Tuber Production ◽

Reproductive Rates ◽

Artificial Shading

Artificial shading studies indicated that competition for photosynthetically active radiation (PAR) will limit tuber production in purple nutsedge. There were no data available to test whether there is a relationship between incident PAR underneath crop canopies and tuber production of this weed. In this study, the effect of crop competition on net reproductive rates of purple nutsedge tubers was measured under field conditions. Purple nutsedge plants were grown in association with bush beans, maize, maize and beans intercropped, sweet potato, pole beans, and bell pepper in a 2-yr field study in Costa Rica. Measurements were taken on the number of tubers produced during the growing season of each crop, and PAR transmittance was monitored weekly for the duration of the respective cropping cycles. Data on transmittance and incident solar radiation were used to calculate the daily average amount of PAR, available 15 cm above the soil surface. Regressions indicated that average incident PAR accounted for 95% of the variation in net reproductive rates. Average incident PAR also allowed a more precise competitive ranking of crops than either average or minimum transmittance. Bush beans had consistently the lowest average incident PAR values and therefore ranked as the most competitive crop in both years. Our data suggest that no net increase in tuber populations occurs if average incident PAR is below 2.7 MJ m−2d−1. Differences in the duration of the cropping cycle accounted only for a small proportion of the overall variation in net reproductive rates of purple nutsedge tubers. Information on the competitive ranking of different crops can be used to design crop rotations that could reduce reliance on herbicides on small farms in Costa Rica.

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A Mobile Platform for Measuring Canopy Photosynthetically Active Radiation Interception in Orchard Systems

HortTechnology ◽

10.21273/horttech.22.2.237 ◽

2012 ◽

Vol 22 (2) ◽

pp. 237-244 ◽

Cited By ~ 21

Author(s):

Bruce D. Lampinen ◽

Vasu Udompetaikul ◽

Gregory T. Browne ◽

Samuel G. Metcalf ◽

William L. Stewart ◽

...

Keyword(s):

Photosynthetically Active Radiation ◽

Juglans Regia ◽

Soil Surface ◽

Mobile Platform ◽

Seasonal Development ◽

Remotely Sensed Data ◽

Data Logger ◽

Yield Data ◽

Canopy Development ◽

Active Radiation

A mobile platform was developed for measuring midday canopy photosynthetically active radiation (PAR) interception in orchards. The results presented are for almond (Prunus dulcis) and walnut (Juglans regia), but the mobile platform can be used in other orchard crops as well. The mobile platform is adjustable to accommodate orchard row spacing from 4.8 to 7.8 m and is equipped with a global positioning satellite (GPS) receiver and radar for positional assessment as well as three IR thermometers for measuring soil surface temperature. Data from the mobile platform are logged at 10 Hz and stored on a data logger. Custom software has been developed to process the data. The mobile platform was used extensively for mapping midday canopy PAR interception in almond and walnut orchards in 2009 and 2010. The mobile platform produced comparable results to those collected with a handheld light bar with the advantage of being able to cover much larger areas and compare these data to mechanically harvested yield data over the same area. For almond orchards, midday canopy PAR interception peaked at ≈70% at an orchard age of ≈12 years. For walnut orchards, midday canopy PAR interception continued to increase to ≈15 years of age and peaked at a level above 80%. The mobile platform was also able to follow seasonal development of midday canopy PAR interception in young and mature orchards. This technology has potential for evaluating new varieties in terms of productivity per unit PAR intercepted, in evaluating hand pruning or mechanical hedging practices in terms of impact on PAR interception/productivity as well as evaluating effectiveness of insect or disease management treatments. It also has potential as a reference point for grower self-assessment to evaluate orchard canopy development compared with other orchards of similar variety, spacing, etc. Finally, this technology could be used as ground truth referencing for remotely sensed data.

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The whole-bole system: a conditioned dual-equation system for precise prediction of tree profiles

Canadian Journal of Forest Research ◽

10.1139/x77-063 ◽

1977 ◽

Vol 7 (3) ◽

pp. 488-497 ◽

Cited By ~ 38

Author(s):

J. P. Demaerschalk ◽

A. Kozak

Keyword(s):

Inflection Point ◽

Tree Height ◽

Ground Level ◽

Equation System ◽

Mathematical Functions ◽

Breast Height ◽

System A ◽

Precise Prediction ◽

Taper Equations ◽

Computerized System

A review is presented of the shortcomings of most existing taper equations which predict diameter along the stem as a function of tree height and diameter at breast height. A new computerized system is developed that has many desirable features for tree profile prediction. This new system consists of two mathematical functions, one describing the upper bole and the other describing the lower bole. The two functions are linked together at the inflection point and are continuous at that point. Tests of this model on 32 species age and locality groupings of British Columbia species show that although there is still a slight bias near ground level, the prediction of diameter inside bark is almost perfect over most of the length of the trees.

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