Laser point-quadrat sampling for estimating foliage-height profiles in broad-leaved forests

2001 ◽  
Vol 31 (3) ◽  
pp. 410-418 ◽  
Author(s):  
Philip J Radtke ◽  
Paul V Bolstad
Keyword(s):  
North Carolina ◽  
Leaf Area ◽  
Field Studies ◽  
Area Index ◽  
Quadrat Sampling ◽  
Range Finding ◽  
The North ◽  
Broad Leaved Forest ◽  
Western North Carolina ◽  
Point Quadrat

A technique for estimating the vertical distribution of foliage area in broad-leaved forests was developed. The technique is similar to optical point-quadrat sampling, where estimates are based on heights to the lowest leaves above numerous sample locations beneath a canopy. In optical point-quadrat sampling, heights to lowest leaves are measured with a telephoto lens. Here, heights were measured using a commercially available laser range-finding instrument. The laser point-quadrat technique was tested in field studies conducted under broad-leaved forest canopies in western North Carolina and east-central Minnesota, U.S.A. Foliage-height profiles obtained by laser point-quadrat sampling were consistent with two of four published foliage-height profiles observed in 1995 at the North Carolina field locations. Total leaf area estimates obtained by laser point quadrats were not significantly correlated with values of leaf area index estimated by recent litter fall analyses at the North Carolina and Minnesota field locations. Although further evaluation and refinement of the technique is needed, laser point-quadrat sampling shows promise as a means of obtaining foliage-height profiles at a significantly reduced effort and with greater accuracy than methods commonly in use today.

scholarly journals Measurement of grapevine canopy leaf area by using an ultrasonic-based method

OENO One ◽  
2013 ◽  
Vol 47 (3) ◽  
pp. 183 ◽  
Author(s):  
Marco Vitali ◽  
Mario Tamagnone ◽  
Tiziana La Iacona ◽  
Claudio Lovisolo
Keyword(s):  
Leaf Area ◽  
Large Scale ◽  
Irrigation Management ◽  
Management Training ◽  
Ultrasonic Sensors ◽  
Leaf Sample ◽  
Area Index ◽  
Canopy Area ◽  
Point Quadrat ◽  
Leaf Canopy

<p style="text-align: justify;"><strong>Aim</strong>: Measurement of leaf area in grapevine has always been a critical point in researches focused on irrigation management, training systems, source-sink interrelationships and efficiency of spray application to canopies. In this work, we propose the use of ultrasonic sensors as a fast and accurate tool for the estimation of large portions of leaf canopy area.</p><p style="text-align: justify;"><strong>Methods and results</strong>: Through outputs of ultrasonic sensors installed on a tractor moving along vineyard rows, we calculated an ultrasonic-based leaf density index that we correlated with three measurements or estimates of canopy area: I) direct measurement of the area of a canopy portion (LAØ), assessed by summing the areas of all the leaves, where each single-leaf area was assessed by regressing the leaf diameter (the maximum width perpendicular to the main rip) against the related leaf area calculated on the basis of a relation between the leaf diameter and the leaf area, previously assessed through an area meter on a 20-leaf sample; II) the point quadrat output (LApq); and III) the canopy leaf area index (LAI) obtained through LAI-2000 (Li-Cor) technology. The measurements were assessed on six cultivars in three replicate rows (8-12 plants per cultivar per row) in a vineyard trained to a vertical trellis system.</p><p style="text-align: justify;"><strong>Conclusion</strong>: When we correlated the three independent control parameters with each other, we obtained highly significant correlations between LApq and LAØ, but less significant correlations between these two and LAI-2000 outputs. Also, the correlations between ultrasonic outputsoutputs and LAØ and LApq were significant, with R2 ranging between 0.84 and 0.85. On the contrary, no significant correlation was found between ultrasonic outputs and LAI-2000 outputs. These results were obtained by averaging all the values belonging to each replicated cultivar (10.5 m along the row, i.e., twelve contiguous vines); on the contrary, when the analysis was done over a shorter distance (3.5 m, i.e., four contiguous vines), the reliability of the ultrasonic-based method decreased.</p><p style="text-align: justify;"><strong>Significance and impact of the study</strong>: These results point to the ultrasonic technology as a powerful tool to estimate large-scale leaf canopy area, with potential applications in precision farming. At the moment, however, the limitation of this approach is the requirement of reference values for leaf area (e.g., assessed by point quadrat) to obtain absolute and not only relative outputs. With this application we can quantify, in a few hours, the canopy of a whole vineyard, in order to analyze different vegetation zones or to follow canopy development.</p>

scholarly journals Simulated insect defoliation and duration of weed interference affected soybean growth

Weed Science ◽  
2006 ◽  
Vol 54 (4) ◽  
pp. 735-742 ◽  
Author(s):  
Travis C. Gustafson ◽  
Stevan Z. Knezevic ◽  
Thomas E. Hunt ◽  
John L. Lindquist
Keyword(s):  
Leaf Area ◽  
Defense Mechanism ◽  
Field Studies ◽  
Area Index ◽  
Early Season ◽  
Weed Interference ◽  
Insect Defoliation ◽  
Weed Growth ◽  
Simultaneous Control ◽  
Vegetative And Reproductive Growth

An improved understanding of crop stress from multiple pests is needed for better implementation of integrated pest management (IPM) strategies. Field studies were conducted in 2003 and 2004 at two locations in eastern Nebraska to describe the effects of simulated early-season insect defoliation of soybean and duration of weed interference on soybean growth. Three levels of simulated defoliation (undefoliated, 30, and 60%) and seven durations of weed interference (weedy and weed free; weed removal at V2, V4, V6, R3, and R5) were evaluated in a split-plot design. Defoliation significantly reduced soybean leaf-area index (LAI), total dry matter (TDM), and crop height in season-long weedy treatments only. Biomass partitioning during vegetative and reproductive growth was affected by both defoliation and weed interference. Increase in soybean relative growth rate (RGR) and biomass production soon after defoliation occurred (e.g., V5 stage) indicated potential defense mechanism by which soybean is able to adjust its physiology in response to the loss of leaf area. Weed interference combined with defoliation caused the greatest yield losses up to 97%. Results from this study indicate the need for monitoring early-season insect density and weed growth to determine if simultaneous control of both pests may be needed.

On Partnering and Tourism: A Comparison of Two Small Towns in Western North Carolina

2005 ◽  
Vol 27 (4) ◽  
pp. 19-21
Author(s):  
Molly Levin
Keyword(s):  
North Carolina ◽  
Small Towns ◽  
Partnership Model ◽  
The North ◽  
Development Organizations ◽  
Western North Carolina ◽  
Community Development Organizations ◽  
Ethnographic Data ◽  
The Impact

Many community development organizations seek to involve their clients in projects through partnerships. This paper addresses the partnership model of the North Carolina-based organization HandMade in America and its Small Towns Revitalization Program. Ethnography plays an important role in this investigation. I spent the summer of 2004 as an intern at HandMade in America (HandMade), collecting ethnographic data in order to create a survey measuring the impact that the Small Towns program is having on the quality of residents' lives. While sitting in numerous living rooms and kitchens talking with men and women, old and young, local and newcomer, it became clear that while there are similarities across the region, each town has its own resources and problems that dictate the concerns of its residents.

Effect of residual leaf area index on spatial components of Tifton 85 pastures and ingestive behaviour of sheep

2017 ◽  
Vol 57 (5) ◽  
pp. 903 ◽  
Author(s):  
W. L. Silva ◽  
J. P. R. Costa ◽  
G. P. Caputti ◽  
A. L. S. Valente ◽  
D. Tsuzukibashi ◽  
...  
Keyword(s):  
Leaf Area Index ◽  
Leaf Area ◽  
Rainy Season ◽  
Structural Characteristics ◽  
Light Interception ◽  
Dry Season ◽  
Area Index ◽  
Dead Material ◽  
Point Quadrat ◽  
Ingestive Behaviour

This study compared the effect of residual leaf area index (rLAI) on the spatial distribution of morphological components of Tifton 85 (Cynodon spp.) pastures and the ingestive behaviour of grazing sheep. Also, it was investigated whether any specific correlation could be found between pasture structural characteristics and sheep ingestive behaviour. Four rLAI treatments (0.8; 1.4; 2.0 and 2.6) with four replications were evaluated per period. Sheep grazed under rotational stocking management and they grazed for 4 days in each pasture while pasture regrowth period was determined by the 95% light interception requirement. Pasture structure was evaluated using inclined point-quadrat, LAI estimates, light interception and leaf : stem ratio. The 2.6 rLAI yielded the highest proportion of dead material in the lower canopy. In the post-grazing period the proportion of leaves increased with increasing rLAI, especially on the canopy surface during the rainy season. In the pre-grazing average pasture height ranged between 19 and 26 cm with dead material and stem observed up to the canopy surface in the dry season. The animals grazed longer on the last day (89.72%) compared with the first day (80.25%) in the dry season. However, they spent less time (11.45%) ruminating in the dry season compared with the rainy season (15.38%), regardless of the grazing day. Grazing time decreased and rumination time increased as rLAI increased. Sheep grazing time correlated negatively with pasture height, before and after grazing. The sheep tend to graze longer on Tifton 85 pastures when rLAI was lower and forage supply was possibly less as on the last grazing day and in the dry season.

scholarly journals Development of the leaf area and the productivity structure of the sunflower hybrids in the north-eastern Forest-Steppe of Ukraine

2019 ◽  
pp. 33-39
Author(s):  
М.М. Sakhoshko ◽  
M.I. Kravchenko ◽  
V.M. Yatsenko ◽  
I.O. Kolosok
Keyword(s):  
Leaf Area ◽  
Field Experiments ◽  
Unit Area ◽  
Geographical Area ◽  
Main Element ◽  
Forest Steppe ◽  
Area Index ◽  
The North ◽  
North Eastern ◽  
Sunflower Crop

At the present stage, the model of leaf plant development is increasingly considered as the main element of genotypes adaptation to specific cultivation conditions, geographical area, etc. Under these conditions, the potential of the hybrid, the range of its adaptation to environmental conditions is determined by the level of interaction between the development of the assimilation apparatus and the generative organs. An urgent task aimed at improving the productivity of sunflower crop due to the use of genotypes adapted to the conditions of the north-eastern Forest-Steppe and Polyssya of Ukraine is to identify typical schemes of interaction of photosynthetic potential and parameters of plant productivity and crop yields. The studies were conducted in accordance with the program for the development of a variety model for the conditions of the north-eastern Forest-Steppe and Polyssya of Ukraine. Field experiments were carried out in 2016‒2019 at the Sumy National Agrarian University and the Institute of the Agriculture of North East of Ukraine. In the studies, 28‒56 hybrids of different originators were tested annually. Sunflower was cultivated according to the technology recommended for the area, with pre-harvesting density of 60 thousand plants / ha. Harvesting was done manually, from two central rows of a 4-rows plot. The results were processed using the Statistics package. The data on yield indices and values of leaf area coefficient (LAC) of crop for groups of varieties separated by the duration of growing season were analyzed. It was found that the increasing of leaf area was accompanied by an increasing of yield in case of comparing groups with dates of technological maturation until 20 August, 1 September and 10 September. In all cases, the maximum value of the leaf area index ranged from 3.12‒3.52 m2/m2. These dynamics of indicators indicated to the regulatory nature of the values of leaf area coefficient (LAC) of modern sunflower crop and the absence of genotypes (or conditions) capable of maintaining these values at the level of more than 3.3‒3.5 m2/m2. According to the analysis of correlation pleiades, the presence of several levels was found and the relative independence of the relationships between the group of parameters, determining the morphological structure of plants and the vertical structure of crop and the group of parameters, characterizing the content of chlorophyll and its concentration per unit area of leaf surface. In practical terms, the results of the analysis indicated the potential informative nature of the complex use of parameters characterizing the morpho-structure of plants, primarily the index of leaf area and the index of chlorophyll concentration per unit area. In order to isolate the typical schemes characteristic of different levels of adaptation to the conditions of the zone, data on 29 sunflower hybrids distributed in the region were clustered. The results of the analysis allowed to distinguish three significantly different algorithms for the realization of the vegetative and generative potential of sunflower hybrids in the area of the north-eastern Forest-Steppe of Ukraine. It has been established that one of the factors for successful realization of the generative potential of sunflower hybrids in the conditions of the zone is the ability to preserve and (in some cases) to improve the structure of relations between the dynamics and parameters of the plant leaf apparatus and the parameters of their generative development.

Comparative growth and development of four spurred anoda (Anoda cristata) accessions

Weed Science ◽  
1998 ◽  
Vol 46 (1) ◽  
pp. 91-98 ◽  
Author(s):  
Mark J. VanGessel ◽  
Jill Schroeder ◽  
Philip Westra
Keyword(s):  
North Carolina ◽  
New Mexico ◽  
Leaf Area ◽  
Growth And Development ◽  
Leaf Shape ◽  
Common Garden ◽  
Field Studies ◽  
Climatic Conditions ◽  
Weed Biology ◽  
Variable Species

Field studies were conducted in Colorado and New Mexico to examine growth and development of spurred anoda accessions from Colorado, Mississippi, New Mexico, and North Carolina. Accessions were grown in a common garden in both locations. Leaf and stem weight ratios, leaf area ratio, and leaf area per plant were determined. North Carolina and Mississippi accessions were similar in morphology and appearance. Leaf shape, degree of pubescence, and coloration were different in the Colorado and New Mexico accessions. At both sites, the Colorado accession was taller and the canopy wider than other accessions. In Colorado in 1993, North Carolina and New Mexico accessions had the highest total weight followed by Colorado, then Mississippi. In 1994, final total weights of North Carolina, Mississippi, and New Mexico accessions were similar and greater than the Colorado accession. All accessions had similar final total weights in New Mexico in 1993. In 1994, Mississippi, North Carolina, and New Mexico accessions had similar total weights. The Colorado accession flowered earlier than other accessions. Seeds from Mississippi and North Carolina accessions grown in Colorado were heavier than the New Mexico or Colorado accession. This research demonstrates why making inferences of weed biology for variable species that occur over diverse geographic and climatic conditions is difficult and why regionally specific data are needed for variable species.

Leaf Area and Competition for Light between Plant Species using Direct Sunlight Transmission

1988 ◽  
Vol 2 (2) ◽  
pp. 159-165 ◽  
Author(s):  
Graham K. Walker ◽  
Robert E. Blackshaw ◽  
Jack Dekker
Keyword(s):  
Leaf Area ◽  
Plant Species ◽  
Chenopodium Album ◽  
Field Studies ◽  
Individual Species ◽  
Light Competition ◽  
Direct Sunlight ◽  
Area Index ◽  
Wild Mustard ◽  
Competition For Light

A technique based on the relationship between leaf area index (LAI) and the transmittance of direct sunlight was developed for thein situstudy of competition for light between plant species. Field studies were conducted in 1984 and 1985 using monocultures and mixtures of rapeseed (Brassica napusL.), wild mustard (Sinapis arvensisL. # SINAR), and common lambsquarters (Chenopodium albumL. # CHEAL). LAI estimated nondestructively by this method agreed closely with LAI determined by conventional destructive techniques. Light measurements at several heights in the canopy were used to determine the vertical distribution of canopy leaf area. Combining this information with species heights allowed the separation of the canopy LAI into individual species LAI, from which light competition could be estimated by calculating the sunlit LAI of each species. The technique permits many detailed measurements in the same canopy throughout the growing season. The light sensor required is not costly and is simple to operate and to maintain.

scholarly journals Cross-generational vowel change in American English

2011 ◽  
Vol 23 (1) ◽  
pp. 45-86 ◽  
Author(s):  
Ewa Jacewicz ◽  
Robert Allen Fox ◽  
Joseph Salmons
Keyword(s):  
North Carolina ◽  
Acoustic Analysis ◽  
American English ◽  
Age Groups ◽  
Widespread Occurrence ◽  
The North ◽  
Western North Carolina ◽  
Generational Changes ◽  
Vowel Systems ◽  
Males And Females

AbstractThis study examines cross-generational changes in the vowel systems in central Ohio, southeastern Wisconsin, and western North Carolina. Speech samples from 239 speakers, males and females, were divided into three age groups: grandparents (66–91 years old), parents (35–51), and children (8–12). Acoustic analysis of vowel dynamics (i.e., formant movement) was undertaken to explore variation in the amount of spectral change for each vowel. A robust set of cross-generational changes in /ɪ, ɛ, æ, ɑ/ was found within each dialect-specific vowel system, involving both their positions and dynamics. With each successive generation, /ɪ, ɛ, æ/ become increasingly monophthongized and /ɑ/ is diphthongized in children. These changes correspond to a general anticlockwise parallel rotation of vowels (with some exceptions in /ɪ/ and /ɛ/). Given the widespread occurrence of these parallel chainlike changes, we term this development the “North American Shift,” which conforms to the general principles of chain shifting formulated by Labov (1994) and others.

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