scholarly journals Field Note–Selecting Plot Sizes When Quantifying Growing Conditions in Understories

2002 ◽  
Vol 19 (3) ◽  
pp. 137-140 ◽  
Author(s):  
Klaus J. Puettmann ◽  
Anthony W. D'Amato
Keyword(s):  
Basal Area ◽  
Diameter Ratio ◽  
Seedling Height ◽  
Plot Size ◽  
Field Note ◽  
Growing Conditions ◽  
The Relationship ◽  
Overstory Trees ◽  
Linear Correlations ◽  
Stand Characteristics

Abstract While the importance of selecting a neighborhood size for competition studies has been documented, the choice of plot sizes has received little attention when measuring the influence of overstory trees on growing conditions of understory seedlings. Based on data from four sites, we show how plot sizes for measures of overstory cover (using a “cone” approach) and basal area (using an angle gauge) were related. The relationship was a function of the height/diameter ratio of the overstory trees, with taller trees increasing the plot sizes for “cone” plots and trees with larger diameters increasing the plot sizes for basal area plots. Further, we point out that data derived from measurements of diffuse noninterceptance (DIFN) using the “cone” approach varied with the choice of cone opening. Smaller cone openings led to a greater range in DIFN values. Linear correlations between these data and 2 yr seedling height pointed out that the optimal plot size, i.e., cone opening, differs among the sites. The lack of any obvious stand characteristics that would explain these differences indicated the need for further investigations.

Sampling Unit, Spatial Distribution of Trees, and Precision

1992 ◽  
Vol 9 (1) ◽  
pp. 3-6 ◽  
Author(s):  
Robin M. Reich ◽  
Loukas G. Arvanitis
Keyword(s):  
Spatial Distribution ◽  
Sample Size ◽  
Spatial Patterns ◽  
Basal Area ◽  
Sampling Unit ◽  
Sample Variance ◽  
Plot Size ◽  
Plot Area ◽  
The Relationship

Abstract The relationship between plot size and sample variance as affected by the spatial patterns of trees, volume, and basal area is reported. This information is useful for practicing foresters in determining the best combination of sample size, plot area, or basal area factor in forest surveys. North. J. Appl. For. 9(1):3-6.

scholarly journals Effects of Cultivar and Ethanol Disinfection on Aseptic Germination of Loquat (Eriobotrya japonica) Seeds

HortScience ◽  
2017 ◽  
Vol 52 (7) ◽  
pp. 941-945
Author(s):  
Kunkun Li ◽  
Weiqi Dong ◽  
Yun Zhao ◽  
Hongxia Xu ◽  
Junwei Chen ◽  
...  
Keyword(s):  
Detrimental Effect ◽  
Germination Rate ◽  
Fruit Tree ◽  
Final Concentration ◽  
Eriobotrya Japonica ◽  
Seedling Height ◽  
Disinfection Procedure ◽  
Aba Content ◽  
Subtropical Fruit ◽  
The Relationship

Loquat (Eriobotrya japonica Lindl.) is an economically important subtropical fruit tree, originating and commercially produced mainly in China and Japan. The aseptic seed germination of 13 loquat cultivars, including 9 white-fleshed cultivars and 4 red-fleshed ones, was studied, and the relationship between the germination rate and the content of endogenous ABA in seeds was explored. The germination rate and the seedling height at 80 days after sowing of white-fleshed cultivars were generally higher than that of red-fleshed ones. The ABA content in seeds was generally lower in white-fleshed cultivars, and the ABA content negatively correlated with the germination rate at 80 days after sowing. A moderate detrimental effect of 75% ethanol disinfection on aseptic germination of loquat seeds was observed, especially, for the cultivar Dahongpao, and the germination rate and seedling height were reduced by around half and one-third, respectively. The addition of plant preservative mixture (PPM) to the germination medium at a final concentration of 25 mg·L−1 effectively controlled contamination when the 75% ethanol disinfection procedure was omitted.

Plot size matters: interference from intergenotypic competition in plant phenotyping studies

2014 ◽  
Vol 41 (2) ◽  
pp. 107 ◽  
Author(s):  
Greg J. Rebetzke ◽  
Ralph (Tony) A. Fischer ◽  
Anthony F. van Herwaarden ◽  
Dave G. Bonnett ◽  
Karine Chenu ◽  
...  
Keyword(s):  
Complex Traits ◽  
Plant Phenotyping ◽  
Controlled Environment ◽  
Canopy Development ◽  
Plot Size ◽  
Field Assessment ◽  
Intergenotypic Competition ◽  
Growing Conditions ◽  
Competition For Resources ◽  
Commercial Field

Genetic and physiological studies often comprise genotypes diverse in vigour, size and flowering time. This can make the phenotyping of complex traits challenging, particularly those associated with canopy development, biomass and yield, as the environment of one genotype can be influenced by a neighbouring genotype. Limited seed and space may encourage field assessment in single, spaced rows or in small, unbordered plots, whereas the convenience of a controlled environment or greenhouse makes pot studies tempting. However, the relevance of such growing conditions to commercial field-grown crops is unclear and often doubtful. Competition for water, light and nutrients necessary for canopy growth will be variable where immediate neighbours are genetically different, particularly under stress conditions, where competition for resources and influence on productivity is greatest. Small hills and rod-rows maximise the potential for intergenotypic competition that is not relevant to a crop’s performance in monocultures. Response to resource availability will typically vary among diverse genotypes to alter genotype ranking and reduce heritability for all growth-related traits, with the possible exception of harvest index. Validation of pot experiments to performance in canopies in the field is essential, whereas the planting of multirow plots and the simple exclusion of plot borders at harvest will increase experimental precision and confidence in genotype performance in target environments.

Comparison of the tussive effects of histamine and methacholine in humans

1983 ◽  
Vol 55 (2) ◽  
pp. 541-546 ◽  
Author(s):  
A. M. Chausow ◽  
A. S. Banner
Keyword(s):  
Chronic Cough ◽  
Volume Ratio ◽  
Forced Expiratory Volume ◽  
Additional Mechanism ◽  
Cough Response ◽  
Inhalation Challenge ◽  
The Relationship ◽  
Linear Correlations

The tussive and bronchoconstrictive effects of histamine inhalation in 7 normals, 7 asthmatics, and 24 patients with chronic cough (PCC) were measured by counting coughs during a standard histamine inhalation challenge. All PCC had a tussive response. Fifteen PCC exhibited significant linear correlations between cough count and either the change in forced expiratory volume at 1.0 (delta FEV1) or conductance-volume ratio (sGaw) (delta sGaw). Normals and asthmatics had little or no cough. Metaproterenol pretreatment in seven PCC reduced both the FEV1 and cough response to histamine without changing the relationship between cough and delta FEV1. The tussive and bronchoconstrictive effects of methacholine inhalation were also measured in 7 asthmatics and 16 PCC. One asthmatic coughed. Fifteen PCC coughed. There were significant linear correlations between cough count and delta FEV1 or delta sGaw in 10 PCC. At comparable delta FEV1 and delta sGaw, histamine produced more cough than methacholine. These data indicate that during inhalation of histamine or methacholine by PCC cough is related to, and may be caused by, bronchoconstriction. Histamine also causes cough by an additional mechanism not related to bronchoconstriction.

A note on the relationship between the quadratic mean stand diameter and harmonic mean basal area under size-biased distribution theory

2003 ◽  
Vol 33 (8) ◽  
pp. 1587-1590 ◽  
Author(s):  
J H Gove
Keyword(s):  
Size Distribution ◽  
Graphical Representation ◽  
Basal Area ◽  
Distribution Theory ◽  
Harmonic Mean ◽  
Quadratic Mean ◽  
Point Sampling ◽  
The Relationship ◽  
Horizontal Point Sampling ◽  
Biased Distribution

This note seeks to extend the utility of size-biased distribution theory as applied to forestry through two relationships regarding the quadratic mean stand diameter. First, the quadratic mean stand diameter's relationship to the harmonic mean basal area for horizontal point sampling, which has been known algebraically from early on, is proved under size-biased distribution theory. Second, a new result, which may prove most valuable in viewing the graphical representation of assumed distributions, is also derived. The results are also shown to apply to the basal area – size distribution, providing a unique duality between the two means.

The effect of spatially variable overstory on the understory light environment of an open-canopied longleaf pine forest

2002 ◽  
Vol 32 (11) ◽  
pp. 1984-1991 ◽  
Author(s):  
Michael A Battaglia ◽  
Pu Mou ◽  
Brian Palik ◽  
Robert J Mitchell
Keyword(s):  
Spatial Variation ◽  
Spatial Patterns ◽  
Longleaf Pine ◽  
Light Availability ◽  
Canopy Structure ◽  
Basal Area ◽  
Pinus Palustris ◽  
Pine Forest ◽  
Large Group ◽  
The Relationship

Spatial aggregation of forest structure strongly regulates understory light and its spatial variation in longleaf pine (Pinus palustris Mill.) forest ecosystems. Previous studies have demonstrated that light availability strongly influences longleaf pine seedling growth. In this study, the relationship between spatial structure of a longleaf pine forest and spatial pattern of understory light availability were investigated by comparing three retention harvest treatments: single-tree, small-group, large-group, and an uncut control. The harvests retained similar residual basal area but the spatial patterns of the residual trees differed. Hemispherical photographs were taken at 300 stations to calculate gap light index (GLI), an estimate of understory light availability. Stand-level mean, variation, and spatial distribution of GLI were determined for each treatment. By aggregating residual trees, stand mean GLI increased by 20%, as well as its spatial variation. Spatial autocorrelation of GLI increased as the size of the canopy gaps increased and the gaps were better defined; thus, the predictability of GLI was enhanced. The ranges of detrended semivariograms were increased from the control to the large-group harvest indicating the spatial patterns of understory GLI became coarser textured. Our results demonstrated that aggregated canopy structure of longleaf pine forest will facilitate longleaf pine seedling regeneration.

scholarly journals Automatic Wheat Ear Counting Using Thermal Imagery

2019 ◽  
Vol 11 (7) ◽  
pp. 751 ◽  
Author(s):  
Jose Fernandez-Gallego ◽  
Ma. Buchaillot ◽  
Nieves Aparicio Gutiérrez ◽  
María Nieto-Taladriz ◽  
José Araus ◽  
...  
Keyword(s):  
Pipeline System ◽  
Counting System ◽  
Thermal Images ◽  
Manual Counting ◽  
Rgb Images ◽  
Growing Conditions ◽  
The Relationship ◽  
Comparability Of Results ◽  
Automatic Pipeline

Ear density is one of the most important agronomical yield components in wheat. Ear counting is time-consuming and tedious as it is most often conducted manually in field conditions. Moreover, different sampling techniques are often used resulting in a lack of standard protocol, which may eventually affect inter-comparability of results. Thermal sensors capture crop canopy features with more contrast than RGB sensors for image segmentation and classification tasks. An automatic thermal ear counting system is proposed to count the number of ears using zenithal/nadir thermal images acquired from a moderately high resolution handheld thermal camera. Three experimental sites under different growing conditions in Spain were used on a set of 24 varieties of durum wheat for this study. The automatic pipeline system developed uses contrast enhancement and filter techniques to segment image regions detected as ears. The approach is based on the temperature differential between the ears and the rest of the canopy, given that ears usually have higher temperatures due to their lower transpiration rates. Thermal images were acquired, together with RGB images and in situ (i.e., directly in the plot) visual ear counting from the same plot segment for validation purposes. The relationship between the thermal counting values and the in situ visual counting was fairly weak (R2 = 0.40), which highlights the difficulties in estimating ear density from one single image-perspective. However, the results show that the automatic thermal ear counting system performed quite well in counting the ears that do appear in the thermal images, exhibiting high correlations with the manual image-based counts from both thermal and RGB images in the sub-plot validation ring (R2 = 0.75–0.84). Automatic ear counting also exhibited high correlation with the manual counting from thermal images when considering the complete image (R2 = 0.80). The results also show a high correlation between the thermal and the RGB manual counting using the validation ring (R2 = 0.83). Methodological requirements and potential limitations of the technique are discussed.

scholarly journals Regeneration, growth of Hill Sal and plant diversity in Community Forest: A case study from Pragatisil Community Forest in Kaski District, Western Nepal

2016 ◽  
Vol 23 (2) ◽  
pp. 37-43 ◽  
Author(s):  
B. K. Paudyal
Keyword(s):  
Plant Species ◽  
Plant Diversity ◽  
Growth Parameters ◽  
Basal Area ◽  
Community Forest ◽  
Shorea Robusta ◽  
Plot Size ◽  
Regeneration Status ◽  
M 10

The study was conducted in the Pragatisil Community Forest, Kaski District, Nepal in 2012 to assess the regeneration status of Sal (Shorea robusta) seedlings, its growth and plant diversity. A plot size of 25 m × 20 m was employed for trees, 10 m ×10 m for poles and 5 m × 5 m for regeneration. The growth parameters measured were dbh and height. A factorial arrangement of treatments was employed; the treatments being slope and aspect. The results showed that there was significant (p<0.05) effect of slope on dbh and basal area whereas there was no effect of aspect on growth parameters measured in the Pragatisil Community Forest. The regeneration of Sal was satisfactory (6,126 seedlings/ha), and there were 32 plant species in this forest. As there was higher basal area per ha in the Pragatisil Community Forest, it is recommended to have thinning of 40% of basal area for enhancing growth of remaining stems.Banko Janakari, Vol. 23, No. 2, 2013

scholarly journals Estimating the Height and Basal Area at Individual Tree and Plot Levels in Canadian Subarctic Lichen Woodlands Using Stereo WorldView-3 Images

2019 ◽  
Vol 11 (3) ◽  
pp. 248 ◽  
Author(s):  
Benoît St-Onge ◽  
Simon Grandin
Keyword(s):  
Remote Sensing ◽  
Basal Area ◽  
Ground Cover ◽  
Structural Data ◽  
Tree Level ◽  
Individual Tree ◽  
Visual Contrast ◽  
The Relationship ◽  
Height Data

Lichen woodlands (LW) are sparse forests that cover extensive areas in remote subarctic regions where warming due to climate change is fastest. They are difficult to study in situ or with airborne remote sensing due to their remoteness. We have tested a method for measuring individual tree heights and predicting basal area at tree and plot levels using WorldView-3 stereo images. Manual stereo measurements of tree heights were performed on short trees (2–12 m) of a LW region of Canada with a residual standard error of ≈0.9 m compared to accurate field or UAV height data. The number of detected trees significantly underestimated field counts, especially in peatlands in which the visual contrast between trees and ground cover was low. The heights measured from the WorldView-3 images were used to predict the basal area at individual tree level and summed up at plot level. In the best conditions (high contrast between trees and ground cover), the relationship to field basal area had a R2 of 0.79. Accurate estimates of above ground biomass should therefore also be possible. This method could be used to calibrate an extensive remote sensing approach without in-situ measurements, e.g., by linking precise structural data to ICESAT-2 footprints.

scholarly journals Effects of Basal Area Factor and Plot Size on Precision and Accuracy of Forest Inventory Estimates

2011 ◽  
Vol 28 (3) ◽  
pp. 152-156 ◽  
Author(s):  
Peter Becker ◽  
Tom Nichols
Keyword(s):  
Forest Inventory ◽  
Basal Area ◽  
Cost Effective ◽  
Sampling Errors ◽  
Plot Size ◽  
Accuracy And Precision ◽  
Coefficients Of Variation ◽  
Fixed Radius ◽  
Tree Number ◽  
Biased Estimates

Abstract We tested the effects of plot size (0.05-0.30 ac) and basal area factor (BAF) (5-30) on the accuracy and precision of per-acre estimates of tree number, basal area, biomass (all for trees ≥4.5 in. dbh), and sawtimber volume (for trees ≥11.6 in. dbh). Field sampling errors, such as missing in-trees, did not affect our tests. Virtual variable- and fixed-radius plots were randomly located within an artificial matrix of 130 real plots in well-stocked upland hardwood forests of sawtimber-sized trees in the Missouri Ozarks. Inventory parameters were essentially independent of plot size and BAF, whereas their coefficients of variation decreased with plot size and increased with BAF. Thus, our results for random plots agreed with sampling theory, unlike a previous study using concentric virtual plots in West Virginia forests. A very concentrated zone of high tree density around some plot centers apparently caused the biased estimates by concentric plots. Compared with the entire composite forest, inventory means were accurately estimated (to within 5%) and size class distributions were well represented for plots ≥0.1 ac or ≤15 BAF. Our procedures provide a basis for selecting an efficient and cost-effective sampling design suited to forest characteristics and the inventory's purpose.

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