Large-scale 35-mm aerial photographs for assessment of vegetation-management research plots in eastern Canada

1993 ◽  
Vol 23 (10) ◽  
pp. 2159-2169 ◽  
Author(s):  
D.G. Pitt ◽  
G.R. Glover
Keyword(s):  
Large Scale ◽  
Woody Plant ◽  
Ground Truth ◽  
Vegetation Management ◽  
Aerial Photographs ◽  
Management Research ◽  
Eastern Canada ◽  
Crown Area ◽  
Vegetation Control ◽  
Horizontal Point Sampling

Two 35-mm cameras were mounted on a boom and suspended from a tethered helium-filled blimp to obtain nominally vertical aerial photographs (1:828 and 1:414 contact scale) of vegetation-management research plots. Photo and ground estimates of woody plant crown area (m2/ha) and rootstock density (number/ha) were compared for several experimental vegetation-control treatments. Horizontal point-sampling estimates of total crown area made directly on 1:93 scale prints (enlarged from 1:414) correlated strongly with equivalent estimates made on the ground (n = 62, r2 = 0.97). An estimated 20 ground-truth plots were required to adequately quantify photo bias and correct subsequent prediction of actual total crown area on the plots studied. Much of the observed photo bias could be attributed to the undersampling of small rootstocks. Exclusion of individual rootstocks less than 0.10 m2 in crown area (or, equivalently, <56 cm in height) resulted in a 1:1 relation between the two sampling methods for estimates of both total crown area (r2 = 0.98) and rootstock density (r2 = 0.97). If data for rootstocks in smaller size classes are not needed, uncorrected photo estimates may be appropriate for evaluation of treatment response. Ground-sampling costs averaged $200 (Canadian) per plot, compared with photo costs of $104 per plot (without ground truth) or $150 per plot (with 20 ground-truth plots). Smaller scale photos (1:828 contact) cost 11% less than the larger scale tested, but resulted in significant undersampling of individual rootstocks less than 0.2 m2 in crown area (or, equivalently, <80 cm in height).

Two-phase sampling of woody and herbaceous plant communities using large-scale aerial photographs

1996 ◽  
Vol 26 (4) ◽  
pp. 509-524 ◽  
Author(s):  
D.G. Pitt ◽  
G.R. Glover ◽  
R.H. Jones
Keyword(s):  
Large Scale ◽  
Ground Truth ◽  
Aerial Photographs ◽  
Herbaceous Plant ◽  
Community Structures ◽  
Sample Design ◽  
Vegetation Community ◽  
Two Phase ◽  
Estimation Precision ◽  
Phase Sample

A two-phase sample design employing large-scale aerial photographs was used to quantify early successional woody and herbaceous plant community structures. Two conventional 35-mm cameras were mounted on a boom and suspended from a helium-filled blimp to obtain low-cost 1:366 scale stereo photographs (1:80 scale prints) of seven experimental vegetation complexes. Estimates of woody crown volume index and herbaceous percent cover were generated for 5 × 5 m plots by calibrating photo measurements to a limited ground-truth sample. The method offered significant increases in estimation precision (>35%) over ground sampling alone, as well as attractive cost advantages (0 to 40%). The highest levels of precision were obtained by measuring entire plots on the photographs. This procedure added approximately 10% to the cost of photo evaluations but resulted in estimates with standard errors that were, on average, 78% smaller than those of ground samples. Simulation trials suggested that more than nine ground-truth sample units per vegetation community type provided only marginal increases in estimation precision. If individual species or species groups of interest are well represented in sample areas, large-scale photographs, employed in a two-phase sample design, can be an effective tool for quantifying and monitoring vegetation community structures in silvicultural and related field studies.

Estimating ovendry mass of trembling aspen and white birch using measurements from aerial photographs

1986 ◽  
Vol 16 (1) ◽  
pp. 163-165 ◽  
Author(s):  
I. S. Alemdag
Keyword(s):  
Pilot Study ◽  
Large Scale ◽  
Tree Height ◽  
Aerial Photographs ◽  
Tree Biomass ◽  
White Birch ◽  
Crown Area ◽  
Preliminary Results ◽  
Total Tree ◽  
Whole Tree

A pilot study tested the estimation of stem, crown, and whole-tree biomass of single trees from measurements of total tree height and crown area taken from large-scale aerial photographs. The results indicated the feasibility of this method, provided that time of photography is optimal. More extensive testing is required to confirm these encouraging preliminary results.

Classification of vegetation in Cucphuong National Park with the aim of large-scale mapping, Vietnam

1996 ◽  
pp. 64-67 ◽  
Author(s):  
Nguen Nghia Thin ◽  
Nguen Ba Thu ◽  
Tran Van Thuy
Keyword(s):  
National Park ◽  
Large Scale ◽  
Satellite Images ◽  
Field Work ◽  
Aerial Photographs ◽  
Vegetation Map ◽  
Dense Forest ◽  
Broad Leaved Forest ◽  
Leaved Forest

The tropical seasonal rainy evergreen broad-leaved forest vegetation of the Cucphoung National Park has been classified and the distribution of plant communities has been shown on the map using the relations of vegetation to geology, geomorphology and pedology. The method of vegetation mapping includes: 1) the identifying of vegetation types in the remote-sensed materials (aerial photographs and satellite images); 2) field work to compile the interpretation keys and to characterize all the communities of a study area; 3) compilation of the final vegetation map using the combined information. In the classification presented a number of different level vegetation units have been identified: formation classes (3), formation sub-classes (3), formation groups (3), formations (4), subformations (10) and communities (19). Communities have been taken as mapping units. So in the vegetation map of the National Park 19 vegetation categories has been shown altogether, among them 13 are natural primary communities, and 6 are the secondary, anthropogenic ones. The secondary succession goes through 3 main stages: grassland herbaceous xerophytic vegetation, xerophytic scrub, dense forest.

Model and Method for Contributor’s Quality Assessment in Community Image Tagging Systems

2018 ◽  
pp. 45-51
Author(s):  
A. V. Ponomarev
Keyword(s):  
Large Scale ◽  
Wide Spectrum ◽  
Preference Relation ◽  
Pairwise Comparison ◽  
Ground Truth ◽  
Comparison Method ◽  
Characteristic Matrix ◽  
Image Tagging ◽  
Proposed Model

Introduction: Large-scale human-computer systems involving people of various skills and motivation into the information processing process are currently used in a wide spectrum of applications. An acute problem in such systems is assessing the expected quality of each contributor; for example, in order to penalize incompetent or inaccurate ones and to promote diligent ones.Purpose: To develop a method of assessing the expected contributor’s quality in community tagging systems. This method should only use generally unreliable and incomplete information provided by contributors (with ground truth tags unknown).Results:A mathematical model is proposed for community image tagging (including the model of a contributor), along with a method of assessing the expected contributor’s quality. The method is based on comparing tag sets provided by different contributors for the same images, being a modification of pairwise comparison method with preference relation replaced by a special domination characteristic. Expected contributors’ quality is evaluated as a positive eigenvector of a pairwise domination characteristic matrix. Community tagging simulation has confirmed that the proposed method allows you to adequately estimate the expected quality of community tagging system contributors (provided that the contributors' behavior fits the proposed model).Practical relevance: The obtained results can be used in the development of systems based on coordinated efforts of community (primarily, community tagging systems). 

Vegetation management on grass-dominated clearcuts planted with Norway spruce in southern Sweden

1999 ◽  
Vol 29 (7) ◽  
pp. 1015-1026 ◽  
Author(s):  
Urban Nilsson ◽  
Göran Örlander
Keyword(s):  
Norway Spruce ◽  
Vegetation Management ◽  
Shoot Length ◽  
Southern Sweden ◽  
Vegetation Control ◽  
Containerized Seedlings ◽  
Soil Temperatures ◽  
Stock Type ◽  
Bare Root ◽  
Relative Differences

A field experiment was established between 1989 and 1993 to study the effects of competing vegetation on growth of planted Norway spruce (Picea abies (L.) Karst.) seedlings. Effects of clearcut age, scarification (mounding), herbicide treatment, and seedling stock type were investigated 5 years after planting. On fresh clearcuts, amounts of vegetation were negligible, whereas 2.1-3.7 Mg·ha-1 was found on 4-year-old and older clearcuts. Soil temperatures were about 10% higher in mounds than in undisturbed ground, while herbicide and clearcut age only marginally affected soil temperatures. Seedlings planted on old clearcuts showed significant reductions in growth due to interference from vegetation. Five years after planting, the reduction in growth corresponded to about 1 year's growth. Most of the interaction between seedlings and vegetation occurred during the first 2 years after planting. Thus, scarification was just as effective as repeated herbicide treatments in reducing competition from vegetation. Differences in periods of drought between years could largely explain variation in leading shoot length. However, leading shoot length was affected in the same way irrespective of vegetation control treatments. Five years after planting, the relative differences in diameter between bare-root and containerized seedlings were the same as at the time of planting.

The potential cost of environmental certification to vegetation management in plantation forests: a New Zealand case study

2011 ◽  
Vol 41 (5) ◽  
pp. 986-993 ◽  
Author(s):  
Carol A. Rolando ◽  
Michael S. Watt ◽  
Jerzy A. Zabkiewicz
Keyword(s):  
New Zealand ◽  
Cost Effective ◽  
Vegetation Management ◽  
Rate Of Return ◽  
Internal Rate Of Return ◽  
Mechanical Control ◽  
Vegetation Control ◽  
High Productivity ◽  
Plantation Forests

Plantation forests certified by the Forest Stewardship Council have restrictions on herbicide use. Since certified plantations are dependant on herbicides for cost-effective vegetation management, compliance requires a shift from current chemical practices. Using New Zealand plantation forests as a case study, discounted cash flow analyses were used to estimate the cost of certification-compliant vegetation control regimes compared with current non-compliant methods. We examined methods that (i) reduce the quantity of herbicides by using spot control and (ii) avoid the use of herbicides by using weed mats, manual, and mechanical control. Cost analyses were undertaken for low-, medium-, and high-productivity sites. The internal rate of return of the non-compliant regime was between 5% and 5.8% across the productivity range. Spot control was cheaper than current non-compliant practice. However, spot control is limited by site suitability and the availability of labour. Non-chemical control methods were expensive relative to other regimes. Reductions in the internal rate of return varied across low- and high-productivity sites between 0.8% and 0.5% for manual control, 1.3% and 0.8% for mechanical control, and 1.7% and 1.0% for weed mats. Meeting the goals of certification while retaining cost-effective vegetation control presents a challenge to the plantation forestry sector.

Species Responses to Grazing and Environmental-Factors in an Arid Halophytic Shrubland Community

1987 ◽  
Vol 35 (2) ◽  
pp. 135 ◽  
Author(s):  
RB Hacker
Keyword(s):  
Environmental Factors ◽  
Soil Salinity ◽  
Large Scale ◽  
Chemical Properties ◽  
Grazing Pressure ◽  
Aerial Photographs ◽  
Small Scale ◽  
Factors Affecting ◽  
Species Responses

Species responses to grazing and environmental factors were studied in an arid halophytic shrubland community in Western Australia. The grazing responses of major shrub species were defined by using reciprocal averaging ordination of botanical data, interpreted in conjunction with a similar ordination of soil chemical properties and measures of soil erosion derived from large-scale aerial photographs. An apparent small-scale interaction between grazing and soil salinity was also defined. Long-term grazing pressure is apparently reduced on localised areas of high salinity. Environmental factors affecting species distribution are complex and appear to include soil salinity, soil cationic balance, geomorphological variation and the influence of cryptogamic crusts on seedling establishment.

Lake-effect rains over Lake Victoria and their association with Mesoscale Convective Systems

2021 ◽  
Author(s):  
Sharon E. Nicholson ◽  
Douglas Klotter ◽  
Adam T. Hartman
Keyword(s):  
Large Scale ◽  
Lake Victoria ◽  
Ground Truth ◽  
Mesoscale Convective Systems ◽  
Convective Systems ◽  
Lake Effect ◽  
Mesoscale Convective ◽  
Strong Convection ◽  
Short Rains ◽  
Lake Catchment

AbstractThis article examined rainfall enhancement over Lake Victoria. Estimates of over-lake rainfall were compared with rainfall in the surrounding lake catchment. Four satellite products were initially tested against estimates based on gauges or water balance models. These included TRMM 3B43, IMERG V06 Final Run (IMERG-F), CHIRPS2, and PERSIANN-CDR. There was agreement among the satellite products for catchment rainfall but a large disparity among them for over-lake rainfall. IMERG-F was clearly an outlier, exceeding the estimate from TRMM 3B43 by 36%. The overestimation by IMERG-F was likely related to passive microwave assessments of strong convection, such as prevails over Lake Victoria. Overall, TRMM 3B43 showed the best agreement with the "ground truth" and was used in further analyses. Over-lake rainfall was found to be enhanced compared to catchment rainfall in all months. During the March-to-May long rains the enhancement varied between 40% and 50%. During the October-to-December short rains the enhancement varied between 33% and 44%. Even during the two dry seasons the enhancement was at least 20% and over 50% in some months. While the magnitude of enhancement varied from month to month, the seasonal cycle was essentially the same for over-lake and catchment rainfall, suggesting that the dominant influence on over-lake rainfall is the large-scale environment. The association with Mesoscale Convective Systems (MCSs) was also evaluated. The similarity of the spatial patterns of rainfall and MCS count each month suggested that these produced a major share of rainfall over the lake. Similarity in interannual variability further supported this conclusion.

Open Source Software Implementation of Anatomical Segmentation

2018 ◽  
Author(s):  
Maggie Hess
Keyword(s):  
Large Scale ◽  
Focused Ultrasound ◽  
Region Growing ◽  
Ground Truth ◽  
Clot Lysis ◽  
Focused Ultrasound Surgery ◽  
Manual Methods ◽  
Areas Of Interest ◽  
Seed Points ◽  
Viable Method

Purpose: Intraventricular hemorrhage (IVH) affects nearly 15% of preterm infants. It can lead to ventricular dilation and cognitive impairment. To ablate IVH clots, MR-guided focused ultrasound surgery (MRgFUS) is investigated. This procedure requires accurate, fast and consistent quantification of ventricle and clot volumes. Methods: We developed a semi-autonomous segmentation (SAS) algorithm for measuring changes in the ventricle and clot volumes. Images are normalized, and then ventricle and clot masks are registered to the images. Voxels of the registered masks and voxels obtained by thresholding the normalized images are used as seed points for competitive region growing, which provides the final segmentation. The user selects the areas of interest for correspondence after thresholding and these selections are the final seeds for region growing. SAS was evaluated on an IVH porcine model.  Results: SAS was compared to ground truth manual segmentation (MS) for accuracy, efficiency, and consistency. Accuracy was determined by comparing clot and ventricle volumes produced by SAS and MS. In Two-One-Sided Test, SAS and MS were found to be significantly equivalent (p < 0.01). SAS on average was found to be 15 times faster than MS (p < 0.01). Consistency was determined by repeated segmentation of the same image by both SAS and manual methods, SAS being significantly more consistent than MS (p < 0.05).  Conclusion: SAS is a viable method to quantify the IVH clot and the lateral brain ventricles and it is serving in a large- scale porcine study of MRgFUS treatment of IVH clot lysis.

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