scholarly journals Effects of Environmental Clutter on Synthesized Chiropteran Echolocation Signals in an Anechoic Chamber

Acoustics ◽  
2021 ◽  
Vol 3 (2) ◽  
pp. 391-410
Author(s):  
Samuel R. Freeze ◽  
Masoud Shirazi ◽  
Nicole Abaid ◽  
Mark Ford ◽  
Alexander Silvis ◽  
...  
Keyword(s):  
Basal Area ◽  
Relative Activity ◽  
Anechoic Chamber ◽  
Future Research ◽  
Automatic Identification ◽  
Echolocation Calls ◽  
Survey Accuracy ◽  
Number Of Stems ◽  
Echolocation Signal ◽  
Woody Growth

Ultrasonic bat detectors are useful for research and monitoring purposes to assess occupancy and relative activity of bat communities. Environmental “clutter” such as tree boles and foliage can affect the recording quality and identification of bat echolocation calls collected using ultrasonic detectors. It can also affect the transmission of calls and recognition by bats when using acoustic lure devices to attract bats to mist-nets. Bat detectors are often placed in forests, yet automatic identification programs are trained on call libraries using echolocation passes recorded largely from open spaces. Research indicates that using clutter-recorded calls can increase classification accuracy for some bat species and decrease accuracy for others, but a detailed understanding of how clutter impacts the recording and identification of echolocation calls remains elusive. To clarify this, we experimentally investigated how two measures of clutter (i.e., total basal area and number of stems of simulated woody growth, as well as recording angle) affected the recording and classification of a synthesized echolocation signal under controlled conditions in an anechoic chamber. Recording angle (i.e., receiver position relative to emitter) significantly influenced the probability of correct classification and differed significantly for many of the call parameters measured. The probability of recording echo pulses was also a function of clutter but only for the detector angle at 0° from the emitter that could receive deflected pulses. Overall, the two clutter metrics were overshadowed by proximity and angle of the receiver to the sound source but some deviations from the synthesized call in terms of maximum, minimum, and mean frequency parameters were observed. Results from our work may aid efforts to better understand underlying environmental conditions that produce false-positive and -negative identifications for bat species of interest and how this could be used to adjust survey accuracy estimates. Our results also help pave the way for future research into the development of acoustic lure technology by exploring the effects of environmental clutter on ultrasound transmission.

Pattern in a derived savanna in Nigeria

1991 ◽  
Vol 7 (4) ◽  
pp. 491-502 ◽  
Author(s):  
P. Greig-Smith
Keyword(s):  
Analysis Of Variance ◽  
Block Size ◽  
Basal Area ◽  
Species Density ◽  
Forest Reserve ◽  
South West ◽  
Derived Savanna ◽  
Woody Growth

ABSTRACTAll woody growth was enumerated in three transects, each 960 m x 20 m, in derived savanna in the Olokemeji Forest Reserve in south-west Nigeria. The data for species density, species basal area and stem girth classes were analysed by nested-block analysis of variance and covariance. The use of ‘total covariance’, the sum of all covariances at a block size, contributes to understanding of the pattern present.Three scales of pattern were evident. Patchiness at 160–320 m is interpreted as a response to soil differences or to the pattern of previous farming, which may itself have been determined by soil differences. Patchiness at 20–40 m is attributable to varying intensity of burning. At the smallest scale, of 10 m, there is evidence of regularity of distribution resulting from interference between individuals, possibly due to competition for water.

scholarly journals Zur Auswirkung der Hangneigungskorrektur auf Schätzwerte im Schweizerischen Landesforstinventar (LFI) | Investigation of the effect of the slope correction method as applied in the Swiss National Forest Inventory of estimates

2001 ◽  
Vol 152 (6) ◽  
pp. 215-225 ◽  
Author(s):  
Michael Köhl ◽  
Peter Brassel
Keyword(s):  
Forest Inventory ◽  
Basal Area ◽  
Correction Method ◽  
National Forest Inventory ◽  
National Forest ◽  
Average Deviation ◽  
Forest Inventories ◽  
Slope Correction ◽  
Number Of Stems ◽  
Elliptical Area

For forest inventories on slopes, it is necessary to correct the test areas, because the circular areas, when projected, become elliptical. Based on 93 samples from the Swiss National Forest Inventory (FNI), it was determined whether the simplified method, which increases the radius to match that of the elliptical area, leads to a distortion of the results. An average deviation of 2% was found between the FNI estimated values and the actual values for the basal area and the number of stems. For estimations of smaller units, greater distortions of the results are expected.

scholarly journals Bayesian Evaluation of Smartphone Applications for Forest Inventories in Small Forest Holdings

Forests ◽  
2020 ◽  
Vol 11 (11) ◽  
pp. 1148
Author(s):  
Andrej Ficko
Keyword(s):  
Mobile Applications ◽  
Mobile Application ◽  
Basal Area ◽  
Small Enterprises ◽  
Private Forest ◽  
P Values ◽  
Forest Inventories ◽  
The Difference ◽  
Number Of Stems ◽  
Small Forest

There are increasingly advanced mobile applications for forest inventories on the market. Small enterprises and nonprofessionals may find it difficult to opt for a more sophisticated application without comparing it to an established standard. In a small private forest holding (19 ha, 4 stands, 61 standing points), we compared TRESTIMA, a computer vision-based mobile application for stand inventories, to MOTI, a smartphone-based relascope, in measuring the number of stems (N) and stand basal area (G). Using a Bayesian approach, we (1) weighted evidence for the hypothesis of no difference in N and G between TRESTIMA and MOTI relative to the hypothesis of difference, and (2) weighted evidence for the hypothesis of overestimating versus underestimating N and G when using TRESTIMA compared to MOTI. The results of the Bayesian tests were then compared to the results of frequentist tests after the p-values of paired sample t-tests were calibrated to make both approaches comparable. TRESTIMA consistently returned higher N and G, with a mean difference of +305.8 stems/ha and +5.8 m2/ha. However, Bayes factors (BF10) suggest there is only moderate evidence for the difference in N (BF10 = 4.061) and anecdotal evidence for the difference in G (BF10 = 1.372). The frequentist tests returned inconclusive results, with p-values ranging from 0.03 to 0.13. After calibration of the p-values, the frequentist tests suggested rather small odds for the differences between the applications. Conversely, the odds of overestimating versus underestimating N and G were extremely high for TRESTIMA compared to MOTI. In a small forest holding, Bayesian evaluation of differences in stand parameters can be more helpful than frequentist analysis, as Bayesian statistics do not rely on asymptotics and can answer more specific hypotheses.

scholarly journals Tree mortality in the dynamics and management of uneven-aged Norway spruce stands in southern Finland

2020 ◽  
Vol 139 (6) ◽  
pp. 989-998
Author(s):  
Sauli Valkonen ◽  
Lucie Aulus Giacosa ◽  
Juha Heikkinen
Keyword(s):  
Tree Mortality ◽  
Stand Structure ◽  
Basal Area ◽  
Repeated Measurements ◽  
Common Causes ◽  
Single Tree Selection ◽  
Spruce Stands ◽  
Causes Of Mortality ◽  
Number Of Stems ◽  
Adverse Influence

Abstract This study focused on tree mortality in spruce-dominated stands managed using the single-tree selection method in southern Finland. Together with regeneration and tree growth, mortality is one of the basic elements of the stand structure and dynamics in selection stands. The study was based on data acquired from a set of 20 permanent experimental plots monitored with repeated measurements for 20 years. The average mortality in the number of stems (N) was 4.45 trees ha−1a−1, in basal area (G) 0.07 m2 ha−1a−1, and in stemwood volume (V) 0.56 m3 ha−1a−1. In relative terms it was 0.50% of N, 0.30% of G and 0.27% of V, respectively. Wind and snow were the most common causes of mortality, while deaths by biotic causes (mammals, insects, pathogens) were extremely rare. Some 6–10% of the total loss in the number of stems and volume was attributable to the loss or removal of trees that sustained serious damage in harvesting. Most of the mortality occurred in the smallest diameter classes of up to 20 cm. Such a high mortality among small trees can have an adverse influence on the sustainability of selection structures if not successfully checked in harvesting and management.

scholarly journals Controlling Beech Root and Stump Sprouts Using the Cut-Stump Treatment

2006 ◽  
Vol 23 (3) ◽  
pp. 155-165 ◽  
Author(s):  
Jeffrey D. Kochenderfer ◽  
James N. Kochenderfer ◽  
Gary W. Miller
Keyword(s):  
Radial Distance ◽  
Basal Area ◽  
Fagus Grandifolia ◽  
Complete Control ◽  
Growing Seasons ◽  
Control Root ◽  
Stump Sprouting ◽  
Number Of Stems ◽  
Cut Stump ◽  
Stump Sprouts

Abstract Application costs and efficacy were determined for cut-stump treatments applied to American beech (Fagus grandifolia Ehrh.) to control root and stump sprouts in central West Virginia. Glyphosate as Glypro (53.8%) was applied to the outer 2 in. of beech stumps from trees >6.0-in. dbh within 1 hour after cutting. In addition to treatment plots, individual beech stumps were treated to determine mortality patterns. The treatments were applied in early September 2001 and evaluated 12 months after treatment. A rating system ranging from 1 to 7 (0 to 100% crown affected) based on visual estimates of symptoms was used to evaluate the efficacy of the treatments. Trees with a rating of 5 (75% crown control or greater) were considered controlled. After 12 months, more than 90% of beech root sprouts ≥1-ft tall to 5.9-in. dbh on treated plots were controlled. Complete control of stump sprouting also was achieved. An average of 93 beech stems was controlled around each treated stump. Mortality around treated stumps declined as the radial distance from stumps increased and stump size decreased. Average application cost (chemical and labor) ranged from $39.43 to 62.34 per acre depending on the basal area and number of stems treated. After two growing seasons, the number of beech root sprouts on more than 90% of the treated regeneration plots remained below levels considered as interfering according to guidelines for Allegheny hardwoods. This study demonstrated that herbicide is readily translocated from the surfaces of freshly cut beech stumps via parent root systems to attached live beech stems. The cut-stump method can be applied in areas where beech is the primary species interfering with the establishment and development of desirable regeneration.

scholarly journals Lessons learned from 12 years of ecological research on partial cuts in black spruce forests of northwestern Québec

2013 ◽  
Vol 89 (03) ◽  
pp. 350-359 ◽  
Author(s):  
Nicole J. Fenton ◽  
Louis Imbeau ◽  
Timothy Work ◽  
Jenna Jacobs ◽  
Hervé Bescond ◽  
...  
Keyword(s):  
Forest Succession ◽  
Black Spruce ◽  
Basal Area ◽  
Forest Harvesting ◽  
Lessons Learned ◽  
Future Research ◽  
Spruce Forests ◽  
Partial Harvest ◽  
Species Groups ◽  
The Impact

Multi-cohort management that creates or maintains an uneven structure within forest stands has been widely advocated as a means to attenuate the impact of forest harvesting. An experimental network was put in place in black spruce forests of northwestern Québec to test this assertion. Here we synthesize the biodiversity results in two main lessons: (1) at least 40% to 60% retention of pre-harvest basal area was required to maintain pre-harvest conditions for most species groups; (2) partial harvests showed the potential to be efficient deadwood delivery systems. In addition to these two main general conclusions, we emphasise that future research should examine whether partial harvest may be able to advance forest succession.

Predicting Thinning Volumes for Pine Plantations

1978 ◽  
Vol 2 (2) ◽  
pp. 59-61
Author(s):  
Richard C. Field ◽  
Jerome L. Clutter ◽  
Earle P. Jones
Keyword(s):  
Basal Area ◽  
Slash Pine ◽  
Pine Plantations ◽  
Number Of Stems

Abstract Equations are presented for estimating the volume removed in thinning from below when the desired reduction in basal area or number of stems is known. The estimators are based on data from slash pine plantations but the methods may be useful for other species.

scholarly journals Salient Object Detection Techniques in Computer Vision—A Survey

Entropy ◽  
2020 ◽  
Vol 22 (10) ◽  
pp. 1174
Author(s):  
Ashish Kumar Gupta ◽  
Ayan Seal ◽  
Mukesh Prasad ◽  
Pritee Khanna
Keyword(s):  
Computer Vision ◽  
Deep Learning ◽  
Object Detection ◽  
Large Scale ◽  
Research Work ◽  
Salient Object Detection ◽  
Future Research ◽  
Automatic Identification ◽  
Salient Object ◽  
Detection Techniques

Detection and localization of regions of images that attract immediate human visual attention is currently an intensive area of research in computer vision. The capability of automatic identification and segmentation of such salient image regions has immediate consequences for applications in the field of computer vision, computer graphics, and multimedia. A large number of salient object detection (SOD) methods have been devised to effectively mimic the capability of the human visual system to detect the salient regions in images. These methods can be broadly categorized into two categories based on their feature engineering mechanism: conventional or deep learning-based. In this survey, most of the influential advances in image-based SOD from both conventional as well as deep learning-based categories have been reviewed in detail. Relevant saliency modeling trends with key issues, core techniques, and the scope for future research work have been discussed in the context of difficulties often faced in salient object detection. Results are presented for various challenging cases for some large-scale public datasets. Different metrics considered for assessment of the performance of state-of-the-art salient object detection models are also covered. Some future directions for SOD are presented towards end.

scholarly journals Modelling regeneration and recruitment in a tropical rain forest

1992 ◽  
Vol 22 (9) ◽  
pp. 1235-1248 ◽  
Author(s):  
Jerome K. Vanclay
Keyword(s):  
Rain Forest ◽  
Tropical Rain Forest ◽  
Growth Models ◽  
Basal Area ◽  
Relative Number ◽  
Site Quality ◽  
Permanent Sample Plots ◽  
Second Stage ◽  
Number Of Stems ◽  
Stand Basal Area

A two-stage model predicts the recruitment (i.e., the number of stems reaching or exceeding 10 cm DBH) of the 100 species that account for 97% of all the recruitment observed on 217 permanent sample plots in the tropical rain forest of north Queensland. The first stage predicts the probability of the occurrence of any recruitment from stand basal area and the presence of that species in the existing stand. These probabilities can be implemented stochastically, or deterministically by summing the probabilities and initiating recruitment on unity. The second stage indicates the expected amount of recruitment, given that it is known to occur, and employs stand basal area, the relative number of trees of that species in the stand, and site quality. This approach is easily implemented in growth models and planning systems.

scholarly journals Automatic identification of bird targets with radar via patterns produced by wing flapping

2008 ◽  
Vol 5 (26) ◽  
pp. 1041-1053 ◽  
Author(s):  
Serge Zaugg ◽  
Gilbert Saporta ◽  
Emiel van Loon ◽  
Heiko Schmaljohann ◽  
Felix Liechti
Keyword(s):  
Bird Migration ◽  
Wind Farms ◽  
Classification Performance ◽  
Future Research ◽  
Support Vector ◽  
Automatic Identification ◽  
Radar Meteorology ◽  
Ground Clutter ◽  
Environmental Impact Assessments ◽  
Radar Signals

Bird identification with radar is important for bird migration research, environmental impact assessments (e.g. wind farms), aircraft security and radar meteorology. In a study on bird migration, radar signals from birds, insects and ground clutter were recorded. Signals from birds show a typical pattern due to wing flapping. The data were labelled by experts into the four classes BIRD, INSECT, CLUTTER and UFO (unidentifiable signals). We present a classification algorithm aimed at automatic recognition of bird targets. Variables related to signal intensity and wing flapping pattern were extracted (via continuous wavelet transform). We used support vector classifiers to build predictive models. We estimated classification performance via cross validation on four datasets. When data from the same dataset were used for training and testing the classifier, the classification performance was extremely to moderately high. When data from one dataset were used for training and the three remaining datasets were used as test sets, the performance was lower but still extremely to moderately high. This shows that the method generalizes well across different locations or times. Our method provides a substantial gain of time when birds must be identified in large collections of radar signals and it represents the first substantial step in developing a real time bird identification radar system. We provide some guidelines and ideas for future research.

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