Coherent response of a group of plantation-grown Scots pine trees to wind loading

Schindler, Dirk; Fugmann, Hannes; Schönborn, Jochen; Mayer, Helmut

doi:10.1007/s10342-010-0474-0

Cited by 22 publications

(10 citation statements)

References 41 publications

(71 reference statements)

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“…Based on previous results on the typical duration of coherent structures in and above the Scots pine forest [22], the cut-off frequencies chosen to separate coherent structures from long-term variations and short-term fluctuations were 0.003 Hz and 0.05 Hz. Thus, the filter removes all variations longer than 300 s and also all fluctuations smaller than event durations of 20 s from the u 1 and w 1 time series.…”

Section: Data Processingmentioning

confidence: 99%

“…The BOD is able to capture important common time-space characteristics in high-dimensional datasets. In the field of plant canopy turbulence, the BOD has already successfully been applied in previous studies focusing on the detection of coherent patterns in the interactions of airflow and plant canopies [22,24,25].…”

Section: Introductionmentioning

confidence: 99%

“…This is important when chemical concentration gradients [18,19] and turbulent carbon and energy fluxes are measured within and above plant canopies [20] to study and model matter and energy cycles. A better understanding of coherent structure propagation into forest canopies is also of importance when tree response to wind loading is investigated [21,22].…”

Section: Introductionmentioning

confidence: 99%

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Coherent Momentum Exchange above and within a Scots Pine Forest

Mohr

Schindler

2016

Atmosphere

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Biorthogonal decomposition (BOD) is used to detect and study synchronous coherent structures occurring at multiple levels in the vertical momentum flux (u 1 w 1 ) within and above a planted Scots pine forest during a 12-week continuous measurement period. In this study, the presented method allowed for the simultaneous detection and quantification of the number of coherent structures (N), their duration (D) and separation (S) at five measurement heights (z 1 -z 5 ) covering the range z 1 /h = 0.11 to z 5 /h = 1.67, with h being the mean stand height at the measurement site. Results presented for five different exchange regimes (C1-C5) and for four different atmospheric stability conditions (stable, transition to stable, near-neutral, forced convection) demonstrate that during the measurement period, above-canopy momentum flux was only to a limited extent involved in the evolution of spatiotemporal momentum flux patterns found within the below-canopy space. Fully-coupled turbulent momentum exchange over the investigated height range occurred during 19% of all analyzed half-hourly datasets. Across the analyzed exchange regimes, the median contribution of strong sweeps and ejections to total momentum transfer above the canopy varied between 30% and 39% while covering 28%-32% of the time. In the below-canopy space, the contribution of coherent structures varied between 19% and 21% while covering the same amount of time. This suggests that momentum transfer through synchronous coherent structures is very efficient above the forest canopy, but attenuated in the below-canopy space. Since the majority of the presented results agrees well with the results from previous studies that analyzed coherent structures at single levels, the BOD is a promising tool for the consistent investigation of synchronous coherent structures at multiple measurement heights.

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Section: Data Processingmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Coherent Momentum Exchange above and within a Scots Pine Forest

Mohr

Schindler

2016

Atmosphere

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“…The dominating periods of the air pressure fluctuations (in s) per 30 min interval were determined by investigating the normalized wavelet variance spectrum [53][54][55]. The wavelet coefficients were calculated for 100 scales using the Morlet wavelet, corresponding to up to 103 s. Then, the normalized wavelet variance spectrum was calculated.…”

Section: Air Pressure Datamentioning

confidence: 99%

Analysis of Air Pressure Fluctuations and Topsoil Gas Concentrations within a Scots Pine Forest

et al. 2016

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High-precision differential air pressure measurements were conducted in the below-canopy space of a Scots pine forest and in the forest soil to investigate small air pressure fluctuations and their effect on soil gas flux. In addition to air pressure measurements, tracer gas concentration in the soil and airflow characteristics above and below the canopy were measured. Results suggest that air pressure fluctuations in the frequency range of 0.01 Hz-0.1 Hz are strongly dependent on abovecanopy wind speed. While amplitudes of the observed air pressure fluctuations (<10 Pa) increase significantly with increasing above-canopy wind speed, the periods decrease significantly with increasing above-canopy wind speed. These air pressure fluctuations are associated with the pressure-pumping effect in the soil. A pressure-pumping coefficient was defined, which describes the strength of the pressure-pumping effect. During the measurement period, pressure-pumping coefficients up to 0.44 Pa·s −1 were found. The dependence of the pressure-pumping coefficient on mean above-canopy wind speed can be described well with a polynomial fit of second degree. The knowledge of this relation simplifies the quantification of the pressure-pumping effect in a Scots pine forest considerably, since only the mean above-canopy wind speed has to be measured. In addition, empirical modeling revealed that the pressure-pumping coefficient explains the largest fraction of the variance of tracer gas concentration in the topsoil.

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“…Compared with broadleaf trees, coniferous trees have been further studied in the recent two decades. In the category of coniferous trees, three major species have been well-explored, which are pine [38][39][40], Douglas fir [41], and Spruce [42][43][44]. On the other hand, the broadleaf species undertaken in this study include Maple tree [26], Oak tree [32], Birch (Betula spp.)…”

Section: Tree Species and The Physical Attributesmentioning

confidence: 99%

A Review of Dynamic Tree Behaviors: Measurement Methods on Tree Sway, Tree Tilt, and Root–Plate Movement

Yang

Hui

Abbas

et al. 2021

Forests

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Urban forest ecosystems are being developed to provide various environmental services (e.g., the preservation of urban trees) to urban inhabitants. However, some trees are deteriorated asymptomatically without exhibiting an early sign of tree displacement, which results in a higher vulnerability under dynamic wind loads, especially during typhoon seasons, in the subtropical and tropical regions. As such, it is important to understand the tilt and sway behaviors of trees to cope up with the probability of tree failure and to improve the efficacy of tree management. Tree behaviors under wind loads have been broadly reviewed in the past literature, yet thorough discussions on the measurement methods for tree displacement and its analysis of broadleaf specimens are lacking. To understand the behavioral pattern of both broadleaf and conifer species, this paper presents a detailed review of sway behavior analysis from the perspectives of the aerial parts of the individual tree, including tree stem, canopy, and trunk, alongside a highlighted focus on the root–plate movement amid the soil-root system. The analytical approaches associated with the time-space domain and the time-frequency domain are being introduced. In addition to the review of dynamic tree behaviors, an integrated tree monitoring framework based on geographic information systems (GIS) to detect and visualize the extent of tree displacement using smart sensing technology (SST) is introduced. The monitoring system aims to establish an early warning indicator system for monitoring the displacement angles of trees over the territory of Hong Kong’s urban landscape. This pilot study highlights the importance of the monitoring system at an operational scale to be applicable in the urban areas showcasing the practical use of the Internet of Things (IoT) with an in-depth understanding of the wind-load effect toward the urban trees in the tropical and subtropical cities.

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Coherent response of a group of plantation-grown Scots pine trees to wind loading

Cited by 22 publications

References 41 publications

Coherent Momentum Exchange above and within a Scots Pine Forest

Coherent Momentum Exchange above and within a Scots Pine Forest

Analysis of Air Pressure Fluctuations and Topsoil Gas Concentrations within a Scots Pine Forest

A Review of Dynamic Tree Behaviors: Measurement Methods on Tree Sway, Tree Tilt, and Root–Plate Movement

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