Effects of an experimental ice storm on forest canopy structure

2020 ◽  
Vol 50 (2) ◽  
pp. 136-145 ◽  
Author(s):  
Robert T. Fahey ◽  
Jeff W. Atkins ◽  
John L. Campbell ◽  
Lindsey E. Rustad ◽  
Meghan Duffy ◽  
...  
Keyword(s):  
Forest Canopy ◽  
Canopy Structure ◽  
Specific Effect ◽  
Canopy Openness ◽  
Ice Accretion ◽  
Ice Storm ◽  
Structural Reorganization ◽  
Ice Storms ◽  
Near Term ◽  
Intermediate Disturbances

Intermediate disturbances are an important component of many forest disturbance regimes, with effects on canopy structure and related functions that are highly dependent on the nature and intensity of the perturbation. Ice storms are an important disturbance mechanism in temperate forests that often result in moderate-severity, diffuse canopy damage. However, it has not previously been possible to distinguish the specific effect of ice storm intensity (as ice accretion) from predisturbance stand characteristics and physiographic factors. In this study, we utilized a novel experimental ice storm treatment to evaluate the effects of variable ice accretion levels on forest canopy structure. Our results verified significant impacts of ice storm disturbance on near-term canopy structural reorganization. Canopy openness, light transmission, and complexity increased significantly relative to predisturbance baselines and undisturbed controls. We documented variable impacts with disturbance intensity, as significant canopy changes largely occurred with ice accretion levels of ≥12.7 mm. Repeated ice storm disturbance (two consecutive years) had marginal, rather than compounding, effects on forest canopy structure. Our findings are relevant to understanding how ice storms can affect near-term forest canopy structural reorganization and ecosystem processes and add to a growing base of knowledge on the effects of intermediate disturbances on canopy structure.

A novel ice storm manipulation experiment in a northern hardwood forest

2012 ◽  
Vol 42 (10) ◽  
pp. 1810-1818 ◽  
Author(s):  
Lindsey E. Rustad ◽  
John L. Campbell
Keyword(s):  
United States ◽  
Forest Canopy ◽  
Forest Ecosystems ◽  
Hardwood Forest ◽  
Canopy Openness ◽  
Northern Hardwood Forest ◽  
Ice Storm ◽  
Northeastern United States ◽  
Northern Hardwood ◽  
Ice Storms

Ice storms are an important natural disturbance within forest ecosystems of the northeastern United States. Current models suggest that the frequency and severity of ice storms may increase in the coming decades in response to changes in climate. Because of the stochastic nature of ice storms and difficulties in predicting their occurrence, most past investigations of the ecological effects of ice storms across this region have been based on case studies following major storms. Here we report on a novel alternative approach where a glaze ice event was created experimentally under controlled conditions at the Hubbard Brook Experimental Forest, New Hampshire, USA. Water was sprayed over a northern hardwood forest canopy during February 2011, resulting in 7–12 mm radial ice thickness. Although this is below the minimum cutoff for ice storm warnings (13 mm of ice) issued by the US National Weather Service for the northeastern United States, this glaze ice treatment resulted in significant canopy damage, with 142 and 218 g C·m–2 of fine and coarse woody debris (respectively) deposited on the forest floor, a significant increase in leaf-on canopy openness, and increases in qualitative damage assessments following the treatment. This study demonstrates the feasibility of a relatively simple approach to simulating an ice storm and underscores the potency of this type of extreme event in shaping the future structure and function of northern hardwood forest ecosystems.

scholarly journals Multidimensional Structural Characterization is Required to Detect and Differentiate Among Moderate Disturbance Agents

2019 ◽  
Author(s):  
Jeff W. Atkins ◽  
Ben Bond-Lamberty ◽  
Robert T. Fahey ◽  
Brady S. Hardiman ◽  
Lisa Haber ◽  
...  
Keyword(s):  
Structural Changes ◽  
Canopy Structure ◽  
Detection Methods ◽  
Ice Storm ◽  
Storm Damage ◽  
Ecological Disturbance ◽  
Moderate Severity ◽  
Terrestrial Lidar ◽  
Ice Storms ◽  
Age Related

The study of vegetation community and structural change has been central to ecology for over a century, yet how disturbances reshape the physical structure of forest canopies remains relatively unknown. Moderate severity disturbance including fire, ice storms, insect and pathogen outbreaks, affects different canopy strata and plant species, which may give rise to variable structural outcomes and ecological consequences. Terrestrial lidar (light detection and ranging) offers an unprecedented view of the interior arrangement and distribution of canopy elements, permitting the derivation of multidimensional measures of canopy structure that describe several canopy structural traits with known linkages to ecosystem functioning. We used lidar-derived canopy structural measured within a machine learning framework to detect and differentiate among various disturbance agents, including moderate severity fire, ice storm damage, age-related senescence, hemlock woolly adelgid, beech bark disease, and chronic acidification. We found that disturbance agents such as fire and ice storms primarily affected the amount and position of vegetation within canopies, while acidification, pathogen and insect infestation, and senescence altered canopy arrangement and complexity. Only two of the six disturbance agents significantly reduced leaf area, indicating that this commonly quantified canopy feature is insufficient to characterize many moderate severity disturbances. Rather, measures of canopy structure, including those that describe multidimensional change, are needed to characterize disturbance at moderate severities because structural changes from these events are spatially and quantitatively variable. Our findings suggest that standard disturbance detection methods, such as optical based remote sensing platforms, may currently be limited in their ability to detect, differentiate, and characterize disturbance. Further, we conclude that a more broadly inclusive definition of ecological disturbance that incorporates multiple aspects of canopy structure change will improve the modeling, detection, and prediction of functional implications of moderate severity disturbance.

scholarly journals Evaluation of hemispherical photos extracted from smartphone spherical panorama images to estimate canopy structure and forest light environment

2020 ◽  
Author(s):  
A. Z. Andis Arietta
Keyword(s):  
Image Quality ◽  
Forest Canopy ◽  
Dynamic Range ◽  
Canopy Structure ◽  
High Dynamic Range ◽  
Canopy Openness ◽  
Traditional Methods ◽  
Area Index ◽  
Site Factor ◽  
High Dynamic

AbstractHemispherical photography (HP) is one of the most commonly employed methods to estimate forest canopy structure and understory light environments. Traditional methods require expensive, specialized equipment, are tedious to deploy, and are sensitive to exposure settings. In contrast, modern smartphone cameras are readily available and make use of ever-improving software to produce images with high dynamic range and clarity, but lack suitable hemispherical lenses. Thus, despite the fact that almost all ecologists and foresters carry a high-powered, image processing device in our pockets, we have yet to fully employ it for the purpose of data collection. As an alternative, hemispherical images can be extracted from spherical panoramas produced by many smartphone camera applications. I compared hemispherical photos captured with a digital single lens reflex camera and 180° lens to those extracted from smartphone spherical panoramas (SSP) for 72 sites representing a range of canopy types and densities. I estimated common canopy and light measures (canopy openness, leaf area index, and global site factor) as well as image quality measures (total gap area, number of gaps, and relative gap size) to compare methods. The SSP HP method leverages built-in features of current generation smartphones including exposure metering over restricted field-of-view, high dynamic range tonal correction, computational sharpening, high pixel density, and automatic leveling via the phone’s built-in gyroscope to yield an accurate alternative to traditional HP in canopy estimation. Although the process of stitching together multiple photos occasionally produces artifacts in the SSP HP images, estimates of canopy openness and global site factor are highly correlated with those of traditional methods (R2> 0.9) and are comparable to under- or over-exposing traditional HP by 1-1.5 stops. In addition to superior image quality, SSP HP requires no additional equipment or exposure settings and is likely to prove more robust to uneven lighting conditions by avoiding wide-angles lenses and exploiting HDR images.

Changes in understory light regime in a beech–maple forest after a severe ice storm

2007 ◽  
Vol 37 (9) ◽  
pp. 1770-1776 ◽  
Author(s):  
Ken Arii ◽  
Martin J. Lechowicz
Keyword(s):  
Soil Surface ◽  
Deciduous Forests ◽  
Permanent Plots ◽  
Canopy Openness ◽  
Ice Storm ◽  
Ice Storms ◽  
Hemispherical Photographs ◽  
Shade Tolerant Species ◽  
The Mean ◽  
Canopy Damage

We assessed canopy openness (%) in an old-growth beech–maple forest immediately before and in the 3 years following a severe ice storm. We estimated canopy openness using hemispherical photographs taken at a height of 0.6 m above the soil surface in 101 permanent plots. Mean canopy openness increased from a prestorm value of 7.7% to 16.6% in the summer immediately following the storm. However, the mean canopy openness returned to prestorm levels within 3 years. The changes in canopy openness immediately after the storm were significantly influenced by canopy openness prior to the storm and also by species composition; plots with lower canopy openness prior to the storm and plots that consisted of more shade-tolerant species had greater canopy damage. While canopy gaps are often considered to promote the establishment of shade-intolerant species in the deciduous forests of eastern North America, gaps created by ice storms at our study site may not persist long enough to promote the establishment of these species.

scholarly journals Forecasting severe ice storms using numerical weather prediction: the March 2010 Newfoundland event

2011 ◽  
Vol 11 (2) ◽  
pp. 587-595 ◽  
Author(s):  
J. Hosek ◽  
P. Musilek ◽  
E. Lozowski ◽  
P. Pytlak
Keyword(s):  
Numerical Weather Prediction ◽  
Weather Prediction ◽  
Storm Event ◽  
Rain Event ◽  
Ice Accretion ◽  
Ice Storm ◽  
Forecast Horizon ◽  
Freezing Rain ◽  
Numerical Weather ◽  
Ice Storms

Abstract. The northeast coast of North America is frequently hit by severe ice storms. These freezing rain events can produce large ice accretions that damage structures, frequently power transmission and distribution infrastructure. For this reason, it is highly desirable to model and forecast such icing events, so that the consequent damages can be prevented or mitigated. The case study presented in this paper focuses on the March 2010 ice storm event that took place in eastern Newfoundland. We apply a combination of a numerical weather prediction model and an ice accretion algorithm to simulate a forecast of this event. The main goals of this study are to compare the simulated meteorological variables to observations, and to assess the ability of the model to accurately predict the ice accretion load for different forecast horizons. The duration and timing of the freezing rain event that occurred between the night of 4 March and the morning of 6 March was simulated well in all model runs. The total precipitation amounts in the model, however, differed by up to a factor of two from the observations. The accuracy of the model air temperature strongly depended on the forecast horizon, but it was acceptable for all simulation runs. The simulated accretion loads were also compared to the design values for power delivery structures in the region. The results indicated that the simulated values exceeded design criteria in the areas of reported damage and power outages.

Comparing indices of understory light availability between hemlock and hardwood forest patches

2009 ◽  
Vol 39 (10) ◽  
pp. 1949-1957 ◽  
Author(s):  
Michael F. Tobin ◽  
Peter B. Reich
Keyword(s):  
Sugar Maple ◽  
Forest Canopy ◽  
Light Availability ◽  
Canopy Structure ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Canopy Openness ◽  
Forest Patches ◽  
Two Indices

We evaluated whether two indices of light availability resolved differences among microsites within deeply shaded understories (<12% of above-canopy photosynthetic photon flux density (PPFD)) and also whether marked differences in forest canopy structure affected how the two indices related to direct measures of incident photosynthetically active radiation (PAR). Incident PAR was measured with gallium–arsenide–phosphide photodiodes at numerous points in two adjacent forest patches in Michigan, USA: one dominated by the evergreen conifer eastern hemlock ( Tsuga canadensis (L.) Carrière), and the other by the deciduous hardwood sugar maple ( Acer saccharum Marsh.). The two indices tested were canopy openness, measured with the LI-COR LAI-2000 plant canopy analyzer, and the percentage of above-canopy PPFD measured in the understory during overcast conditions (%PPFD). Canopy openness and %PPFD did not effectively predict the long-term mean of daily PPFD. However, both indices reliably predicted the long-term mean of daily median PPFD, an alternative standard of directly measured incident PAR that reduces the relative contribution of sunflecks. The relationships of both indices with mean daily median PPFD differed between hemlock and hardwood patches. Hence, the effect of canopy structure should be considered when using these indices to draw conclusions about differences in light availability between forest patches, particularly when narrow ranges of light availability in deep shade are important.

scholarly journals Quantitative Ice Accretion Information from the Automated Surface Observing System

2007 ◽  
Vol 46 (9) ◽  
pp. 1423-1437 ◽  
Author(s):  
Charles C. Ryerson ◽  
Allan C. Ramsay
Keyword(s):  
United States ◽  
The United States ◽  
Ice Thickness ◽  
Ice Storm ◽  
Design Standards ◽  
Ice Storms ◽  
Ice Accumulation ◽  
Direct Measurements ◽  
Improved Design ◽  
Precipitation Events

Abstract Freezing precipitation is a persistent winter weather problem that costs the United States millions of dollars annually. Costs and infrastructure disruption may be greatly reduced by ice-storm warnings issued by the National Weather Service (NWS), and by the development of climatologies that allow improved design of infrastructure elements. However, neither the NWS nor developers of climatologies have had direct measurements of ice-storm accumulations as a basis for issuing warnings and developing storm design standards. This paper describes the development of an aviation routine/special weather report (METAR/SPECI) remark that will report quantitative ice thickness at over 650 locations during ice storms using new algorithms developed for the Automated Surface Observing System (ASOS). Characteristics of the ASOS icing sensor, a field program to develop the algorithms, tests of accuracy, application of the algorithms, and sources of error are described, as is the implementation of an ice-thickness METAR/SPECI remark. The algorithms will potentially allow freezing precipitation events to be tracked with regard to ice accumulation in near–real time as they progress across the United States.

Understory biomass estimation based on Structure from Motion data by Multi-layered forest drone survey

2021 ◽  
Author(s):  
Yupan Zhang ◽  
Yuichi Onda ◽  
Hiroaki Kato ◽  
Xinchao Sun ◽  
Takashi Gomi
Keyword(s):  
Structure From Motion ◽  
Forest Structure ◽  
Large Scale ◽  
Forest Canopy ◽  
Point Clouds ◽  
Understory Vegetation ◽  
Biomass Estimation ◽  
Canopy Openness ◽  
Cubic Model ◽  
Overlap Analysis

&lt;p&gt;Understory vegetation is an important part of evapotranspiration from forest floor. Forest management changes the forest structure and then affects the understory vegetation biomass (UVB). Quantitative measurement and estimation of&amp;#160; UVB is a step cannot be ignored in the study of forest ecology and forest evapotranspiration. However, large-scale biomass measurement and estimation is challenging. In this study, Structure from Motion (SfM) was adopted simultaneously at two different layers in a plantation forest made by Japanese cedar and Japanese cypress to reconstruct forest structure from understory to above canopy: i) understory drone survey in a 1.1h sub-catchment to generate canopy height model (CHM) based on dense point clouds data derived from a manual low-flying drone under the canopy; ii) Above-canopy drone survey in whole catchment (33.2 ha) to compute canopy openness data based on point clouds of canopy derived from an autonomous flying drone above the canopy. Combined with actual biomass data from field harvesting to develop regression models between the CHM and UVB, which was then used to map spatial distribution of&amp;#160; UVB in sub-catchment. The relationship between UVB and canopy openness data was then developed by overlap analysis. This approach yielded high resolution understory over catchment scale with a point cloud density of more than 20 points/cm&lt;sup&gt;2&lt;/sup&gt;. Strong coefficients of determination (R-squared = 0.75) of the cubic model supported prediction of UVB from CHM, the average UVB was 0.82kg/m&lt;sup&gt;2&lt;/sup&gt; and dominated by low ferns. The corresponding forest canopy openness in this area was 42.48% on average. Overlap analysis show no significant interactions between them in a cubic model with weak predictive power (R-squared &lt; 0.46). Overall, we reconstructed the multi-layered structure of the forest and provided models of UVB. Understory survey has high accuracy for biomass measurement, but it&amp;#8217;s inherently difficult to estimate UVB only based on canopy openness result.&lt;/p&gt;

Drone-acquired data reveal the importance of forest canopy structure in predicting tree diversity

2022 ◽  
Vol 505 ◽  
pp. 119945
Author(s):  
Jian Zhang ◽  
Zhaochen Zhang ◽  
James A. Lutz ◽  
Chengjin Chu ◽  
Jianbo Hu ◽  
...  
Keyword(s):  
Forest Canopy ◽  
Canopy Structure ◽  
Tree Diversity

scholarly journals Spatial Variation in Canopy Structure across Forest Landscapes

2018 ◽  
Author(s):  
Brady S. Hardiman ◽  
Elizabeth A. LaRue ◽  
Jeff W. Atkins ◽  
Robert T. Fahey ◽  
Franklin W. Wagner ◽  
...  
Keyword(s):  
Temperate Forest ◽  
Forest Canopy ◽  
Spatial Scales ◽  
Canopy Structure ◽  
Ecosystem Functions ◽  
Lidar System ◽  
Stable Point ◽  
Eastern Usa ◽  
Forested Landscapes ◽  
Patch Scale

Forest canopy structure (CS) controls many ecosystem functions and is highly variable across landscapes, but the magnitude and scale of this variation is not well understood. We used a portable canopy lidar system to characterize variation in five categories of CS along N = 3 transects (140&ndash;800 m long) at each of six forested landscapes within the eastern USA. The cumulative coefficient of variation was calculated for subsegments of each transect to determine the point of stability for individual CS metrics. We then quantified the scale at which CS is autocorrelated using Moran&rsquo;s I in an Incremental Autocorrelation analysis. All CS metrics reached stable values within 300 m but varied substantially within and among forested landscapes. A stable point of 300 m for CS metrics corresponds with the spatial extent that many ecosystem functions are measured and modeled. Additionally, CS metrics were spatially autocorrelated at 40 to 88 m, suggesting that patch scale disturbance or environmental factors drive these patterns. Our study shows CS is heterogeneous across temperate forest landscapes at the scale of 10&rsquo;s of meters, requiring a resolution of this size for upscaling CS with remote sensing to large spatial scales.

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