Ice Storm Damage Research Articles

Ambrosia beetle (Coleoptera: Curculionidae: Scolytinae) responses to ice storm damage in mesic, mixed deciduous forests in southeast Ohio, United States

Ambrosia beetle (Coleoptera: Curculionidae: Scolytinae) responses to ice storm damage in mesic, mixed deciduous forests in southeast Ohio, United States

Stem Defect Rates and Ice Storm Damage for Families of Pinus taeda from Coastal and Piedmont Provenances Planted on a North Carolina Piedmont Site

Abstract Twenty Pinus taeda L. families from both the Coastal Plain and Piedmont provenances in the southeastern United States were planted on an upper Piedmont site that experienced a severe ice storm at age 3 years. Storm damage and defect rates through age 11 years were compared with the seed transfer distance and the seed parents’ breeding values to develop prediction models for storm damage and rates of forking, stem break, and sawtimber potential. Warmer-source families had higher probability of limb or stem breaks and foliage injury from the storm. Taller trees were more likely to experience breaks and foliage injury, even after accounting for seed transfer distance. Trees with forks or fusiform rust (Cronartium quercuum f. sp. fusiforme) infection had a higher probability of breaks. Trees with limb breaks or foliage injury did not have reduced sawtimber potential, but broken stems reduced sawtimber potential. The storm did not cause immediate mortality, but trees with major limb breaks, stem breaks, or foliage injury were less likely to be alive at age 8 years. At age 11 years, families with the best combination of breeding values for forking, straightness, and rust resistance had a predicted 60% of stems having sawtimber potential, whereas families with the worst combination had 30%. Study Implications: Planting warmer-source Pinus taeda (loblolly pine) families farther north and inland may lead to greater growth but poses a risk of damage from cold temperatures and ice storms. Trees grown for solid-wood products must be relatively defect-free and require a longer rotation, whereas bioenergy and pulpwood can use smaller, defective trees. This analysis presents predictions of defect rates through age 11 years based on the seed source and breeding values using data from a planting in the upper Piedmont of North Carolina. Land managers can use these models to weigh the benefits and risks when choosing families for reforestation.

Ice storm damage to oak forests in subtropical China

Ice storms, as important sources of frequent and injurious disturbances, drive forest dynamics in the Northern Hemisphere. However, stand-level differential vulnerability to ice storms and the associated factors that predispose forest stands remain unclear. This is particularly concerning in the subtropics where the frequency of ice storms is predicted to increase with global warming. Here we assessed how the impact on three forest stands (early and late secondary-growth forests, and old-growth forests) differed after an extreme ice storm during 20–21 March 2022, and identified the abiotic and biotic factors that determine the damage intensity in the Shennongjia World Natural Heritage Site, a biodiversity conservation hotspot in central China. We found a stand-specific ‘mid-domain effect’ where the late secondary-growth forest sustained the most severe damage, the early secondary-growth forest sustained the least, and the old-growth forest suffered an intermediate amount. ‘Crown broken’ was the most severe damage type across all three forest stands, although the proportion of ‘branch broken’ was also high in the old-growth forest. Topography played a significant role in determining the vulnerability of the early secondary-growth forest to severe ice storms whereas the forest structure and composition were important factors in explaining the damage rates in the old-growth forest, although they differed among the damage categories. In contrast, topography, forest structure and composition generally explain the intensity of damage in the late secondary-growth forests. Our results highlight that, in subtropical forests, the intensity of damage caused by severe ice storms and related determining factors are stand-level dependent. We also suggest exploring potential management strategies (e.g., slow-growing hardwood species that can resist storms should be the main species for reforestation in early secondary-growth forests) to mitigate the risk of future severe ice storms, as well as other wind-related climatic extremes.

Mastication Fuels Did Not Alter Fire Severity or Stand Structure in an Upland Oak Woodland

Abstract In the eastern deciduous forest region, open oak woodlands once occupied significant areas that are now closed-canopy forests, negatively affecting wildlife habitat and biodiversity. We superimposed midstory mastication and prescribed fire treatments onto sites with ice storm damage, subsequently subjected to sanitation thinning for management restoration. Mastication reduced stem density and basal area, created a variable cover of masticated material, and increased cover of forbs, graminoids, and tree regeneration. Prescribed fire was implemented two years after mastication treatment. We examined fuel changes and whether masticated fuels altered fire severity. Masticated duff depth decreased significantly two years after treatment; no change occurred on nonmasticated treatments. Masticated 1-hour fuels decreased 80% compared to 35% in nonmasticated treatments and masticated 10 h fuels decreased 45% compared to 9.6% in treatments without mastication. Prescribed fire reduced 1, 10, and 100 h fuels on the burn only treatment, and 10 h fuels on the mastication/burn treatment. Burn severity, measured by composite burn index, did not differ between treatments, nor did we measure significant effects of mastication on fire temperature or char height. Fire had no significant effect on stand structure but should be reexamined in three to five years. Repeated burning at three to five y intervals may also be beneficial.

The response of the invasive princess tree (Paulownia tomentosa) to wildland fire and other disturbances in an Appalachian hardwood forest

This study examined the response of princess tree (Paulownia tomentosa) to different disturbances and its potential to spread throughout its current range in the U.S. The study was established in Shawnee State Forest in southern Ohio, USA, which has historically experienced disturbances from mining, logging, ice storms and wildfire. Plots were established for vegetation sampling where fire had occurred with and without princess tree present, and where no fire had occurred with and without princess tree present. To determine the influence of disturbance types on the density of princess tree, redundancy analysis (RDA) was used. High stem density of princess tree seedlings occurred in areas that experienced high fire intensities and herbicide treatment. Seedlings on southwest slopes increased in abundance as the time from the last logging activity increases. Princess tree saplings were present in greater densities in areas that experienced medium fire intensities and the highest ice storm damage. Sapling density is greatest as ground cover and vegetation height increases and slope decreases. Princess trees reach maximum stem density on northeast slopes in areas not impacted by the 2009 fire. All disturbances considered, including wildfire, have created conditions conducive to princess tree growth and expansion into forest areas.

Growth of Sugar Maple (Acer saccharum Marsh.) after Ice Storm Damage and Forest Tent Caterpillar (Malacosoma disstria Hubner) Defoliation

The January 1998 ice storm broke off tree crowns across a wide geographic area in northeastern North America, and forest tent caterpillar (Malacosoma disstria Hubner) defoliated some of the same stands in 2004–2007. We assessed the post-event growth responses of upper canopy sugar maples (Acersaccharum Marsh.) in previously thinned and recently rehabilitated even-aged northern hardwood stands in New York State, USA. Cores from ice-storm-damaged trees showed an initial radial growth reduction, a recovery after one year, and an increase to or above pre-storm levels after three years. A later forest tent caterpillar defoliation in the same stand caused a second reduction of growth, and another recovery after one year. We observed greater post-storm radial growth on trees released by a post-ice storm rehabilitation treatment than in the untreated control, with growth exceeding pre-storm rates. Cores from another site thinned 38 years earlier and impacted only by the forest tent caterpillar showed a more moderate growth reduction, and a prompt but smaller post-defoliation growth response than among trees affected by both the ice storm and defoliation. Findings reflect the potential for growth of upper canopy sugar maple trees to recover after a single or two closely occurring crown disturbances, and provide guidance to managers who must decide about removing or continuing to manage stands after similar kinds of ice storm damage or defoliation.

Tree growth and survival over 61 years at the Second International Larch Provenance Test in southeastern Michigan, USA

Abstract Provenance trials remain an important tool for understanding genetic variation in forest trees. Maintaining decades-old experiments is critical for revealing maladaptation of translocated populations to local sites and meaningful divergence in survival and growth. We revisited the Second International Larch Provenance Test in southeastern Michigan, which featuring 24 provenances of European and Japanese larch. We compiled data collected when the plantation was 25, 41, and 61 years from seed to supplement data published at 19 years from seed. Divergence in survival rates first became pronounced at 41 years from seed. Plantation sources of unknown origin and continental Sudeten provenances had the highest rates of survival. High-elevation sources from the southern Alps performed the poorest. Survival differences were likely driven by ice storm damage and severe growing season droughts, both of which occurred at least 1-2 times per decade in southeastern Michigan over the last 60 years. Provenance performance for growth mirrored that of survival, although sources varied more in their survival than in their growth. Growth rate among sources varied over the 43-year sampling period, with intervals of fast growth occurring in several of the overall poor-performing provenances. Diameter was moderately correlated to both elevation and latitude, with inconsistent correlations to climatic variables. Broad geographical variation in provenance performance was also important in explaining variation in growth. Our data corroborate that monitoring of long-term provenance trials could be an important source of information needed to predict and understand how forest species may respond to imminent climate change and may be critical for developing strategies for its mitigation.

Canopy gap characteristics and spatial patterns in a subtropical forest of South China after ice storm damage

The divergent gap characteristics and spatial patterns of canopy gaps created by natural or artificial disturbances can exert a dominant influence on forest structure and composition. However, little research has been conducted on the effects of ice storm damage on canopy gaps in subtropical mature forests of South China. In this study, one semi-natural site was dominated by a broad-leaf forest and two managed sites were representative of plantations with coniferous forests. Based on airborne laser scanning data and field evidence across sites, statistical analyses were used to examine gap characteristics following ice storms of moderate severity. Generalized Ripley’s K-function analysis was applied to test gap spatial patterns at a range of scales, and spatial point pattern analysis was used to quantitate the relative importance of specific influences on patterns of gap occurrence. The results revealed that the average gap size was 75.7 m2 and that 12.2 gaps occurred per hectare. Most gaps were single-tree fall events. In addition to more gaps, the mean gap size was smaller and the shape was more complex in the semi-natural site than in two managed sites. Large differences in gap characteristics were observed among snapped, uprooted, snag, and artificial gap damage types. Gaps generally showed a clustered distribution at large scales (e.g. 70m), whereas spatial patterns varied with gap damage types at different sites. The occurrence of gaps was strongly related to slope and topographic position at the semi-natural site, whereas slope, stem density, and human accessibility (proximity to pathways) were the most important factors affecting gap occurrence at the managed sites. We suggest that gap-based silvicultural treatments and natural disturbances regimes conjoin, highlighting interactions with other factors such as microsite conditions, non-tree vegetation and more.

Application of multidimensional structural characterization to detect and describe moderate forest disturbance

AbstractThe study of vegetation community and structural change has been central to ecology for over a century, yet the ways in which disturbances reshape the physical structure of forest canopies remain relatively unknown. Moderate severity disturbances affect different canopy strata and plant species, resulting in 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 (CSTs) with known links to ecosystem function. We used lidar‐derived CSTs within a machine learning framework to detect and describe the structural changes that result from 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 fire and ice storms primarily affected the amount and position of vegetation within canopies, while acidification, senescence, pathogen, and insect infestation altered canopy arrangement and complexity. Only two of the six disturbance agents significantly reduced leaf area, counter to common assumptions regarding many moderate severity disturbances. While findings are limited in their generalizability due to lack of replication among disturbances, they do suggest that the current limitations of standard disturbance detection methods—such as optical‐based remote sensing platforms, which are often above‐canopy perspectives—limit our ability to understand the full ecological and structural impacts of disturbance, and to evaluate the consistency of structural patterns within and among disturbance agents. A more broadly inclusive definition of ecological disturbance that incorporates multiple aspects of canopy structural change may potentially improve the modeling, detection, and prediction of functional implications of moderate severity disturbance as well as broaden our understanding of the ecological impacts of disturbance.

Ice-storm damage to trees in mixed Central European forests: damage patterns, predictors and susceptibility of tree species

AbstractIn northern temperate forests, ice storms are a common disturbance agent, though climate change may alter their occurrence patterns. Their impact on forest ecosystems is complex, as they influence both structure and processes. In 2014, an ice storm of high intensity and large spatial extent occurred in Slovenia, Central Europe, which enabled a detailed study of ice damage to individual trees across a broader spatial scale. Pre- and post-ice storm measurement data on 11 414 trees on 960 permanent plots were used to examine ice damage patterns on trees in the disturbed forest area (~8700 km2) to determine the predictors of ice damage to trees and to investigate the relative susceptibility of eight groups of tree species in mixed Central European forests. We used a novel approach to modelling ice-storm intensity across the region based on measured data on air temperature, precipitation amount and duration, precipitation intensity and wind speed. The ice storm damaged 31 percent of the analysed trees; high variability in the damage rate was observed across the disturbed area. For the tree species, a susceptibility to ice damage index (SI) ranging between 0 (no damage) and 1 (complete damage) was calculated based on terrestrial assessment of trees. Tree species differed significantly in susceptibility to ice damage: Abies alba (SI = 0.14) and Quercus sp. (SI = 0.11) were rather resistant; Picea abies, Fagus sylvatica and Acer sp. (SI = 0.23–0.28) were moderately to very susceptible; and Pinus sp. (SI = 0.62) was extremely susceptible to ice damage. Eight predictors and three interactions were included in an ordinal logistic regression model of tree damage: ice damage on trees depends mainly on ice-storm intensity, elevation and tree species, whilst tree dbh and social status, tree size and tree species diversity indices and slope were relatively less important. Our study illustrates the complexity of damage patterns on trees due to ice storms and the significance of ice-storm intensity and tree species as predictors when modelling ice damage on individual trees.

Coordinating Electricity and Transportation Networks: Enhancing power grid resilience strategies against ice storms

Ice storms have seriously threatened power network security over the last decades. In 1998, an ice storm that struck North America damaged more than 1,000 transmission towers. In 2008, a severe ice storm struck South China, destroying thousands of transmission lines and towers, resulting in more than USd50 billion in economic loss. During this storm, the Chenzhou power network in the Hunan province suffered an outage, and the city experienced a weeklong power blackout. Figures 1 and 2 depict samples of damaged transmission lines and towers brought down by unbalanced tensions caused by ice-covered lines. Table 1 summarizes the corresponding damages to the transmission infrastructure, showing that more than 800 towers and 400 lines (i.e., in excess of 220 kV) were impaired. Moreover, the extent of ice storm damage in the distribution network included more than 60,000 towers and 47,000 lines.

The potential to characterize ecological data with terrestrial laser scanning in Harvard Forest, MA.

Contemporary terrestrial laser scanning (TLS) is being used widely in forest ecology applications to examine ecosystem properties at increasing spatial and temporal scales. Harvard Forest (HF) in Petersham, MA, USA, is a long-term ecological research (LTER) site, a National Ecological Observatory Network (NEON) location and contains a 35 ha plot which is part of Smithsonian Institution's Forest Global Earth Observatory (ForestGEO). The combination of long-term field plots, eddy flux towers and the detailed past historical records has made HF very appealing for a variety of remote sensing studies. Terrestrial laser scanners, including three pioneering research instruments: the Echidna Validation Instrument, the Dual-Wavelength Echidna Lidar and the Compact Biomass Lidar, have already been used both independently and in conjunction with airborne laser scanning data and forest census data to characterize forest dynamics. TLS approaches include three-dimensional reconstructions of a plot over time, establishing the impact of ice storm damage on forest canopy structure, and characterizing eastern hemlock (Tsuga canadensis) canopy health affected by an invasive insect, the hemlock woolly adelgid (Adelges tsugae). Efforts such as those deployed at HF are demonstrating the power of TLS as a tool for monitoring ecological dynamics, identifying emerging forest health issues, measuring forest biomass and capturing ecological data relevant to other disciplines. This paper highlights various aspects of the ForestGEO plot that are important to current TLS work, the potential for exchange between forest ecology and TLS, and emphasizes the strength of combining TLS data with long-term ecological field data to create emerging opportunities for scientific study.

Species, tree size, and overstory environment affect likelihood of ice storm damage to understory trees in a mature Douglas-fir forest

Abstract Glaze events (i.e., ice storms) are a potential source of disturbance whose effects have not been heavily researched in forests in the Pacific Northwest. This study examines the effects of species, size, and overstory environment on occurrence, source, and severity of damage sustained by planted understory trees in a mature Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) forest as a result of the glaze event that struck the central Oregon Coast Range in November 2014. Understory tree species were Douglas-fir, grand fir ( Abies grandis (Douglas ex D. Don) Lindl.), western hemlock ( Tsuga heterophylla (Raf.) Sarg.), and western redcedar ( Thuja plicata Donn ex D. Don). Overall, western redcedar was damaged least frequently, and western hemlock was damaged most frequently. Redcedar was less susceptible to crown damage and more susceptible to bending damage than the other three species, while hemlock showed the opposite trend. We found significantly lower (P

The effects of a large-scale ice storm event on the drivers of bark beetle outbreaks and associated management practices

Abstract Large-scale disturbances in forests are becoming more frequent due to a changing climate. Biotic disturbances can have cascading effects and therefore have a significant economic impact in forestry. It is therefore important to gain an understanding of the drivers of forest pest outbreaks in epidemic situations after large-scale disturbances and the implications for forest management. We investigated the influence of drivers on the bark beetle outbreaks following a large-scale ice storm in 2014 in Slovenia. A country-wide survey was done on the variables affecting ice storm damage to spruce trees. Additionally, the influence of the drivers of bark beetle attacks on outbreak intensity was assessed and compared under epidemic and endemic situations, and the effectiveness of forest management measures was assessed. Spruce trees were either uprooted or snapped, or the crown was lightly to severely damaged. The outbreaks under endemic situations were potentiated by the increasing amount of spruce and reduced by increasing slope. After the ice storm, the amount of sanitary felling because of outbreaks increased in areas with more steeper slopes, where the ice storm took place. An increase in the level of disturbance and a higher availability of dead and weakened trees positively affected bark beetle populations. The removal of dead trees alone in the first year after the ice storm was found to be an insufficient measure for preventing bark beetle outbreaks. The ineffectiveness of current practices suggests that bark beetle management should be reconsidered with regard to large-scale disturbances. When defining measures against bark beetle outbreaks, drivers in epidemic situations should be prioritized over those that are important in endemic situations. The results imply that the known factors that affect bark beetle attacks are not necessarily the same as those that drive bark beetle attacks after extraordinary disturbance events. Mixed stands should be promoted in forests for sustainable management.

Acid rain mitigation experiment shifts a forested watershed from a net sink to a net source of nitrogen

Decades of acid rain have acidified forest soils and freshwaters throughout montane forests of the northeastern United States; the resulting loss of soil base cations is hypothesized to be responsible for limiting rates of forest growth throughout the region. In 1999, an experiment was conducted that reversed the long-term trend of soil base cation depletion and tested the hypothesis that calcium limits forest growth in acidified soils. Researchers added 1,189 kg Ca(2+) ha(-1) as the pelletized mineral wollastonite (CaSiO3) to a 12-ha forested watershed within the Hubbard Brook Experimental Forest in the White Mountains of New Hampshire. Significant increases in the pH and acid-neutralizing capacity of soils and streamwater resulted, and the predicted increase in forest growth occurred. An unanticipated consequence of this acidification mitigation experiment began to emerge a decade later, with marked increases in dissolved inorganic nitrogen (DIN) exports in streamwater from the treated watershed. By 2013, 30-times greater DIN was exported from this base-treated watershed than from adjacent reference watersheds, and DIN exports resulting from this experiment match or exceed earlier reports of inorganic N losses after severe ice-storm damage within the study watershed. The discovery that CaSiO3 enrichment can convert a watershed from a sink to a source of N suggests that numerous potential mechanisms drive watershed N dynamics and provides new insights into the influence of acid deposition mitigation strategies for both carbon cycling and watershed N export.

Effects of gap size on diversity of soil fauna in a Cunninghamia lanceolata stand damaged by an ice storm in southern China

Cunninghamia lanceolata (Lamb.) Hook. is economically the most important tree species in southern China and has been cultivated in plantations on a large scale. This species is widely used in construction, furniture, utensils and shipbuilding. Soil fertility of C. lanceolata stands affects soil structure, porosity and nutrient availability, which causes changes in fauna activity. During January to February 2008, an ice storm caused extensive damage to C. lanceolata stands. Despite the environmental importance of soil fauna, basic information on the distribution and diversity of soil fauna in C. lanceolata stands after ice storm damage is lacking. To assess the response of soil fauna diversity and distribution to forest gaps following the ice storm, five small gaps (each 30–40 m2), five large gaps (each 80–100 m2) and five canopy cover plots were selected within a 2-ha C. lanceolata stand. Soil samples were collected from 0 to 10 cm depth in March 2011 to measure soil fauna diversity and abundance. The abundance and community composition of the soil fauna varied with gap size. In canopy cover sites, the number of individuals was 2.0 and 5.2 times greater than in the small gaps and large gaps. Three taxa (Nematoda, Oribatida and Insecta) of soil invertebrates occurred commonly, and Nematoda dominated the communities in all three habitat types. The Shannon–Wiener diversity index, Margalef diversity index, and Pielou evenness index were high in the small gaps, indicating that they harbored the most species, with the most even distribution, and the highest diversity. Our results indicated that gap size apparently affected abundance and community composition of the soil fauna.

Linking ice accretion and crown structure: towards a model of the effect of freezing rain on tree canopies.

Despite a longstanding interest in variation in tree species vulnerability to ice storm damage, quantitative analyses of the influence of crown structure on within-crown variation in ice accretion are rare. In particular, the effect of prior interception by higher branches on lower branch accumulation remains unstudied. The aim of this study was to test the hypothesis that intra-crown ice accretion can be predicted by a measure of the degree of sheltering by neighbouring branches. Freezing rain was artificially applied to Acer platanoides L., and in situ branch-ice thickness was measured directly and from LiDAR point clouds. Two models of freezing rain interception were developed: 'IceCube', which uses point clouds to relate ice accretion to a voxel-based index (sheltering factor; SF) of the sheltering effect of branch elements above a measurement point; and 'IceTree', a simulation model for in silico evaluation of the interception pattern of freezing rain in virtual tree crowns. Intra-crown radial ice accretion varied strongly, declining from the tips to the bases of branches and from the top to the base of the crown. SF for branches varied strongly within the crown, and differences among branches were consistent for a range of model parameters. Intra-crown variation in ice accretion on branches was related to SF (R(2) = 0·46), with in silico results from IceTree supporting empirical relationships from IceCube. Empirical results and simulations confirmed a key role for crown architecture in determining intra-crown patterns of ice accretion. As suspected, the concentration of freezing rain droplets is attenuated by passage through the upper crown, and thus higher branches accumulate more ice than lower branches. This is the first step in developing a model that can provide a quantitative basis for investigating intra-crown and inter-specific variation in freezing rain damage.

Patterns and drivers of ice storm damage in temperate forests of Central Europe

Ice storms are important natural disturbances in temperate forests, yet have received little attention outside North America. Following an extreme ice storm in Slovenia, we examined patterns of ice damage within and among temperate forest sites and quantified differences in susceptibility to damage with respect to tree species and size across a gradient of storm intensity and site conditions. Based on a damage survey of 60 plots distributed across six unmanaged forest sites, ordinal logistic regression was used to examine patterns of ice damage as a function of storm intensity, species, tree size, and slope steepness. Our findings indicate that a complex interaction among these drivers gave rise to substantial variation in damage type and severity among species, plots, and stands. Fagus sylvatica, the most dominant species, was one of the most susceptible species to severe ice damage, while conifers (Abies alba and Picea abies) were least susceptible. Crown damage was the most common damage type at low storm intensity, while uprooting increased at higher intensity, particularly for large trees on steep slopes. Differences in species susceptibility to ice damage, combined with variation in storm intensity and site conditions, gave rise to heterogeneous damage patterns that have the potential to alter successional pathways. Based on an analysis of historical records, moderate-to-severe ice storms recur relatively frequently in the region, suggesting that they play a more important role in forest dynamics than previously thought.

Effects of Simulated Ice Storm Damage on Midrotation Loblolly Pine Stands

We simulated ice damage by shooting a portion of live crown from midrotation (ages 14–16 years) loblolly pine (Pinus taeda L.) stands in southeastern Oklahoma to study the postice damage effects in thinned, thinned-pruned, and nonthinned-nonpruned stands. Four years after damage, diameter growth was faster in the thinned plots than the nonthinned plots as expected. Relative basal area growth (rBAgrowth; basal area growth over the 4-year period/initial basal area) decreased as the fraction of live crown ratio loss (LCRloss) increased in all stands. While the slope of the relationship was similar among silvicultural treatments, the intercept for the nonthinned plots was lower. The result was that a 50% loss of live crown predicted rBAgrowth reductions of 28% in thinned and 64% in nonthinned plots. Canopy opening due to the simulated damage did not have a positive growth effect on the undamaged trees. We did not detect any differences in stem taper, probably because the study included data for only a 4-year recovery period. We conclude that stands can recover from moderate ice storm damage without large loss in production and that thinned stands have less reduction in basal area growth than nonthinned stands.

Ice storms generate spatially heterogeneous damage patterns at the watershed scale in forested landscapes

The effects of large‐scale disturbances play a pivotal role in shaping ecosystem structure and function. Interactions between disturbances and a multitude of biophysical factors at different scales generate spatially heterogeneous patterns of damage on vegetated landscapes. However, research on large‐scale disturbances is often conducted at one spatial extent because of the challenges associated with quantifying patterns of damage in vegetation across multiple spatial extents. Consequently, the literature has identified many different and often conflicting biophysical controls of vegetation damage, which is likely a consequence of the historical and spatial contingency of particular geographic locations. We investigated the influence of biophysical factors and spatial extent of ice storm damage patterns across the entire Ouachita National Forest and in 65 individual watersheds. This allowed for an assessment of how spatial extent and contingency might influence statistical results and therefore any conclusions drawn from these analyses. Two pre‐ and post‐storm Landsat 7 ETM+ scenes (October 6, 1999 and September 25, 2001) were acquired to map ice storm damage based on the normalized difference vegetation index (NDVI) change. Field sites verified the relationship between NDVI and actual forest damage from the storms. We derived topographic variables from a digital elevation model (DEM) and biological variables from GAP‐generated data. The relationship between ice storm damage patterns and biophysical factors across the entire national forest landscape was weak. However, the relationship between damage severity, topography, and forest type increased significantly at the watershed scale, though the specific variable displaying the strongest influence varied by individual watershed. This research demonstrates that complex topography and biological factors interact with the meteorological characteristics of ice storms to generate spatially heterogeneous damage patterns in forests at the watershed scale. It is likely that the damage patterns corresponding to a particular watershed will be repeated during future disturbances.