Disturbance Agents and Their Associated Effects on the Health of Interior Douglas-Fir Forests in the Central Rocky Mountains

Giunta, Andrew D.; Jenkins, Michael J.; Hebertson, Elizabeth G.; Munson, A. Steven

doi:10.3390/f7040080

Cited by 11 publications

(14 citation statements)

References 169 publications

(232 reference statements)

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“…glauca ) but those are not distinguished in the FIA database. Therefore, Douglas-fir in plots occurring in California or in the western portion of the species' range west of the Cascade mountains in Washington and Oregon was labeled as coast Douglas-fir and all others were labeled as Rocky Mountain Douglas-fir, after Giunta et al [ 37 ].…”

Section: Methodsmentioning

confidence: 99%

An empirical, hierarchical typology of tree species assemblages for assessing forest dynamics under global change scenarios

2017

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The composition of tree species occurring in a forest is important and can be affected by global change drivers such as climate change. To inform assessment and projection of global change impacts at broad extents, we used hierarchical cluster analysis and over 120,000 recent forest inventory plots to empirically define forest tree assemblages across the U.S., and identified the indicator and dominant species associated with each. Cluster typologies in two levels of a hierarchy of forest assemblages, with 29 and 147 groups respectively, were supported by diagnostic criteria. Groups in these two levels of the hierarchy were labeled based on the top indicator species in each, and ranged widely in size. For example, in the 29-cluster typology, the sugar maple-red maple assemblage contained the largest number of plots (30,068), while the butternut-sweet birch and sourwood-scarlet oak assemblages were both smallest (6 plots each). We provide a case-study demonstration of the utility of the typology for informing forest climate change impact assessment. For five assemblages in the 29-cluster typology, we used existing projections of changes in importance value (IV) for the dominant species under one low and one high climate change scenario to assess impacts to the assemblages. Results ranged widely for each scenario by the end of the century, with each showing an average decrease in IV for dominant species in some assemblages, including the balsam fir-quaking aspen assemblage, and an average increase for others, like the green ash-American elm assemblage. Future work should assess adaptive capacity of these forest assemblages and investigate local population- and community-level dynamics in places where dominant species may be impacted. This typology will be ideal for monitoring, assessing, and projecting changes to forest communities within the emerging framework of macrosystems ecology, which emphasizes hierarchies and broad extents.

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Section: Methodsmentioning

confidence: 99%

An empirical, hierarchical typology of tree species assemblages for assessing forest dynamics under global change scenarios

2017

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“…Historically, storms and snow breakage events in Europe and North America have provided a large surplus of suitable breeding material for bark beetles, leading to outbreaks (Giunta et al. ; Seidl et al. ).…”

Section: Introductionmentioning

confidence: 99%

Sentinel‐2 accurately maps green‐attack stage of European spruce bark beetle (Ips typographus, L.) compared with Landsat‐8

Abdullah

Skidmore

Darvishzadeh

et al. 2018

Remote Sens Ecol Conserv

123

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Natural disturbances induced by insect outbreaks have increased in forest ecosystems over the past decades. To minimize economic loss and prevent a mass outbreak, early detection of bark beetle green attack -a period when trees have yet to show visual signs of infestation stress -is therefore crucial to effective and timely forest management. In this study, we evaluated the ability of spectral vegetation indices extracted from Landsat-8 and Sentinel-2 imagery to map bark beetle green attack using principal component analysis (PCA) and partial least square discriminate analysis (PLS-DA). A recent infestation map produced through visual interpretation of high-resolution aerial photographs validated the final infestation output maps. Leaf spectral measurements alongside total chlorophyll and nitrogen concentration, leaf water content and leaf dry matter content were measured to assess the impact of bark beetle green attack on foliar properties. We observed that the majority of spectral vegetation indices (SVIs) calculated from Sentinel-2, particularly red-edge dependent indices (NDRE 2 and 3) and water-related indices (SR-SWIR, NDWI, DSWI and LWCI), were able to discriminate healthy from infested plots. In contrast, only the water-related indices (NDWI, DSWI and RDI) from Landsat-8 were able to discriminate between healthy and infested plots efficiently. The total number of pixels identified as harboring a green attack that matched with ground truth data (aerial photography) was higher for Sentinel-2 (67%) than for Landsat-8 (36%) SVIs, indicating the elevated sensitivity of Sentinel-2 imagery to changes induced by bark beetle green attack. We also determined that foliar chlorophyll and leaf water content were significantly higher (P < 0.05) in healthy trees than in green-attacked trees. Our study highlights the potential of Sentinel-2 data for the early detection of bark beetle infestations and the production of reliable infestation maps at the green-attack stage.

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“…We attributed the increase in fire severity during the red phase to the reduction in fuel moisture content that occurs when needles die. Lower fuel moisture levels during the red phase are critical to alter the threshold required for crown ignition (Jolly et al 2012, Giunta et al 2016 and transition from the surface into the canopy. For example, dead red-phase lodgepole pine (Pinus contorta Douglas ex Loudon) needles averaged ~12 % moisture content compared to green needles that averaged ~109 % moisture content; and dead needles ignited up to four times faster than green needles in laboratory ignition tests (Jolly et al 2012).…”

Section: Discussionmentioning

confidence: 99%

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2017

Fire Ecology

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Previous studies have suggested that bark beetles and fires can be interacting disturbances, whereby bark beetlecaused tree mortality can alter the risk and severity of subsequent wildland fires. However, there remains considerable uncertainty around the type and magnitude of the interaction between fires following bark beetle attacks, especially in drier forest types such as those dominated by ponderosa pine (Pinus ponderosa Lawson & C. Lawson). We used a full factorial design across a range of factors thought to control bark beetle−fire interactions, including the temporal phase of the RESUMENEstudios previos han sugerido que los escarabajos de la corteza y el fuego pueden ser disturbios interactivos, por lo que la mortalidad de árboles causada por estos escarabajos puede alterar el riesgo y la severidad de incendios subsecuentes. Sin embargo, una considerable incertidumbre persiste en torno al tipo y magnitud de la interacción entre los incendios que siguen al ataque de insectos, especialmente en tipos de bosques secos como los dominados por pino ponderosa (Pinus ponderosa Lawson & C. Lawson). Usamos un diseño factorial a través de un rango de factores que pensamos controlaban la interacción entre el escarabajo de la corteza y los incendios, incluyendo la fase temporal del estallido del insecto, el nivel Fire Ecology Volume 13, Issue 3, 2017 doi: 10.4996/fireecology.130300123 Sieg et al.: Bark Beetle-Fire Disturbance Interactions Page 2 outbreak, level of mortality, and wind speed. We used a three-dimensional physics-based model, HIGRAD/FIRE-TEC, to simulate fire behavior in fuel beds representative of 60 field plots across five national forests in northern Arizona, USA. The plots were dominated by ponderosa pine, and encompassed a gradient of bark beetlecaused mortality due to a mixture of both Ips and Dendroctonus species. Non-host species included two sprouting species, Gambel oak (Quercus gambelii Nutt.) and alligator juniper (Juniperus deppeana Steud.), as well as other junipers and pinyon pine (Pinus edulis Engelm.). The simulations explicitly accounted for the modifications of fuel mass and moisture distribution caused by bark beetle-caused mortality. We first analyzed the influence of the outbreak phase, level of mortality, and wind speed on the severity of a subsequent fire, expressed as a function of live and dead canopy fuel consumption. We then computed a metric based on canopy fuel loss to characterize whether bark beetles and fire are linked disturbances and, if they are, if the linkage is antagonistic (net bark beetle and fire severity being less than if the two disturbances occurred independently) or synergistic (greater combined effects than independent disturbances). Both the severity of a subsequent fire and whether bark beetles and fire are linked disturbances depended on the outbreak phase of the bark beetle mortality and attack severity, as well as the fire weather (here, wind). Greater fire severity and synergistic interactions were generally associated with the "red phase"...

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Disturbance Agents and Their Associated Effects on the Health of Interior Douglas-Fir Forests in the Central Rocky Mountains

Cited by 11 publications

References 169 publications

An empirical, hierarchical typology of tree species assemblages for assessing forest dynamics under global change scenarios

An empirical, hierarchical typology of tree species assemblages for assessing forest dynamics under global change scenarios

Sentinel‐2 accurately maps green‐attack stage of European spruce bark beetle (Ips typographus, L.) compared with Landsat‐8

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