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Highlights • Aerial detection surveys are a critical technique for monitoring forest health. • Overall accuracy for aerial detection survey observations was >70%. • Damage type observations for mortality and defoliation had high-levels of accuracy. • Accuracy declined as the observations went from less to more specific calls. • Aerial surveyors had high agreement when mapping the location of polygons. Abstract Insects and diseases annually cause millions of hectares of defoliation and mortality to forested landscapes in the U.S. To monitor these disturbance events, the USDA Forest Service, Forest Health Protection and cooperating state partners conduct annual aerial detection surveys. These data represent the largest, and most historical, remote sensing dataset linking forest disturbances to specific insects and diseases. However, formal accuracy assessments of these data are exceptionally limited in scale and scope. Our two primary objectives were to (1) assess the accuracy of aerial detection survey data for delineating forest disturbances attributed to insects, diseases, and abiotic events across multiple ecological regions and (2) assess the repeatability of aerial surveyors to locate and observe defoliation and mortality on a forested landscape. The methodology used in our study represents the procedures adopted nationwide for aerial detection surveys. We used a stepdown approach in our analyses to show the accuracy of aerial survey observations from broad to specific categories, such as from feeding guilds to specific damage agents. We used error matrices to compare the accuracy of aerially detected events and ground observations. Overall accuracy in all the error matrices was >70% for comparisons of aerial survey observations to ground-collected data. Damage type observations for tree mortality and defoliation had high-levels of accuracy with only 2% and 5% commission error, respectively. More than half of the ground-collected data verified bark beetle-caused tree mortality, representing low commission error (9%). Accuracy declined as the specificity for observations went from genera to species level for tree species and damaging agents, but many of the prominent tree species and damaging agents had zero and low commission errors. In small polygons (<2 ha), aerial surveyors accurately observed counts for tree injury and mortality more frequently than over- and underestimated observations, whereas trees acre−1 observations were more commonly overestimated than correct trees acre−1 observations. Greater agreement of polygons occurred when tree injury and mortality were mapped on high-resolution imagery than during aerial detection surveys in the repeatability test, but similar usage of points and polygons were used to note injury between the two survey techniques. In addition, m ean hectares mapped were comparable for all polygons and defoliation polygons between the survey techniques. The results from this study improve insect and disease survey techniques nationwide and increase the use of these data while acknowledging its accuracies and limitations. [ABSTRACT FROM AUTHOR]

Abstract: The Warner Mountains of northeastern California on the Modoc National Forest experienced a high incidence of tree mortality (2001–2007) that was associated with drought and bark beetle (Coleoptera: Curculionidae, Scolytinae) attack. Various silvicultural thinning treatments were implemented prior to this period of tree mortality to reduce stand density and increase residual tree growth and vigor. Our study: (1) compared bark beetle-caused conifer mortality in forested areas thinned from 1985 to 1998 to similar, non-thinned areas and (2) identified site, stand and individual tree characteristics associated with conifer mortality. We sampled ponderosa pine (Pinus ponderosa var ponderosa Dougl. ex Laws.) and Jeffrey pine (Pinus jeffreyi Grev. and Balf.) trees in pre-commercially thinned and non-thinned plantations and ponderosa pine and white fir (Abies concolor var lowiana Gordon) in mixed conifer forests that were commercially thinned, salvage-thinned, and non-thinned. Clusters of five plots (1/50thha) and four transects (20.1×100.6m) were sampled to estimate stand, site and tree mortality characteristics. A total of 20 pre-commercially thinned and 13 non-thinned plantation plot clusters as well as 20 commercially thinned, 20 salvage-thinned and 20 non-thinned mixed conifer plot clusters were established. Plantation and mixed conifer data were analyzed separately. In ponderosa pine plantations, mountain pine beetle (Dendroctonus ponderosae Hopkins) (MPB) caused greater density of mortality (treesha−1 killed) in non-thinned (median 16.1treesha−1) compared to the pre-commercially thinned (1.2treesha−1) stands. Percent mortality (treesha−1 killed/trees ha−1 host available) was less in the pre-commercially thinned (median 0.5%) compared to the non-thinned (5.0%) plantation stands. In mixed conifer areas, fir engraver beetles (Scolytus ventralis LeConte) (FEN) caused greater density of white fir mortality in non-thinned (least square mean 44.5treesha−1) compared to the commercially thinned (23.8treesha−1) and salvage-thinned stands (16.4 trees ha−1). Percent mortality did not differ between commercially thinned (least square mean 12.6%), salvage-thinned (11.0%), and non-thinned (13.1%) mixed conifer stands. Thus, FEN-caused mortality occurred in direct proportion to the density of available white fir. In plantations, density of MPB-caused mortality was associated with treatment and tree density of all species. In mixed conifer areas, density of FEN-caused mortality had a positive association with white fir density and a curvilinear association with elevation. [Copyright &y& Elsevier]

Abstract: Fire injury was characterized and survival monitored for 5677 trees >25cm DBH from five wildfires in California that occurred between 2000 and 2004. Logistic regression models for predicting the probability of mortality 5-years after fire were developed for incense cedar (Calocedrus decurrens (Torr.) Florin), white fir (Abies concolor (Gord. & Glend.) Lindl. ex Hildebr.), sugar pine (Pinus lambertiana Douglas), Jeffrey pine (P. jeffreyi Balf.), and ponderosa pine (P. ponderosa C. Lawson). Differences in crown injury variables were also compared for Jeffrey and ponderosa pine. Most mortality (70–88% depending on species) occurred within 2 years post-wildfire and had stabilized by year 3. Crown length and crown volume injury variables predicted tree mortality equally well; however, the variables were not interchangeable. Crown injury and cambium kill rating was significant in predicting mortality in all models. DBH was only a significant predictor of mortality for white fir and the combined ponderosa and Jeffrey pine models developed from the McNally Fire; these models all predicted increasing mortality with increasing tree size. Red turpentine beetle (Dendroctonus valens) was a significant predictor variable for sugar pine, ponderosa pine, and Jeffrey pine; ambrosia beetle (Trypodendron and Gnathotrichus spp.) was a significant predictor variable for white fir. The mortality models and post-fire tree survival characteristics provide improved prediction of 5-year post-wildfire tree mortality for several California conifers. The models confirm the overall importance of crown injury in predicting post-fire mortality compared to other injury variables for all species. Additional variables such as cambium kill, bark beetles, and tree size improved model accuracies, but likely not enough to justify the added expense of data collection. [Copyright &y& Elsevier]

Abstract: Many forests that historically experienced frequent low-intensity wildfires have undergone extensive alterations during the past century. Prescribed fire is now commonly used to restore these fire-adapted forest ecosystems. In this study, we examined the influence of prescribed burn season on levels of tree mortality attributed to prescribed fire effects (direct mortality) and bark beetles (Coleoptera: Curculionidae, Scolytinae) (indirect mortality) in ponderosa pine, Pinus ponderosa Dougl. ex Laws., and Jeffrey pine, Pinus jeffreyi Grev. and Balf., forests in California, USA. A total of 816 trees (9.9% of all trees) died during this 3-yr study. Significantly higher levels of tree mortality (all sources) occurred following early and late season burns compared to the untreated control, but no significant difference was observed between burn treatments. The majority (461 trees) of tree deaths were attributed to direct mortality from prescribed burns and was strongly concentrated (391 trees) in the smallest diameter class (<20.2cm diameter at breast height, dbh). For the largest trees (>50.7cm dbh), significantly higher levels of tree mortality occurred on early season burns than the untreated control, most of which resulted from indirect mortality attributed to bark beetle attacks, specifically western pine beetle, Dendroctonus brevicomis LeConte, and mountain pine beetle, D. ponderosae Hopkins. Red turpentine beetle, D. valens LeConte, was the most common bark beetle species found colonizing trees, but tree mortality was not attributed to this species. A total of 355 trees (4.3% of all trees) were killed by bark beetles. Dendroctonus brevicomis (67 trees, 18.9%) and D. ponderosae (56 trees, 15.8%), were found colonizing P. ponderosa; and Jeffrey pine beetle, D. jeffreyi Hopkins, was found colonizing P. jeffreyi (seven trees, 2.0%). We also found pine engraver, Ips pini (Say) (137 trees, 38.6%), and, to a much lesser extent, Orthotomicus (=Ips) latidens (LeConte) (85 trees, 23.9%) and emarginate ips, I. emarginatus (LeConte) (3 trees, 0.8%) colonizing P. ponderosa and P. jeffreyi. Few meaningful differences in levels of indirect tree mortality attributed to bark beetle attack were observed between early and late season burns. The incidence of root and root collar pathogens (Leptographium and Sporothrix spp.), including species known to be vectored by bark beetles, was low (18% of trees sampled). The implications of these and other results to management of P. ponderosa and P. jeffreyi forests are discussed in detail. [Copyright &y& Elsevier]