Linking remote sensing and various site factors for predicting the spatial distribution of eastern hemlock occurrence and relative basal area in Maine, USA

Introduced invasive pests are perhaps the most important and persistent catalyst for changes in forest composition. Infestation and outbreak of the hemlock woolly adelgid (Adelges tsugae; HWA) along the eastern coast of the USA, has led to widespread loss of hemlock (Tsuga canadensis (L.) Carr.), and a shift in tree species composition toward hardwood stands. Developing an understanding of the geographic distribution of individual species can inform conservation practices that seek to maintain functional capabilities of ecosystems. Modeling is necessary for understanding changes in forest composition, and subsequent changes in biodiversity, and one that can be implemented at the species level. By integrating the use of remote sensing, modeling, and Geographic Information Systems (GIS) coupled with expert knowledge in forest ecology and disturbance, we can advance the methodologies currently available in the literature on predictive modeling. This paper describes an approach to modeling the spatial distribution of the less common but foundational tree species eastern hemlock throughout the state of Maine (∼84,000 km2) at a high resolution. There are currently no published accuracy assessments on predictive models for high resolution continuous distribution of eastern hemlock relative basal area that span the geographic extent covered by our model, which is at the northern limit of the species’ range. A two stage mapping approach was used where presence/absence was predicted with an overall accuracy of 85% and the continuous distribution (percent basal area) was predicted with an accuracy of 84%. Overall, these findings are quite good despite high variability in the training dataset and the general minor component that eastern hemlock represents in the primary forest types in Maine. Eastern hemlock occurs along the southern half of the state stretching the east-west span with little to no occurrence in the northern regions. Several environmental and site characteristics, particularly average yearly maximum and minimum temperatures, were found to be positively correlated with hemlock occurrence. Eastern hemlock dominated stands appeared predominantly in the southwest corner of the state where HWA monitoring efforts can be focused. Given the importance of climate variables in predicting eastern hemlock, forecasts of future range shifts should be possible using data generated from climate scenarios

Follow-up imaging of benign pediatric liver tumors

Though surgery has been recommended in the past for the management of benign hepatic tumors, the current emphasis is on medical management. This report of 4 cases with long-term (8–28 months) follow-up emphasizes the natural history of these tumors which serves to indicate the advantages and disadvantages of CT and ultrasound. The lesions typically involute with some calcification. Calcification can technically be a problem in follow-up with sonography.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46688/1/247_2006_Article_BF02386841.pd

Forest carbon sequestration:the impact of forest management

In this chapter, we describe alternative ways in which forests and forestry can help to mítigate climate change, along with the potential impact of these activities. The three carbon storage compartments should be considered inall impact estimates. Carbon content in living biomass is easily estimated via species-specific equations or by applying factors to oven-dry biomass weights (e.g.,lbañez et al.,2002, Herrero et al.,2011,Castaño and Bravo, 2012).Litter carbon content has been analysed in many studies on primary forest productivity, though information regarding the influence of forest management on litter carbon content is less abundant (Blanco et al., 2006). In the last decade,efforts have been made to assess soil carbon in forests, but studies on the effect of forest management on soils show discrepancies (Lindner and Karjalainen,2007).Hoover (2011), for example,found no difference in forest floor carbon stocks among stands subjected to partial or complete harvest treatments in the United States.Instituto Universitario de Gestión Forestal Sostenibl

Improved tree height estimation of secondary forests in the Brazilian Amazon

This paper presents a novel approach for estimating the height of individual trees in secondary forests at two study sites: Manaus (central Amazon) and Santarém (eastern Amazon) in the Brazilian Amazon region. The approach consists of adjusting tree height-diameter at breast height (H:DBH) models in each study site by ecological species groups: pioneers, early secondary, and late secondary. Overall, the DBH and corresponding height (H) of 1,178 individual trees were measured during two field campaigns: August 2014 in Manaus and September 2015 in Santarém. We tested the five most commonly used log-linear and nonlinear H:DBH models, as determined by the available literature. The hyperbolic model: H = a.DBH/(b+DBH) was found to present the best fit when evaluated using validation data. Significant differences in the fitted parameters were found between pioneer and secondary species from Manaus and Santarém by F-test, meaning that site-specific and also ecological-group H:DBH models should be used to more accurately predict H as a function of DBH. This novel approach provides specific equations to estimate height of secondary forest trees for particular sites and ecological species groups. The presented set of equations will allow better biomass and carbon stock estimates in secondary forests of the Brazilian Amazon

Response of Douglas-fir leaf area index and litterfall dynamics to Swiss needle cast in north coastal Oregon, USA

Sources of variation in leaf area index (LAI; m$^{2}$ of projected leaf area per m$^{2}$ of ground area) and its seasonal dynamics are not well known in managed Douglas-fir stands, despite the importance of leaf area in forecasting forest growth, particularly in stands impacted by insects or disease. The influence of Swiss needle cast (SNC) on coastal Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb] Franco) LAI and litterfall dynamics was quantified by destructively sampling 122 stems from 36 different permanent plots throughout north coastal Oregon, USA, and by monitoring litterfall for 3 years in 15 of these plots. LAI, total annual litterfall, and the seasonal distribution of foliage and fine woody litterfall were all influenced by stand structural attributes, physiographic features, and SNC severity. Mean LAI in this study was 5.44 $\pm$ 2.16. The relatively low LAIs were attributed primarily to the effects of SNC on foliage retention, and secondarily to its direct measurement by hierarchical foliage sampling in contrast to indirect measurement by light interception or tree allometry. For a given stand structure and SNC severity, LAI was 36% greater in the fall after current year foliage was fully developed and older aged classes had not yet senesced. Annual litterfall expressed as a proportion of LAI at the start of the growing season varied from 0.13 to 0.53 and declined with increasing initial LAI. SNC also shifted more of the annual foliage litterfall to earlier in the spring. Fine woody litterfall experienced a different seasonal shift as the peak occurred later in the year on sites with high SNC, but this only occurred on northerly aspects. Defoliation from the endemic SNC pathogen can drastically reduce LAI and change both total and seasonal foliage litterfall patterns.Réponse de l'index foliaire (LAI) et de la dynamique de chute de litière du Douglas à la rouille suisse dans la zone côtière du Nord Oregon. Les sources de variation de l'index foliaire (LAI, m$^{2}$ de surface projetée des feuilles par m$^{2}$ de surface de sol) et sa dynamique saisonnière ne sont pas bien connues dans les peuplements aménagés de Douglas, malgré l'importance de la surface foliaire dans les prévisions de la croissance des forêts, particulièrement dans les peuplements touchés par des insectes ou les maladies. L'influence de la rouille suisse (SNC) sur l'index foliaire et la dynamique de chute de litière de Pseudotsuga menziesii var. menziesii [Mirb.] Franco ont été quantifiées grâce à un échantillonnage destructif de 122 tiges dans 36 placeaux permanents dans la zone côtière du Nord Oregon (USA) et le suivi pendant 3 ans des chutes de litière dans 15 de ces placeaux. L'index foliaire, la chute annuelle totale de litière, et la distribution du feuillage et la litière ligneuse fine ont tous été influencés par les attributs structuraux, les caractéristiques physiographiques et la gravité de SNC. Dans cette étude la moyenne de l'index foliaire était de 5,44 $\pm$ 2,16. Les index foliaires relativement faibles ont été essentiellement attribués aux effets de SNC sur le maintien du feuillage, et secondairement sur ses mesures directes par un échantillonnage hiérarchisé par opposition aux mesures indirectes par interception de la lumière ou par des méthodes d'allométrie au niveau des arbres. Pour une structure de peuplement et une gravité de SNC données, l'index foliaire a été 36 % plus élevé à l'automne après le plein développement du feuillage de l'année en cours et avant la sénescence des classes plus âgées. La chute annuelle de litière exprimée en proportion de l'index foliaire au début de la saison de croissance a varié de 0,13 à 0,53 et a baissé avec l'augmentation de l'index foliaire initial. La SNC a aussi enlevé plus que la chute annuelle de feuillage de la litière plus tôt au printemps. La litière ligneuse fine a été rencontrée à différents moments dans la saison alors que le pic s'est produit plus tard dans l'année dans les sites présentant une SNC élevée, mais ceci s'est seulement produit dans les expositions au nord. La défoliation par le pathogène endémique SNC peut réduire considérablement l'index foliaire et change à la fois les modèles de chute totale et de chute saisonnière de litière