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Patterns in foliar nitrogen (N) stable isotope ratios (δ15N) have been shown to reveal trends in terrestrial N cycles, including the identification of ecosystems where N deficiencies limit forest ecosystem productivity. However, there is a gap in our understanding of within-species variation and species-level response to environmental gradients or forest management. Our objective is to examine the relationship between site index, foliar %N, foliar δ15N and spectral reflectance for managed Douglas-fir (Pseudotsuga menziesii) and loblolly pine (Pinus taeda) plantations across their geographic ranges in the Pacific Northwest and the southeastern United States, respectively. Foliage was measured at 28 sites for reflectance using a handheld spectroradiometer, and further analyzed for δ15N and N concentration. Unlike the prior work for grasslands and shrubland species, our results show that foliar δ15N and foliar %N are not well correlated for these tree species. However, multiple linear regression models suggest a strong predictive ability of spectroscopy data to quantify foliar δ15N, with some models explaining more than 65% of the variance in the δ15N. Additionally, moderate to strong explanations of variance were found between site index and foliar δ15N (R2 = 0.49) and reflectance and site index (R2 = 0.84) in the Douglas-fir data set. The development of relationships between foliar spectral reflectance, δ15N and measures of site productivity provides the first step toward mapping canopy δ15N for these managed forests with remote sensing.

Understanding the genomic and environmental basis of cold adaptation is key to understand how plants survive and adapt to different environmental conditions across their natural range. Univariate and multivariate genome-wide association (GWAS) and genotype-environment association (GEA) analyses were used to test associations among genome-wide SNPs obtained from whole-genome resequencing, measures of growth, phenology, emergence, cold hardiness, and range-wide environmental variation in coastal Douglas-fir (Pseudotsuga menziesii). Results suggest a complex genomic architecture of cold adaptation, in which traits are either highly polygenic or controlled by both large and small effect genes. Newly discovered associations for cold adaptation in Douglas-fir included 130 genes involved in many important biological functions such as primary and secondary metabolism, growth and reproductive development, transcription regulation, stress and signaling, and DNA processes. These genes were related to growth, phenology and cold hardiness and strongly depend on variation in environmental variables such degree days below 0c, precipitation, elevation and distance from the coast. This study is a step forward in our understanding of the complex interconnection between environment and genomics and their role in cold-associated trait variation in boreal tree species, providing a baseline for the species' predictions under climate change.

Non-native pathogens affect forests throughout North America, resulting in changes in species composition, structure, and ecosystem processes. We studied the effects of the emergent disease sudden oak death (SOD) and the resulting functional extinction of tanoak, a highly susceptible native tree with flammable litter, on future community flammability. We quantified four flammability metrics (flame height; flaming duration; smoldering duration; and fuel consumed) for litter from each of five species that co-occur with tanoak and for species mixtures with and without tanoak (n = 14). We combined these flammability metrics in a Principal Components Analysis to evaluate potential shifts in litter flammability from pre-SOD (with tanoak litter) to post-SOD (where tanoak was replaced equally with remaining species). Litter flammability changed following the loss of tanoak, but the differences were species- and community-specific. Mixed-evergreen fuels where coast Douglas-fir litter replaced tanoak experienced consistent declines in flammability. Few substantive changes occurred in communities where coast redwood or other hardwoods co-occurred. We found consistent synergistic flammability effects when multiple species' litters were mixed; in cases where two or more species were mixed, most (75%) combinations burned with higher intensity (+8.1%) and fuelbeds flamed for a longer duration (+17.1%). Our work demonstrates that potential surface fire behavior in northwestern California may be dampened where Douglas-fir replaces tanoak, while those communities with other hardwoods or coast redwood may have redundant fuels and tanoak's absence in future fires may be inconspicuous. These results underscore the potential for cascading effects of non-native pathogens on ecosystem function in fire-prone ecosystems.

Non-native pathogens affect forests throughout North America, resulting in changes in species composition, structure, and ecosystem processes. We studied the effects of the emergent disease sudden oak death (SOD) and the resulting functional extinction of tanoak, a highly susceptible native tree with flammable litter, on future community flammability. We quantified four flammability metrics (flame height; flaming duration; smoldering duration; and fuel consumed) for litter from each of five species that co-occur with tanoak and for species mixtures with and without tanoak (n = 14). We combined these flammability metrics in a Principal Components Analysis to evaluate potential shifts in litter flammability from pre-SOD (with tanoak litter) to post-SOD (where tanoak was replaced equally with remaining species). Litter flammability changed following the loss of tanoak, but the differences were species- and community-specific. Mixed-evergreen fuels where coast Douglas-fir litter replaced tanoak experienced consistent declines in flammability. Few substantive changes occurred in communities where coast redwood or other hardwoods co-occurred. We found consistent synergistic flammability effects when multiple species' litters were mixed; in cases where two or more species were mixed, most (75%) combinations burned with higher intensity (+8.1%) and fuelbeds flamed for a longer duration (+17.1%). Our work demonstrates that potential surface fire behavior in northwestern California may be dampened where Douglas-fir replaces tanoak, while those communities with other hardwoods or coast redwood may have redundant fuels and tanoak's absence in future fires may be inconspicuous. These results underscore the potential for cascading effects of non-native pathogens on ecosystem function in fire-prone ecosystems.

This paper presents the results of air-pollutant influence on one-year and two-year old needles of Douglas-fir. The aim of this research was determining of resistance of these species. The analysis was performed on samples collected in a Douglas-fir culture established in polluted area of Kolubara coal basin during re-cultivation process of remained material. Control samples from unpolluted area were collected in Douglas-fir culture near mountain Juhor. There has been examined injuries of chlorenchyma cells, evaluating the degree of damage to the chlorenchyma tissue based on the stage of cell disruption which affected the way of the appearance of tannins in the central vacuole. The obtained results showed that the surface area of damaged chlorenchyma cells was significantly increased in polluted environment. At cellular level, there was no complete destruction of thylakoid system, and negative influence of air-pollutants before all affected changing of chloroplasts form, stroma granulation, increasing of thylakoid area, changing of plastoglobulins and collecting of fat in cytoplasm. This kind of changes in one-year and two-year old needles in samples originated from polluted area of Kolubara coal basin included numerous cells from chlorenchyma tissue. This confirms that Douglas-fir is not resistant on air-pollutants influence in researched area.

In the Douglas-fir (Pseudotsuga menziesii Mirb. Franco) and redwood (Sequoia sempervirens (D. Don) Endl.) forests of the central California coast, Sudden Oak Death (SOD) has led to landscape-scale mortality of tanoak (Notholithocarpus densiflorus (Hook. and Arn.) Manos, Cannon and S.H. Oh). As tanoak mortality progresses, fuel loads and potential fire behavior in these forests are changing. We documented increases in fuel loads over time in long-term monitoring plots in infested forests at Point Reyes National Seashore. Throughout the study, we observed a significant positive relationship between dead tanoak basal area and surface fuels. We used the fire behavior modeling program BehavePlus to compare potential fire behavior between diseased and healthy stands. Model outputs indicated the potential for longer flame lengths, higher rates of spread and more intense surface fire in diseased stands. The potential for increased fire intensity in diseased redwood and Douglas-fir forests may create additional challenges for fire and natural resources managers and may affect the ecology of these forests into the future.

One mechanism of invasive species success is the production of allelopathic chemicals that negatively affect native competitors. A highly invasive shrub, Cytisus scoparius, impedes Douglas-fir tree establishment in clearcuts, even years after its removal. This impediment may be from the allelopathic alkaloids of C. scoparius that could indirectly hinder Douglas-fir by inhibiting their mutualistic ectomycorrhizal fungi (EMF). I extracted and quantified alkaloids from C. scoparius tissue for use in a laboratory bioassay. I then tested if and how these alkaloids affected EMF growth. In a second assay, I tested the effects of three concentrations of pure sparteine, the primary alkaloid in C. scoparius , on fungal growth. Sparteine was the only alkaloid recovered from the extraction which yielded 0.32 mg sparteine/g fresh weight, a lower concentration than previously reported values. Both the crude extract and pure sparteine significantly affected fungal growth, but only sparteine produced a species-specific response. Growth was inhibited by increasing sparteine concentrations, and most species were inhibited at 1.4 mM, the concentration found in C. scoparius. One common EMF, Wilcoxina mikolae, was unaffected by sparteine while others, like Suillus caerulescens and Cenococcum geophilum, were more sensitive and stopped growing entirely at 5 to 10 mM. These results suggest that the alkaloids of C. scoparius may seriously hinder EMF, and indirectly Douglas-fir, contributing to the competitive dominance of the invasive shrub.

One mechanism of invasive species success is the production of allelopathic chemicals that negatively affect native competitors. A highly invasive shrub, Cytisus scoparius, impedes Douglas-fir tree establishment in clearcuts, even years after its removal. This impediment may be from the allelopathic alkaloids of C. scoparius that could indirectly hinder Douglas-fir by inhibiting their mutualistic ectomycorrhizal fungi (EMF). I extracted and quantified alkaloids from C. scoparius tissue for use in a laboratory bioassay. I then tested if and how these alkaloids affected EMF growth. In a second assay, I tested the effects of three concentrations of pure sparteine, the primary alkaloid in C. scoparius , on fungal growth. Sparteine was the only alkaloid recovered from the extraction which yielded 0.32 mg sparteine/g fresh weight, a lower concentration than previously reported values. Both the crude extract and pure sparteine significantly affected fungal growth, but only sparteine produced a species-specific response. Growth was inhibited by increasing sparteine concentrations, and most species were inhibited at 1.4 mM, the concentration found in C. scoparius. One common EMF, Wilcoxina mikolae, was unaffected by sparteine while others, like Suillus caerulescens and Cenococcum geophilum, were more sensitive and stopped growing entirely at 5 to 10 mM. These results suggest that the alkaloids of C. scoparius may seriously hinder EMF, and indirectly Douglas-fir, contributing to the competitive dominance of the invasive shrub.

In the Douglas-fir (Pseudotsuga menziesii Mirb. Franco) and redwood (Sequoia sempervirens (D. Don) Endl.) forests of the central California coast, Sudden Oak Death (SOD) has led to landscape-scale mortality of tanoak (Notholithocarpus densiflorus (Hook. and Arn.) Manos, Cannon and S.H. Oh). As tanoak mortality progresses, fuel loads and potential fire behavior in these forests are changing. We documented increases in fuel loads over time in long-term monitoring plots in infested forests at Point Reyes National Seashore. Throughout the study, we observed a significant positive relationship between dead tanoak basal area and surface fuels. We used the fire behavior modeling program BehavePlus to compare potential fire behavior between diseased and healthy stands. Model outputs indicated the potential for longer flame lengths, higher rates of spread and more intense surface fire in diseased stands. The potential for increased fire intensity in diseased redwood and Douglas-fir forests may create additional challenges for fire and natural resources managers and may affect the ecology of these forests into the future.

Vorhersagen gehen davon aus, dass sich die klimatischen Bedingungen in Zentraleuropa in den kommenden Jahrzehnten verändern werden. Längere Trockenperioden und weniger Niederschläge im Sommer werden erwartet. Pflanzen können ihren Standort nicht wechseln, so dass sie sich an die neuen Gegebenheiten adaptieren oder über ihre Nachkommen neue ökologische Nischen besiedeln müssen. Aufgrund der langen Generationszeit bei Bäumen ist es wichtig zu wissen, ob und wie sie mit den erwarteten klimatischen Bedingungen umgehen können. Förster machen sich bereits heute über die Zusammensetzung künftiger Wälder Gedanken, da Baumarten und Populationen ausgewählt werden müssen, die mit dem veränderten Klima nur wenig Probleme haben. Die Douglasie (Pseudotsuga menziesii) ist hierbei eine vielversprechende Baumart, da sie sich in ihrem natürlichen Verbreitungsgebiet in Nordamerika an unterschiedliche Habitate und Klimazonen adaptiert hat. Sie kann in zwei Varietäten unterteilt werden, die Küsten- und die Inlandsdouglasie, die sich genotypisch und phänotypisch, z.B. in der Trockentoleranz, unterscheiden. Bei Anbauversuchen in Deutschland zeigten die Bäume, hauptsächlich Küstendouglasien, gute Wuchsleistungen. Daher wurde ein Forschungsprojekt, "DougAdapt", konzipiert, das genotypische und phänotypische Unterschiede zwischen verschiedenen Provenienzen der Küsten- und Inlandsdouglasien analysieren und den Einfluss des Genotyps auf den Phänotyp untersuchen sollte. Um die genetische Diversität der Provenienzen zu untersuchen, wurden zunächst Referenzsequenzen generiert, da es, bis auf eine begrenzte Anzahl von Genen, keine Sequenzinformation für die Douglasie gab. Selbst mit kostengünstigen modernen Sequenziertechnologien ist es sehr teuer das ~ 19 Gigabasen große Genom der Douglasie vollständig zu erfassen und zu entschlüsseln. Eine Alternative stellt die Transkriptomsequenzierung dar, bei der nur Gene, d.h. die für Proteine codierenden Bereiche des Genoms, sequenziert werden. Die in dies, Predictions assume severe changes in the climatic conditions in Central Europe in the coming decades. Longer periods of drought and less precipitation during summer are expected. Plants cannot change their habitat and have to adapt to the new conditions or their offspring has to colonize new ecological niches. Due to the long generation times in trees it is important to know if and how trees can cope with the expected climatic conditions. Forest managers already give thought to the composition of future forests, because they have to choose species and populations which have no or only few problems with the changed climate. Douglas-fir (Pseudotsuga menziesii) is a promising tree species for this purpose, because it is adapted to different habitats and climate zones in its natural distribution range in North America. The two main varieties, coastal and interior Douglas-fir, differ genotypically and phenotypically, e.g. in drought tolerance. Douglas-fir trees, mainly of the coastal variety, showed good growth performances in field trials in Germany. Hence, a research project called "DougAdapt" was designed to analyze and to link genotypic and phenotypic differences in several coastal and interior Douglas-fir provenances. In this project, trees from field trials and from greenhouse experiments were sampled. To analyze the genetic diversity of the provenances we first generated reference sequences. Even with modern and cost-efficient next-generation sequencing technologies it would be very expensive to decipher the ~ 19 gigabases of the Douglas-fir genome completely. An alternative to whole genome sequencing is transcriptome sequencing, in which only the coding regions of a genome are sequenced. The transcriptome sequencing, which was performed for the first time in Douglas-fir, resulted in a large number of putative unique transcripts (PUTs). Comparisons with published transcriptomes of other plant species showed that the PUTs represented the transcriptome of Douglas-fi

Biljni pokrivač, naročito šumsko drveće, se javlja kao aktivni faktor u procesu prihvatanja zagadjenja iz atmosfere, i predstavlja prvi nivo taloženja atmosferskih zagadjivača, a zemljište krajnji receptor. Kod šumskih ekosistema postoji samo jedan tip ulaska elemenata, ali postoji više puteva transfera zbog prisustva prizemne flore i spratova drveća. Drveća koja rastu u umerenoj klimatskoj zoni, gde su izražene sezonske promene, imaju osobinu da formiraju po jedan prsten prirasta godišnje. Prstenovi prirasta ili godovi su približno koncentrični slojevi drveta, koji nastaju radom kambijuma u jednoj vegetacionoj sezoni drveta. Prstenovi prirasta predstavljaju široko dostupan izvor dugogodišnjih podataka o prošlim vremenima i kao takvi su jedinstven svedok stanja životne sredine. Hemijski sastav drveta stoga može odražavati sastav sredine u kojoj je drvo raslo. Mnoge studije u urbanim i idustrijskim sredinama, otkrile su da hemijski sadržaj drveta može ukazati na promene u životnoj sredini tokom vremena i omogućiti rekonstrukciju zagadjujućih epizoda. Malo toga se zna o koncentraciji elemenata u prstenovima prirasta drveća ruralnih sredina i šumskih ekosistema, a još manje o koncentraciji elemenata u prstenovima prirasta u SR Srbiji. U okviru ovih istraživanja koturovi dve četinarske vrste: ariša (Larix europaea Lam.) i duglazije (Pseudotsuga menziesii Mirb.) sa tri lokacije u Republici Srbiji (Avala, REIK-Kolubara i Kučevo) su uzorkovani i razvrstani u periode od po tri godine. Merene su koncentracije makro (Ca, Mg, K, P) i mikro (Fe, Mn, Cu, Zn, Al, Cd, Pb i Sr) elemenata u prstenovima prirasta, kori i zemljištu optički emisionim spektrometrom sa induktivno spregnutom plazmom (ICP-OES). Uzorci zemljišta su prethodno pripremani sekvencijalnom ekstrakcijom u cilju dobijanja ukupne, dostupne i potencijalno dostupne koncentracije elemenata u zemljištu..., Plant cover, particularly forest trees, is emerging as an active factor in the acceptance of pollution from the atmosphere, and plants form the first level of deposition of these pollutants, while soil is the ultimate receptor. In forest ecosystems, there is only one type of elements entry, but there are multiple transfer pathways due to the presence of ground flora and tree floors. Trees that grow in temperate regions, where the seasonal changes are pronounced, usually form visible annual growth ring. Growth rings or tree-rings are approximately concentric wood layers, which are the result of cambium work in one growing season. Tree-rings are widely available source of long-term data about past times and as such are unique witness of the environment condition. The chemical composition of wood may therefore reflect the environment composition in which the tree grew. Many studies in urban and industrial areas revealed that wood chemical content can point on changes in the environment through time and allow the reconstruction of pollution episodes. Little is known about the tree-ring element concentrations in rural and forest ecosystems, and even less about the element concentrations in tree- rings in Serbia. In this study stem disks of two coniferous species: larch (Larix europaea Lam.) and Douglas-fir (Pseudotsuga menziesii Mirb.) from three locations in the Republic of Serbia (Avala, REIK-Kolubara and Kučevo) were sampled and divided into periods of three years. Macro (Ca, Mg, K, P) and micro (Fe, Mn, Cu, Zn, Al, Cd, Pb and Sr) element concentrations in tree-rings, bark and soil were measured by inductively coupled plasma atomic emission spectrometry (ICP-OES). Soil samples were previously prepared by a sequential extraction method in order to obtain total, available and potentially available element concentrations in soil. The analysis of the measured macro and micro element concentrations in the tree vegetative parts is of great importance for assessing observed

Herbivory by black-tailed deer affects growth form and survival of conifer seedlings in western Oregon and Washington, especially Douglas-fir. Several deterrents have been employed to reduce damage to forest resources yet most are ineffective or cost prohibitive. Use of chemical repellents is socially appealing because they offer a potential non-lethal alternative to reduce plant damage (i.e., browse). Commercial deer repellents may employ one or more mechanisms in their formulation, which affect taste, odor, visual, and/or tactile cues when consumed by deer. I evaluated the commercial SeaDust Wildlife Controllant™ as a tool to repel black-tailed deer from Douglas-fir seedlings during spring bud burst in western Oregon (mid-May through early July), because its ingredients have the potential to employ multiple avoidance mechanisms targeted on tactile, taste, and odor cues. Evidence indicated that deer browse was affected by an interaction of treatment and site; therefore, sites were evaluated separately. Treated seedlings were browsed less by deer than untreated seedlings on 2 of 3 tree farms where percent browse ranged from 0.08%-0.17% in treated plots and 0.15%-0.37% in control plots. Browse was similar at the third tree farm (0.15%). However, number of seedlings browsed in the third tree farm was greater than one site and less than the other, suggesting that statistical significance may not represent biological significance in this study. Future research is needed to incorporate acceptable loss to browsing and cost:benefit analyses.

Biljni pokrivač, naročito šumsko drveće, se javlja kao aktivni faktor u procesu prihvatanja zagadjenja iz atmosfere, i predstavlja prvi nivo taloženja atmosferskih zagadjivača, a zemljište krajnji receptor. Kod šumskih ekosistema postoji samo jedan tip ulaska elemenata, ali postoji više puteva transfera zbog prisustva prizemne flore i spratova drveća. Drveća koja rastu u umerenoj klimatskoj zoni, gde su izražene sezonske promene, imaju osobinu da formiraju po jedan prsten prirasta godišnje. Prstenovi prirasta ili godovi su približno koncentrični slojevi drveta, koji nastaju radom kambijuma u jednoj vegetacionoj sezoni drveta. Prstenovi prirasta predstavljaju široko dostupan izvor dugogodišnjih podataka o prošlim vremenima i kao takvi su jedinstven svedok stanja životne sredine. Hemijski sastav drveta stoga može odražavati sastav sredine u kojoj je drvo raslo. Mnoge studije u urbanim i idustrijskim sredinama, otkrile su da hemijski sadržaj drveta može ukazati na promene u životnoj sredini tokom vremena i omogućiti rekonstrukciju zagadjujućih epizoda. Malo toga se zna o koncentraciji elemenata u prstenovima prirasta drveća ruralnih sredina i šumskih ekosistema, a još manje o koncentraciji elemenata u prstenovima prirasta u SR Srbiji. U okviru ovih istraživanja koturovi dve četinarske vrste: ariša (Larix europaea Lam.) i duglazije (Pseudotsuga menziesii Mirb.) sa tri lokacije u Republici Srbiji (Avala, REIK-Kolubara i Kučevo) su uzorkovani i razvrstani u periode od po tri godine. Merene su koncentracije makro (Ca, Mg, K, P) i mikro (Fe, Mn, Cu, Zn, Al, Cd, Pb i Sr) elemenata u prstenovima prirasta, kori i zemljištu optički emisionim spektrometrom sa induktivno spregnutom plazmom (ICP-OES). Uzorci zemljišta su prethodno pripremani sekvencijalnom ekstrakcijom u cilju dobijanja ukupne, dostupne i potencijalno dostupne koncentracije elemenata u zemljištu..., Plant cover, particularly forest trees, is emerging as an active factor in the acceptance of pollution from the atmosphere, and plants form the first level of deposition of these pollutants, while soil is the ultimate receptor. In forest ecosystems, there is only one type of elements entry, but there are multiple transfer pathways due to the presence of ground flora and tree floors. Trees that grow in temperate regions, where the seasonal changes are pronounced, usually form visible annual growth ring. Growth rings or tree-rings are approximately concentric wood layers, which are the result of cambium work in one growing season. Tree-rings are widely available source of long-term data about past times and as such are unique witness of the environment condition. The chemical composition of wood may therefore reflect the environment composition in which the tree grew. Many studies in urban and industrial areas revealed that wood chemical content can point on changes in the environment through time and allow the reconstruction of pollution episodes. Little is known about the tree-ring element concentrations in rural and forest ecosystems, and even less about the element concentrations in tree- rings in Serbia. In this study stem disks of two coniferous species: larch (Larix europaea Lam.) and Douglas-fir (Pseudotsuga menziesii Mirb.) from three locations in the Republic of Serbia (Avala, REIK-Kolubara and Kučevo) were sampled and divided into periods of three years. Macro (Ca, Mg, K, P) and micro (Fe, Mn, Cu, Zn, Al, Cd, Pb and Sr) element concentrations in tree-rings, bark and soil were measured by inductively coupled plasma atomic emission spectrometry (ICP-OES). Soil samples were previously prepared by a sequential extraction method in order to obtain total, available and potentially available element concentrations in soil. The analysis of the measured macro and micro element concentrations in the tree vegetative parts is of great importance for assessing observed

Herbivory by black-tailed deer affects growth form and survival of conifer seedlings in western Oregon and Washington, especially Douglas-fir. Several deterrents have been employed to reduce damage to forest resources yet most are ineffective or cost prohibitive. Use of chemical repellents is socially appealing because they offer a potential non-lethal alternative to reduce plant damage (i.e., browse). Commercial deer repellents may employ one or more mechanisms in their formulation, which affect taste, odor, visual, and/or tactile cues when consumed by deer. I evaluated the commercial SeaDust Wildlife Controllant™ as a tool to repel black-tailed deer from Douglas-fir seedlings during spring bud burst in western Oregon (mid-May through early July), because its ingredients have the potential to employ multiple avoidance mechanisms targeted on tactile, taste, and odor cues. Evidence indicated that deer browse was affected by an interaction of treatment and site; therefore, sites were evaluated separately. Treated seedlings were browsed less by deer than untreated seedlings on 2 of 3 tree farms where percent browse ranged from 0.08%-0.17% in treated plots and 0.15%-0.37% in control plots. Browse was similar at the third tree farm (0.15%). However, number of seedlings browsed in the third tree farm was greater than one site and less than the other, suggesting that statistical significance may not represent biological significance in this study. Future research is needed to incorporate acceptable loss to browsing and cost:benefit analyses.

BackgroundThe development of affordable woody biomass feedstocks represents a significant opportunity in the development of cellulosic biofuels. Primary woodchips produced by forest mills are considered an ideal feedstock, but the prices they command on the market are currently too expensive for biorefineries. In comparison, forestry residues represent a potential low-cost input but are considered a more challenging feedstock for sugar production due to complexities in composition and potential contamination arising from soil that may be present. We compare the sugar yields, changes in composition in Douglas-fir woodchips and forestry residues after pretreatment using ionic liquids and enzymatic saccharification in order to determine if this approach can efficiently liberate fermentable sugars.ResultsThese samples were either mechanically milled through a 2 mm mesh or pretreated as received with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate [C2mim][OAc] at 120°C and 160°C. IL pretreatment of Douglas-fir woodchips and forestry residues resulted in approximately 71-92% glucose yields after enzymatic saccharification. X-ray diffraction (XRD) showed that the pretreated cellulose was less crystalline after IL pretreatment as compared to untreated control samples. Two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR) revealed changes in lignin and hemicellulose structure and composition as a function of pretreatment. Mass balances of sugar and lignin streams for both the Douglas-fir woodchips and forestry residues throughout the pretreatment and enzymatic saccharification processes are presented.ConclusionsWhile the highest sugar yields were observed with the Douglas-fir woodchips, reasonably high sugar yields were obtained from forestry residues after ionic liquid pretreatment. Structural changes to lignin, cellulose and hemicellulose in the woodchips and forestry residues of Douglas-fir after [C2mim][OAc] pretreatment are analyzed by XRD and 2D-NM

BackgroundThe development of affordable woody biomass feedstocks represents a significant opportunity in the development of cellulosic biofuels. Primary woodchips produced by forest mills are considered an ideal feedstock, but the prices they command on the market are currently too expensive for biorefineries. In comparison, forestry residues represent a potential low-cost input but are considered a more challenging feedstock for sugar production due to complexities in composition and potential contamination arising from soil that may be present. We compare the sugar yields, changes in composition in Douglas-fir woodchips and forestry residues after pretreatment using ionic liquids and enzymatic saccharification in order to determine if this approach can efficiently liberate fermentable sugars.ResultsThese samples were either mechanically milled through a 2 mm mesh or pretreated as received with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate [C2mim][OAc] at 120°C and 160°C. IL pretreatment of Douglas-fir woodchips and forestry residues resulted in approximately 71-92% glucose yields after enzymatic saccharification. X-ray diffraction (XRD) showed that the pretreated cellulose was less crystalline after IL pretreatment as compared to untreated control samples. Two-dimensional nuclear magnetic resonance spectroscopy (2D-NMR) revealed changes in lignin and hemicellulose structure and composition as a function of pretreatment. Mass balances of sugar and lignin streams for both the Douglas-fir woodchips and forestry residues throughout the pretreatment and enzymatic saccharification processes are presented.ConclusionsWhile the highest sugar yields were observed with the Douglas-fir woodchips, reasonably high sugar yields were obtained from forestry residues after ionic liquid pretreatment. Structural changes to lignin, cellulose and hemicellulose in the woodchips and forestry residues of Douglas-fir after [C2mim][OAc] pretreatment are analyzed by XRD and 2D-NM

The use of nitrogenous fertilizers in agricultural and forestry practices coupled with increased fossil fuel combustion and resulting nitrogen (N) deposition across the landscape have contributed to a near doubling of N inputs to terrestrial ecosystems. With such dramatic changes have come adverse environmental consequences including the acidification of soil and water resources and an increased rate of biodiversity loss in both flora and fauna. A method of rapidly predicting ecosystem susceptibility to N loss across large spatial scales would facilitate the identification of those systems most likely to contribute to potentially adverse environmental impacts. To begin the development of such a framework, this research utilizes study sites located throughout the geographic ranges of Douglas-fir (Pseudotsuga menziesii) and loblolly pine (Pinus taeda) to explore relationships between hyperspectral remote sensing, N stable isotope ratios ("15N) and growth response to nitrogenous fertilizer. In both species multiple linear regression models relating leaf-level reflectance to "15N showed strong predictive capabilities, with some models explaining more than 65% of the variance in "15N. Significant correlations between "15N metrics and growth response to N fertilization were also observed in both species. Additional exploratory analysis of the inclusion of "15N metrics with other environmental and edaphic variables to predict fertilizer growth response showed an increase in model performance with the addition of the enrichment factor (EF ="15NFol - "15NSoil). This research demonstrates the ability of hyperspectral reflectance to predict "15N and reveals the potential of "15N to be included in future models to predict fertilizer growth response.

The fine-scale assessment of both spatially and non-spatially distributed genetic variation is crucial to preserve forest genetic resources through appropriate forest management. Cryptic within-population genetic structure may be more common than previously thought in forest tree populations, which has strong implications for the potential of forests to adapt to environmental change. The present study was aimed at comparing within-population genetic structure in European beech (Fagus sylvatica L.) plots experiencing different disturbance levels. Five plot pairs made up by disturbed and undisturbed plots having the same biogeographic history were sampled throughout Europe. Overall, 1298 individuals were analyzed using four highly polymorphic nuclear microsatellite markers (SSRs). Bayesian clustering within plots identified 3 to 11 genetic clusters (within-plot hST ranged from 0.025 to 0.124). The proportion of within-population genetic variation due to genetic substructuring (FCluPlot = 0.067) was higher than the differentiation among the 10 plots (FPlotTot = 0.045). Focusing on the comparison between managed and unmanaged plots, disturbance mostly explains differences in the complexity of within-population genetic structure, determining a reduction of the number of genetic clusters present in a standardized area. Our results show that: i) genetic substructuring needs to be investigated when studying the within-population genetic structure in forest tree populations, and ii) indices describing subtle characteristics of the within-population genetic structure are good candidates for providing early signals of the consequences of forest management, and of disturbance events in general.

This paper investigates the effect of thermal pretreatment temperatures between 200 and 370 C on the yield and composition of products (bio-charm gasm water and organics) obtained when Douglas-fir wood was subsequently pyrolyzed in an auger reactor at 500 C. The yield of products was reported for the pretreatment and pyrolysis steps separately, and for the two steps added. The maximum yield of bio-oils achieved without pretreatment was close to 59 mass%. A decrease in total liquid yield was observed when the biomass was pretreated at 300 C. At higher temperatures, the yields of Douglas-fir primary degradation products (lignin oligomers, anhydrosugars and alkylated and methoxylated phenols) decreased. The overall water yield increased gradually to 14 mass% at a pretreatment temperature of 290 C. The yield of lignin oligomers also decreased as the pretreatment temperature increased. A drastic reduction in the yield of methoxylated phenols derived from guaiacyl (G) was observed when the biomass was pretreated at temperatures over 300 C. This drastic reduction in the yield of methoxylated lignin derivatives can be explained by the formation of liquid intermediates that facilitate the formation of ionic species, enhancing dehydration reactions leading to the production of o-quinone methide intermediates critical for bio-char formation.

Structural Engineering, Civil Engineering and Geosciences

Structural Engineering, Civil Engineering and Geosciences

A timber frame is a structural building system composed of heavy timber members connected using carpentry-style joinery that may include metal fasteners. A common variant of mortise-and-tenon joints are keyed (or wedged) through-tenon joints. No research on the behavior of wedged joints in timber frames is available. This research provides design knowledge of keyed through-tenon joints from experimental observations and comparisons between mathematical models and experimental measurement. Evaluation of through-tenon keyed mortise and tenon joints was performed by measuring tensile load and stiffness of white oak (Quercus alba) and Douglas-fir (Pseudotsuga menziesii) joints with four- and 11-inch tenons with one and two keys and comparing these results to mathematical models developed from the National Design Specification of Wood Construction (NDS), General Dowel Equations for Calculating Lateral Connection Values (TR-12), and engineering mechanics. Variables included joint species (white oak or Douglas-fir), protruding tenon length (four or 11 inches), and number of keys (one or two). Joints were tested to ultimate load, then model input specimens were cut from tested joints and additional key stock to generate inputs for joint load predictions that were compared to experimental joint load results for validation. Forty joints were tested with white oak keys and six of these joints were retested with ipe (Tabebuia) keys. Joints with four-inch tenons behaved in a brittle manner with tenon failures. Most joints with 11-inch tenons behaved in a ductile manner with key bending and crushing failures. Joint load and stiffness was similar between white oak and Douglas-fir joints. Joints with 11-inch tenons had greater load and stiffness than with four-inch tenons. Joints with two keys had greater load and stiffness than joints with one key, after normalizing joint load and stiffness responses on key width. Joints retested with ipe keys had greater load than joints original

Ultrasonic pre-treatment of small and pressure saturated Douglas-fir heartwood specimens at 20 kHz fixed frequency with an acoustic horn resulted in increased specific permeability coefficient in both radial and tangential directions. Statistical analysis revealed that there was a high correlation between ultrasonic treatment time and specific permeability coefficient. Improvement rate of permeability in both radial and tangential directions was nearly the same regardless of treatment time.

Ultrasonic pre-treatment of small and pressure saturated Douglas-fir heartwood specimens at 20 kHz fixed frequency with an acoustic horn resulted in increased specific permeability coefficient in both radial and tangential directions. Statistical analysis revealed that there was a high correlation between ultrasonic treatment time and specific permeability coefficient. Improvement rate of permeability in both radial and tangential directions was nearly the same regardless of treatment time.

Ultrasonic pre-treatment of small and pressure saturated Douglas-fir heartwood specimens at 20 kHz fixed frequency with an acoustic horn resulted in increased specific permeability coefficient in both radial and tangential directions. Statistical analysis revealed that there was a high correlation between ultrasonic treatment time and specific permeability coefficient. Improvement rate of permeability in both radial and tangential directions was nearly the same regardless of treatment time.

Ultrasonic pre-treatment of small and pressure saturated Douglas-fir heartwood specimens at 20 kHz fixed frequency with an acoustic horn resulted in increased specific permeability coefficient in both radial and tangential directions. Statistical analysis revealed that there was a high correlation between ultrasonic treatment time and specific permeability coefficient. Improvement rate of permeability in both radial and tangential directions was nearly the same regardless of treatment time.

egastigmus spermotrophus (Hymenoptera: Torymidae) is a seed pest of Douglas-fir (Pseudotsuga menziesii) in its natural range of North America. Along with seeds, this invading species was accidentally introduced to Europe where it became the major pest in Douglas-fir seed orchards and stands. The high rates of seed parasitism observed in Europe were first ascribed to a reduced control by natural enemies which apparently did not followed M. spermotrophus from their native American range. However, our survey showed that the parasitoid censuses carried out so far were incomplete. Several other chalcid parasitoid species were present in the stands surveyed in Belgium. Four parasitoid species emerged from Douglas-fir seeds infested by the Douglas-fir seed chalcid. Two pteromalids of North American origin, Mesopolobus spermotrophus and Mesopolobus americus, were dominant whereas a few specimens of an eupelmid, Brasema urozonus, and of another pteromalid, Anogmus hohenheimensis, were also observed. Our results strongly suggest that the previous evaluations of parasitoids populations were biased by an inadequate timing in the censuses.

Megastigmus spermotrophus (Hymenoptera: Torymidae) is a seed pest of Douglas-fir (Pseudotsuga menziesii) in its natural range of North America. Along with seeds, this invading species was accidentally introduced to Europe where it became the major pest in Douglas-fir seed orchards and stands. The high rates of seed parasitism observed in Europe were first ascribed to a reduced control by natural enemies which apparently did not followed M. spermotrophus from their native American range. However, our survey showed that the parasitoid censuses carried out so far were incomplete. Several other chalcid parasitoid species were present in the stands surveyed in Belgium. Four parasitoid species emerged from Douglas-fir seeds infested by the Douglas-fir seed chalcid. Two pteromalids of North American origin, Mesopolobus spermotrophus and Mesopolobus americus, were dominant whereas a few specimens of an eupelmid, Brasema urozonus, and of another pteromalid, Anogmus hohenheimensis, were also observed. Our results strongly suggest that the previous evaluations of parasitoids populations were biased by an inadequate timing in the censuses. © 2007 Elsevier Inc. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

Megastigmus spermotrophus (Hymenoptera: Torymidae) is a seed pest of Douglas-fir (Pseudotsuga menziesii) in its natural range of North America. Along with seeds, this invading species was accidentally introduced to Europe where it became the major pest in Douglas-fir seed orchards and stands. The high rates of seed parasitism observed in Europe were first ascribed to a reduced control by natural enemies which apparently did not followed M. spermotrophus from their native American range. However, our survey showed that the parasitoid censuses carried out so far were incomplete. Several other chalcid parasitoid species were present in the stands surveyed in Belgium. Four parasitoid species emerged from Douglas-fir seeds infested by the Douglas-fir seed chalcid. Two pteromalids of North American origin, Mesopolobus spermotrophus and Mesopolobus americus, were dominant whereas a few specimens of an eupelmid, Brasema urozonus, and of another pteromalid, Anogmus hohenheimensis, were also observed. Our results strongly suggest that the previous evaluations of parasitoids populations were biased by an inadequate timing in the censuses. © 2007 Elsevier Inc. All rights reserved., SCOPUS: ar.j, info:eu-repo/semantics/published

Thousands of ectomycorrhizal (ECM) fungal species exist, but estimates of global species richness of ECM fungi differ widely. Many genera have been proposed as being ECM, but ill a number of studies evidence for the hypothesized ECM habit is lacking. Progress in estimating ECM species richness is therefore slow. Ill this paper we have retrieved studies providing evidence for the ECM habit of fungal species and For the identification of the mycobiont(s) ill specific ECM associations, using published and web-based mycorrhiza literature. The identification methods considered are morpho-anatomical, characterization or naturally occurring ECMs, pure Culture synthesis, molecular identification, and isotopic evidence. In addition, phylogenetic information is also considered as a relevant criterion to assess ECM habit. OF 343 fungal genera for which all ECM status has been alleged, about two thirds have Supportive published evidence or ECM Status can be at least hypothesized. For the remaining taxa, Currently no indication exists as for their I-CM nutritional habit, besides field observations or associations with putative hosts. Our survey clearly indicates that current knowledge of ECM fungal diversity, as Supported by experimental evidence, is only partly complete, and that inclusion of many Funga genera in this trophic and ecological category is not verified at this stage. Care must thus be used when compiling lists of ECM and saprotrophic full studies oil the basis of published information only. On the basis of our literature search we conservatively estimate ECM species richness around 7750 species. However, oil the basis of estimates of knowns and unknowns in macromycete diversity, a final estimate or ECM species richness Would likely be between 20000 and 25000.

Little is known about water transfer via mycorrhizal hyphae to plants, despite its potential importance in seedling establishment and plant community development, especially in arid environments. Therefore, this process was investigated in the study reported in this paper in laboratory-based tripartite mesocosms containing the shrub Arctostaphylos viscida (manzanita) and young seedlings of sugar pine (Pinus lambertiana) and Douglas-fir (Pseudotsuga menziesii). The objectives were to determine whether water could be transported through mycorrhizal symbionts shared by establishing conifers and A. viscida and to compare the results obtained using two tracers: the stable isotope deuterium and the dye lucifer yellow carbohydrazide. Water containing the tracers was added to the central compartment containing single manzanita shrubs. The fungal hyphae were then collected as well as plant roots from coniferous seedlings in the other two compartments to determine whether water was transferred via fungal hyphae. In addition, the length of the hyphae and degree of mycorrhizal colonisation were determined. Internal transcribed spacer–restriction fragment length polymorphism (ITS-RFLP) analysis was used to identify the fungal species involved in dye (water) transfer. Results of the stable isotope analysis showed that water is transferred via mycorrhizal hyphae, but isotopically labelled water was only detected in Douglas-fir roots, not in sugar pine roots. In contrast, the fluorescent dye was transported via mycorrhizal hyphae to both Douglas-fir and sugar pine seedlings. Only 1 of 15 fungal morphotypes (identified as Atheliaceae) growing in the mesocosms transferred the dye. Differences were detected in the water transfer patterns indicated by the deuterium and fluorescent dye tracers, suggesting that the two labels are transported by different mechanisms in the same hyphae and/or that different fungal taxa transfer them via different routes to host plants. We conclude that bot

The mountain beaver is a semi-fossorial rodent of the Pacific Northwest and is among a variety of herbivores that retard plant growth and cause tree seedling deformities and mortality. Douglas-fir seedlings are planted in the Pacific Northwest from February through March, a period coinciding with mountain beaver parturition. Previous research suggested that in spring, lactating females depend more on conifers than do non-lactating females and males. We conducted experiments to determine if female reproductive condition influenced seedling damage, and if physiological stage of the seedling affected damage. Dormant and flushing trees were offered to 6 pregnant and 6 non-pregnant females in 2002 and 2003. We found no difference between female condition and damage in 2002, but there was a significant difference between type of tree and damage (F6,79 = 6.75, P < 0.001). In 2003, we found a difference in seedling damage (F3,95 = 16.41, P < 0.001), with tree type (P < 0.001) and female condition (P = 0.02) contributing to the model. More flushing trees were damaged in both years than dormant trees, once bud break occurred. Statistical analyses of fructose (F5,23 = 12.07, P < 0.001) and glucose (F5,23 = 12.86, P < 0.001) concentration data indicate that tree type (dormant or flushing) was a significant effect (P < 0.001). The interaction between tree type and week sampled was also significant in both the glucose (P = 0.002) and fructose response (P = 0.009). Both fructose and glucose concentrations were the lowest in new flushing trees, and mountain beaver did not appear to be selecting flushing trees for their needle sugar content. Water concentration also varied between tree type but was not affected by the sampling time (F5,20 = 35.46, P < 0.001). New and dormant growth tissues had similar water concentrations that were greater than old growth tissue. Mountain beaver are dependent upon a constant water source, although it does not appear that damage

The mountain beaver is a semi-fossorial rodent of the Pacific Northwest and is among a variety of herbivores that retard plant growth and cause tree seedling deformities and mortality. Douglas-fir seedlings are planted in the Pacific Northwest from February through March, a period coinciding with mountain beaver parturition. Previous research suggested that in spring, lactating females depend more on conifers than do non-lactating females and males. We conducted experiments to determine if female reproductive condition influenced seedling damage, and if physiological stage of the seedling affected damage. Dormant and flushing trees were offered to 6 pregnant and 6 non-pregnant females in 2002 and 2003. We found no difference between female condition and damage in 2002, but there was a significant difference between type of tree and damage (F6,79 = 6.75, P < 0.001). In 2003, we found a difference in seedling damage (F3,95 = 16.41, P < 0.001), with tree type (P < 0.001) and female condition (P = 0.02) contributing to the model. More flushing trees were damaged in both years than dormant trees, once bud break occurred. Statistical analyses of fructose (F5,23 = 12.07, P < 0.001) and glucose (F5,23 = 12.86, P < 0.001) concentration data indicate that tree type (dormant or flushing) was a significant effect (P < 0.001). The interaction between tree type and week sampled was also significant in both the glucose (P = 0.002) and fructose response (P = 0.009). Both fructose and glucose concentrations were the lowest in new flushing trees, and mountain beaver did not appear to be selecting flushing trees for their needle sugar content. Water concentration also varied between tree type but was not affected by the sampling time (F5,20 = 35.46, P < 0.001). New and dormant growth tissues had similar water concentrations that were greater than old growth tissue. Mountain beaver are dependent upon a constant water source, although it does not appear that damage

Black bear (Ursus americanus) damage to trees is a severe problem in the Pacific Northwest. Significant damage has been observed for many years, especially in highly managed private industrial forests in western Washington. The introduction of intensive silvicultural techniques resulted in higher yields, but may have also made trees more vulnerable to black bear destruction. Early lethal control efforts lost public support and the forest products industry investigated different methods that concentrated on non-lethal management tools. In 1985, the Washington Forest Protection Association introduced supplemental bear feeding as a damage prevention program in high damage areas during the spring months. This became a very successful alternative to the earlier methods of killing bears. The supplemental feeding program has great support from land managers and the public as an economically viable additional tool to black bear population control.

Black bear (Ursus americanus) damage to trees is a severe problem in the Pacific Northwest. Significant damage has been observed for many years, especially in highly managed private industrial forests in western Washington. The introduction of intensive silvicultural techniques resulted in higher yields, but may have also made trees more vulnerable to black bear destruction. Early lethal control efforts lost public support and the forest products industry investigated different methods that concentrated on non-lethal management tools. In 1985, the Washington Forest Protection Association introduced supplemental bear feeding as a damage prevention program in high damage areas during the spring months. This became a very successful alternative to the earlier methods of killing bears. The supplemental feeding program has great support from land managers and the public as an economically viable additional tool to black bear population control.

Mountain beavers (Aplodontia rufa) cause considerable damage to forest trees in the Pacific Northwest. Feeding injuries result in mortality, growth losses. deformity of trees, and understocked plantations. Losses are most severe in new plantations with significant damage problems also occurring in sapling stands. Trapping, and placing physical barriers around individual trees, are the most common methods of control. Both methods are costly but effective in reducing damage.

Damage to coniferous seedlings and trees by forest rodents, including forest lagomorphs, is a major factor limiting prompt regeneration and causing significant losses in young stands. Manipulating the vegetation to adversely influence food and cover thereby reducing animal numbers is proposed as an approach to alleviating damage. The adaptability, high reproductive potential, opportunistic feeding behavior, and mobility of forest rodents combined with the species diversity of rodent communities, rapid recovery of vegetation, and need for long-term protection make habitat manipulation for damage control a difficult approach. However, an example is presented where herbicide-induced reduction in vegetative cover and availability of summer foods resulted in a significant reduction of clipping damage to Douglas-fir seedlings by snowshoe hares.

An attempt was made to identify the olfactory cues produced by Douglas-fir seeds which attract deer mice (Peromyscus maniculatus) to the seeds. The olfactometers used are described, and the merits of different statistical analyses of the data are discussed. The odors produced by whole Douglas-fir seed and by the endosperm were preferred among the fractions tested to date. Deer mice were repelled by Douglas-fir turpentine, cedar oil, and, to a lesser degree, one extract.

Principal methods being used to alleviate browsing damage to Douglas-fir (Pseudotsuga menziesii) seedlings by black-tailed deer (Odocoileus hemionus columbianus) in the Pacific Northwest are animal repellents applied to foliage and plastic mesh cylinders around individual seedlings. As an alternate method, we demonstrated that prompt establishment of highly palatable native forbs reduced summer browsing on planted seedlings to the point that black-tailed deer were no longer a factor limiting Douglas-fir regeneration. We believe that establishing native forbs is a sound ecological approach to deer-reforestation problems; furthermore, it should have wide utility because it integrates forest- and wildlife-management objectives by promoting prompt regeneration of conifers and enhancing wildlife habitat.

Mountain beavers (Aplodontia rufa) cause considerable damage to forest trees in the Pacific Northwest. Feeding injuries result in mortality, growth losses. deformity of trees, and understocked plantations. Losses are most severe in new plantations with significant damage problems also occurring in sapling stands. Trapping, and placing physical barriers around individual trees, are the most common methods of control. Both methods are costly but effective in reducing damage.

An attempt was made to identify the olfactory cues produced by Douglas-fir seeds which attract deer mice (Peromyscus maniculatus) to the seeds. The olfactometers used are described, and the merits of different statistical analyses of the data are discussed. The odors produced by whole Douglas-fir seed and by the endosperm were preferred among the fractions tested to date. Deer mice were repelled by Douglas-fir turpentine, cedar oil, and, to a lesser degree, one extract.

Damage to coniferous seedlings and trees by forest rodents, including forest lagomorphs, is a major factor limiting prompt regeneration and causing significant losses in young stands. Manipulating the vegetation to adversely influence food and cover thereby reducing animal numbers is proposed as an approach to alleviating damage. The adaptability, high reproductive potential, opportunistic feeding behavior, and mobility of forest rodents combined with the species diversity of rodent communities, rapid recovery of vegetation, and need for long-term protection make habitat manipulation for damage control a difficult approach. However, an example is presented where herbicide-induced reduction in vegetative cover and availability of summer foods resulted in a significant reduction of clipping damage to Douglas-fir seedlings by snowshoe hares.

Principal methods being used to alleviate browsing damage to Douglas-fir (Pseudotsuga menziesii) seedlings by black-tailed deer (Odocoileus hemionus columbianus) in the Pacific Northwest are animal repellents applied to foliage and plastic mesh cylinders around individual seedlings. As an alternate method, we demonstrated that prompt establishment of highly palatable native forbs reduced summer browsing on planted seedlings to the point that black-tailed deer were no longer a factor limiting Douglas-fir regeneration. We believe that establishing native forbs is a sound ecological approach to deer-reforestation problems; furthermore, it should have wide utility because it integrates forest- and wildlife-management objectives by promoting prompt regeneration of conifers and enhancing wildlife habitat.

For almost a half century now, repeated failures in direct seeding operations on cutover forest lands in North America had been largely blamed on the unproven destruction of the seed supply by small mammals. In 1960, the Canadian Wildlife Service undertook a research project to ascertain the possible fate of white spruce seeds placed into the natural environment and the influence which small mammal populations may have upon such a seed supply. By equipping each seed with a microscopic radio-transmitter (radio isotopes), the seeds could be left in the field for up to one year and then recovered intact or as seed coat fragments to provide data on seed fate. Recovery success on 21,800 white spruce seeds in ten years of study has been 90%. Recoveries indicate near 50% of spring sown seeds could be destroyed by small mammals within 17 weeks in some years despite the fact that these seeds had been previously treated with the widely accepted protective coating of aluminum powder-endrin-arasan-latex. Late winter seeding reduced losses to small mammals by 2/3. No direct relationship between numbers of small mammals present and the number of seeds destroyed could be demonstrated. A critical examination of seed treatment procedures widely used has led to the development of a new seed coating formulation employing a potent rodent repellent, R-55. Under laboratory conditions, the new coating yielded improved germination and a high degree of protection against small mammals. The new coating treatment received limited field testing during 1969 and is currently undergoing refinement and more extensive laboratory and field testing in Alberta.

In a program to evaluate repellents for protecting Douglas-fir (Pseudotsuga menziesii) seedlings from browsing by black-tailed deer (Odocoileus hemionus columbianus), a preference-testing system was developed to supplement preliminary pen tests. The system uses an apparatus that presents individual test deer with a choice between two foods (usually feed pellets treated with a candidate repellent or a marginally palatable standard). The two foods are presented, in alternating positions, only long enough for the deer to make a choice; results are recorded in terms of percent choices made for the candidate repellent, or percent consumption. Tests thus far with a number of candidate repellents, including several chemical fractions derived from putrefied fish, have generally given clear-cut results, and the system appears very promising for this kind of evaluation. Although semi-tame deer and an experienced operator are required, the system uses very small amounts of candidate repellents, produces evaluations on a material in 1 to 2 days, can be used year-round, and permits observations of deer behavior during the choice process.

This paper focuses on managing wildlife damage in forest environments, with emphasis on the use of vertebrate pesticides in the western United States. Types of forest damage caused by vertebrates fall into the categories of seed destruction, foliage clipping and browsing, and root and bark injuries. Consumption of natural seedfall or following direct-seeding applications for reforestation varies with tree species as well as with vertebrate seed predators, which include both rodents and birds. With Douglas-fir, deer mice (Peromyscus spp.) are cause the greatest losses. For Ponderosa pine, deer mice, chipmunks, and ground squirrels are primarily responsible for seed loss. Seeding in black walnut is primarily impacted by gray squirrels and the eastern fox squirrel. Success with rodenticide treatments in advance of seed applications were only effective for short periods, as rodent populations rebounded quickly. Current efforts are relying on various seed coatings that provide greater efficacy. Clipping by small rodents is a particular problem with newly emerged seedlings; existing seedlings are also damaged by snowshoe hares and mountain beaver in the Pacific Coast states. Contact repellents have been effective but may need to be re-applied periodically. Browsing damage to existing conifer stands is caused primarily by deer and elk, and there is no general solution for this problem. Root injury to seedling and small saplings is most frequently caused by pocket gophers. A variety of animals may cause bark injuries: meadow mice (Microtus spp.) can seriously damage seedlings, while bark damage to both young and also mature trees can be caused by porcupine, woodrats, rabbits, squirrels, and pocket gophers. Bear damage to bark is usually seen on mature trees. Seed treatment formulations using endrin as the active ingredient are described, as are a foliar repellent treatment using TMTD, and the manufacture and use of salt blocks containing strychnine for porcupine control. Pe