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The plant microbiome has proven to be an essential and often overlooked aspect of plant physiological ecology. Plant interactions with microbes are thought to have enabled the transition of plants from aquatic to terrestrial systems, thus co-evolving for millions of years. Consequently, microbes have important consequences for plant performance, nutrient cycling, and potentially even plant species ranges. However, our knowledge of these processes derives from only a few model systems. My dissertation explores these relationships in coast redwood forests where, despite their notoriety, plant-microbial relationships remain unexplored. Redwoods are the largest and some of the oldest plants on Earth, yet their geographical ranges are very constrained. As such, redwood forests serve as an excellent system to explore plant-microbial interactions and how they might expand or limit species ranges. In Chapter 1, I demonstrate two unexpected and important findings related to the redwood root mycobiome. First, I show for the first time that, in addition to its expected association with arbuscular-mycorrhizal fungi (AMF), redwood roots are also associated with with ecto- and ericoid mycorrhizal fungi. To our knowledge, this is the first evidence that this predominantly AMF-associated tree is also colonized by the other two primary types of mycorrhizal fungi. These findings challenge the common practice of AMF-specific sequencing methods and the paradigm that plant species are assumed to associate with only one type of mycorrhizal fungi. This is important because it may link this tree species to the surrounding trees and shrubs that co-occur in these habitats. Secondly, I describe unique structures, which I call “rhizonodes”, that show many parallels in microbial community assembly to well-described nodules in N-fixing plants where rhizonodes act as reservoirs of AMF in the redwood roots. The presence of rhizonodes similarly are a unique finding that seem to occur in other predominantly AMF-associated tree species, but have been widely overlooked. We posit that these structures may be important domiciles for AMF in many of the upwards of 80% of plant species predicted to form relationships with this group. These findings also suggest that arbuscular mycorrhizal fungi (AMF) may play key roles in redwood physiology.In Chapter 2, I focus on redwood association with AMF and the functional consequences of these interactions for plant hosts. I found that mycorrhization of coast redwood proceeds a number of downstream consequences for redwood hosts including in morphology, growth, allocation, hormonal physiology, drought-response, and leaf-level physiology. In addition, I found that mycorrhizal seedlings demonstrate progressively higher rates of photosynthesis compared to non-mycorrhizal seedlings in response to rising CO2. Together, these findings indicate that mycorrhizal fungi are likely to become increasingly important more broadly for plant response to climate change.In Chapter 3, I demonstrate the importance of site-specific water-availability on the root-associated bacterial community in redwood. Previous work on crop plants has shown that artificial drought selects for monoderm bacteria, or bacterial taxa with a single, thick cell-wall layer. I present evidence of similar trends for a long-lived tree species in response to local water-availability. While the consequences of interactions with these types of bacteria remain unknown, as increased intensity and severity of drought are predicted as a result of climate change, I highlight the importance of testing the downstream consequences of monoderm versus diderm dominated bacterial communities on plant physiology, nutrient cycling, and ecosystem function. Taken together, these studies suggest that the root microbiome is an important axis in understanding the response of redwood forest to climatic and environmental change predicted in the Anthropocene. Further, our study of a basal gymnosperm highlights important gaps in our understanding and categorization of plant-microbe interactions and emphasizes the importance of future investigations on non-model plant organisms.

This Natural Resources Condition Assessment (NRCA) is part of a Servicewide eff ort in the National Park Service(NPS) to complete comparable NRCAs for each of 270 NPS units across the 32 NPS Vital Signs Monitoringnetworks between 2006 and 2014. The Sequoia and Kings Canyon National Parks (parks) approach is uniquein several particulars: (1) its construction was made possible through signifi cant added park base funds; (2) theparks professional staff and university partners were equally challenged to work cooperatively to create “actionableresults;” and (3) more than 80 professionals contributed to authoring and presenting this 2,600+ page conditionassessment.

Remote aquatic ecosystems are exposed to an assortment of semivolatile organic compounds (SOCs) originating from current and historic uses, of local and global origin. Here, a representative suite of 57 current- and historic-use pesticides, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons were surveyed in the plasma of the western pond turtle (Emys marmorata) and their potential prey items and habitat. California study sites included Sequoia National Park, Whiskeytown National Recreation Area, and Six Rivers National Forest. Each was downstream of undeveloped watersheds and varied in distance from agricultural and urban pollution sources. SOCs were detected frequently in all sites with more found in turtle plasma and aquatic macroinvertebrates in the two sites closest to agricultural and urban sources. Summed PCBs were highest in Whiskeytown National Recreation Area turtle plasma (mean; 1.56ng/g ww) compared to plasma from Sequoia National Park (0.16ng/gww; p=0.002) and Six Rivers National Forest (0.07ng/g ww; p=0.001). While no current-use pesticides were detected in turtle plasma at any site, both current- and historic-use pesticides were found prominently in sediment and macroinvertebrates at the Sequoia National Park site, which is immediately downwind of Central Valley agriculture. SOC classes associated with urban and industrial pollution were found more often and at higher concentrations at Whiskeytown National Recreation Area. These findings demonstrate a range of SOC exposure in a turtle species with current and proposed conservation status and shed additional light on the fate of environmental contaminants in remote watersheds.

© 2015 John Wiley & Sons Ltd. Studies that model the effect of climate change on terrestrial ecosystems often use climate projections from downscaled global climate models (GCMs). These simulations are generally too coarse to capture patterns of fine-scale climate variation, such as the sharp coastal energy and moisture gradients associated with wind-driven upwelling of cold water. Coastal upwelling may limit future increases in coastal temperatures, compromising GCMs' ability to provide realistic scenarios of future climate in these coastal ecosystems. Taking advantage of naturally occurring variability in the high-resolution historic climatic record, we developed multiple fine-scale scenarios of California climate that maintain coherent relationships between regional climate and coastal upwelling. We compared these scenarios against coarse resolution GCM projections at a regional scale to evaluate their temporal equivalency. We used these historically based scenarios to estimate potential suitable habitat for coast redwood (Sequoia sempervirens D. Don) under 'normal' combinations of temperature and precipitation, and under anomalous combinations representative of potential future climates. We found that a scenario of warmer temperature with historically normal precipitation is equivalent to climate projected by GCMs for California by 2020-2030 and that under these conditions, climatically suitable habitat for coast redwood significantly contracts at the southern end of its current range. Our results suggest that historical climate data provide a high-resolution alternative to downscaled GCM outputs for near-term ecological forecasts. This method may be particularly useful in other regions where local climate is strongly influenced by ocean-atmosphere dynamics that are not represented by coarse-scale GCMs.

© 2015. 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.

Summary: Few studies have quantified pathogen impacts to ecosystem processes, despite the fact that pathogens cause or contribute to regional-scale tree mortality. We measured litterfall mass, litterfall chemistry, and soil nitrogen (N) cycling associated with multiple hosts along a gradient of mortality caused by Phytophthora ramorum, the cause of sudden oak death. In redwood forests, the epidemiological and ecological characteristics of the major overstory species determine disease patterns and the magnitude and nature of ecosystem change. Bay laurel (Umbellularia californica) has high litterfall N (0.992%), greater soil extractable NO3-N, and transmits infection without suffering mortality. Tanoak (Notholithocarpus densiflorus) has moderate litterfall N (0.723%) and transmits infection while suffering extensive mortality that leads to higher extractable soil NO3-N. Redwood (Sequoia sempervirens) has relatively low litterfall N (0.519%), does not suffer mortality or transmit the pathogen, but dominates forest biomass. The strongest impact of pathogen-caused mortality was the potential shift in species composition, which will alter litterfall chemistry, patterns and dynamics of litterfall mass, and increase soil NO3-N availability. Patterns of P. ramorum spread and consequent mortality are closely associated with bay laurel abundances, suggesting this species will drive both disease emergence and subsequent ecosystem function. © 2013 New Phytologist Trust.

Fens and wet meadows are important mountain wetland types, but influences onassemblage structure of associated invertebrates are poorly understood compared with other aspects of the ecology of these habitats. We sought to determine the relative contributions of terrestrial and aquatic invertebrates to diversity and abundance in these wetlands, the extent to which terrestrial and aquatic invertebrate assemblages differ with wetland type, and to what degree the aquatic assemblages vary as a function of slow sheet flow. We compared assemblages in fens and wet meadows, with and without flow, at 80 backcountry sites dispersed across the 6200 km2 landscape of Yosemite, Sequoia,and Kings Canyon National Parks in the Sierra Nevada mountains of California,U.S.A., using standard aquatic and terrestrial sweep netting. Cicadellid leafhoppers, aphids, and thomisid crab spiders were the most abundant terrestrial taxa. Cicadellids,Lepidoptera, anthomyiid, muscid, chloropid, and ephydrid flies, and thomisids were more abundant in fens than in wet meadows. Only mirid leaf bugs were significantly more abundant in wet meadows than fens. Sphaeriid clams and chironomid midges dominated aquatic assemblages both with and without flow. Chloroperlid stoneflies, mites, clams, and flatworms were all more abundant in flow, and Hemiptera and mosquitos were significantly more abundant in quiescent water. Mosquitos were more abundant in wet meadows, but there were few other population differences as a functionof wetland type. Terrestrial diversity was 1.1 to 2.0 times that of aquatic diversity,depending on metric and habitat. Fens had greater terrestrial abundance, richness,evenness, and diversity than wet meadows; there were fewer differences as a function of wetland type for aquatic fauna. Presence or absence of slow sheet flow had more effect on these aquatic assemblages than did wetland type. Cluster analyses, ordination, and multi-response permutation procedures were generally consistent with the univariate results. Vegetation-based wetland classifications should be extrapolated to faunal assemblages with caution, particularly for aquatic invertebrates.

Fire is a major component of the disturbance regime and a critical determinant of competitive outcomes in many ecosystems. In forests dominated by coast redwood (Sequoia sempervirens), fire was frequent and ubiquitous prior to European settlement, but fires have been exceedingly small and rare over the last 70–80 years because of aggressive fire prevention and suppression policies. As a result, many aspects of redwood fire ecology remain poorly understood. However, in 2008 a single storm ignited numerous fires throughout the redwood region, providing a rare opportunity to conduct replicated fire effects research. One year post-fire, we investigated competitive dynamics by quantifying bole survival and basal sprouting, for redwood and associated species, at four field sites that spanned much of the latitudinal range of redwood and encompassed (1) second-growth and old-growth stands, (2) burned and unburned areas, and (3) a wide range of fire severities. We employed a mixed effects analytical framework and found that: (1) the probability of bole survival was greater for redwood than for its primary competitor (tanoak; Notholithocarpus densiflorus), (2) this divergence was much more pronounced at higher fire severities, and (3) tanoak exhibited a slight advantage in terms of post-fire basal sprouting, but the dominance of tanoak basal sprouts in burned areas was reduced relative to unburned areas. For many disturbance types in many ecosystems, the empirical data necessary for effective management decisions are lacking, and studies incorporating vegetative tree regeneration are especially scarce. Our work demonstrates the importance of utilizing unique field research opportunities to test current theories, while unequivocally documenting that fires of all severities increased the abundance of redwood relative to tanoak, and that higher severity fires more strongly favored redwood.

Evaluations of plant water use in ecosystems around the world reveal a shared capacity by many dif- ferent species to absorb rain, dew, or fog water directly into their leaves or plant crowns. This mode of water uptake provides an important water subsidy that relieves foliar water stress. Our study provides the first comparative evaluation of foliar uptake capacity among the dominant plant taxa from the coast redwood ecosystem of California where crown-wetting events by summertime fog frequently occur during an otherwise drought-prone season. Previous research demonstrated that the dominant overstory tree species, Sequoia sempervirens, takes up fog water by both its roots (via drip from the crown to the soil) and directly through its leaf surfaces. The present study adds to these early findings and shows that 80% of the dominant species from the redwood forest exhibit this foliar uptake water acquisition strategy. The plants studied include canopy trees, understory ferns, and shrubs. Our results also show that foliar uptake provides direct hydration to leaves, increasing leaf water content by 2-11%. In addition, 60% of redwood forest species investigated demonstrate noc- turnal stomatal conductance to water vapor. Such findings indicate that even species unable to absorb water directly into their foliage may still receive indirect benefits from nocturnal leaf wetting through suppressed transpiration. For these species, leaf-wetting events enhance the efficacy of nighttime re-equilibration with available soil water and therefore also increase pre-dawn leaf water potentials.

International audience; Young coast redwood (Sequoia sempervirens (D. Don.) Endl.) trees were pruned to various heights to examine the effect of pruning severity on epicormic sprouting. Seven separate stands were used with as many as six treatments per stand in coastal Humboldt County, California, USA.* Epicormic sprout development was affected by pruning severity but primarily at the most severe pruning treatments that removed all but the branches in the top 15% of tree height. Less severe treatments produced sprouts but the number and size of these sprouts were comparable to unpruned trees.* Natural clonal patterns were also used to explore patterns of sprouting between genotypes. Linear mixed-effects models were developed to predict sprouting frequency as a function of pruning severity while accounting for the nested data structure (i.e., stem sections sampled nested within genotypes within treatments within sites).* Comparing variances attributed to each of these random effects indicated that at any level of pruning severity, differences in epicormic sprouting between genotypes and sites expressed soon after pruning had disappeared after six growing seasons. Epicormic branches were more common two years after pruning than six years indicating many branches were dying. Branches were more common in the middle of the pruned bole, possibly because of competition from basal sprouts and the expanding tree crown.; De jeunes séquoias de Californie (Sequoia sempervirens (D. Don.) Endl.) ont été élagués à différentes hauteurs afin d'examiner l'effet de l'intensité de l'élagage sur les rejets épicormiques. Sept peuplements ont été utilisés avec jusqu'à six traitements par peuplement dans la région côtière du Comté de Humboldt en Californie (USA).* Le développement des rejets épicormiques a été affecté par l'intensité de l'élagage, mais surtout par les traitements les plus sévères qui ont presque supprimé toutes les branches au sommet sur 15 % de la hauteur des arbres. Des traitements moins sévères ont produit des rejets, mais le nombre et la dimension de ces rejets étaient comparables à ceux des arbres non élagués.* Des clones naturels ont également été utilisés pour explorer les modèles de rejet entre génotypes. Des modèles linéaires a effets mixtes ont été développés pour prédire la fréquence des rejets en fonction de l'intensité de l'élagage, en prenant en compte la structure imbriquée des données (c'est-à-dire, les sections du tronc échantillonnées, imbriquées avec les génotypes, les traitements et les stations).* La comparaison des variances attribuées à chacun de ces effets aléatoires a indiqué qu'à tout niveau d'intensité d'élagage, les différences de rejets épicormiques entre les génotypes et les stations exprimées peu de temps après la taille avaient disparu au bout de six saisons de croissance.* Les branches épicormiques ont été plus fréquentes deux ans après l'élagage que six ans plus tard indiquant que de nombreuses branches sont en train de mourir. Les branches ont été plus fréquentes dans le milieu de la partie du tronc élaguée, peut-être en raison de la concurrence des rejets de la base et de l'expansion du houppier.

B/OGEOGHAPHIA » vol. XVII - 1993 (Pubblicato I131 oltobre 7 994) ll popolamenlo animale e vegetale de||'Appennino Umbro-Marchigiano The fossil forest of Dunarobba (Umbria - Central Italy): palaeoforestry history through a palynological study MONICA MEN EGHINI and ARTURO PAGANELLI Departmem‘ of Biology — Um'versz'ty of Pczdml — Via Trz'en‘e, 75 — I-35 121 Pzzdomz Key words: palynology, Central Italy, «Tiberino Lake», Villafranchian stage, Coast redwood (Seqzzoizz remperuirezzr) SUMMARY The discovery of the Fossil Forest at Dunarobba, situated at about 400 m a.s.l., lead to a project of inter- disciplinary research which is still taking place‘ The trunks from this forest (about 50) were all found in their growing position and were submerged by a considerable clay bank; they were large in size (diameter about 2 metres and up to 8 m tall) and scarcely mineralized. All the trunks studied so far belong to a single species: Taxodiaxylozz gypracezzzzz, with anatomic characte- ristics similar to the present-day Sequoia 5e27zpemz'rcm* (Biondi at £11., 1991). An ancient palynological flora has emerged which is qualitatively rich, with a predominance of AP. Pollen grains of Seqztoza, Sciadapzlyr, Tzzxozz'z‘zm2, Cycadaceae (Stazzgeria type), Nyrra, Celtis, and Encom- mia were found, along with pollens of Tsuga, Cedrus, Carya, Pterocarya, and Zelkova. The predominant taxa were Sequoia and Taxodium which, along with Aim/r, Salix, Cyperaceae, and Po- tamogetonaceae, spores of Omzzmda and Lycapadium types, and of Polypodiaceae, gave evidence of a humid forest with marsh areas, similar to the present-day coastal forests of California, where the presenbday Seqzzoirl remperuz'renr grows. Attention is drawn to the scientific significance of this important plant paleontological record, and the correspondence between the xilological and palynological examinations, is emphasized. Even though the interdisciplinary research project is still being undertaken, an attempt has been made to provide a chronological interpretation for the deposit. INTRODUCTION During an excavation of clay for brick production by the Briziarelli kiln to- wards 198O in the surroundings of the borough of Avigliano Umbro (province of Terni), at Dunarobba (within the geographical coordinates: 42°39’42”— 42°39’53” lat. N and 12°27’O8”—12°27’40” long. E Greenwich, 400 m a.s.l.), nu- merous large—size trunks were uncovered. The trunks had a diameter of about 2 meters and were up to 8 meters tall. The most striking feature of the findings was their low degree of mineralisation and especially the fact that the trunks were found in their growing position — which is really very unusual — though slightly inclined towards NE. A survey undertaken in the surrounding area sho— wed that many more trunks lay buried in clay, also in vertical position, so that 101