Douglas-fir Seeds Research Articles

Current and Predicted Future Winter Warm Spells Would Affect Douglas Fir (Pseudotsuga menziesii (Mirb.), Franco) Seeds in the Early Stage of Germination More Than in the Late Stage of Germination

Most tree species in the temperate climatic zone (including Douglas fir) disperse seeds in autumn. Some of them must be exposed to cold (0–10 °C) and moist conditions (cold stratification) to overcome dormancy and trigger germination. In the Northern Hemisphere, winter warm spells occur more frequently and last longer than in recent decades from eastern Canada to Europe. Our main research objective was to investigate the influence of current (1 or 3 days at day/night temperatures: 15 °C/10 °C) and future predicted (5 days at day/night temperatures: 25 °C/15 °C) winter warm spells on dormancy breaking and germination traits (germination energy—GE; germination capacity—GC; final germination capacity—FGC) of Douglas fir seeds from four old-growth stands in northern Poland. For this purpose, we interrupted cold stratification of seeds at different time points, i.e., after 3 weeks; 6 weeks; 9 or 3 weeks and 6 weeks; 3 and 9 weeks; 6 and 9 weeks; 3 and 6 weeks and 9 weeks. We found that for GE and GC, all main effects (populations—P; days of warm spell—D; stratification duration—W) and interactions were significant (except interaction P×D). FGC was significantly affected by the effects P and D and interactions of D × W and P × D × W. In addition, we found that the predicted warm spells negatively affected the early germination stage (GE and GC) of Douglas fir, but both current and future predicted winter conditions will not negatively affect the late germination stage (FGC).

Douglas-fir seedling quality in biochar-amended peat substrates

Artificial forest regeneration using nursery produced growing stock is commonplace in the Pacific Northwest. High quality seedlings are needed for outplanting success, which depends on a seedling’s ability to establish new roots and overcome stress. Containerized seedling stock is typically grown in artificial growing media. Peat, a popular component of growing media, is a non-renewable resource. Biochar has similar physical attributes to peat, which makes it a potential alternative. In our study, we grew Douglas-fir seedlings in containers with biochar-amended peat-based growing media to determine if biochar could improve seedling quality. Douglas-fir seeds were sown in March 2016 and seedlings were grown under standard light and temperature conditions at an operational forest nursery for nine months. After nine months, seedling quality was assessed for height, diameter, cold hardiness, and root growth potential. Using biochar did not improve Douglas-fir seedling quality, except for slightly increasing cold hardiness and root growth potential for equivalently sized seedlings. Seedlings grown without biochar had increased height and diameter compared to seedlings with biochar and they had higher root growth potential (all dependent on fertilizer rates). Douglas-fir seedling quality might be improved with biochar amendment if negative growth impacts of soil reaction can be overcome.

Assisted phytostabilisation of As, Pb and Sb-contaminated Technosols with mineral and organic amendments using Douglas fir (Pseudotsuga menziesii (Mirb.) Franco).

Phytoremediation of metal(loid)s by conifers is not widely studied, although conifers may be interesting, particularly in temperate-cold areas and/or on acidic soils. In this study, seeds of Douglas fir were sown in greenhouse and cultivated for 3months on two Technosols highly contaminated with different concentrations of Pb, As and Sb and collected in two French old former mines located in massif Central or close to it: a mine of gold at La Petite Faye and a mine of lead and silver at Pontgibaud. Two amendments, a nutrient solution (NS) and composted sewage sludge (CSS), were tested in order to stimulate Douglas fir growth and to reduce the metal(loid)s mobility and phytoavailability. The speciation determined by sequential extractions as well as mineralogy highlight different geochemical behaviours of Pb, As and Sb as a function of the Technosol. In all cases, CSS amendments significantly reduced Pb phytoavailability as well as the uptake and translocation of Pb and As. Moreover, CSS stimulated the growth of Douglas firs highlighting that this amendment could be a good strategy for a better phytostabilisation of these metal(loid)s.

Secondary dormancy imposition in pre-chilled, dried seeds of Douglas fir (Pseudotsuga menziesii) during storage

Secondary dormancy imposition in pre-chilled, dried seeds of Douglas fir (<i>Pseudotsuga menziesii</i>) during storage

Clark's Nutcracker Breeding Season Space Use and Foraging Behavior.

Considering the entire life history of a species is fundamental to developing effective conservation strategies. Decreasing populations of five-needle white pines may be leading to the decline of Clark’s nutcrackers (Nucifraga columbiana). These birds are important seed dispersers for at least ten conifer species in the western U.S., including whitebark pine (Pinus albicaulis), an obligate mutualist of Clark’s nutcrackers. For effective conservation of both Clark’s nutcrackers and whitebark pine, it is essential to ensure stability of Clark’s nutcracker populations. My objectives were to examine Clark’s nutcracker breeding season home range size, territoriality, habitat selection, and foraging behavior in the southern Greater Yellowstone Ecosystem, a region where whitebark pine is declining. I radio-tracked Clark’s nutcrackers in 2011, a population-wide nonbreeding year following a low whitebark pine cone crop, and 2012, a breeding year following a high cone crop. Results suggest Douglas-fir (Pseudotsuga menziesii) communities are important habitat for Clark’s nutcrackers because they selected it for home ranges. In contrast, they did not select whitebark pine habitat. However, Clark’s nutcrackers did adjust their use of whitebark pine habitat between years, suggesting that, in some springs, whitebark pine habitat may be used more than previously expected. Newly extracted Douglas-fir seeds were an important food source both years. On the other hand, cached seeds made up a relatively lower proportion of the diet in 2011, suggesting cached seeds are not a reliable spring food source. Land managers focus on restoring whitebark pine habitat with the assumption that Clark’s nutcrackers will be available to continue seed dispersal. In the Greater Yellowstone Ecosystem, Clark’s nutcracker populations may be more likely to be retained year-round when whitebark pine restoration efforts are located adjacent to Douglas-fir habitat. By extrapolation, whitebark pine restoration efforts in other regions may consider prioritizing restoration of whitebark pine stands near alternative seed sources.

Особливості посівних якостей насіння Pseudotsuga menziesii Mirb. Franco у насадженнях західного регіону України

Вивчено посівні якості однорідних партій насіння Pseudotsuga menzie­sii Mirb. Franco – чистоту, масу 1000 насінин, схожість, енергію проростання, зараження фітопатогенами за результатами аналізу середніх зразків Львівською державною зональною лісонасінною інспекцією впродовж 1990-2012 рр. Встановлено, що у лісових насадженнях західного регіону України посівні якості насіння псевдотсуги є невисокими. Із 33-ох досліджених однорідних партій лише у 17-ти з них насіння відповідає вимогам стандарту.&#x0D; Широке впровадження псевдотсуги в лісові насадження стримується відсутністю у потрібних обсягах об’єктів лісонасінної бази. Розширення та упорядкування останньої дало б змогу заготовляти насіння з більш високими посівними якостями, у більших обсягах, ширше використовувати насінний потенціал цього цінного інтродукованого деревного виду.

Douglas fir (pseudotsuga menziesii) plantlets responses to as, PB, and sb-contaminated soils from former mines

ABSTRACTPhytoremediation of metalloids by conifers is not widely studied although they may be relevant for several contaminated sites, especially those located in cold areas and sometimes under dry climates. Here, seeds of Douglas fir were sown in greenhouse on three soils collected in two French former mines: a gold mine (soils L1 and L2) and a lead and silver mine (soil P). These soils are highly contaminated by Pb, As, and Sb at different concentrations. Plants were harvested after ten weeks. Growth parameters, primary metabolite content, and shoot and root ionomes were determined. Douglas firs grown on the soils L1 and P had a lower biomass than controls and a higher oxidation status whereas those grown on the soil L2 exhibited a more developed root system and only slight modifications of carbon and nitrogen nutrition. Based on trace element (TE) concentrations in shoots and roots and their translocation factor (TF), Douglas fir could be a relevant candidate for As phytoextraction (0.8 g. kg−1 dry weight in shoots and a TF of 1.1) and may be used to phytostabilize Pb and Sb (8.8 g and 127 mg. kg−1 in roots for Pb and Sb, respectively, and TF lower than 0.1).

Correlation between seedling length and Canadian Douglas-fir height

This paper presents the results of the studies of Douglas-fir seeds from Canada aimed at understanding and controlling the processes of the genetic growth potential of Douglas-fir in Serbia. The research was focused on the early stage of Douglas-fir growth, i.e. at the stage of seed germination in the laboratory. We tested the correlation between seed germination, seedling length and the height of plants in the nursery. The seeds from 13 Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) localities were obtained from Canada and compared under laboratory and nursery conditions. The seeds from different altitudes, latitudes and longitudes come from a part of the natural range of Douglas-fir in Canada. Before they are transferred and introduced, seed material must be tested with regard to the potential success of the selected tree species within the shortest possible time. This is necessary for the introduction of a tree species with a widespread natural range. Douglas-fir is a highly productive coniferous tree species with a broad geographical and ecological range. It has a wider natural range than other conifers and greater chances of successful adaptation to new ecosystems. Descriptive statistics, analysis of variance for regression, regression and correlation were used to analyse the data. A strong correlation was established between the height of four-year-old seedlings and seed characteristics (germination rate and seedling length).

Pathogenicity and Virulence of Pythium Species Obtained from Forest Nursery Soils on Douglas-Fir Seedlings.

Pythium species are common soilborne oomycetes that occur in forest nursery soils throughout the United States. Numerous species have been described from nursery soils. However, with the exception of P. aphanidermatum, P. irregulare, P. sylvaticum, and P. ultimum, little is known about the potential for other Pythium species found in nursery soils to cause damping-off of tree seedlings. A greenhouse study was conducted to evaluate the pathogenicity and virulence of 44 Pythium isolates representing 16 species that were originally recovered from soil at three forest nurseries in Washington and Oregon. Seeds of Douglas-fir (Pseudotsuga menziesii) were planted into soil infested with each of the isolates. Seedling survival, the number of surviving seedlings with necrotic root lesions, and taproot length were evaluated 4 weeks later. Responses of Douglas-fir to inoculation varied significantly depending on Pythium species and isolate. Eight species (P. dissotocum, P. irregulare, P. aff. macrosporum, P. mamillatum, P. aff. oopapillum, P. rostratifingens, P. sylvaticum, and P. ultimum var. ultimum) significantly reduced the number of surviving seedlings compared to the noninoculated treatment. However, all Pythium species caused a greater percentage of seedlings to develop root lesions (total mean 40%) than was observed from noninoculated seedlings (17%). Taproot length varied little among Pythium treatments and was not a useful character for evaluating pathogenicity. Results confirm the ability of P. irregulare, P. mamillatum, and P. ultimum var. ultimum to cause damping-off of Douglas-fir seedlings, and are indicative that other species such as P. dissotocum, P. aff. macrosporum, P. aff. oopapillum, P. rostratifingens, and P. sylvaticum may also be responsible for seedling loss.

Seed wasp invasions promoted by unregulated seed trade affect vegetal and animal biodiversity

Cone and seed insects are considered the most important predators of tree seeds during the pre-dispersal phase of development. Among them, exotic seed chalcids in the genus Megastigmus invaded Europe as a result of the rapidly-increasing and mostly unregulated seed trade for afforestation and ornamental plantations. Unlike their economic impact in seed orchards, until recently, little attention was paid to the ecological impact of these insects. In the present study, selected case studies of alien Megastigmus spp. were considered to assess their specific impact on the potential of natural regeneration of native woody plants and on the native entomofauna competing for seed resource. We re-analyzed data from former studies that did not focus on these ecological interactions and, here, present previously unpublished results. Seeds of Douglas-fir, true cedars, true firs and wild roses were sampled all over Europe, and the relative importance of the native and invasive chalcid species was assessed as well as their specific impact on seed yield. In most cases, the recent arrival of alien chalcids resulted in a significant decrease in the regeneration potential of the host trees. In the absence of competitors, alien chalcids occupied the entire seed niche in Douglas-fir, but their impact tended to decrease after the arrival of invasive seed bugs. In firs, alien chalcids tended to displace the native chalcids, but not in wild roses and cedars, where their damage was increasing. Different biological traits that might explain invasive success of alien chalcids are discussed. However, no general invasive patterns seem to exist.

Establishment constraints of an alien and a native conifer in different habitats

Alien plants are subjected to different biotic and environmental barriers that limit their establishment success in the introduced range. Pseudotsuga menziesii (Douglas fir), a native conifer from Northwest America, is considered one of the most invasive forestry conifers in Europe. However, little is known about the ecological filters that constrain plant establishment at early life-cycle stages and differences in habitat invasibility to this species. We conducted field experiments to compare the establishment potential (i.e. post-dispersal seed removal, seed germination, seedling survival and growth) of Douglas fir in beech forests, holm-oak forests and heathlands; and compared it with the taxonomically close native conifer Abies alba (Silver fir). Douglas fir seeds were more removed than Silver fir in holm-oak and in heathlands. In all habitats, seed germination was significantly higher for Douglas fir compared to that of Silver fir and, seedling mortality was extremely high in both species due to soil disturbance by wild boars and drought stress. Douglas fir mortality was only lower than Silver fir in beech forests. However, species did not differ in seedling growth. Overall, the probability of invasion success of Douglas fir decreased along the sequential stages of plant establishment in all habitats. Only high seed germination rates of Douglas fir would predict its high invasive capacity but these advantages are counterbalanced by high seedling mortality. Results showed a mismatch between invasibility and current pattern of Douglas fir invasion in the study area. Therefore, future research focused on seed production and on different components of biotic resistance is recommended to elucidate which processes are favoring its establishment success.

Fire and mice: Seed predation moderates fire's influence on conifer recruitment

In fire-adapted ecosystems, fire is presumed to be the dominant ecological force, and little is known about how consumer interactions influence forest regeneration. Here, we investigated seed predation by deer mice (Peromyscus maniculatus) and its effects on recruitment of ponderosa pine (Pinus ponderosa) and Douglas-fir (Pseudotsuga menziesii) seedlings in unburned and recently burned fire-adapted montane forests in west-central Montana, USA. Deer mice were almost twice as abundant in burned than unburned stands. Deer mouse removal of seeds from petri dishes was two times higher in burned than in unburned stands, and seed removal levels were 8% higher for ponderosa pine than for the smaller Douglas-fir seeds. In seed-addition experiments, emergence of seedlings in deer mouse-exclusion cages was almost six times higher in burned compared to unburned forest. In both burned and unburned forest, emergence was lower for ponderosa pine than for Douglas-fir. Seedling survival to establishment did not differ between conifer species but was considerably higher in burned than in unburned forest. However, effects of seed predation on recruitment prevailed over fire effects: in cages allowing access by deer mice, emergence and establishment were extremely rare for both conifer species in both burned and unburned forest. This research suggests that consumer interactions can substantially influence recruitment even in fire-adapted forest ecosystems.

Conifer seed predation in harvested and burned dry Douglas-fir forests in southern British Columbia

Consumption of seeds of Douglas-fir ( Pseudotsuga menziesii (Mirb.) Franco) and ponderosa pine ( Pinus ponderosa Dougl. ex P. &amp; C. Laws.) was measured in dry Douglas-fir forest at the Opax Mountain Silvicultural Systems site and a nearby burned area as one component of understanding limited natural regeneration in these sites. Seeds were placed in plots surrounded by a physical barrier to invertebrates, enclosed in mesh impermeable to small mammals, covered by litter, or unprotected in clear-cut, partially harvested, uncut, and burned areas and monitored for three several-day sessions in 2 years. Daily survival rates of unprotected seeds of both species were equally low: 0.63 in uncut forest, 0.45 in partially harvested and clear-cut sites, and 0.03 in the burned area. Experimental reductions of coarse woody debris reduced seed predation moderately in patch cuts but not in uncut forest. Litter cover or selective exclosure of ground-dwelling invertebrates reduced seed losses only slightly, whereas small mammal exclosures eliminated most seed loss. Deer mice ( Peromyscus maniculatus Wagner) are likely the most important seed predators. High rates of seed predation in dry Douglas-fir forests likely limit natural regeneration in harvested and burned stands.

A North American invasive seed pest, Megastigmus spermotrophus (Wachtl) (Hymenoptera: Torymidae): Its populations and parasitoids in a European introduction zone

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.

Parasitism of seed of Douglas fir (Pseudotsuga menziesii) by the seed chalcid, Megastigmus spermotrophus, and its influence on seed hormone physiology

Parasitism of Douglas fir (Pseudotsuga menziesii) megagametophytes by the seed chalcid, Megastigmus spermotrophus Wachtl, occurs naturally after pollination but before fertilization. In the absence of fertilization, the presence of insect larvae within the megagametophyte prevents abortion and the storage tissue continues to develop as if the seed had been fertilized. We investigated the effect of parasitism on the metabolism of abscisic acid (ABA), auxins, cytokinins, and gibberellins during early development of Douglas fir seeds. Hormones and hormone metabolites of infested and uninfested megagametophytes with or without pollination were analyzed by HPLC–ESI/MS/MS. At 1 week after Megastigmus introduction, the insect’s presence stimulated ABA accumulation in unpollinated megagametophytes compared to unpollinated, unparasitized megagametophytes. In pollinated material, parasitism did not stimulate ABA accumulation compared to levels present in unparasitized megagametophytes. In all four treatments, the metabolism of ABA occurred primarily through conjugation to the ABA glucose ester (ABAGE), while the 7′-, 8′- and, 9′-hydroxylation pathways were only minor. ABAGE levels declined with time in all treatments and this occurred to a greater extent in pollinated, parasitized megagametophytes, suggesting that the insect’s presence induced the dramatic decrease in ABAGE. Although there were temporal variations in the auxin, cytokinin, and gibberellin profiles of parasitized megagametophytes, the profiles were generally similar to those of unparasitized megagametophytes. Our results suggest that failure of parasitized megagametophytes to abort may be due to the insect inducing similar hormone profiles to those present during normal development of Douglas fir seed.

Secondary dispersal of bigcone Douglas-fir (Pseudotsuga macrocarpa) seeds

Abstract Large-seeded pines ( Pinus spp.) are known to be dispersed by seed-caching corvids (i.e. jays and nutcrackers) and rodents (e.g. chipmunks and mice), with a concomitant decrease in seed dispersability by wind. We tested the idea that seeds of bigcone Douglas-fir ( Pseudotsuga macrocarpa ), which are winged but larger than the seeds of other members of Pseudotsuga , are dispersed by a combination of wind and seed-caching rodents. We compared characteristics of seeds from P. macrocarpa in southern California (mean seed mass 132.6 mg) to seeds of a population of Pseudotsuga menziesii (Douglas-fir) in northern California (24.8 mg). We also tested whether rodents would cache seeds of P. macrocarpa . Seeds of P. macrocarpa had greater wing loadings (1.37 mg/mm 2 ) and descent velocities (2.47 m/s) than those of P. menziesii (0.52 mg/mm 2 and 1.28 m/s, respectively). These data indicate that the wind dispersability of P. macrocarpa is likely to be less than that of P. menziesii , but this loss of wind dispersability is partially compensated for by secondary dispersal of seeds by rodents, which readily gathered and cached the larger seeds of P. macrocarpa up to 34 m from source trees. Large seed size confers several advantages to P. macrocarpa , most importantly attracting seed-caching animals that effectively bury seeds.

Effect of moist chilling and priming treatments on the germination of Douglas-fir and noble fir seeds

Effect of moist chilling and priming treatments on the germination of Douglas-fir and noble fir seeds

British Columbia Regional Meeting, 2004

British Columbia Regional Meeting, 2004

The effect of moisture content and prechill duration on dormancy breakage of Douglas fir seeds (Pseudotsuga menziesiivar.menziesii[Mirb.] Franco)

AbstractSeeds of Douglas fir (Pseudotsuga menziesiivar.menziesii[Mirb.] Franco) were initially germinated at six constant temperatures (10–35°C), following 0–48 weeks incubation under moist conditions at 4°C, i.e. prechill or stratification. The best, single germination temperature was 15°C for determining the efficacy of subsequent dormancy breakage treatments. Seeds from the same seedlot were then adjusted to 10, 15, 20, 25, 30, 35 and 40% moisture contents (mcfw, fresh weight basis), prechilled for 0, 2, 4, 8, 16, 32, 64 and 128 weeks and transferred to 15°C. A smoothed bivariate spline was used to model the results and showed that virtually all combinations of moisture content and prechill duration significantly stimulated germination capacity, but that the optimal germination percentage (≥93%) was stimulated only by various combinations of between 30 and 35% mcfw and 25 and 48 weeks prechill. At optimal moisture contents (30 and 35%) , extending the prechill duration beyond 48 weeks led to a decrease in germination capacity. This was not due to dormancy reintroduction, but was caused largely by seed death. Regression models using a weighting function, to account for differences in standard deviations, demonstrated significant increases in the mean moisture content of individual seeds at higher moisture contents (≥25%) and longer prechill durations (≥64 weeks) that were concomitant with significant decreases in dry weight. The most likely explanation for this was seed respiration. The combined results suggest that dormancy breakage in Douglas fir seeds requires a hydration level sufficient for respiration to take place, and that, after maximal dormancy release, seeds at the highest mc (35–40%) exhaust their food reserves and begin to deteriorate.

Biochemical assays for identifying seeds of lodgepole pine and other conifers fed on by Leptoglossus occidentalis Heidemann (Hemiptera: Coreidae)

Radiography is a valuable tool for assessing quality of conifer seeds, but it cannot differentiate between aborted seeds and seeds that have been emptied by western conifer seed bug (Leptoglossus occidentalis Heidemann) feeding. We tested three biochemical marker-based assays that were developed to identify L. occidentalis damage to seeds of Douglas-fir, Pseudostuga menziesii (Mirb.) Franco, for their use in lodgepole pine, Pinus contorta var. latifolia Engelmann. The three assays included measurement of storage protein reserve depletion, immunodetection of fragments of insoluble (crystalloid) storage proteins, and immunodetection of L. occidentalis salivary proteins. Aborted seeds contained significantly less soluble and insoluble protein than seeds that were fed on by L. occidentalis. Polyclonal antibodies raised against 11S globulin crystalloid proteins or L. occidentalis salivary gland extracts only immunoreacted with proteins in seeds exposed to L. occidentalis feeding. In a single-blind test, antibody raised against salivary-gland extracts correctly distinguished between undamaged full seeds, unfilled aborted seeds, and seeds fed on by L. occidentalis. Immunodetection of L. occidentalis salivary proteins was also performed on seeds of Abies amabilis Dougl. ex J. Forbes, Tsuga heterophylla (Raf.) Sarg., Picea sitchensis Bong (Carr.), Pinus ponderosa Lawson, and Pinus monticola Dougl. ex D. Don. For all species, immunoreactive polypeptides were only detected in seeds fed on by L. occidentalis. These biochemical marker-based techniques could help researchers and seed orchard managers estimate seed losses caused by L. occidentalis in commercial seed orchards and natural forest stands.Key words: Leptoglossus occidentalis, saliva, biochemical markers, polyclonal antibody, immunodetection, Pinus contorta.