Effects of tree cover, understory vegetation, and litter on regeneration of Douglas-fir (Pseudotsuga menziesii) in southwestern Argentina

1998 ◽  
Vol 28 (5) ◽  
pp. 683-692 ◽  
Author(s):  
F D Caccia ◽  
C L Ballaré
Keyword(s):  
Seed Germination ◽  
Pseudotsuga Menziesii ◽  
Seedling Emergence ◽  
Canopy Cover ◽  
Douglas Fir ◽  
Understory Vegetation ◽  
Tree Cover ◽  
Growth And Survival ◽  
Thermal Environments ◽  
Seedling Predation

The factors and processes that regulate Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) natural regeneration in southwestern Argentina are unknown. We investigated (i) the germination responses of P. menziesii seeds to variations in the radiation and thermal environments imposed by canopy cover and litter, (ii) the effects of litter on seedling emergence, and (iii) the effects of understory vegetation on seedling performance and seed and seedling predation. Seed germination was high in darkness and under canopies. Under a combination of canopy types and litter covers, germination showed a negative correlation with temperature between 23 and 40°C. Germination was not altered by changes in red/far-red ratio. These results suggest that the presence of an overstory canopy promotes P. menziesii seed germination compared with a no-canopy situation (e.g., a clearcut). Litter inhibited seedling emergence by reducing water availability and by acting as a mechanical barrier. Understory vegetation (established saplings) reduced seedling growth and survival. However, our results suggest that direct competition between seedlings and understory vegetation is not the principal force regulating regeneration; indirect effects appear to be of paramount importance because P. menziesii seed and seedling consumption (presumably by rodents) is greatly encouraged by the presence of dense vegetation patches in the understory.

Relationship of Pacific Madrone Sprout Growth to Productivity of Douglas-Fir Seedlings and Understory Vegetation

1990 ◽  
Vol 5 (1) ◽  
pp. 20-24 ◽  
Author(s):  
Thomas F. Hughes ◽  
John C. Tappeiner ◽  
Michael Newton
Keyword(s):  
Pseudotsuga Menziesii ◽  
Secondary Succession ◽  
Douglas Fir ◽  
Understory Vegetation ◽  
Diameter Growth ◽  
Area Index ◽  
Old West ◽  
Pacific Madrone ◽  
Relationship Of ◽  
Sprout Growth

Abstract We studied the development of Pacific madrone (Arbutus menziesii) sprout clumps of various initial densities and their effect on Douglas-fir (Pseudotsuga menziesii) seedling growth and understory vegetation. Five years after density treatments, average leaf area index (LAI) of 9-year-oldmadrone sprouts ranged from 3.6-1.0 m²/m² and total aboveground biomass from 25,630-8,390 kg/ha on the high- and low-density plots, respectively. Diameter of 9-year-old Douglas-fir was inversely related to madrone LAI and ranged from about 27 mm on the high-density plots to 54 mmin the absence of madrone. Analyses of diameter growth trends also indicated that, in the absence of madrone, Douglas-fir grew significantly (P = 0.001 to 0.023) faster than in other treatments. An index of shrub, forb, and grass density was inversely related to madrone LAI, suggesting thatunderstory species are quickly excluded from young madrone stands during secondary succession. We provide equations relating the 5-year growth of 9-year-old Douglas-fir to measures of madrone density and seedling size made when the plantation was 5 years old. West. J. Appl. For. 5(1):20-24.

Drying and storage of prechilled Douglas fir, Pseudotsuga menziesii, seeds

1999 ◽  
Vol 29 (2) ◽  
pp. 172-177 ◽  
Author(s):  
C Muller ◽  
E Falleri ◽  
E Laroppe ◽  
M Bonnet-Masimbert
Keyword(s):  
Moisture Content ◽  
Pseudotsuga Menziesii ◽  
Traditional Method ◽  
Detrimental Effect ◽  
Seedling Emergence ◽  
Douglas Fir ◽  
Dormancy Release ◽  
Optimal Temperature ◽  
Germination Speed ◽  
And Storage

Douglas fir, Pseudotsuga menziesii (Mirb.) Franco, seeds exhibit relative dormancy as they do not germinate at suboptimal temperature (15°C), whereas at optimal temperature (20°C) some germination occurred. Thus, germination at 15°C was chosen to estimate dormancy release. In the first experiment, seeds were prechilled at 32% moisture content (MC) for 0-34 weeks at 3°C. Long chilling treatments enhanced germinability and, more markedly, germination speed both at 20°C and at 15°C. Seeds pretreated for the longest periods were then dried to 6.7% MC and stored up to 6 months without any detrimental effect on germination at 15°C. In the second experiment, seeds from a second seedlot were prechilled for 18 weeks and then stored at three different MCs over a period of 17 months. Seeds stored at the lowest MC (6.7%) germinated fastest and to the highest percentage both at 15 and 20°C. In the nursery, seedling emergence tests confirmed results from this experiment. In most cases, comparisons between seeds prechilled at controlled MC before storage and those stratified with the traditional method resulted in better performance of the first ones, both in the laboratory and in the nursery.

scholarly journals Twenty-Year Response of Ponderosa Pine (Pinus ponderosa Laws.) to Treatment with Hexazinone in Northeastern Oregon

2009 ◽  
Vol 24 (3) ◽  
pp. 151-156
Author(s):  
Amanda Lindsay ◽  
Paul Oester ◽  
Elizabeth Cole
Keyword(s):  
Pseudotsuga Menziesii ◽  
Pinus Ponderosa ◽  
Ponderosa Pine ◽  
Seedling Survival ◽  
Douglas Fir ◽  
Individual Tree ◽  
Growth And Survival ◽  
Competing Vegetation ◽  
Plant Associations ◽  
Initial Control

Abstract Chemical control of competing vegetation with hexazinone is a common and effective silvicultural treatment for ensuring ponderosa pine (Pinus ponderosa Laws.) plantation success on dry sites in the western United States, yet few studies document the effect for more than the first few years after planting. This study, re-evaluated 20 years after planting, followed ponderosa pine growth and survival when hexazinone was applied in broadcast and spot treatments for control of competing vegetation. We continued work from the first 5 years after establishment that identified early differences in ponderosa pine seedling survival and growth with treatment. Examination of 20-year trends indicated that individual tree volume and volume per hectare continued to diverge among treatments. The economic differences among treatments may increase as more surviving, faster-growing trees in the broadcast treatments reach higher-value products sooner. Initial control of competing vegetation increased the likelihood of seedling survival and increased tree size after 20 years. Results pertained to ponderosa pine of the Douglas-fir/spiraea (Pseudotsuga menziesii var. glauca Beissn./Spiraea betulifolia Pall.) and Douglas-fir/common snowberry (Pseudotsuga menziesii var. glauca Beissn./Symphoricarpos albus [L.] S. F. Blake) plant associations in northeastern Oregon, but they should apply to similar sites throughout much of the intermountain West.

Effects of Site Preparation on Douglas-Fir Seedling Growth and Survival

1990 ◽  
Vol 5 (2) ◽  
pp. 49-51 ◽  
Author(s):  
Don Minore ◽  
Howard G. Weatherly
Keyword(s):  
Pseudotsuga Menziesii ◽  
Seedling Growth ◽  
Height Growth ◽  
Site Preparation ◽  
Douglas Fir ◽  
Progeny Test ◽  
Seedling Height ◽  
Soil Humus ◽  
Growth And Survival ◽  
Mechanical Site Preparation

Abstract The effects of five yarding-slash treatment combinations on Douglas-fir (Pseudotsuga menziesii) growth and survival were compared by obtaining seedling heights, potential seedling heights, survival percentages, soil-penetration resistances, and the occurrence of visible soil-humus for 149 progeny-test plantations in western Oregon. Survival was not improved by mechanical site preparation, and seedlings grown on the compacted, low-humus soils associated with piling slash off site did not grow as tall during their first 5 years as seedlings growing on similar sites where slash had been broadcast-burned. Tilling (disking or ripping) did not benefit seedling height growth. West. J. Appl. For. 5(2):49-51, April 1990.

Facilitation of Leymus mollis by Honckenya peploides on coastal dunes in subarctic Quebec, Canada

2001 ◽  
Vol 79 (11) ◽  
pp. 1327-1331 ◽  
Author(s):  
Jean-Michel Gagné ◽  
Gilles Houle
Keyword(s):  
Seed Germination ◽  
Primary Succession ◽  
Seedling Recruitment ◽  
Interspecific Interactions ◽  
Seedling Emergence ◽  
Coastal Dunes ◽  
Eastern Canada ◽  
Growth And Survival ◽  
Successional Species ◽  
Leymus Mollis

Plant recruitment in the very first stages of primary succession is limited by seed availability and harsh abiotic conditions. Facilitation, the positive effect of an earlier successional species on a later successional one, is often significant during primary succession and may result from the trapping of seeds and (or) the improvement of seed germination, seedling emergence, establishment, growth, and survival. We examined the effect of mature Honckenya peploides (L.) Ehrh. (Caryophyllaceae) plants on Leymus mollis Trin. (Poaceae) seedling recruitment on a coastal dune in subarctic Quebec, Canada. Facilitative effects of H. peploides on L. mollis may be critical because the latter species is a key element in the dynamics of the coastal dunes at high latitudes in eastern Canada. Honckenya peploides forms small mounds on the upper beach (the embryo dunes) that are typically distinct from the foredune. Leymus mollis progression towards the upper beach occurs through clonal growth, but seedling recruitment is also significant and contributes to the population genetic diversity. We determined L. mollis seedling emergence and growth and estimated various abiotic variables in two habitats on the upper beach: the embryo dunes and the bare, flat areas beside embryo dunes. Sand accumulation and substrate salinity were higher on the embryo dunes than beside them. Leymus mollis seedling emergence was more important on embryo dunes, although seedling growth was lower there. Our results suggest that the embryo dunes formed by H. peploides facilitate L. mollis recruitment possibly by trapping seeds and improving seed germination and seedling emergence.Key words: coastal dunes, facilitation, Honckenya peploides, interspecific interactions, Leymus mollis, sand burial.

scholarly journals Diversity of Medicinal Plants among Different Tree Canopies

2021 ◽  
Vol 13 (5) ◽  
pp. 2640
Author(s):  
Muhammad Zubair ◽  
Akash Jamil ◽  
Syed Bilal Hussain ◽  
Ahsan Ul Haq ◽  
Ahmad Hussain ◽  
...  
Keyword(s):  
Medicinal Plants ◽  
Coniferous Forest ◽  
Canopy Cover ◽  
Local Communities ◽  
Tree Canopy ◽  
Tree Cover ◽  
Open Spaces ◽  
Floral Diversity ◽  
Tree Canopy Cover ◽  
Closed Canopy

The moist temperate forests in Northern Pakistan are home to a variety of flora and fauna that are pivotal in sustaining the livelihoods of the local communities. In these forests, distribution and richness of vegetation, especially that of medicinal plants, is rarely reported. In this study, we carried out a vegetation survey in District Balakot, located in Northeastern Pakistan, to characterize the diversity of medicinal plants under different canopies of coniferous forest. The experimental site was divided into three major categories (viz., closed canopy, open spaces, and partial tree cover). A sampling plot of 100 m2 was established on each site to measure species diversity, dominance, and evenness. To observe richness and abundance, the rarefaction and rank abundance curves were plotted. Results revealed that a total of 45 species representing 34 families were available in the study site. Medicinal plants were the most abundant (45%) followed by edible plants (26%). Tree canopy cover affected the overall growth of medicinal plants on the basis of abundance and richness. The site with partial canopy exhibited the highest diversity, dominance, and abundance compared to open spaces and closed canopy. These findings are instrumental in identifying the wealth of the medicinal floral diversity in the northeastern temperate forest of Balakot and the opportunity to sustain the livelihoods of local communities with the help of public/private partnership.

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

Plant Disease ◽  
2013 ◽  
Vol 97 (6) ◽  
pp. 744-748 ◽  
Author(s):  
Jerry E. Weiland ◽  
Bryan R. Beck ◽  
Anne Davis
Keyword(s):  
Pseudotsuga Menziesii ◽  
Seedling Survival ◽  
The United States ◽  
Douglas Fir ◽  
Tree Seedlings ◽  
Pythium Species ◽  
Forest Nursery ◽  
Damping Off ◽  
Greenhouse Study ◽  
Forest Nurseries

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.

scholarly journals Effect of Environmental Factors on the Germination and Emergence of Drunken Horse Grass (Achnatherum inebrians)

Weed Science ◽  
2020 ◽  
pp. 1-29
Author(s):  
Yonghuan Yue ◽  
Guili Jin ◽  
Weihua Lu ◽  
Ke Gong ◽  
Wanqiang Han ◽  
...  
Keyword(s):  
Seed Germination ◽  
Environmental Factors ◽  
Abiotic Factors ◽  
Seedling Emergence ◽  
Management Strategies ◽  
Germination Percentage ◽  
Western China ◽  
Burial Depth ◽  
Achnatherum Inebrians ◽  
Water Ph

Abstract Drunken horse grass [Achnatherum inebrians (Hance) Keng] is a perennial poisonous weed in western China. A comprehensive understanding of the ecological response of A. inebrians germination to environmental factors would facilitate the formulation of better management strategies for this weed. Experiments were conducted under laboratory conditions to assess the effects of various abiotic factors, including temperature, light, water, pH and burial depth, on the seed germination and seedling emergence of A. inebrians. The seeds germinated at constant temperatures of 15, 20, 25, 30, 35°C and in alternating-temperature regimes of 15/5, 20/10, 25/15, 30/20, 35/25, 40/30°C, and the seed germination percentages under constant and alternating temperatures ranged from 51% to 94% and 15% to 93%, respectively. Maximum germination occurred at a constant temperature of 25°C, and germination was prevented at 45/35°C. Light did not appear to affect seed germination. The germination percentage of seeds was more than 75% in the pH range of 5 to 10, with the highest germination percentage at pH 6. The seeds germinated at osmotic potentials of 0 MPa to -1.0 MPa, but decreasing osmotic potential inhibited germination, with no germination at -1.2MPa. After 21 d of low osmotic stress, the seeds that did not germinate after rehydration had not lost their vitality. The seedling emergence percentage was highest (90%) when seeds were buried at 1 cm but declined with increasing burial depth and no emergence at 9 cm. Deep tillage may be effective in limiting the seed germination and emergence of this species. The results of this study provide useful information on the conditions necessary for A. inebrians germination and provide a theoretical basis for science-based prediction, prevention and control of this species.

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