Growth of Populus tremuloides in association with Calamagrostis canadensis

1998 ◽  
Vol 28 (3) ◽  
pp. 396-401 ◽  
Author(s):  
Simon M Landhäusser ◽  
Victor J Lieffers
Keyword(s):  
Populus Tremuloides ◽  
Inhibitory Effect ◽  
Root Competition ◽  
Total Biomass ◽  
Nutrient Regime ◽  
Calamagrostis Canadensis ◽  
Negative Effect ◽  
Soil Temperatures ◽  
Biomass Plant ◽  
Root Collar

Three experiments were conducted to examine the effects of Calamagrostis canadensis (Michx.) Beauv. on the growth of Populus tremuloides Michx. Containerized seedlings of P. tremuloides were transplanted into large pots and subjected to (1) three soil temperatures (20, 12, and 6°C), (2) root competition with C. canadensis, or (3) presence or absence of C. canadensis litter, each at two nutrient regimes. In the first experiment, significant differences (p = 0.0001) in pre- and neo-formed leaf area and root and shoot dry weights were observed for plants subjected to the three different soil temperatures. In experiment two, the presence of C. canadensis significantly (p < 0.001) reduced total biomass, plant height, and root collar calliper of P. tremuloides. In the third experiment, a significant interaction (p = 0.027) between C. canadensis litter and nutrient regime was observed, with the greatest inhibitory effect on P. tremuloides growth resulting from litter at the low nutrient regime. Low soil temperature had the strongest negative effect on P. tremuloides of the four factors investigated. However, direct competition with C. canadensis, low nutrient conditions, and C. canadensis litter likely would add to the growth suppression of P. tremuloides by this grass. The results of this study have significant implications for the management of P. tremuloides after harvesting.

The effect of soil temperature and light on sprouting and rooting of root cuttings of hybrid aspen clones

2005 ◽  
Vol 35 (11) ◽  
pp. 2671-2678 ◽  
Author(s):  
N Stenvall ◽  
T Haapala ◽  
S Aarlahti ◽  
P Pulkkinen
Keyword(s):  
Soil Temperature ◽  
Populus Tremuloides ◽  
Hybrid Aspen ◽  
Light Conditions ◽  
Dark Treatment ◽  
Sand Mixture ◽  
Negative Effect ◽  
Soil Temperatures ◽  
Time Required ◽  
Better Than

Root cuttings from five clones of hybrid aspen (Populus tremula L. × Populus tremuloides Michx.) obtained from 2-year-old stock plants were grown in a peat–sand mixture (soil) at four soil temperatures (18, 22, 26, and 30 °C). Half of the cuttings were grown in light and the rest in darkness. The root cuttings that were grown at the highest soil temperature sprouted and rooted significantly better than the cuttings grown at the lower temperatures. Light did not affect the sprouting of root cuttings but did have a negative effect on their rooting. Moreover, the clones varied significantly in sprouting and rooting percentages, as well as in the time required for sprouting. In general, higher soil temperatures hastened sprouting of the cuttings. Sprouting was also faster in the light than in the dark treatment. Differences in soil temperature, light conditions, or clone had no significant effect on rooting time.

A study of root and shoot interactions between cereals and peas in mixtures

1993 ◽  
Vol 120 (1) ◽  
pp. 13-24 ◽  
Author(s):  
M. P. Tofinga ◽  
R. Paolini ◽  
R. W. Snaydon
Keyword(s):  
Relative Yield ◽  
Root Competition ◽  
Total Biomass ◽  
N Content ◽  
Total N ◽  
Resource Complementarity ◽  
Relative Yield Total ◽  
Shoot Competition ◽  
Competitive Abilities ◽  
Different Sources

SUMMARYWheat, barley and two morphologically contrasting cultivars of peas (leafy and semi-leafless) were grown in pure stands, at standard agricultural densities, and in additive mixtures of cereals with peas. The stands were grown in boxes in the field, and partitions were used to separate the effects of root and shoot interactions. The cereals and peas were either planted at the same time, or one species was planted 10 days before the other. The origin of the N present in each species was determined by applying N fertilizer labelled with 15N.Both cultivars of peas had greater shoot and root competitive abilities than wheat or barley, probably because of their larger seed size; leafy peas had greater shoot and root competitive abilities than semi-leafless peas. Sowing peas after cereals reduced their competitive ability.The relative yield total (RYT) of cereal-pea mixtures, based on total biomass, averaged 1·6 when only the root systems interacted, and 1·4 when only the shoot systems interacted, but did not differ significantly from 10 when both root and shoot systems interacted. RYT values were greater when peas were grown with wheat, rather than with barley, and when peas were sown at the same time as the cereals.Shoot competition from peas increased the N% of cereals, but substantially reduced their total N content, because biomass yield was reduced. Shoot competition from cereals had no effect on the N% of peas, and only slightly reduced their total N content. Shoot competition between cereals and peas had no significant effect upon the proportion of N derived from various sources by either cereals or peas.Root competition from peas significantly reduced both the N% and total N content of cereals. Root competition from cereals had little effect on the N% of peas, but significantly reduced their total N content and increased the proportion of N derived from rhizobial fixation from 76 to 94%. Since cereals and peas largely used different sources of N, resource complementarity for N was probably an important component of intercropping advantage, when the roots of cereals and peas shared soil resources.

scholarly journals Androgens and Postmeiotic Germ Cells Regulate Claudin-11 Expression in Rat Sertoli Cells

Endocrinology ◽  
2005 ◽  
Vol 146 (3) ◽  
pp. 1532-1540 ◽  
Author(s):  
Anne Florin ◽  
Magali Maire ◽  
Aline Bozec ◽  
Ali Hellani ◽  
Sonia Chater ◽  
...  
Keyword(s):  
Germ Cells ◽  
Sertoli Cells ◽  
Inhibitory Effect ◽  
Positive Control ◽  
Maximum Effect ◽  
Dependent Manner ◽  
Adult Age ◽  
Adult Rat ◽  
Protein Levels ◽  
Negative Effect

In the present study we investigated whether fetal exposure to flutamide affected messenger and protein levels of claudin-11, a key Sertoli cell factor in the establishment of the hemotesticular barrier, at the time of two key events of postnatal testis development: 1) before puberty (postnatal d 14) during the establishment of the hemotesticular barrier, and 2) at the adult age (postnatal d 90) at the time of full spermatogenesis. The data obtained show that claudin-11 expression was inhibited in prepubertal rat testes exposed in utero to 2 and 10 mg/kg·d flutamide. However, in adult testes, the inhibition was observed only with 2, and not with 10, mg/kg·d of the antiandrogen. It is shown here that these differences between prepubertal and adult testes could be related to dual and opposed regulation of claudin-11 expression resulting from positive control by androgens and an inhibitory effect of postmeiotic germ cells. Indeed, testosterone is shown to stimulate claudin-11 expression in cultured Sertoli cells in a dose- and time-dependent manner (maximum effect with 0.06 μm after 72 h of treatment). In contrast, postmeiotic germ cells potentially exert a negative effect on claudin-11 expression, because adult rat testes depleted in spermatids (after local irradiation) displayed increased claudin-11 expression, whereas in a model of cocultured Sertoli and germ cells, spermatids, but not spermatocytes, inhibited claudin-11 expression. The apparent absence of claudin-11 expression changes in adult rat testes exposed to 10 mg/kg·d flutamide therefore could result from the antagonistic effects of 1) the inhibitory action of the antiandrogen and 2) the stimulatory effect of the apoptotic germ cells on claudin-11 expression. Together, due to the key role of claudin-11 in the hemotesticular barrier, the present findings suggest that such regulatory mechanisms may potentially affect this barrier (re)modeling during spermatogenesis.

scholarly journals Fauna asociada a la pesquería de Arca Zebra (Mollusca Bivalvia: Arcidae) en Venezuela

2018 ◽  
Vol 47 (1) ◽  
Author(s):  
Roberto Díaz-Fermín ◽  
Vanessa Acosta-Balbás
Keyword(s):  
Community Structure ◽  
New Record ◽  
Diversity Index ◽  
Economic Viability ◽  
Total Biomass ◽  
Total Abundance ◽  
Physical Damage ◽  
Negative Effect ◽  
Fishing Resources ◽  
Pinctada Imbricata

Arca zebra, constitutes one of the fishing resources with the greatest economic impact in northeastern Venezuela, since it forms banks of commercial importance. During a period of nine months (May 2010-August2011) the community structure of the organisms from the trawling fishery carried out by the fishermen of the area was identified, quantified and described. The biomass and abundance of the different groups were estimated to perform Abundance-Biomass Comparison Curves (ABC) with the objective of determining the degree of affectation by the trawling activity. A total of3 249 organisms belonging to 130 species were grouped in five Phyla: Mollusca, Annelida, Arthropoda, Echinodermata and Chordata. The Sanders' diversity index was 122.9 with mollusks (70.87) and polychaetes (29.91) as the most diverse taxa. Mollusks had the highest abundance followed by polychaetes, crustaceans, echinoderms and ascidians. Mollusks and echinoderms made the largest contribution to total biomass. The most frequent species were: Mithraculus forceps, Phallucia nigra, Echinometra lucunter, Eunice rubra and Pinctada imbricata. The microgastropods Triphora melanura is recognized as a new record for the area and the polychaete Oenone fulgida, for Venezuela. The ABC curve showed that total abundance of organisms was above total biomass, suggesting that the fishery of Arca zebra has a negative effect on most groups of organisms, mainly on echinoderms, since many of them suffer strong physical damage at the time of extraction, therefore, there is a need to modify the trawl nets, increasing the mesh opening, butwithout endangering the economic viability of the fishery.

scholarly journals Use of an Aspen Overstory to Control Understory Herbaceous Species, Bluejoint Grass (Calamagrostis canadensis), and Fireweed (Epilobium angustifolium)

2004 ◽  
Vol 21 (2) ◽  
pp. 74-79 ◽  
Author(s):  
Chris Maundrell ◽  
Chris Hawkins
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Ground Cover ◽  
Photosynthetic Photon Flux Density ◽  
Photon Flux ◽  
Photon Flux Density ◽  
Photosynthetic Photon Flux ◽  
Calamagrostis Canadensis ◽  
Canopy Opening ◽  
Epilobium Angustifolium

Abstract To enhance white spruce [Picea glauca (Moench) Voss] regeneration and growth, the potential for using an aspen (Populus tremuloides Michx.) overstory to suppress bluejoint grass [Calamagrostis canadensis (Michx.)] and fireweed (Epilobium angustifolium L) was investigated. Response to canopy opening was assessed on 10 treatments where the canopy had been incrementally opened. At the summer solstice, measurements of attenuated light were taken at 1.3 meters (breast height). Bluejoint grass and fireweed both responded with greater ground cover as the photosynthetic photon flux density increased (R2 = 0.84, P = 0.0002; R2 = 0.90, P = 0.0001; respectively). Where aspen has developed an overstory canopy, it may be possible to control competing vegetation to create favorable environmental conditions for spruce re-establishment, growth, and release while encouraging a sustainable mixedwood stand.

A comparison of growth and physiology in Picea glauca and Populus tremuloides at different soil temperatures

2001 ◽  
Vol 31 (11) ◽  
pp. 1922-1929 ◽  
Author(s):  
Simon M. Landhäusser ◽  
Annie DesRochers ◽  
Victor J. Lieffers
Keyword(s):  
Populus Tremuloides ◽  
Picea Glauca ◽  
Soil Temperatures

Comparison of teosinte (Zea mexicana L.) and inter-subspecific hybrids (Zea mays L.×Zea mexicana) for high forage yield under two sowing regimes

2015 ◽  
Vol 66 (1) ◽  
pp. 49 ◽  
Author(s):  
Imtiaz Akram Khan Niazi ◽  
Saeed Rauf ◽  
Jaime A. Teixeira da Silva ◽  
Hassan Munir
Keyword(s):  
Zea Mays ◽  
Heat Stress ◽  
Zea Mays L ◽  
Agronomic Traits ◽  
Plant Biomass ◽  
Stress Conditions ◽  
Forage Yield ◽  
Total Biomass ◽  
Percentage Survival ◽  
Biomass Plant

This study was undertaken to evaluate the response of teosinte (Zea mexicana L.) and intersubspecific hybrids to heat stress, in particular productivity. Unlike maize (Zea mays L.), teosinte demonstrated thermophilic properties, namely lower heat injury, sustained chlorophyll content under heat stress (36−45°C) and high percentage survival of seedlings (at 55°C). Teosinte also had the ability to produce large plant biomass (27% and 55% higher yield than maize under non-stressed and stress conditions, respectively) and therefore could be exploited as a forage crop. However, teosinte forage had low animal intake (1.48 kg day–1) because of high pubescence density (10.38 view–1) and low sweetness (9.90°Brix). There was a high percentage of heterosis in variable intersubspecific crosses and traits, and a high magnitude of over-dominance for many traits, for example 5.93–7.06 for total biomass plant–1. Hybrids showed additional advantages, including high oil (20% and 4%) and protein (14% and 25%) contents compared with teosinte under non-stressed and stress conditions, respectively. Moreover, inter-subspecific hybrids were also resistant to heat stress, with the capacity for sustaining growth for a longer period (20% and 33% higher than maize under non-stressed and stress conditions, respectively). Genetic distance between parents—calculated from stable agronomic traits—could be used to select parents for high heterosis under both heat stress and non-stressed conditions.

Root competition, not soil compaction, restricts access to soil resources for aspen on a reclaimed mine soil

Botany ◽  
2017 ◽  
Vol 95 (7) ◽  
pp. 685-695 ◽  
Author(s):  
Simon W. Bockstette ◽  
Bradley D. Pinno ◽  
Miles F. Dyck ◽  
Simon M. Landhäusser
Keyword(s):  
Populus Tremuloides ◽  
Resource Availability ◽  
Soil Compaction ◽  
Surface Mining ◽  
Root Competition ◽  
Herbaceous Plants ◽  
Limiting Factors ◽  
Mine Soil ◽  
Belowground Competition ◽  
Deep Tillage

Restricted rooting space in response to soil compaction and belowground competition with herbaceous plants are two main limiting factors for successful reforestation after surface mining. Fine-textured, nutrient-rich soils with adequate soil moisture are particularly susceptible to both of these concerns and while there are recognized ways to manage competition, attempts to alleviate soil compaction through mechanical means have produced varying results. While roots of some herbaceous plants may penetrate compacted soil layers, possibly offering an alternative means to overcome physical restrictions, these potential benefits need to be weighed against negative effects from competition with planted trees. We examined the individual and combined impact of soil decompaction (deep tillage) and management of competing vegetation (herbicide) on soil properties, resource availability, and above- and below-ground growth of aspen (Populus tremuloides Michx.) seedlings on a reconstructed mine soil affected by severe subsoil compaction. Our findings suggest that although deep tillage reduced bulk density, this did not increase resource availability and had limited effect on seedling growth. In contrast, competition with smooth brome grass (Bromus inermis Leyss.) drastically reduced aspen belowground growth because the grass rapidly occupied available rooting space, while simultaneously lowering the availability of water and nutrients, in particular nitrogen.

Dynamics of regeneration gaps following harvest of aspen stands

2006 ◽  
Vol 36 (7) ◽  
pp. 1818-1833 ◽  
Author(s):  
Daniel A MacIsaac ◽  
Philip G Comeau ◽  
S Ellen Macdonald
Keyword(s):  
Spatial Heterogeneity ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
Natural Disturbance ◽  
White Spruce ◽  
Deciduous Trees ◽  
Trembling Aspen ◽  
Calamagrostis Canadensis ◽  
Edaphic Conditions ◽  
Over Time

This study assessed the dynamics of gap development in postharvest regeneration in five stands in northwestern Alberta dominated by trembling aspen (Populus tremuloides Michx.). The pattern of gap development over time was determined from analysis of air photographs taken preharvest and 1, 4, 10, and 12 years postharvest. The area of each stand covered by gaps increased after harvest because of the addition of harvest-related gaps over and above those that had been present prior to harvest. The blocks we studied had a combined gap area of up to 29% of stand area 12 years postharvest. We measured regeneration characteristics, microsite, soil, light, and browse conditions in 30 aspen regeneration gaps (gaps in regeneration that were not gaps preharvest and were not due to obvious harvest-related disturbance) 14 years following harvest. Although deciduous trees within postharvest regeneration gaps were the same age as those outside (i.e., in a fully stocked matrix of newly established even-aged aspen stems), they were often suppressed, with significantly lower density and growth. Within the 14-year-old postharvest regenerating aspen stands, aspen height varied from 1 to 11 m; this substantial variability appeared to be largely due to the influence of browsing. There was little evidence of ongoing regeneration within postharvest regeneration gaps, indicating that these gaps will probably persist over time. This may impact future deciduous stocking and volume. It is unknown what may have initiated the formation of these gaps, although results suggest that they are not due to edaphic conditions or disease in the preharvest stands. There is evidence that bluejoint (Calamagrostis canadensis (Michx.) Beauv.) cover and browsing are important factors in the maintenance of postharvest regeneration gaps. The spatial heterogeneity resulting from gaps could be advantageous, however, either as part of ecosystem-based management emulating natural disturbance or as a template for mixedwood management, where white spruce (Picea glauca (Moench) Voss) are established in gaps.

The effect of ectomycorrhizae on water relations in aspen (Populus tremuloides) and white spruce (Picea glauca) at low soil temperatures

2002 ◽  
Vol 80 (6) ◽  
pp. 684-689 ◽  
Author(s):  
Simon M Landhäusser ◽  
Tawfik M Muhsin ◽  
Janusz J Zwiazek
Keyword(s):  
Stomatal Conductance ◽  
Soil Temperature ◽  
Water Uptake ◽  
Water Relations ◽  
Populus Tremuloides ◽  
Picea Glauca ◽  
White Spruce ◽  
Hydraulic Conductance ◽  
Root Hydraulic Conductance ◽  
Soil Temperatures

Low soil temperatures, common during the growing season in northern forests, have the potential to impede plant growth. In this study, water uptake, water relations, and growth characteristics were examined in aspen (Populus tremuloides) and white spruce (Picea glauca) seedlings that were inoculated with ectomycorrhizal fungi and grown at 20°C daytime air temperatures and low soil temperatures of 4°C and 8°C. Mycorrhizal associations had little effect on root and shoot biomass at both soil temperatures. Root hydraulic conductance (Kr) was higher in both mycorrhizal plant species compared to nonmycorrhizal plants, but there was no soil temperature effect on Kr in either species. Mycorrhizae also increased shoot water potential (Ψw) in Populus tremuloides but had no effect on Ψw in Picea glauca. The increases in Kr and Ψw were not reflected by changes in stomatal conductance (gs) and transpiration rates (E), suggesting that the reduction of water flow in seedlings exposed to low soil temperature was not likely the factor limiting gs in both plant species.Key words: boreal forest, root hydraulic conductance, root growth, stomatal conductance, water uptake.

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