Black spruce regeneration at the treeline ecotone: synergistic impacts of climate change and caribou activityThis article is a contribution to the series Tree recruitment, growth, and distribution at the circumpolar forest–tundra transition.

2011 ◽  
Vol 41 (3) ◽  
pp. 460-468 ◽  
Author(s):  
Geneviève Dufour Tremblay ◽  
Stéphane Boudreau
Keyword(s):  
Climate Warming ◽  
Seedling Establishment ◽  
Black Spruce ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Seed Viability ◽  
Climatic Conditions ◽  
Tree Regeneration ◽  
Lichen Cover ◽  
Recent Climate

Tree regeneration at treeline is often inhibited by harsh climatic conditions and ecological constraints such as the presence of a continuous lichen cover. The objective of this study was to verify if recent climate warming and increased caribou (Rangifer tarandus L.) activity, which destroys the lichen cover, could act synergistically to increase black spruce (Picea mariana (Mill.) B.S.P.) regeneration. We collected cones produced in 2006–2007 to compare seed viability with data from 1989 to 1995. We conducted experimental plantations (field and controlled conditions) to determine if germination and seedling emergence were higher in disturbed environments where mineral soil was exposed. We sampled naturally established seedlings to evaluate the relationship between the year of establishment and caribou activity and to compare growth in disturbed and undisturbed environments. We found that seed viability was significantly higher in 2006–2007 compared with 1989–1995. The number of germinated seeds per cone increased by a factor >1000. Germination and seedling establishment were higher in the disturbed environment (mineral soil). Finally, although seedling establishment in areas with continuous lichen cover was rather constant over the last 50 years, 73.5% of the seedlings recorded on bare mineral soil became established in the years following high caribou activity. Our results suggest that climate warming and caribou activity are likely to act synergistically to promote black spruce regeneration at treeline.

Direct seeding of black spruce in northwestern Ontario: Seedbed relationships

1994 ◽  
Vol 70 (2) ◽  
pp. 151-158 ◽  
Author(s):  
R. L. Fleming ◽  
D. S. Mossa
Keyword(s):  
Seedling Establishment ◽  
Black Spruce ◽  
Mineral Soil ◽  
Soil Surface ◽  
Direct Seeding ◽  
First Year ◽  
Strongly Correlated ◽  
Seedling Mortality ◽  
Northwestern Ontario ◽  
Seedbed Preparation

A series of spot seeding experiments was set out on coarse-textured upland sites in northwestern Ontario to investigate how black spruce (Picea mariana [Mill.] B.S.P.) seedling establishment and growth could be improved by site selection and seedbed preparation. Virtually all germination occurred within the first growing season. Annual seedling mortality rates were greatest during the first year, then declined steadily and stabilized at low levels (<10%) after the third year. The highest fifth-year establishment ratios (seedlings/viable seed sown) were found on seedbeds derived from materials near the mineral soil/humus interface. On wetter sites (i.e., higher Soil Moisture Regimes) the best seedbeds occurred closer to the soil surface. Mean fifth year establishment ratios for the best seedbeds were 0.032 on moderately fresh to fresh sites, 0.146 on very fresh to moderately moist sites, and 0.082 on moist to very moist sites. On adjacent lowland sites, slow-growing, compact Sphagnum mosses had a mean establishment ratio of 0.179. Mean fifth-year seedling heights on upland sites ranged from 12 to 14 cm, and were not strongly correlated with site or seedbed type. Key words: direct seeding, black spruce, seedbed, seedling establishment, site type and germination

Seed dispersal and seedling establishment of Linaria vulgaris Mill.

1991 ◽  
Vol 71 (3) ◽  
pp. 771-782 ◽  
Author(s):  
Léonie B. Nadeau ◽  
Jane R. King
Keyword(s):  
Seed Dispersal ◽  
Seedling Establishment ◽  
Seedling Emergence ◽  
Seed Viability ◽  
Parent Plant ◽  
Linaria Vulgaris ◽  
Root Piece ◽  
Seedling Distribution ◽  
Seed Deposition ◽  
Major Factors

The importance of seeds to the establishment and spread of Linaria vulgaris infestations in Alberta was assessed in 1988 and 1989. Stands were established on 17 May 1988. One 10-cm-long root piece with a 10-cm-tall shoot was planted in the centre of each of nine plots on fallow land and of nine plots in a barley crop. Over 90% of seeds in 1988, and over 80% in 1989 fell within a 0.5-m radius of the parent plants with very few seeds falling outside a 1.5-m radius. Seed deposition vs. distance followed a negative polynomial function. It was estimated that over 210 000 seeds m−2 fell less than 0.5 m away from the parent plant over the 1988 growing season. The presence of Gymnaetron sp. and Brachypterolus sp. in 1989 reduced seed deposition to a total of 1410 seeds m−2 within 0.5 m of the parent plant. The few seedlings that were established occurred in clumps, with densities varying from 1.3 to 7.0 seedlings cm−2 in May and from 0.8 to 7.8 seedlings cm−2 in June 1989. In 1988, total seedling emergence per plot varied between 0.13 and 0.23%. Seed viability and dormancy were major factors influencing seedling establishment. Seed viability was as low as 40% (tetrazolium test), and germination was maximized in the laboratory following a wet stratification at 5 °C for a period of at least 8 wk. Key words: Toadflax, Linaria vulgaris, seed dispersal, seedling establishment, seedling distribution

Characterisation of production of organic rich topsoil from sludge

2000 ◽  
Vol 42 (9) ◽  
pp. 195-201 ◽  
Author(s):  
P. Andreasen ◽  
P. B. Mortensen ◽  
A. Stubsgaard ◽  
B. Langdahl
Keyword(s):  
Organic Matter ◽  
Oxygen Consumption ◽  
Oxygen Transport ◽  
Mineral Soil ◽  
Climatic Conditions ◽  
Growth Media ◽  
Soil Mixture ◽  
Water Suspension ◽  
Aerobic Process ◽  
Stable Product

The stabilisation of a sludge-mineral soil mixture and a method to evaluate the state of stabilisation were investigated. The organic matter and nitrogen content are reduced up to 50% during a stabilisation process of three months under Danish climatic conditions. The stabilisation was shown to be an aerobic process limited by oxygen transport within the mixture. The degree of stabilisation was evaluated by oxygen consumption in a water suspension and the results showed that a stable product was achieved when oxygen consumption was stable and in the level of natural occurring aerobic soils (0.1 mgO2/(g DS*hr). The study thereby demonstrates that a stability of a growth media can be controlled by the oxygen consumption method tested.

Evidence of temperature control of production and nutrient cycling in two interior Alaska black spruce ecosystems

1981 ◽  
Vol 11 (2) ◽  
pp. 259-274 ◽  
Author(s):  
Keith Van Cleve ◽  
Richard Barney ◽  
Robert Schlentner
Keyword(s):  
Black Spruce ◽  
Mineral Soil ◽  
Soil Nutrient ◽  
North Slope ◽  
Nutrient Pools ◽  
Soil Biological Activity ◽  
Nutrient Mineralization ◽  
Interior Alaska ◽  
Soil Temperatures ◽  
And Function

Selected indices of structure and function were used to evaluate the effect of differing soil thermal regimes on soil-permafrost-dominated (muskeg) and permafrost-free (north-slope) black spruce ecosystems in interior Alaska. The poorly drained, permafrost site displayed cooler soil temperatures and higher soil moisture content than were encountered on the well-drained north slope. Mineral soil nutrient pools generally were largest on the permafrost site. However, low soil temperature acted as a negative feedback control, suppressing soil biological activity, nutrient mineralization, and tree primary production to lower levels on the soil-permafrost-dominated site as compared with the permafrost-free site. Forty percent larger accumulation of tree biomass and 80% greater annual tree productivity occurred on the warmer site.

Silvicultural treatments, microclimatic conditions and seedling response in Southern Interior clearcuts

1998 ◽  
Vol 78 (1) ◽  
pp. 115-126 ◽  
Author(s):  
R. L. Fleming ◽  
T. A. Black ◽  
R. S. Adams ◽  
R. J. Stathers
Keyword(s):  
Soil Moisture ◽  
Seedling Establishment ◽  
Initial Period ◽  
Mineral Soil ◽  
Soil Disturbance ◽  
Near Surface ◽  
Lower Elevation ◽  
Organic Horizons ◽  
Soil Temperatures ◽  
Microclimatic Conditions

Post-harvest levels of soil disturbance and vegetation regrowth strongly influence microclimate conditions, and this has important implications for seedling establishment. We examined the effects of blading (scalping), soil loosening (ripping) and vegetation control (herbicide), as well as no soil disturbance, on growing season microclimates and 3-yr seedling response on two grass-dominated clearcuts at different elevations in the Southern Interior of British Columbia. Warmer soil temperatures were obtained by removing surface organic horizons. Ripping produced somewhat higher soil temperatures than scalping at the drier, lower-elevation site, but slightly reduced soil temperatures at the wetter, higher-elevation site. Near-surface air temperatures were more extreme (higher daily maximums and lower daily minimums) over the control than over exposed mineral soil. Root zone soil moisture deficits largely reflected transpiration by competing vegetation; vegetation removal was effective in improving soil moisture availability at the lower elevation site, but unnecessary from this perspective at the higher elevation site. The exposed mineral surfaces self-mulched and conserved soil moisture after an initial period of high evaporation. Ripping and scalping resulted in somewhat lower near-surface available soil water storage capacities. Seedling establishment on both clearcuts was better following treatments which removed vegetation and surface organic horizons and thus enhanced microclimatic conditions, despite reducing nutrient supply. Such treatments may, however, compromise subsequent stand development through negative impacts on site nutrition. Temporal changes in the relative importance of different physical (microclimate) and chemical (soil nutrition) properties to soil processes and plant growth need to be considered when evaluating site productivity. Key words: Microclimate, soil temperature, air temperature, soil moisture, clearcut, seedling establishment

Recent climate warming and the Varas rock glacier activity, Cordillera Oriental, Central Andes of Argentina

GeoResJ ◽  
2017 ◽  
Vol 14 ◽  
pp. 67-79 ◽  
Author(s):  
Mateo A Martini ◽  
Jorge A Strelin ◽  
Eliseo Flores ◽  
Ricardo A Astini ◽  
Michael R Kaplan
Keyword(s):  
Climate Warming ◽  
Central Andes ◽  
Rock Glacier ◽  
Recent Climate

Position of cones within cone clusters determines seed survival in black spruce during wildfire

2019 ◽  
Vol 49 (2) ◽  
pp. 121-127 ◽  
Author(s):  
T.B. Splawinski ◽  
D.F. Greene ◽  
S.T. Michaletz ◽  
S. Gauthier ◽  
D. Houle ◽  
...  
Keyword(s):  
Black Spruce ◽  
Seed Viability ◽  
Heat Fluxes ◽  
Wake Flow ◽  
Windward Side ◽  
Fire Intensity ◽  
Burned Area ◽  
Individual Plant ◽  
Buoyant Plumes ◽  
Porous Bodies

It has recently become clear that the regeneration density of serotinous species within a burned area declines with local fire intensity. It is assumed that this occurs because variation in local fire intensity leads to variation in incident heat fluxes and, ultimately, seed necrosis. We argue here that this same relationship between incident heat flux and seed necrosis is important at the scale of individual plant crowns. Using Picea mariana (Mill.) B.S.P. (black spruce), we show that postfire seed viability increases with crown height, depth into the crown, and angle from wind direction (with the windward side enjoying greater viability). All three effects are what one would expect given the physics of buoyant plumes, interactions of moving fire lines with wake flow around cylinders, and heat transfer in porous bodies such as a tree crown. We conclude by discussing the broader consequences of cone cluster size and global change on regeneration in serotinous species.

Direct seeding of PinusSylvestris using microsite preparation and invigorated seed lots of different quality: 2-year results

1994 ◽  
Vol 24 (1) ◽  
pp. 77-86 ◽  
Author(s):  
Hans Winsa ◽  
Urban Bergsten
Keyword(s):  
Seed Quality ◽  
Seedling Survival ◽  
Seedling Emergence ◽  
Mineral Soil ◽  
Direct Seeding ◽  
Growing Seasons ◽  
Humus Layer ◽  
Negative Effect ◽  
Mean Germination Time ◽  
Better Than

Direct seeding of Pinussylvestris L. is a regeneration method, with potential for development considering scarification, microsite preparation, seed invigoration, and seed quality. Three seed lots of different quality concerning seed weight, germination percent, and mean germination time were used on two sites in northern Sweden. Microsite preparation, 2 cm deep pyramidal indentations, of the mineral soil improved seedling emergence on the two sites by 48 and 62%, respectively, compared with seeding without preparation other than removal of the humus layer. Microsite preparation in combination with invigorated seed, i.e., seed incubated at 30% moisture content for 7 days at 15 °C, resulted in seedling emergence of about 85% for the highest and about 50% for the lowest seed quality at both sites. Noninvigorated seed, seeded without microsite preparation, reached about 55% for the highest and 22% at one and 43% at the other for the lowest seed quality. Without microsite preparation there was no, or a negative, effect of seed invigoration on seedling emergence. Seedling survival after the first winter improved significantly with better seed quality. Survival averaged 92 and 72% at the two sites, with frost heaving causing most mortality. Seedlings from invigorated and redried seed survived better than seedlings from untreated seed. Seedlings from the best seed quality had higher values in seedling height, about 35%, shoot length, about 60%, and needle length, about 30%, after two growing seasons than seedlings from lower seed qualities. Invigoration and microsite preparation had no effect on measured growth characteristics.

scholarly journals Potential Role of Sequential Glufosinate and Foramsulfuron Applications for Management of Fescues (Festucaspp.) in Wild Blueberry

2017 ◽  
Vol 31 (1) ◽  
pp. 100-110 ◽  
Author(s):  
Scott N. White ◽  
Shanthanu Krishna Kumar
Keyword(s):  
Field Study ◽  
Seed Production ◽  
Potential Role ◽  
Seedling Recruitment ◽  
Seedling Emergence ◽  
Seed Viability ◽  
Early Spring ◽  
Seedling Mortality ◽  
Wild Blueberry

Sheep and hair fescue are perennial, tuft forming grasses that spread by seed and form dense sods in wild blueberry fields. These sods compete with the crop for resources and hinder harvest. Field and greenhouse studies were conducted in 2015 to evaluate 1) the effect of sequential glufosinate and foramsulfuron applications on suppression of fescues in the greenhouse and field, and 2) efficacy of glufosinate and foramsulfuron on fescue seedlings when applied at 2, 4, 6, and 8 wk after seedling emergence in the greenhouse. Glufosinate applications at 750 and 1,005 g ai ha−1followed by foramsulfuron application at 35 g ai ha−1reduced fescue leaf number and biomass relative to foramsulfuron application alone in the greenhouse. In the field study, fescue flowering tuft density, tuft inflorescence height, seed production, and seed viability were reduced by foramsulfuron alone, but there was a trend towards lower seed production and tuft height when fescues were treated with glufosinate at 1,005 g ha−1followed by foramsulfuron. Foramsulfuron caused low seedling mortality at all application timings evaluated, but glufosinate caused >90% mortality in seedlings when applied at 2, 4, 6, or 8 wk after seedling emergence. Our results suggest that sequential applications of these herbicides are less effective under field conditions relative to results obtained in the greenhouse, though burndown glufosinate applications may have a role in reducing fescue seedling recruitment. Additional research should be conducted to determine the effect of early spring and autumn glufosinate applications on fescue seedling recruitment and suppression of established fescue tufts with subsequent foramsulfuron applications.

Sign in / Sign up

Export Citation Format

Share Document