Natural plant recolonization of surficial disturbances, Tuktoyaktuk Peninsula Region, Northwest Territories

1973 ◽  
Vol 51 (11) ◽  
pp. 2177-2196 ◽  
Author(s):  
Helios Hernandez
Keyword(s):  
Plant Cover ◽  
Mineral Soil ◽  
Energy Budgets ◽  
Mackenzie Delta ◽  
Calamagrostis Canadensis ◽  
Disturbed Areas ◽  
Sedge Meadows ◽  
Tall Shrub ◽  
Seismic Lines ◽  
Plant Recolonization

Seismic lines or winter roads were sampled where they passed through three different plant communities in the Mackenzie Delta and through four of the major tundra communities in the Tuktoyaktuk Peninsula. Winter seismic lines have been less detrimental than summer lines for all communities examined. Although winter roads through upland areas remove most of the vegetation cover, the peat layer usually remains intact and soil energy budgets are relatively little affected. Wetland sedge meadows are highly susceptible to summer disturbance but least affected by winter operations. Winter-disturbed forested and tall shrub communities recover faster initially than similarly disturbed upland tundra communities.Eriophorum vaginatum and Carex bigelowii appeared to be stimulated by disturbances which did not eliminate them, with Eriophorum often flowering more abundantly in disturbed areas. This probably results from warmer soils and greater nutrient uptake.Summer seismic lines (1965), originally bladed to permafrost, resulted in exposure of mineral soil and thus led to secondary succession in tundra communities. Arctagrostis latifolia, Calamagrostis canadensis, Poa arctica, and Luzula confusa are the most typical and abundant pioneers of upland mesic sites. Wet sites are colonized predominantly by Arctophila fulva and Carex aquatilis. Once established, these species expanded rhizomatously. Six years after exposure of mineral soil, plant cover was usually 30 to 50%.Thaw was generally increased 80 to 100% where mineral soil was exposed, 30 to 50% if the peat remained intact, and 10% if plant cover was little altered. Subsurface ice has occasionally been exposed, resulting in thermokarst subsidence. Water erosion has not been a factor, probably because of the low precipitation in the region.

Vesicular – arbuscular mycorrhizae in disturbed and revegetated sites from La Gran Sabana, Venezuela

1992 ◽  
Vol 70 (1) ◽  
pp. 73-79 ◽  
Author(s):  
Gisela Cuenca ◽  
Milagros Lovera
Keyword(s):  
Arbuscular Mycorrhizae ◽  
Plant Cover ◽  
Ground Cover ◽  
Arbuscular Mycorrhizal ◽  
Most Probable Number ◽  
Probable Number ◽  
Organic Layers ◽  
Vesicular Arbuscular Mycorrhizae ◽  
Disturbed Areas ◽  
Vesicular Arbuscular

Savannas growing on stony, old and nutrient-poor soils of southern Venezuela were severely disturbed by removal of the soil organic layers with bulldozers for road building. Introduced species Brachiaria decumbens, Brachiaria humidicola, Pueraria phaseoloides, and Calopogonium sp. were sown. The substrate was fertilized and limed. Plant cover, vesicular – arbuscular mycorrhizae colonization, spore number, and most probable number of propagulels in undisturbed savanna, disturbed nonrevegetated savanna, and six revegetated savannas were assessed. The perturbation reduced the mycorrhizal propagule number in comparison with the undisturbed savanna. In the nonrevegetated areas the mean percent ground cover 2 years after disturbance was low (0.04%). In revegetated areas an increase in mycorrhizal propagule number occurred and the mycorrhizal colonization of the sown species was high. In restored areas there was an increase in species of nonmycotrophic Amaranthaceae. The results support other predictions on the mycorrhizae in successional biomes, because in the extremely nutrient-poor soils studied the colonizing species were mainly mycotrophic. The reclamation program applied in disturbed areas was useful because it has allowed the recovery of vesicular – arbuscular mycorrhizal inoculum and there was an increase in the recolonization of native plants. Key words: disturbance, endomycorrhizae, revegetation, savanna, vesicular – arbuscular mycorrhizae.

Do changes in soil properties after rooting by wild boars (Sus scrofa) affect understory vegetation in Swiss hardwood forests?

2012 ◽  
Vol 42 (3) ◽  
pp. 585-592 ◽  
Author(s):  
Sven Wirthner ◽  
Martin Schütz ◽  
Deborah S. Page-Dumroese ◽  
Matt D. Busse ◽  
James W. Kirchner ◽  
...  
Keyword(s):  
Sus Scrofa ◽  
Forest Ecosystems ◽  
Plant Cover ◽  
Mineral Soil ◽  
Hardwood Forests ◽  
Microbial Biomass C ◽  
Wild Boars ◽  
Total Plant ◽  
C And N ◽  
Wild Boar Rooting

Recovering from small fragmented populations, wild boars ( Sus scrofa L.) have considerably increased their numbers and their habitat range in many European countries during the past two decades. Although several studies have focused on the impact of wild boar rooting on selected vegetation properties, little is known about effects on entire forest ecosystems. The main goal of our study was to assess how rooting by boars alters soil and vegetation properties. We measured soil chemical and biological properties (C and N concentrations, N availability, and microbial biomass C) as well as several vegetation characteristics (total plant cover, plant species diversity, and number and height of saplings) on paired rooted and non-rooted plots in six hardwood forests in Switzerland. We found that rooting by wild boars led to significant increases in mineral soil C and N concentrations and microbial biomass C, which could lead to improved growth conditions for plants. However, total plant cover and sapling counts were reduced on rooted plots, possibly due to mechanical disturbance or due to reduced plant available N (measured as supply rate in contrast with the observed increase in total stocks of mineral soil N). In view of these results, simple characterizations of wild boar rooting as beneficial or detrimental to forest ecosystems should be handled with care.

Arctic plant communities east of the Mackenzie Delta

1974 ◽  
Vol 52 (7) ◽  
pp. 1731-1745 ◽  
Author(s):  
Ian G. W. Corns
Keyword(s):  
Plant Communities ◽  
Aerial Photography ◽  
Community Type ◽  
Two Dimensional ◽  
Areal Extent ◽  
Mackenzie Delta ◽  
Floristic Similarity ◽  
Tundra Vegetation ◽  
Community Types ◽  
Tall Shrub

Tundra vegetation was analyzed on the basis of 64 sampled and 12 described stands representing a wide variety of plant community types immediately east of the Mackenzie Delta, Northwest Territories. Five main types (Tall Shrub – Herb, Medium Shrub (alder), Low Shrub – Heath, Herb – Low Shrub – Heath, and Herb) and 11 subgroups were distinguished and classified on the basis of floristic similarity using a two-dimensional ordination and by physiognomy. A total of 70 species were sampled or observed in the stands. Floristically, the Sedge–Cottongrass–Heath type was the most diverse and the Wet-Sedge Polygon – Herb type, the least diverse. The areal extent of each major community type was determined using aerial photography for Richards Island, Caribou Hills, Eskimo Lakes, Tuktoyaktuk, and Atkinson Point study areas.

Persistent impact of conventional seismic lines on boreal vegetation structure following wildfire

2021 ◽  
Author(s):  
Quinn E. Barber ◽  
Christopher W. Bater ◽  
Anna Dabros ◽  
Jaime Pinzon ◽  
Scott E. Nielsen ◽  
...  
Keyword(s):  
Laser Scanning ◽  
Vascular Plant ◽  
Plant Cover ◽  
Airborne Laser Scanning ◽  
Forest Recovery ◽  
Tree Cover ◽  
Vegetation Height ◽  
Airborne Laser ◽  
Tall Tree ◽  
Seismic Lines

Linear disturbances from geological exploration (i.e., seismic lines) have an extensive footprint across much of Canada’s western boreal forest; however, how seismic lines interact with subsequent wildfire remains poorly understood. We assessed whether wildfires effectively mitigate the footprint of seismic lines by promoting forest recovery. We evaluated the forest structure of legacy seismic lines burned in 2001 and 2002 by comparing them against adjacent unburned control plots, using metrics derived from airborne laser scanning (ALS) data collected between 2007 and 2009. Airborne laser scanning metrics identified persistent differences in vegetation height and structure between seismic lines and adjacent forest controls, seven to nine years post-fire. Median canopy height was 2.90 m lower on upland seismic lines and 1.94 m lower on lowland seismic lines than on adjacent controls, corresponding to a 21% and 25% height reduction, respectively. Field surveys revealed greater graminoid and non-vascular plant cover, and lower tall-tree cover and dead vegetative matter, on seismic lines, in comparison with controls. Our results show that tree recovery remains significantly delayed on most upland and lowland burned seismic lines in our study area, and that additional management efforts or longer timescales may be required to restore these fragmented landscapes.

Rhizome growth of Calamagrostis canadensis in response to soil nutrients and bulk density

1996 ◽  
Vol 76 (3) ◽  
pp. 545-550 ◽  
Author(s):  
S. M. Landhäusser ◽  
K. J. Stadt ◽  
V. J. Lieffers ◽  
D. H. McNabb
Keyword(s):  
Bulk Density ◽  
Nutrient Availability ◽  
Mineral Soil ◽  
Soil Bulk Density ◽  
Tree Seedlings ◽  
Calamagrostis Canadensis ◽  
Rhizome Growth ◽  
Mineral Soils ◽  
Rhizome Biomass ◽  
Split Container

In a series of experiments, we investigated rhizome spread and the growth of C. canadensis, as governed by changes in soil bulk density and nutrient availability. The ability of rhizomes originating from vigorous Calamagrostis canadensis plants to penetrate mineral soil with different bulk densities and their response to various nutrient conditions were assessed in a split container experiment. Decreasing biomass and length of rhizomes with increasing soil bulk density showed that clonal expansion of C. canadensis onto areas of exposed mineral soil from adjacent swards was limited mainly by soil bulk density. No nutrient effect on rhizome growth was detectable; the rhizomes were probably well supplied with nutrients by translocation from the mother plant. Results of a second split container experiment indicated that rhizome growth was better in organic than in mineral soils. In a third experiment, entire C. canadensis plants were grown in mineral soil at different levels of soil bulk density and nutrient condition. Here, rhizome biomass and expansion were limited mainly by nutrient availability; however, once the nutritional needs of the plants were met, increasing bulk density reduced the amount of rhizome spread. These results could be useful in reforestation, e.g. selecting those methods of site preparation which reduce the growth and competitive ability of C. canadensis relative to tree seedlings. Key words: Compaction, rhizome, litter, mineral soil, yield, Calamagrostis canadensis

Wind dispersed seeds and plant recovery on the Mount St. Helens debris avalanche

1989 ◽  
Vol 67 (5) ◽  
pp. 1434-1441 ◽  
Author(s):  
Virginia H. Dale
Keyword(s):  
Plant Density ◽  
Plant Cover ◽  
Debris Avalanche ◽  
Long Distance ◽  
Spider Webs ◽  
Climate Conditions ◽  
Disturbed Areas ◽  
Successional Species ◽  
Average Plant ◽  
Mount St Helens

Seed dispersal and plant establishment were monitored for 4 years on the debris avalanche created by the 1980 eruption of Mount St. Helens. The number of plants on the deposit increased over time to a high of almost 2 plants/m2 by 1983. The number of species per 250-m2 plot has increased to a mean of 10.3 in 1983 with 76 species being present over the entire deposit. Four years after the eruption only 30% of the species present before the eruption had reestablished themselves, and average plant cover was less than 1%. The debris avalanche has been invaded primarily via wind-dispersed seed of early successional species that survived or have become established in adjacent disturbed areas. Most of the early successional species on the avalanche have plumed seeds that are adapted not only for long distance dispersal, but also for being trapped in wet areas or by spider webs. Fluctuations in the density of seeds dispersed to the deposit were related to variation in precipitation. Neither seed abundance nor plant density correlated with absolute distance to a seed source or soil texture conditions. Colonization patterns are more influenced by the available biota and prevailing climate conditions than by substrate alterations resulting from the eruption.

Fuel characteristics of arctic plant species and simulated plant community flammability by Rothermel's model

1981 ◽  
Vol 59 (5) ◽  
pp. 898-907 ◽  
Author(s):  
T. W. Sylvester ◽  
Ross W. Wein
Keyword(s):  
Fire Behavior ◽  
Volume Ratio ◽  
Woody Species ◽  
Caloric Content ◽  
Mackenzie Delta ◽  
Vaccinium Uliginosum ◽  
Forest Tundra ◽  
Calamagrostis Canadensis ◽  
Epilobium Angustifolium ◽  
Fuel Characteristics

The relative fuel-potentials of 12 northern tundra and forest–tundra ground species of the Mackenzie delta area were evaluated from measured fuel characteristics by simulating a test fire with the Rothermel (1972) fire behavior model. The relative importance of the fuel parameters were in decreasing order: moisture content, biomass, fineness (surface/volume ratio), packing ratio, silica-free ash content, and caloric content. The fuel-potential ratings of the vascular species and of the communities were differentiated primarily by their leaf characteristics. Dead leaves of Calamagrostis canadensis and Eriophorum vaginatum constituted the most flammable fuels measured. Evergreen Ledum palustre and Empetrum nigrum were clearly differentiated from the live vascular species by higher flammability ratings. Of the cryptogam fuels, Cladonia-type lichens were rated intermediate between the above evergreen ericoids and the deciduous woody species (Betula glandulosa, Vaccinium uliginosum, Salix glauca), while Sphagnum sp. was rated comparable to the latter groups. Epilobium angustifolium received the lowest ratings of all species.Subject to the limitations with respect to ether-extractive contents, the relative fuel potential of tundra and forest–tundra plant communities can be rated on measured fuel characteristics, community composition, and the criteria of the Rothermel model. Possible applications of this study were raised, particularly the use of relatively nonflammable plants in land management.

Soil chemical changes and plant succession following experimental burning in immature jack pine

1998 ◽  
Vol 78 (1) ◽  
pp. 93-104 ◽  
Author(s):  
T. J. Lynham ◽  
G. M. Wickware ◽  
J. A. Mason
Keyword(s):  
Pinus Banksiana ◽  
Plant Cover ◽  
Mineral Soil ◽  
Weather Conditions ◽  
Organic Soil ◽  
Jack Pine ◽  
Plant Succession ◽  
Chemical Changes ◽  
Soil Layers ◽  
Rate Of Increase

In 1975 and 1976, an experimental burning program was conducted in an immature stand of boreal jack pine (Pinus banksiana Lamb.) growing on level, granitic outwash sands in northern Ontario. Nine 0.4-ha plots were burned under a range of fire weather conditions and sampling was conducted to examine the effect of fire on soil chemical changes and revegetation. Results indicated that depth of burn (DOB) affected both soil chemical changes and plant succession on these pine sites. Vaccinium angustifolium Ait., Oryzopsis spp,. Waldsteinia fragarioides (Michx.) Tratt, Salix spp. and Viola adunca Sm. increased in cover at two levels of DOB but the increase was greatest at the lower DOB and decreased to pre-burn levels after 10 yr. Comptonia peregrina (L.) Coult., Epilobium angustifolium L., Polytrichum commune Hedw. and Amelanchier sanguinea (Pursh) DC. were not found in the pre-burn surveys but appeared after burning. Vegetation cover for these species was always higher at the deeper DOB but decreased almost to zero after 10 yr. Other species such as Pleurozium schreberi (Brid.) Mitt., Linnaea borealis L., Corylus cornuta Marsh., Cladina rangiferina (L.) Nyl. and Aralia nudicaulis L. were eliminated from the site and did not recover even after 10 yr. Soil pH increased 0.3 to 1.0 pH units in the organic and mineral soil layers. The rate of increase in pH was always steeper at the higher DOB and pH returned to pre-burn levels in the mineral soil layers after 10 yr. Immediately after burning, exchangeable Ca in the mineral soil layers doubled but 10 yr later, Ca returned to pre-burn levels. Phosphorus and K increased in the mineral soil, leveled off and were still elevated after 10 yr. Total Kjeldahl N was reduced by 50% in the organic soil while N in all mineral soils increased, and was still increasing after 10 yr. Except for immediate post-fire increases in pH, Ca and N, soil chemical changes were small or they rebounded to pre-burn levels 10 yr after burning. Therefore it is unlikely that these changes were the cause of the plant cover changes that persisted to 10 yr. Key words: Soil nutrients, plant succession, fire, depth of burn, jack pine

Reindeer grazing reduces seed and propagule bank in the High Arctic

2006 ◽  
Vol 84 (11) ◽  
pp. 1740-1752 ◽  
Author(s):  
Elisabeth J. Cooper
Keyword(s):  
Seed Bank ◽  
Rangifer Tarandus ◽  
Plant Cover ◽  
High Arctic ◽  
Propagule Bank ◽  
Disturbed Areas ◽  
Propagule Banks ◽  
Colonization Potential ◽  
Grazing History ◽  
Plant Allocation

It is commonly assumed that plant establishment in the High Arctic is limited by severe abiotic conditions and by a paucity of propagules and seeds. Heavy reindeer grazing may reduce plant allocation to reproduction and removes significant proportions of flowers and seeds, thus reducing contributions to seed rain and seed bank. In contrast, foraging and trampling may break up existing mature plants, increasing the vegetative propagules in the soil. To determine the effect of grazing on colonization potential in the High Arctic, two studies were carried out: (i) a comparison of seed bank inside and outside three long-term reindeer ( Rangifer tarandus platyrhnchus (Vrolic)) exclosures and (ii) an investigation of the germinable seed and propagule bank of two neighbouring peninsulas with contrasting reindeer grazing history in northwestern Svalbard (79°N, 12°E). Seed banks inside reindeer exclosures germinated significantly more seedlings (596 seedlings·m–2) than those outside (263 seedlings·m–2). Species composition and total plant cover was similar on both peninsulas, but forage-plant cover was lower on the heavily grazed peninsula (Brøggerhalvøya) than on the adjacent lightly grazed peninsula (Sarsøyra). Brøggerhalvøya had significantly lower species richness and density of seed and propagule bank (0.21 ± 0.02 germinating species per sample, 0.15 ± 0.02 propagule species per sample, 416 ± 103 seedlings·m–2, 283 ± 78 propagules·m–2) than did Sarsøyra (0.44 ± 0.40 germinating species per sample, 0.35 ± 0.03 propagule species per sample,1016 ± 188 seedlings·m–2, 782 ± 238 propagules·m–2). These results imply that reindeer depleted both the seed and the propagule banks, thus reducing the potential for colonization of disturbed areas. Grazing may, therefore, have a lasting impact on High Arctic plant communities.

Sign in / Sign up

Export Citation Format

Share Document