Grazing Effects on Snow Accumulation on Rough Fescue Grasslands

Krzic, M., Lamagna, S. F., Newman, R. F., Bradfield, G. and Wallace, B. M. 2014. Long-term grazing effects on rough fescue grassland soils in southern British Columbia. Can. J. Soil Sci. 94: 337–345. Rough fescue (Festuca campestris Rydb.) is a highly palatable forage species with little resistance to continuous grazing. The objective of this study was to evaluate the effects of long-term cattle grazing on soil properties, above-ground biomass, and canopy cover of key grass species on rough fescue grasslands in the southern interior British Columbia. Soil and vegetation properties were determined on a total of six open grassland sites located at the Lac du Bois and Hamilton Mountain. At all sites, grazing use has decreased over time, with the heaviest grazing occurring prior to 1960. The long-term (25–75 yr) elimination of grazing on these semi-arid grasslands has led to greater above-ground biomass and canopy cover of rough fescue, as well as increased soil polysaccharides; however, no differences in total soil C, N, and aggregate stability were found between pastures with and without grazing. Both soil bulk density and mechanical resistance were greater on grazed plots compared with those without grazing, with differences being more pronounced at the Hamilton Mountain location. The current grazing regime has not allowed for the elimination of negative effects of overgrazing on soil compaction on these rough fescue grasslands, especially at the location that continued to be grazed more heavily (i.e., Hamilton Mountain). Our findings suggest that soils in these grazing-sensitive grasslands need more than 75 yr to fully recover from the impacts of overgrazing.

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Seasonal variations in the properties and structural composition of sea ice and snow cover in the Bellingshausen and Amundsen Seas, Antarctica

Journal of Glaciology ◽

10.3189/s0022143000002902 ◽

1997 ◽

Vol 43 (143) ◽

pp. 138-151 ◽

Cited By ~ 2

Author(s):

M. O. Jeffries ◽

K. Morris ◽

W.F. Weeks ◽

A. P. Worby

Keyword(s):

Sea Ice ◽

Isotopic Composition ◽

Snow Cover ◽

Sea Water ◽

Ice Cores ◽

Ice Cover ◽

Snow Accumulation ◽

Ice Formation ◽

Frazil Ice ◽

Core Sets

AbstractSixty-three ice cores were collected in the Bellingshausen and Amundsen Seas in August and September 1993 during a cruise of the R.V. Nathaniel B. Palmer. The structure and stable-isotopic composition (18O/16O) of the cores were investigated in order to understand the growth conditions and to identify the key growth processes, particularly the contribution of snow to sea-ice formation. The structure and isotopic composition of a set of 12 cores that was collected for the same purpose in the Bellingshausen Sea in March 1992 are reassessed. Frazil ice and congelation ice contribute 44% and 26%, respectively, to the composition of both the winter and summer ice-core sets, evidence that the relatively calm conditions that favour congelation-ice formation are neither as common nor as prolonged as the more turbulent conditions that favour frazil-ice growth and pancake-ice formation. Both frazil- and congelation-ice layers have an av erage thickness of 0.12 m in winter, evidence that congelation ice and pancake ice thicken primarily by dynamic processes. The thermodynamic development of the ice cover relies heavily on the formation of snow ice at the surface of floes after sea water has flooded the snow cover. Snow-ice layers have a mean thickness of 0.20 and 0.28 m in the winter and summer cores, respectively, and the contribution of snow ice to the winter (24%) and summer (16%) core sets exceeds most quantities that have been reported previously in other Antarctic pack-ice zones. The thickness and quantity of snow ice may be due to a combination of high snow-accumulation rates and snow loads, environmental conditions that favour a warm ice cover in which brine convection between the bottom and top of the ice introduces sea water to the snow/ice interface, and bottom melting losses being compensated by snow-ice formation. Layers of superimposed ice at the top of each of the summer cores make up 4.6% of the ice that was examined and they increase by a factor of 3 the quantity of snow entrained in the ice. The accumulation of superimposed ice is evidence that melting in the snow cover on Antarctic sea-ice floes ran reach an advanced stage and contribute a significant amount of snow to the total ice mass.

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Abrupt decrease in recent snow accumulation at Mount Qomolangma (Everest), Himalaya

Journal of Glaciology ◽

10.3189/s0022143000001465 ◽

1999 ◽

Vol 45 (151) ◽

pp. 585-586

Author(s):

Hou Shugui ◽

Qin Dahe ◽

Cameron P. Wake ◽

Paul A. Mayewski

Keyword(s):

Snow Accumulation ◽

Abrupt Decrease

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Can the mass balance of the entire glacier area of the Tien Shan be estimated?

Annals of Glaciology ◽

10.3189/1992aog16-1-173-179 ◽

1992 ◽

Vol 16 ◽

pp. 173-179

Author(s):

M.B. Dyurgerov ◽

M.G. Kunakhovitch ◽

V.N. Mikhalenko ◽

A. M. Sokalskaya ◽

V. A. Kuzmichenok

Keyword(s):

Mass Balance ◽

Vertical Profile ◽

River Basins ◽

Annual Runoff ◽

Snow Accumulation ◽

Tien Shan ◽

Exponential Dependence ◽

Glacier Area ◽

Equilibrium Line Altitude ◽

Boundary Area

The total area of glacierization of the Tien Shan in the boundary area of the USSR is about 8000 km2. The computation of mass balance was determined for this area in 12 river basins.In computation procedure, the vertical profile of snow accumulation in these regions and exponential dependence of variation of ablation with altitude are used. Thus the mass balance in each basin, bn, was calculated on the basis of these curves and represented in its relation with the equilibrium line altitude (ELA). It is shown that the relation ELA = f(bn) is linear when the range of bn values is close to zero, and in all altitude intervals this relation can be described by hypsographic curves, in all basins bn positive up to an ELA elevation of 3450 to 3500 m a.s.l. For average annual altitude of ELA, bn is negative for all regions. So the glaciers of these mountains add about 4 km3 of water to the total annual runoff.

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Modeling the Water and Energy Balance of Vegetated Areas with Snow Accumulation

Vadose Zone Journal ◽

10.2136/vzj2008.0183 ◽

2009 ◽

Vol 8 (4) ◽

pp. 1013-1030 ◽

Cited By ~ 20

Author(s):

T. J. Kelleners ◽

D. G. Chandler ◽

J. P. McNamara ◽

M. M. Gribb ◽

M. S. Seyfried

Keyword(s):

Energy Balance ◽

Snow Accumulation

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Disturbance, species loss and compensation: Wildfire and grazing effects on the avian community and its food supply in the Serengeti Ecosystem, Tanzania

Austral Ecology ◽

10.1111/j.1442-9993.2010.02167.x ◽

2010 ◽

Vol 36 (4) ◽

pp. 403-412 ◽

Cited By ~ 16

Author(s):

A. K. NKWABI ◽

A. R E. SINCLAIR ◽

K. L. METZGER ◽

S. A. R. MDUMA

Keyword(s):

Food Supply ◽

Species Loss ◽

Avian Community ◽

Serengeti Ecosystem ◽

Grazing Effects

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Flowering Phenology Adjustment and Flower Longevity in a South American Alpine Species

Plants ◽

10.3390/plants10030461 ◽

2021 ◽

Vol 10 (3) ◽

pp. 461

Author(s):

Mary T. K. Arroyo ◽

Ítalo Tamburrino ◽

Patricio Pliscoff ◽

Valeria Robles ◽

Maria Colldecarrera ◽

...

Keyword(s):

Natural Populations ◽

Flowering Phenology ◽

Snow Accumulation ◽

Growth Potential ◽

Controlled Study ◽

Temperature Threshold ◽

Flower Longevity ◽

Passive Warming ◽

Alpine Species ◽

Flowering Onset

Delayed flowering due to later snowmelt and colder temperatures at higher elevations in the alpine are expected to lead to flowering phenological adjustment to prevent decoupling of peak flowering from the warmest time of the year, thereby favoring pollination. However, even if flowering is brought forward in the season at higher elevations, an elevational temperature gap is likely to remain between the high- and low-elevation populations of a species at the time these reach peak flowering on account of the atmospheric reduction in temperature with increasing elevation. The negative effect of this temperature gap on pollination could be compensated by plastically-prolonged flower life spans at higher elevations, increasing the probability of pollination. In a tightly temperature-controlled study, the flowering phenology adjustment and flower longevity compensation hypotheses were investigated in an alpine species in the Andes of central Chile. The snow free period varied from 7 to 8.2 months over 810 m elevation. Temperatures were suitable for growth on 82–98% of the snow free days. Flowering onset was temporally displaced at the rate of 4.6 d per 100 m increase in elevation and flowering was more synchronous at higher elevations. Flowering phenology was adjusted over elevation. The latter was manifest in thermal sums tending to decrease with elevation for population flowering onset, 50% flowering, and peak flowering when the lower thermal limit for growth (TBASE) was held constant over elevation. For TBASE graded over elevation so as to reflect the growing season temperature decline, thermal sums did not vary with elevation, opening the door to a possible elevational decline in the thermal temperature threshold for growth. Potential flower longevity was reduced by passive warming and was more prolonged in natural populations when temperatures were lower, indicating a plastic trait. Pollination rates, as evaluated with the Relative Pollination Rate index (RPR), when weighted for differences in floral abundance over the flowering season, declined with elevation as did fruit set. Contrary to expectation, the life-spans of flowers at higher elevations were not more prolonged and failed to compensate for the elevational decrease in pollination rates. Although strong evidence for phenological adjustment was forthcoming, flower longevity compensation did not occur over Oxalis squamata’s elevational range. Thus, flower longevity compensation is not applicable in all alpine species. Comparison with work conducted several decades ago on the same species in the same area provides valuable clues regarding the effects of climate change on flowering phenology and fitness in the central Chilean alpine where temperatures have been increasing and winter snow accumulation has been declining.

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