Effect of population, environment, and maturation on the frost hardiness of yellow-cedar (Chamaecyparisnootkatensis)

1994 ◽  
Vol 24 (5) ◽  
pp. 945-953 ◽  
Author(s):  
B.J. Hawkins ◽  
J. Russell ◽  
R. Shortt
Keyword(s):  
Air Temperature ◽  
Electrolyte Leakage ◽  
High Elevation ◽  
Genetic Component ◽  
Frost Hardiness ◽  
Diverse Populations ◽  
Rooted Cuttings ◽  
Stock Types

Three 2-year-old experimental plantations of yellow-cedar (Chamaecyparisnootkatensis (D. Don) Spach.) seedlings and stecklings (rooted cuttings) from 4- and 12-year-old hedges were analyzed periodically for frost hardiness between September 1991 and May 1992. The plantations were at different elevations and latitudes, and seedlings and stecklings of three geographically diverse populations were represented. Frost hardiness was assessed using the freeze-induced electrolyte leakage method on upper, primary branches. Air temperature at the low elevation sites was monitored. Frost hardiness of all plants increased from September to the end of January, and then decreased. Plants grown at high elevation were consistently more hardy than those grown at low elevation; however, no obvious differences in hardiness between the two latitudes were evident. Seedlings and stecklings of parents from certain families and populations developed greater hardiness than stock of parents from other areas, showing that frost hardiness of yellow-cedar plants has a genetic component. The three stock types did not show any consistent, significant differences in hardiness; however, stecklings from 12- and 4-year-old hedges were, on average, slightly more hardy than seedlings.

Photoperiod and night frost influence the frost hardiness of Chamaecyparisnootkatensis clones

1993 ◽  
Vol 23 (7) ◽  
pp. 1408-1414 ◽  
Author(s):  
B.J. Hawkins
Keyword(s):  
Electrolyte Leakage ◽  
Frost Hardiness ◽  
Relative Influence ◽  
Controlled Environment ◽  
Rooted Cuttings ◽  
Subzero Temperatures ◽  
Controlled Environments

Frost hardiness in yellow cypress (Chamaecyparisnootkatensis (D. Don) Spach) was studied over the winter to determine the relative influence of photoperiod and subzero temperatures on the hardening and dehardening processes. Stecklings (rooted cuttings) of five clones from each of three provenances were grown outdoors and in two controlled-environment chambers at 10:5 °C day:night temperatures and 12- or 6-h photoperiods. Half of the plants in each photoperiod treatment were subject to a 4-h night frost, three times per week from December through to March. Frost hardiness was assessed at intervals using the freeze-induced electrolyte leakage method. Variability in frost hardiness was greater among clones within provenances than among provenances. Significant differences in hardiness among clones existed throughout the experiment; however, the ranking of clones by hardiness was not consistent. Stecklings in the 6-h photoperiod were consistently more hardy than their counterparts subjected to 12-h photoperiods. Stecklings placed outdoors had equivalent hardiness to those in the 6-h photoperiod until the advent of natural frosts in January. At this time, the outdoor trees were the most hardy. Night frost also significantly increased frost hardiness in stecklings in controlled environments. Stecklings in all treatments began to deharden between January and March. The outdoor plants dehardened most rapidly. Stecklings in the controlled environments dehardened slowly until the night-frost treatment ended, whereupon previously frozen plants dehardened more rapidly than their unfrozen counterparts.

scholarly journals Extreme and variable torpor among high-elevation Andean hummingbird species

2020 ◽  
Vol 16 (9) ◽  
pp. 20200428
Author(s):  
Blair O. Wolf ◽  
Andrew E. McKechnie ◽  
C. Jonathan Schmitt ◽  
Zenon J. Czenze ◽  
Andrew B. Johnson ◽  
...  
Keyword(s):  
Body Temperature ◽  
Air Temperature ◽  
Species Differences ◽  
Phylogenetic Signal ◽  
High Elevation ◽  
Tropical Andes ◽  
Cold Environments ◽  
Fuel Metabolism ◽  
Fat Reserves ◽  
Evolutionarily Conserved

Torpor is thought to be particularly important for small endotherms occupying cold environments and with limited fat reserves to fuel metabolism, yet among birds deep torpor is both rare and variable in extent. We investigated torpor in hummingbirds at approximately 3800 m.a.s.l. in the tropical Andes by monitoring body temperature ( T b ) in 26 individuals of six species held captive overnight and experiencing natural air temperature ( T a ) patterns. All species used pronounced torpor, with one Metallura phoebe reaching a minimum T b of 3.26°C, the lowest yet reported for any bird or non-hibernating mammal. The extent and duration of torpor varied among species, with overnight body mass ( M b ) loss negatively correlated with both minimum T b and bout duration. We found a significant phylogenetic signal for minimum T b and overnight M b loss, consistent with evolutionarily conserved thermoregulatory traits. Our findings suggest deep torpor is routine for high Andean hummingbirds, but evolved species differences affect its depth.

scholarly journals Air temperature variability in a high-elevation Himalayan catchment

2016 ◽  
Vol 57 (71) ◽  
pp. 212-222 ◽  
Author(s):  
Martin Heynen ◽  
Evan Miles ◽  
Silvan Ragettli ◽  
Pascal Buri ◽  
Walter W. Immerzeel ◽  
...  
Keyword(s):  
Air Temperature ◽  
Land Surface ◽  
Monsoon Season ◽  
High Elevation ◽  
Catchment Scale ◽  
Diurnal Variability ◽  
Atmosphere Interaction ◽  
Temperature Seasonality ◽  
Lapse Rates ◽  
High Elevations

AbstractAir temperature is a key control of processes affecting snow and glaciers in high-elevation catchments, including melt, snowfall and sublimation. It is therefore a key input variable to models of land–surface–atmosphere interaction. Despite this importance, its spatial variability is poorly understood and simple assumptions are made to extrapolate it from point observations to the catchment scale. We use a dataset of 2.75 years of air temperature measurements (from May 2012 to November 2014) at a network of up to 27 locations in the Langtang River, Nepal, catchment to investigate air temperature seasonality and consistency between years. We use observations from high elevations and from the easternmost section of the basin to corroborate previous findings of shallow lapse rates. Seasonal variability is strong, with shallowest lapse rates during the monsoon season. Diurnal variability is also strong and should be taken into account since processes such as melt have a pronounced diurnal variability. Use of seasonal lapse rates seems crucial for glacio-hydrological modelling, but seasonal lapse rates seem stable over the 2–3 years investigated. Lateral variability at transects across valley is high and dominated by aspect, with south-facing sites being warmer than north-facing sites and deviations from the fitted lapse rates of up to several degrees. Local factors (e.g. topographic shading) can reduce or enhance this effect. The interplay of radiation, aspect and elevation should be further investigated with high-elevation transects.

Photoperiod influences dehardening of Chamaecyparisnootkatensis seedlings

1993 ◽  
Vol 23 (11) ◽  
pp. 2452-2454 ◽  
Author(s):  
B.J. Hawkins ◽  
S.E. McDonald
Keyword(s):  
Significant Influence ◽  
Electrolyte Leakage ◽  
Frost Hardiness ◽  
Controlled Environment

In early January, seedlings of yellow cypress (Chamaecyparisnootkatensis (D. Don) Spach) were placed in controlled-environment chambers under constant, increasing, and decreasing photoperiods. Seedlings from all treatments were assessed for frost hardiness at 2-week intervals using the freeze-induced electrolyte leakage method. Seedlings subject to increasing day lengths began to deharden immediately and at a greater rate than seedlings under a constant photoperiod. Seedlings in the decreasing photoperiod treatment maintained maximum hardiness for 42 days and then began to deharden spontaneously, although photoperiod continued to decrease. Once dehardening began in this treatment, it proceeded at the fastest rate of all treatments. These results indicate that photoperiod has a significant influence on the initiation and rate of dehardening in yellow cypress, and maximum hardiness cannot be maintained indefinitely.

APPLYING ESTIMATED TEMPERATURE NORMALS TO THE ZONATION OF THE CANADIAN GREAT PLAINS FOR WHEAT

1969 ◽  
Vol 49 (3) ◽  
pp. 263-276 ◽  
Author(s):  
G. D. V. Williams
Keyword(s):  
Great Plains ◽  
Air Temperature ◽  
Spring Wheat ◽  
Time Scale ◽  
High Elevation ◽  
Great Slave Lake ◽  
Minimum Air Temperature

Regression estimates of temperature normals at nearly 1200 locations based on latitude, longitude and elevation were used, together with photoperiod data, in a biometeorological time scale equation to compute where spring wheat would mature, and the normal minimum air temperature at maturity. The resulting wheat zonation, which seemed reasonably realistic, indicated that an elevation of 1200 m in the southwest corner of Alberta was equivalent to about 160 m near Great Slave Lake. Southern parts of the Great Plains were zoned as favorable for maturing wheat, except in the foothills and some other areas of relatively high elevation, such as the Cypress Hills. North of Edmonton the favorable areas, with estimated normal minimum at wheat maturity of at least 5 °C, were confined to the main valleys, and the area where wheat would theoretically mature extended down the Mackenzie valley to around Wrigley.

A comparison of analytical approaches for assessing freezing damage in black spruce using electrolyte leakage methods

1996 ◽  
Vol 74 (6) ◽  
pp. 952-958 ◽  
Author(s):  
K. D. Odlum ◽  
T. J. Blake
Keyword(s):  
Critical Temperature ◽  
Electrolyte Leakage ◽  
Black Spruce ◽  
Frost Hardiness ◽  
Initial Increase ◽  
Cool Temperature ◽  
Freezing Damage ◽  
Intact Seedling ◽  
Temperature Hardening ◽  
Analytical Approaches

To compare different methods of quantifying shoot frost damage during controlled plant freezing tests, frost hardening of black spruce (Picea mariana (Mill.) BSP) seedlings exposed to three temperature hardening regimes over 16 weeks was assessed using electrolyte leakage and intact seedling methods. Electrolyte leakage was expressed as index of injury and was quantified either as the temperature needed to induce an index of injury of 5% (DT5) or as the critical temperature (CT), the mildest temperature at which damage was first detected statistically. Damage to intact shoots was expressed as percent shoot browning and was quantified as the temperature at which 50% of needle tissue on the shoots was damaged (sLT50) or as the temperature at which 50% of terminal buds were killed (bLT50). Seedling response to hardening temperature varied, depending on the method used to quantify frost hardiness. When expressed as critical temperature, hardening continued over the 16 weeks at a constant rate with no differences detected between treatments. Intact seedling shoot damage, sLT50 and bLT50, described a hardening process in which there was a large initial increase in hardening in the first 8 weeks, with less hardening occurring during the subsequent 8 weeks. Also, significant temperature effects were detected, with the greatest hardening occurring in a cool temperature (4 °C), the least in a warm temperature (20 °C), and an intermediate amount in a moderate temperature (10 °C). When quantified as DT5, the pattern of hardening was somewhat intermediate to the other two. Methods of determining frost hardiness were highly correlated, with the strongest correlation being between sLT50 and bLT50 (r2 = 0.903). Both electrolyte leakage methods, DT5 and CT, were linearly related to one another (r2 = 0.666) and were more sensitive than the intact seedling methods, since they both detected damage at warmer temperatures. DT5 was better correlated to intact measures of hardiness than was CT. Keywords: black spruce, index of injury, frost hardiness, critical temperature, damaging temperature, LT50.

Stomatal characteristics and transpiration of three species of conifer seedlings planted on a high elevation south-facing clear-cut

1987 ◽  
Vol 17 (10) ◽  
pp. 1273-1282 ◽  
Author(s):  
N. J. Livingston ◽  
T. A. Black
Keyword(s):  
Air Temperature ◽  
Vapour Pressure ◽  
Soil Water Potential ◽  
Vapour Pressure Deficit ◽  
High Elevation ◽  
Boundary Line ◽  
Silver Fir ◽  
Clear Cut ◽  
Physiological Variables ◽  
Stomatal Responses

Douglas-fir (Pseudotsugamenziessi (Mirb.) Franco), western hemlock (Tsugaheterophylla (Raf.) Sarg.), and Pacific silver fir (Abiesamabalis (Doug.) Forbes) seedlings were planted in the spring as 1-0 container-grown plugs on a south-facing high elevation clear-cut located on Mount Arrowsmith, Vancouver Island, British Columbia, and their stomatal responses to environmental and physiological variables were determined over two successive growing seasons. The stomatal responses of all three species to changes in environmental variables and time did not differ over the 2 years nor were there differences in response between seedlings planted a year apart. A simple multiplicative boundary-line model that related seedling stomatal conductance (gs) to measurements of hourly average solar irradiance, air temperature, vapour pressure deficit, and average root zone soil water potential accounted for over 70% of the variability in gs. When the number of hours from sunrise was included as an independent variable, over 85% of the variability in gs could be explained. Daily seedlings transpiration rates on a projected leaf area basis were successfully estimated by summing the product of the calculated average gs and D/(RvT′) where D is the vapour pressure deficit, Rv is the gas constant for water vapour, and T′ is the absolute air temperature.

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