Elevational and spatial variation in daytime ozone concentrations in the Virginia Blue Ridge Mountains: implications for forest exposure

1989 ◽  
Vol 19 (4) ◽  
pp. 422-426 ◽  
Author(s):  
F. S. Gilliam ◽  
J. T. Sigmon ◽  
M. A. Reiter ◽  
D. O. Krovetz
Keyword(s):  
Deciduous Forest ◽  
Canopy Structure ◽  
Elevational Gradient ◽  
Early Spring ◽  
Early Summer ◽  
Deciduous Trees ◽  
Blue Ridge ◽  
Canopy Development ◽  
Leaf Emergence ◽  
Blue Ridge Mountains

Ozone (O3) concentrations before and during the early growing season were monitored continuously at two closely located areas in the Virginia Blue Ridge Mountains: a deciduous forest watershed (Shaver Hollow) and a predominantly open grassy meadow (Big Meadows). In addition, O3 concentrations and canopy development (percent leaf emergence) were measured simultaneously at three sites along the elevational gradient of the Shaver Hollow watershed. When the canopy at Shaver Hollow was leafless, patterns of O3 concentration were similar between the forest and meadow, increasing steadily toward early spring, with low variability of hourly daytime measurements. Greater differences in O3 concentration between forest and meadow and higher variability occurred during the period May-June, a time when the canopy changed from 15 to 100% leaf emergence. Several factors varying along the elevational gradient, related to both canopy structure and meteorological conditions, appeared to be important in affecting absolute O3 concentrations as well as the variability of daytime means in Shaver Hollow. The high metabolic activity of new leaves may act as a sink for O3; the canopy itself may act as a physical barrier to O3 transport, restricting mixing of O3 to intermittent bursts. The coincidence of seasonal increases in O3 concentration in late spring and early summer with the development of new leaves of dominant deciduous trees in this watershed suggests that O3 may represent a potential problem for eastern hardwood forests.

THERMAL EVOLUTION OF ULTRAMAFIC BODIES IN THE EASTERN BLUE RIDGE MOUNTAINS, NC

2018 ◽  
Author(s):  
Anna VanDusen ◽  
◽  
Katharine Johanesen ◽  
Kaylee Pennell ◽  
Adam J. Ianno ◽  
...  
Keyword(s):  
Thermal Evolution ◽  
Blue Ridge ◽  
Blue Ridge Mountains

scholarly journals Fire, land cover, and temperature drivers of bat activity in winter

Fire Ecology ◽  
2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Marcelo H. Jorge ◽  
Sara E. Sweeten ◽  
Michael C. True ◽  
Samuel R. Freeze ◽  
Michael J. Cherry ◽  
...  
Keyword(s):  
Land Cover ◽  
Habitat Management ◽  
Deciduous Forest ◽  
Pinus Palustris ◽  
Growing Season ◽  
Early Spring ◽  
Bat Activity ◽  
White Nose Syndrome ◽  
Dormant Season ◽  
Wind Energy Development

Abstract Background Understanding the effects of disturbance events, land cover, and weather on wildlife activity is fundamental to wildlife management. Currently, in North America, bats are of high conservation concern due to white-nose syndrome and wind-energy development impact, but the role of fire as a potential additional stressor has received less focus. Although limited, the vast majority of research on bats and fire in the southeastern United States has been conducted during the growing season, thereby creating data gaps for bats in the region relative to overwintering conditions, particularly for non-hibernating species. The longleaf pine (Pinus palustris Mill.) ecosystem is an archetypal fire-mediated ecosystem that has been the focus of landscape-level restoration in the Southeast. Although historically fires predominately occurred during the growing season in these systems, dormant-season fire is more widely utilized for easier application and control as a means of habitat management in the region. To assess the impacts of fire and environmental factors on bat activity on Camp Blanding Joint Training Center (CB) in northern Florida, USA, we deployed 34 acoustic detectors across CB and recorded data from 26 February to 3 April 2019, and from 10 December 2019 to 14 January 2020. Results We identified eight bat species native to the region as present at CB. Bat activity was related to the proximity of mesic habitats as well as the presence of pine or deciduous forest types, depending on species morphology (i.e., body size, wing-loading, and echolocation call frequency). Activity for all bat species was influenced positively by either time since fire or mean fire return interval. Conclusion Overall, our results suggested that fire use provides a diverse landscape pattern at CB that maintains mesic, deciduous habitat within the larger pine forest matrix, thereby supporting the diverse bat community at CB during the dormant season and early spring.

Net precipitation assessment in a grassland and soil moisture response at plot scale in a temperate climate

2021 ◽  
Author(s):  
Gökben Demir ◽  
Johanna Clara Metzger ◽  
Janett Filipzik ◽  
Christine Fischer ◽  
Beate Michalzik ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Spatial Variation ◽  
Canopy Structure ◽  
Sampling Period ◽  
Temperate Climate ◽  
Small Scale ◽  
Spatial Effects ◽  
Mixed Effect ◽  
Canopy Development ◽  
Canopy Effect

<div> <p>Evidence on spatial variation of net precipitation in grasslands is scarce. Challenges arise due to a small-scale canopy structure of grasslands.</p> <p>In this study, we designed and tested a new in-situ measurement device (interception grid) to assess net precipitation in grasslands. The collector allows the natural development of the canopy. We tested the device both in the lab for splash loss and in the field to test its capacity to assess net precipitation. In the field, we installed 25 collectors on a grassland within the Hainich Critical Zone Exploratory (Thuringia, Germany), 23 of which were paired with soil moisture sensors. We conducted weekly measurements gross and net precipitation (above and below the canopy), along with grass height in 2019 (March-August) and 2020 (January -February). We categorized the data into two groups (‘covered,’ ‘uncovered’), accounting for canopy development.</p> <p>In the lab, we found that the drop size strongly affects splash loss. Drops of ca. 2 mm, created more than 16% splash loss, decreasing to less than 3% for drops <1.5 mm. Drop sizes <1.75 mm during the sampling period (2019) suggest low to intermediate splash loss in the field, further decreased in the covered period as the canopy contact slows down the drops. Grid measurements corrected with estimated splash loss during the uncovered period agreed well with gross precipitation. Using linear mixed effect models, we found that wind speed and grass height significantly affected the grid measurements of covered periods. Therefore, grids were able to capture net precipitation variation due to grass development. These steps encouraged us to examine the canopy effect in the soil moisture response to rainfall.</p> <p>Soil moisture response over the entire period was not related to the spatial variation of net precipitation. However, for the drier period (June-August 2019), when the spatial variation in soil moisture is higher, and the overall response to rain events stronger, net precipitation slightly affected soil moisture response. LMEM analysis to estimate factors on soil moisture response showed that grass height, net precipitation are significant predictors. Yet, there is no remarkable difference between using net precipitation and gross precipitation as potential drivers for soil moisture response, indicating that the spatial effects are comparatively small. Overall, our findings suggest that the grids are cable to catch canopy effects on the precipitation, while the effect of wind on under-catch still needs to be investigated further.</p> </div>

scholarly journals MANAGEMENT OF LATE SPRING-EARLY SUMMER PASTURE SURPLUSES IN HILL COUNTRY

1984 ◽  
pp. 199-206 ◽  
Author(s):  
G.W. Sheath ◽  
R.W. Webby ◽  
W.J. Pengelly
Keyword(s):  
Early Spring ◽  
Early Summer ◽  
Late Spring ◽  
First Year ◽  
Hill Country ◽  
Continuous Grazing ◽  
Summer Pasture ◽  
Animal Performances ◽  
Grazing Policy ◽  
Made In

Comparisons of controlling late spring to early summer pasture growth on either easy or steep contoured land with either a fast rotation or continuous grazing policy were made in self-contained farmlets for two years. Pasture control was maintained over more land by controlling steep land first and with continuous grazing. Animal performances (ewes, steers) were generally similar for the mid-November to early January treatment period, and subsequently until May shearing. In the first year better animal performances occurred in "steep control" farmlets during winter and early spring, but this was less evident in the second year. Priority control of steep land during late spring-early summer is recommended because of likely longer-term benefits in pasture composition,density and production. Quick rotation grazing through the period provides a better ability to recognise and manage pasture quantities and should be adopted if summer droughts are anticipated. For well fenced properties in summer-wet areas and with integrated stock grazing, continuous grazing during late spring-early summer may be equally suitable. Keywords: hill country, grazing management, pasture control

scholarly journals Seasonal patterns of pasture production in the Bay of Plenty and Waikato

1991 ◽  
pp. 67-72
Author(s):  
J.A. Baars ◽  
G.J. Goold ◽  
M.F. Hawke ◽  
P.J. Kilgarriff ◽  
M.D. Rolm
Keyword(s):  
Growth Rates ◽  
Early Spring ◽  
Early Summer ◽  
Growth Patterns ◽  
Climatic Data ◽  
Large Contribution ◽  
Pasture Production ◽  
Summer Peak ◽  
The Difference

Patterns of pasture growth were measured on 3 farms in the Bay of Plenty (BOP) and at No2 Dairy (Ruakura Agricultural Centre) in the Waikato from 1989 to 199 1. A standardised trim technique with cages and 4-weekly cutting under grazing was used. Long-term seasonal growth patterns, using a predictive pasture model, were also simulated. Simulated pasture growth from long-term climatic data shows that pasture growth rates are higher in winter, early spring and late autumn in the BOP than the Waikato. However, the actual measurements over the 2 years show that pasture growth over the latter periods is lower at the BOP sites than at the Waikato site. In the BOP the spring peak is much later than in the Waikato while an early summer peak, with higher growth rates than in the Waikato, occurred in the BOP. No such summer peak was evident in the Waikato. The difference between the two regions is caused by the large contribution of subtropical grasses to sward production in summer and autumn, The prolific summer growth of subtropical grasses may explain the low ryegrass content and low pasture production in winter. The lower than expected autumn, winter, spring production may also becaused by low clover content, possibly a result of competition from subtropical grasses and a sulphur deficiency. The apparent low amount of nitrogen fixed by clover may explain the low rates of pasture production over the cooler season. Applications of nitrogen fertiliser may substantially increase dry matter production from April to September. Keywords pasture,simulation,subtropical grasses, Paspalum, Digitaria sanguinalis, growth rates

The diet of grizzly bears in the Flathead River drainage of southeastern British Columbia

1995 ◽  
Vol 73 (4) ◽  
pp. 704-712 ◽  
Author(s):  
Bruce N. McLellan ◽  
Fred W. Hovey
Keyword(s):  
National Park ◽  
Ursus Arctos ◽  
Handling Time ◽  
Early Spring ◽  
Early Summer ◽  
Grizzly Bears ◽  
Green Vegetation ◽  
Heracleum Lanatum ◽  
Shepherdia Canadensis ◽  
Food Consumed

Based on the analysis of 1100 feces or scats, the seasonal diet of grizzly bears (Ursus arctos) in the Flathead drainage between 1979 and 1991 was estimated. In the early spring, major foods included ungulates and hedysarum roots (Hedysarum sulphurescens). Later in the spring and early summer, green vegetation that mainly included horsetails (Equisetum arvense), graminoids, and cow parsnip (Heracleum lanatum) dominated the diet. Later in the summer, berries, particularly huckleberries (Vaccinium spp.) and soopolallie (Shepherdia canadensis), were most common. In the autumn, berries, ungulates, and hedysarum roots were major foods. Seasonal changes in nutrients were measured for major foods. The volume of a food consumed within a season was inversely related to food quality, suggesting that food availability and handling time may have been more important factors influencing diet selection. The proportions of food items in the scats, and species of fruit in particular, varied among years. The Flathead and contiguous Waterton Lakes National Park are so far the only study areas in North America that contain all major bear foods found across the interior of the continent, and in particular, both major berry species, huckleberries and soopolallie. This observation supports the hypothesis that a favourable food base in the Flathead is partially responsible for the high density of bears found there. It is important for managers to realize the possible uniqueness of the Flathead area and not extrapolate information without due caution.

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