scholarly journals Variation in overstory nitrogen uptake in a small, high-elevation southern Appalachian spruce-fir watershed

2002 ◽  
Vol 32 (10) ◽  
pp. 1741-1752 ◽  
Author(s):  
M Barker ◽  
H Van Miegroet ◽  
N S Nicholas ◽  
I F Creed
Keyword(s):  
Stand Structure ◽  
N Uptake ◽  
High Elevation ◽  
N Deposition ◽  
Root Turnover ◽  
Betula Alleghaniensis ◽  
Atmospheric N Deposition ◽  
Great Smoky Mountains ◽  
Smoky Mountains ◽  
Balsam Woolly Adelgid

High-elevation red spruce (Picea rubens Sarg.) – Fraser fir (Abies fraseri (Pursh) Poir.) forests of the southern Appalachians exhibit considerable spatial heterogeneity in structure, and possibly in N uptake, because of a combination of natural disturbances and heavy fir mortality caused by infestations of the exotic balsam woolly adelgid (Adelges piceae Ratz). The objectives of this study are to determine spatial variability in tree N uptake in a small high-elevation catchment in the Great Smoky Mountains National Park, compare outcomes among calculation methods, and assess the influence of stand and landscape properties on N uptake. Tree N uptake is estimated for fifty 20 × 20 m plots in the Noland Divide Watershed (NDW). Components considered in the calculations are stem growth, foliage increment, and mortality of spruce, fir, and yellow birch (Betula alleghaniensis Britt.) from 1993 and 1998 stand inventories; throughfall N flux measured in summers 1998 and 1999; litterfall N return for 1 year in a subset of 12 plots; tissue N analyses; and atmospheric N deposition and root turnover estimates from the literature. Overstory N uptake varies spatially within NDW, with a CV of 9–41% depending on the calculation method. Variability among methods is even higher, with an almost 15-fold difference between the smallest and largest average overstory uptake estimate (5 vs. 74 kg·ha–1·year–1). Only 5 and 3 kg·ha–1·year–1 of N is sequestered in wood and foliar increment, respectively, while 36 kg·ha–1 of N returns annually as aboveground litterfall. Uptake and its components are correlated with measures of stand structure but not with elevation or aspect.

scholarly journals Downscaling Climate over Complex Terrain: High Finescale (<1000 m) Spatial Variation of Near-Ground Temperatures in a Montane Forested Landscape (Great Smoky Mountains)*

2009 ◽  
Vol 48 (5) ◽  
pp. 1033-1049 ◽  
Author(s):  
Jason D. Fridley
Keyword(s):  
Soil Moisture ◽  
Moisture Content ◽  
Sensor Network ◽  
Spatial Scales ◽  
High Elevation ◽  
Great Smoky Mountains ◽  
Weather Patterns ◽  
Synoptic Weather ◽  
Temperature Regimes ◽  
Smoky Mountains

Abstract Landscape-driven microclimates in mountainous terrain pose significant obstacles to predicting the response of organisms to atmospheric warming, but few if any studies have documented the extent of such finescale variation over large regions. This paper demonstrates that ground-level temperature regimes in Great Smoky Mountains National Park (Tennessee and North Carolina) vary considerably over fine spatial scales and are only partially linked to synoptic weather patterns and environmental lapse rates. A 120-sensor network deployed across two watersheds in 2005–06 exhibited finescale (&lt;1000-m extent) temperature differences of over 2°C for daily minima and over 4°C for daily maxima. Landscape controls over minimum temperatures were associated with finescale patterns of soil moisture content, and maximum temperatures were associated with finescale insolation differences caused by topographic exposure and vegetation cover. By linking the sensor array data to 10 regional weather stations and topographic variables describing site radiation load and moisture content, multilevel spatial models of 30-m resolution were constructed to map daily temperatures across the 2090-km2 park, validated with an independent 50-sensor network. Maps reveal that different landscape positions do not maintain relative differences in temperature regimes across seasons. Near-stream locations are warmer in the winter and cooler in the summer, and sites of low elevation more closely track synoptic weather patterns than do wetter high-elevation sites. This study suggests a strong interplay between near-ground heat and water balances and indicates that the influence of past and future shifts in regional temperatures on the park’s biota may be buffered by soil moisture surfeits from high regional rainfall.

Size- and age-class distributions of Fraser fir following balsam woolly adelgid infestation

2000 ◽  
Vol 30 (6) ◽  
pp. 948-957 ◽  
Author(s):  
George F Smith ◽  
N S Nicholas
Keyword(s):  
Permanent Plots ◽  
Seedling Mortality ◽  
Regeneration Potential ◽  
Abies Fraseri ◽  
Great Smoky Mountains ◽  
Fraser Fir ◽  
Advance Regeneration ◽  
Size And Age Structure ◽  
Smoky Mountains ◽  
Balsam Woolly Adelgid

Fraser fir (Abies fraseri (Pursh) Poir.) has suffered catastrophic mortality throughout most of its native range from an exotic insect, the balsam woolly adelgid (Adelges piceae Ratz.). To assess the regeneration potential and viability of fir populations, overstory and understory Fraser fir size and age structure were analyzed. The data were collected from thirty-six 400-m2 permanent plots, stratified into four stand canopy composition types, established near the summits of five mountains in the Great Smoky Mountains. We found that, where canopy mortality was severe, fir advance regeneration was re-entering the overstory. In seriously impacted stands, mortality of large fir and increased recruitment have produced distributions characterized by few large fir and relatively high densities of small fir. Densities of 0- to 10-year-old fir seedlings and fir seedlings [Formula: see text]0.25 m tall were much lower in stands dominated by dead fir than in mostly intact fir stands. While the lack of reproducing adults appears to be the main cause, competition with invasive species and higher seedling mortality from environmental factors probably contribute. These results lead to a hypothesis that Fraser fir will undergo a regeneration-mortality cycle with a decrease in the numbers of each successive generation.

Nitrogen fertilization enhances cold tolerance of red spruce seedlings

1989 ◽  
Vol 19 (8) ◽  
pp. 1037-1043 ◽  
Author(s):  
D. H. DeHayes ◽  
M. A. Ingle ◽  
C. E. Waite
Keyword(s):  
Cold Tolerance ◽  
N Uptake ◽  
Late Summer ◽  
N Deposition ◽  
Early Summer ◽  
Red Spruce ◽  
Atmospheric N Deposition ◽  
N Application ◽  
Cold Tolerant ◽  
Autumn And Winter

Red spruce (Picearubens Sarg.) seedlings were treated with one of four concentrations of NH4NO3 (0, 300, 1500, and 3000 kg N•ha−1•year−1) applied to the soil, with and without triple superphosphate, during early, mid-, or late summer. Laboratory freezing assessments indicated that cold tolerance of treated seedlings generally increased with increasing nitrogen (N) uptake, with the exception of the highest N treatment. Seedlings receiving 1500 kg N•ha−1•year−1 were most cold tolerant on most sample dates. In general, these seedlings were hardier than those receiving 300 kg N•ha−1•year−1, which were hardier than unfertilized control seedlings. Seedlings receiving supplemental N also acclimated to cold more rapidly in autumn and deacclimated more slowly in spring than unfertilized controls. Supplemental phosphorus (P) had no influence on cold tolerance, and there was no evidence of a N × P interaction. Significant differences in cold tolerance associated with time of N application (early, mid-, and late summer) were detected in autumn and winter, but not in spring. In general, seedlings receiving N in mid- or late summer were as hardy or hardier than seedlings fertilized in early summer, regardless of the concentration of fertilizer. Significant interactions between N and timing of treatments occurred primarily because N applied in early summer resulted in only a slight increase in cold tolerance, whereas mid- and late summer N application resulted in a substantial increase in cold tolerance. Combined results suggest that it is highly unlikely that either the amount or timing of atmospheric N deposition is responsible for the winter injury frequently observed in red spruce.

scholarly journals Aridity and plant uptake interact to make dryland soils hotspots for nitric oxide (NO) emissions

2016 ◽  
Vol 113 (19) ◽  
pp. E2608-E2616 ◽  
Author(s):  
Peter M. Homyak ◽  
Joseph C. Blankinship ◽  
Kenneth Marchus ◽  
Delores M. Lucero ◽  
James O. Sickman ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
N Uptake ◽  
N Deposition ◽  
N Availability ◽  
Plant N Uptake ◽  
N Loss ◽  
Atmospheric N Deposition ◽  
Soil Microbial ◽  
California Grassland ◽  
No Emissions

Nitric oxide (NO) is an important trace gas and regulator of atmospheric photochemistry. Theory suggests moist soils optimize NO emissions, whereas wet or dry soils constrain them. In drylands, however, NO emissions can be greatest in dry soils and when dry soils are rewet. To understand how aridity and vegetation interact to generate this pattern, we measured NO fluxes in a California grassland, where we manipulated vegetation cover and the length of the dry season and measured [δ15-N]NO and [δ18-O]NO following rewetting with15N-labeled substrates. Plant N uptake reduced NO emissions by limiting N availability. In the absence of plants, soil N pools increased and NO emissions more than doubled. In dry soils, NO-producing substrates concentrated in hydrologically disconnected microsites. Upon rewetting, these concentrated N pools underwent rapid abiotic reaction, producing large NO pulses. Biological processes did not substantially contribute to the initial NO pulse but governed NO emissions within 24 h postwetting. Plants acted as an N sink, limiting NO emissions under optimal soil moisture. When soils were dry, however, the shutdown in plant N uptake, along with the activation of chemical mechanisms and the resuscitation of soil microbial processes upon rewetting, governed N loss. Aridity and vegetation interact to maintain a leaky N cycle during periods when plant N uptake is low, and hydrologically disconnected soils favor both microbial and abiotic NO-producing mechanisms. Under increasing rates of atmospheric N deposition and intensifying droughts, NO gas evasion may become an increasingly important pathway for ecosystem N loss in drylands.

scholarly journals Land Snails of Selected Rare High Elevation Forests and Heath Balds of the Great Smoky Mountains National Park

2012 ◽  
Vol 128 (2) ◽  
pp. 27-32
Author(s):  
Daniel C. Dourson ◽  
Keith Langdon
Keyword(s):  
National Park ◽  
Land Snail ◽  
High Elevation ◽  
Land Snails ◽  
Restricted Range ◽  
Great Smoky Mountains ◽  
Smoky Mountains ◽  
High Elevation Forests ◽  
First Time ◽  
One New Species

Abstract Selected high elevation forests and heath balds of the Great Smoky Mountains National Park (GSMNP) between Newfound Gap and Thunderhead Mountain were comprehensively sampled for the first time. Thirty-three species including one new species Fumonelix langdoni (Dourson) were documented occurring at elevations between 1,372 m to 2,012 m. Two previous land snail inventories in the park by Thompson (1981) and Dourson (2005) added sixteen species, bringing the total land snail fauna to forty nine species living above 1,372 m within park boundaries. Overall species richness declines with elevation yet numbers of snails appear to change little with increasing altitude. Heath balds were comparably rich sites for gastropods, Vitrinizonites latissimus (Lewis) being the most frequently observed land snail. Mesodon altivagus, (Pilsbry) and Fumonelix jonesiana (Archer) both documented during the survey are of global importance, a result of an exceptionally restricted range within the park. One ambiguous species in the genus Fumonelix (Polygyridae) is discussed and likely represents new taxa. Appalachina chilhoweensis (J. Lewis) was found at 1,666 m, representing the highest elevation the species has been documented to date.

scholarly journals Diversity and density of the EM fungal community present in high elevation Fraser fir forests of Great Smoky Mountains National Park

2014 ◽  
Vol 9 (0) ◽  
pp. 1 ◽  
Author(s):  
Richard Baird ◽  
C. Elizabeth Stokes ◽  
John Frampton ◽  
Benjamin Smith ◽  
Clarence Watson ◽  
...  
Keyword(s):  
Fungal Community ◽  
National Park ◽  
High Elevation ◽  
Great Smoky Mountains ◽  
Fraser Fir ◽  
Smoky Mountains
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