Is coarse woody debris a net sink or source of nitrogen in the red spruce – Fraser fir forest of the southern Appalachians, U.S.A.?

2004 ◽  
Vol 34 (3) ◽  
pp. 716-727 ◽  
Author(s):  
I F Creed ◽  
D L Morrison ◽  
N S Nicholas
Keyword(s):  
Coarse Woody Debris ◽  
Woody Debris ◽  
Red Spruce ◽  
Organic N ◽  
Southern Appalachians ◽  
N Dynamics ◽  
Fraser Fir ◽  
N Source ◽  
Ammonium N ◽  
Export Signal

The red spruce (Picea rubens Sarg.) – Fraser fir (Abies fraseri (Pursh) Poir.) forest of the southern Appalachians contains a significant amount of coarse woody debris (CWD) that may affect the nitrogen (N) export signal in streams originating from this N-saturated system. Interpretation of the N sink versus source status of CWD of red spruce and Fraser fir was dependent on the method used. Over a chronosequence of decay, (1) N concentrations suggested a N sink (i.e., a net gain of N of 923% in red spruce and 563% in Fraser fir relative to N in live trees); (2) N contents that reflected changes in density suggested a smaller N sink (i.e., a net gain of N of 218% in red spruce and 125% in Fraser fir relative to N in live trees), but the stoichiometry of N and C suggested a N source in early stages of decay and a N source in the most advanced stage of decay only; and (3) N contents that reflected changes in volume suggested a N source (i.e., a net N loss of –172% in red spruce and –122% in Fraser fir). The C/N ratios in CWD suggested that the shift from a N source to a N sink represented a shift from the mobilization of dissolved organic N to the immobilization of ammonium N and (or) nitrate N. The magnitude of the net change in N contents in both red spruce and Fraser fir was amongst the highest reported in literature, suggesting that CWD plays a particularly important role in N dynamics in N saturated forests.

scholarly journals Impacts of Labile Organic Carbon Concentration on Organic and Inorganic Nitrogen Utilization by a Stream Biofilm Bacterial Community

2013 ◽  
Vol 79 (23) ◽  
pp. 7130-7141 ◽  
Author(s):  
Suchismita Ghosh ◽  
Laura G. Leff
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Inorganic Nitrogen ◽  
Bacterial Community Composition ◽  
Organic N ◽  
Humic Matter ◽  
Bacterial Protein ◽  
N Dynamics ◽  
N Source ◽  
Algal Exudate

ABSTRACTIn aquatic ecosystems, carbon (C) availability strongly influences nitrogen (N) dynamics. One manifestation of this linkage is the importance in the dissolved organic matter (DOM) pool of dissolved organic nitrogen (DON), which can serve as both a C and an N source, yet our knowledge of how specific properties of DOM influence N dynamics are limited. To empirically examine the impact of labile DOM on the responses of bacteria to DON and dissolved inorganic nitrogen (DIN), bacterial abundance and community composition were examined in controlled laboratory microcosms subjected to various combinations of dissolved organic carbon (DOC), DON, and DIN treatments. Bacterial communities that had colonized glass beads incubated in a stream were treated with various glucose concentrations and combinations of inorganic and organic N (derived from algal exudate, bacterial protein, and humic matter). The results revealed a strong influence of C availability on bacterial utilization of DON and DIN, with preferential uptake of DON under low C concentrations. Bacterial DON uptake was affected by the concentration and by its chemical nature (labile versus recalcitrant). Labile organic N sources (algal exudate and bacterial protein) were utilized equally well as DIN as an N source, but this was not the case for the recalcitrant humic matter DON treatment. Clear differences in bacterial community composition among treatments were observed based on terminal restriction fragment length polymorphisms (T-RFLP) of 16S rRNA genes. C, DIN, and DON treatments likely drove changes in bacterial community composition that in turn affected the rates of DON and DIN utilization under various C concentrations.

Selected Nova Scotia old-growth forests: Age, ecology, structure, scoring

2003 ◽  
Vol 79 (3) ◽  
pp. 632-644 ◽  
Author(s):  
Bruce J Stewart ◽  
Peter D Neily ◽  
Eugene J Quigley ◽  
Lawrence K Benjamin
Keyword(s):  
Age Structure ◽  
Coarse Woody Debris ◽  
Sugar Maple ◽  
Dead Wood ◽  
Woody Debris ◽  
Large Diameter ◽  
Basal Area ◽  
Red Spruce ◽  
White Pine ◽  
Old Growth

A study of four old-growth stands in Nova Scotia was conducted to document the ecological characteristics of these currently rare Acadian forest ecosystems. Stands were selected to represent the two dominant climax forest types, hemlock–red spruce–eastern white pine, and sugar maple–yellow birch–beech. Data include measurements of age structure, species composition, diameter distribution, basal area, height, coarse woody debris, snags, vertical structure, and canopy condition. All stands were determined to be uneven-aged. Old-growth reference ages calculated for the stands ranged from 164 to 214 years. All stands displayed broad diameter distributions that had peak basal area representation in the 40- to 50-cm diameter classes. Volumes of dead wood ranged from 111 to 148 m3/ha in the softwood stands and from 63 to 83m3/ha in the hardwood stands. Dead wood consisted of approximately one-third snags and two thirds downed coarse woody debris. Measurements from the stands were used to evaluate Nova Scotia's recently developed Old Forest Scoring System. Six stand attributes were rated for a maximum score of 100: stand age, primal value, number of large-diameter trees, length of large-diameter dead wood, canopy structure, and understorey structure. Based on the age attribute, three of the four stands were classed as Mature Old Growth and one was very close, indicating that all are in the shifting mosaic stage of late forest succession. The scores for all stands were relatively high, ranging from 75 to 85, as would be expected from some of the best old-growth stands in the province. Key words: old growth, climax, primal, late succession, uneven-aged, scoring, coarse woody debris, age structure, diameter, Acadian forest, northern hardwood, red spruce, eastern hemlock, white pine, sugar maple, yellow birch, American beech

A comparison of techniques for measuring density and concentrations of carbon and nitrogen in coarse woody debris at different stages of decay

2004 ◽  
Vol 34 (3) ◽  
pp. 744-753 ◽  
Author(s):  
I F Creed ◽  
K L Webster ◽  
D L Morrison
Keyword(s):  
Coarse Woody Debris ◽  
Woody Debris ◽  
Significant Degree ◽  
Picea Rubens ◽  
Classification Systems ◽  
Southern Appalachians ◽  
Abies Fraseri ◽  
Carbon And Nitrogen ◽  
Comparison Of Techniques ◽  
The Relationship

This research considered the relationship between the stage of decay and the concentration of nitrogen (N, %) and the ratio of carbon to N (C/N) in coarse woody debris. Density (g/cm3) was used as an indicator of the stage of decay. In samples collected from the red spruce – Fraser fir (Picea rubens Sarg. – Abies fraseri (Pursh) Poir.) forest of the southern Appalachians, density explained up to 60% of the variation in N and C/N in coarse woody debris. The technique used to estimate density was important. Laboratory-based methods (including displacement and mensuration density) explained the greatest degree of the variation, with coefficients of determination (r2) ranging from 0.39 to 0.59 (p < 0.001) for N and from 0.39 to 0.58 for C/N (p < 0.001). Field-based methods (including penetrometer and resisto graph readings) explained a smaller but still significant degree of the variation, with r2 ranging from 0.17 to 0.25 (p < 0.01) for N and from 0.14 to 0.26 for C/N (p < 0.05). Consideration of within-bole heterogeneity in density improved the explanation of variation in N and C/N for a single bole. Density provides a continuous indicator of stage of decay that is not bound by the artificiality of discrete decay classification systems. Furthermore, statistical models relating density to N and C/N provide a means of hind casting and (or) forecasting changes in N and C/N in coarse woody debris at different stages of decay.

Ice damage in spruce–fir forests of the Black Mountains, North Carolina

1989 ◽  
Vol 19 (11) ◽  
pp. 1487-1491 ◽  
Author(s):  
N. S. Nicholas ◽  
S. M. Zedaker
Keyword(s):  
North Carolina ◽  
High Elevation ◽  
Red Spruce ◽  
Southern Appalachians ◽  
Eastern North America ◽  
Ecosystem Monitoring ◽  
Fraser Fir ◽  
Average Decrease ◽  
Ice Storms ◽  
Second Growth

Spruce–fir ecosystem monitoring was initiated in 1985 in the southern Appalachians, United States, after reports of a red spruce (Picearubens Sarg.) decline in the northeast. Ice storms during the winter of 1986–1987 had a severe impact on spruce–fir forests in the Black Mountains of North Carolina, the location of Mount Mitchell, the highest peak in eastern North America. Mortality rates were higher for red spruce than for Fraser fir (Abiesfraseri (Pursh.) Poir.), 8.1 and 2.4%, respectively. Recent ice damage was apparent in 12.4% of surviving overstory stems, with red spruce having a 17% average decrease in height. Frequency of damage to stems tended to increase with increasing elevation. Little is known about the successional dynamics of southern high elevation montane second-growth forests. Our results suggest that ice storms may be an important cause of damage and mortality.

scholarly journals Salinity Tolerance of Turf-type Tall Fescue as Affected by Nitrogen Sources

HortScience ◽  
2018 ◽  
Vol 53 (11) ◽  
pp. 1695-1699
Author(s):  
Zhao Xiang ◽  
Zhu Huisen ◽  
Gao Yang ◽  
Li Deying
Keyword(s):  
Salinity Stress ◽  
Tall Fescue ◽  
Nitrification Inhibitor ◽  
Nitrogen Sources ◽  
Organic N ◽  
Salt Treatment ◽  
Turf Quality ◽  
N Source ◽  
Nitrate N ◽  
Ammonium N

Tall fescue [Schedonorus arundinaceus (Schreb) Dumort] has potential in cool arid regions, where it is often subject to salinity stress. The objective of this 2-year field study was to investigate the effect of nitrogen sources on tall fescue turf quality under salinity stress in the northern Great Plains of North America. ‘Wolfpack’, ‘Wolfpack II’, ‘Tar Heel’, ‘Tar Heel II’, ‘Jaguar 3’, ‘Jaguar 4G’, and ‘Arid 3’ were treated with NaCl and CaCl2 in equal amounts. Six N sources were used for fertilization: nitrate-N, urea-N, ammonium-N, urea-N/ammonium-N/nitrate-N, urea-N with urase and nitrification inhibitor, and organic N. Salt treatment reduced turf quality of all cultivars. Turf quality was affected differently by N source. Regardless of salt treatments, urea stabilized with a urease inhibitor and a nitrification inhibitor consistently had the best turf quality. Equal amounts of nitrate, ammonium, and urea-N yielded the lowest turf quality. However, there was no interaction between N source and salt treatment. These results were also supported by green density (GD), dark-green color index (DGCI), shoot chlorophyll (Chl) content, and leaf relative water content (RWC). Tall fescue cultivars responded to salinity treatment differently, with ‘Wolfpack II’ being the cultivar ranked consistently at the top and maintained above the acceptable level of visual quality.

Decay classes of coarse woody debris in a lowland Dipterocarp forest: implications for volume, density, and carbon estimates

Biotropica ◽  
2021 ◽  
Author(s):  
Ekaterina Shorohova ◽  
Ekaterina Kapitsa ◽  
Andrey Kuznetsov ◽  
Svetlana Kuznetsova ◽  
Valentin Lopes de Gerenuy ◽  
...  
Keyword(s):  
Coarse Woody Debris ◽  
Woody Debris ◽  
Volume Density ◽  
Dipterocarp Forest ◽  
Lowland Dipterocarp Forest

scholarly journals Forest stand structure and coarse woody debris determine the biodiversity of beetle communities in Mediterranean mountain beech forests

2021 ◽  
pp. e01637
Author(s):  
Francesco Parisi ◽  
Michele Innangi ◽  
Roberto Tognetti ◽  
Fabio Lombardi ◽  
Gherardo Chirici ◽  
...  
Keyword(s):  
Coarse Woody Debris ◽  
Stand Structure ◽  
Woody Debris ◽  
Forest Stand ◽  
Beech Forests ◽  
Forest Stand Structure
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