uid=BNZ,o=lter,dc=ecoinformatics,dc=org all public read knb-lter-bnz.64.10 David W. Valentine

Department of Forest Sciences University of Alaska Fairbanks O'Neill Bldg Fairbanks AK 99775-7200 United States

(907) 474-7614 (907) 474-6184 dvalentine@alaska.edu http://www.uaf.edu/snras/departments/forestry/faculty/valentine/ Bonanza Creek LTER Data Manager

Boreal Ecology Cooperative Research Unit University of Alaska Fairbanks P.O. Box 756780 Fairbanks AK 99775 USA

907-474-6364 907-474-6251 jpdowning@alaska.edu http://www.lter.uaf.edu 2003-08-13 Ledum palustre (Labrador tea) is a late successional evergreen shrub widely distributed in boreal ecosystems that readily leaches high concentrations of soluble phenolic compounds into water. We selected this species in order to study whether leaf leachates could be responsible for the effects of plant canopy on N cycling under natural conditions. Organic matter content, soil respiration and net N mineralization were measured in organic and mineral soil horizons and gross N mineralization was also measured in mineral soils sampled underneath L. palustre in a hardwood forest dominated by Populus tremuloides and Betula neoalaskana. Soils were amended with L. palustre litter leachates and incubated in the laboratory. Because mineral soil is also influenced by the overlying organic horizon we also characterized some simple indices of the organic horizon carbon quality (lignin, cellulose and condensed tannins) to look for differences in likely decomposability. Our objectives were i) to determine whether L. palustre presence and L. palustre leachates addition changed soil N availability, and ii) to determine the specific N cycling processes that were affected, including changes in mineralization, nitrification or immobilization. We wanted to know whether L. palustre leachates could be a mechanism through which plant presence would impact N cycling. Ledum palustre phenolic compounds nitrogen cycling nitrogen mineralization organic carbon organic nitrogen Biogeochemistry

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http://www.lter.uaf.edu/data_detail.cfm?datafile_pkey=64 1999-08-01 1999-08-31

Completed

Bonanza Creek LTER Data Manager

Boreal Ecology Cooperative Research Unit University of Alaska Fairbanks P.O. Box 756780 Fairbanks AK 99775 USA

907-474-6364 907-474-6251 jpdowning@alaska.edu http://www.lter.uaf.edu Bonanza Creek LTER

Boreal Ecology Cooperative Research Unit University of Alaska Fairbanks P.O. Box 756780 Fairbanks AK 99775 USA

907-474-6364 907-474-6251 Bonanza Creek LTER

The organic horizon (Oe and Oa) and the top 7 cm of mineral soil were sampled in three different locations inside the 1 m2 quadrat, and samples were bulked together by horizon within each site. Organic and mineral horizons were sieved through 5.6 and 2 mm mesh, respectively, and kept at 4 ºC. Soils sampled under L. palustre and in nearby no Ledum sites were incubated in the dark at 15 ºC for 30 days. Organic (20 g) and mineral soil (50 g fresh weight) were placed into 250 mL jars fitted with septa to allow headspace samplings. Samples were amended with litter leachate or distilled water (4 and 6 mL for organic and mineral soils, respectively) just before starting the incubation. Additional distilled water was added to the soils to bring moisture to field capacity.

Total C and N were analyzed at the end of incubation using a CNS analyzer (LECO Model 2000). Condensed tannin concentrations were analyzed by the proantocyanidin method (Waterman and Mole 1994). Organic horizon was dried at 65 ºC, ground and analyzed at the University of Alaska Palmer Research Station for cellulose, hemicellulose and lignin using the Van Soest procedure (Goering and Van Soest, 1970). Soil respiration was measured every week by analyzing CO2 accumulated in the jars by a Gas Chromatograph (Shimadzu GC-14A) fitted with a methanizer and flame ionization detector. Potential net N mineralization rates were calculated as the difference between initial and final KCl extractable ammonium and nitrate concentrations using a modified Technicon AutoAnalyzer II system.

1999-08-01 1999-08-31

Once

172_1702_Castells_et_al_dataset.txt Text Unicode (*.txt) OM depth (cm) NDF, ADF, Hemicel.lulose, Cel.lulose, Lignin, Organic C, Organic N (%) tannins (mg g-1DM) pH, C/N (no units) initial NH4+, initial NO3-, final NH4+ Control, final NH4+ leachate, final NO3- Control, final NO3- leachate (mg g-1DM) N mineralization Control, N mineralization leachate (ng g-1DW day-1) na not availbale nd not detectable 172_1702_Castells_et_al_dataset.txt 2 \n \n column \t http://metacat.lternet.edu/das/dataAccessServlet?docid=knb-lter-bnz..&urlTail=/ascii/files/172_1702_Castells_et_al_dataset.txt Site type Site type Site Type string Site Type Site # Site # Site number integer Site number O/M O/M O/M float dimensionless real OM Depth OM Depth Organic Matterial Depth float centimeter real NDF NDF Neutral detergent fiber float dimensionless real ADF ADF Acid detergent fiber float dimensionless real Hemicellulose Hemicellulose Hemicellulose float dimensionless real Cellulose Cellulose Cellulose float dimensionless real Lignin Lignin Lignin float dimensionless real tannins tannins Tannins float dimensionless real pH pH pH float dimensionless real Organic C Organic C Organic Carbon float dimensionless real Organic N Organic N Organic Nitrogen float dimensionless real C/N C/N Carbon/Nitrogen Ratio float dimensionless real initial NH4+ initial NH4+ initial NH4+ float dimensionless real initial NO3- initial NO3- initial NO3- float dimensionless real final NH4+ control final NH4+ control final NH4+ control float dimensionless real final NH4+ leachate final NH4+ leachate final NH4+ leachate float dimensionless real final NO3- Control final NO3- Control final NO3- Control float dimensionless real final NO3- leachate final NO3- leachate final NO3- leachate float dimensionless real N mineralization Control N mineralization Control Nitrogen mineralization control float dimensionless real N mineralization leachate N mineralization leachate Nitrogen mineralization leachate float dimensionless real