TD23 Abstract Long-term Carbon, Nitrogen, and Phosphorus Dynamics of Leaf and Fine Root Litter in North American Ecosytems. ABSTRACTOR: Mark Harmon DATE: AUGUST 1992 Update March 1996 JMS KEYWORDS: decomposition, decay rates, litterbags, leaf litter, fine roots, wood, nitrogen, phosphorus, carbon fractions. PARAMETERS: mass loss, Kjeldahl nitrogen, phosphorus, lignin, non- polar extractives, sugars, water soluable phenolics, hydrolyzable carbohydrates, ash. VEGETATION ZONE: Includes all major terrestrial biomes in North America. Twenty-eight sites are involved. Individual site descriptions are stored in the TD2306 file. COMMUNITY TYPE: Site Biome Andrews cool temperate conifer Arctic Lakes tussock tundra Barro Colorado Isl moist tropical Bonanza Creek boreal conifer Blodgett temperate conifer Cedar Creek tall grass/ forest transition Central Plains shortgrass steppe Coweeta warm temperate hardwood Curley Valley cold desert Florida warm temperate conifer Guanica dry tropical forest Hubbard Brook cool temperate hardwood Harvard Forest cool temperate hardwood Jornada warm desert Juneau cool temperate conifer Kellogg agriculture Konza tallgrass prairie LaSelva wet tropical Luquillo wet tropical Loch Vale cold alpine conifer Monte Verde tropical cloud forest Niwot Ridge alpine tundra North Inlet coastal marine Northern Lakes cool temperate mixed Olympics cool temperate conifer Santa Margarita chaparral Sevilleta desert Virginia Coast coastal marine TAXA: The following species are being examined: ASPEN (Populus tremuloides), BEACH GRASS (Ammophila breviligulata), BEECH (Fagus grandifolia), BIG BLUE STEM (Schizachyrium gerardi), BLACK GRAMA (Bouteloua eriopoda), BLACK LOCUST (Robinea pseudoacacia), BLUE GRAMA (Bouteloua gracilis), CEANOTHUS (Ceanothus greggii), CHESTNUT OAK (Quercus prinus), CREOSOTE BUSH (Larrea tridentata), DOUGLAS-FIR (Pseudotsuga menzesii), DRYPETES (Drypetes glauca), KOBRESIA (Kobresia myosuroides), LITTLE BLUE STEM (Schizachyrium scoparium), PACIFIC RHODODENDRON (Rhododendron macrophyllum), PACIFIC DOGWOOD (Cornus nuttalii), RAMIN (Gonystylus bancanus), RED PINE (Pinus resinosa), SLASH PINE (Pinus elliottii), SPARTINA (Spartina alternaifolia), SUGAR MAPLE (Acer saccharum), VOCHYSIA (Vochysia ferragenea), WAX MYRTLE (Myrica cerifer), WESTERN REDCEDAR (Thuja plicata), WHEAT (Triticum aestivum), eastern white pine (Pinus strobus), YELLOW BIRCH (Betula lutea), WHITE FIR (Abies concolor), SUBALPINE FIR (Abies lasiocarpa), GYMNANTHES (Gymnanthes lucida). SOIL TYPE: Various soils, described in TD2305 file for each site. RESEARCH AREA/REGION: North America including one Central American site. SITE LOCATION: Twenty one sites are involved as of 10/90. These include the 17 LTER sites and 4 non-LTER sites. Seven additional sites were added in 1991 bringing the total to twenty-eight. Site LATITUDE LONGITUDE Andrews 44o14'N 122o11'W Arctic Lakes 68o38'N 149o34'W Barro Colorado 9o10'N 79o51'W Bonanza Creek 64o45'N 148o00'W Blodgett 38o52'N 105o38'W Cedar Creek 45o24'N 93o12'W Central Plains 40o49'N 104o46'W Coweeta 35o00'N 83o30'W Curley Valley Florida 29o30'N 82o15'W Guanica 17o57'N 65o52'W Hubbard Brook 43o56'N 71o45'W Harvard Forest 42o40'N 72o15'W Jornada 32o30'N 106o45'W Juneau 58o00'N 134o00'W Kellogg 42o24'N 85o24'W Konza 39o05'N 96o35'W LaSelva 10o00'N 83o00'W Loch Vale 40o17'N 105o39'W Luquillo 19o00'N 66o00'W Monte Verde 10o18'N 84o48'W Niwot Ridge 40o03'N 105o37'W North Inlet 33o30'N 79o13'W Northern Lakes 46o00'N 89o40'W Olympics 47o50'N 123o53'W Santa Margarita 33o30'N 106o40'W Sevilleta 34o29'N 106o40'N Virginia Coast 37o30'N 75o40'W PERMANENT PLOTS: STUDY PURPOSE, GOALS: The primary objective of this study is to examine the control that substrate quality and climate have on patterns of long-term decomposition and nitrogen accumulation in above- and below-ground fine litter. Of particular interest will be to examine the degree these two factors control the formation of stable organic matter and nitrogen after extensive decay. SITE CHARACTER: Site Mean Annual Thornthaite Temp C Precip mm AET mm Andrews 10 2500 552 Arctic Lakes -10 250 171 Barro Colorado 26 2614 Bonanza Creek -5 286 202 Blodgett 14 1121 363 Cedar Creek 11 660 726 Central Plains 9 311 309 Coweeta 13 1800 702 Curley Valley Florida 21 1350 Guanica 26 150 Hubbard Brook 5 1300 552 Harvard Forest 7 1119 578 Jornada 19 230 231 Juneau 4 1368 Kellogg 9 920 646 Konza 13 835 736 LaSelva 25 4000 Loch Vale 2 1115 Luquillo 23 3456 Monte Verde 18 2300 Niwot Ridge -4 930 257 North Inlet 16 1150 948 Northern Lakes 5 760 548 Olympics 10 3200 524 Santa Margarita 16 400 Sevilleta 16 229 223 Virginia Coast 14 1050 757 EXPERIMENTAL/SAMPLING DESIGN: The major factors to be considered in this experiment will be site, species of and type of litter (leaves, vs. roots vs dowels) , and time. Twenty-eight sites, representing a wide array of moisture and temperature conditions, will be used for litter incubations. Ten types of "standard" litters will be sent to each site. These include three types of fine roots (graminoid, hardwood, and conifer), six types of leaf litter (which range in lignin/nitrogen ratio from 5 to 75), and wooden dowels. Samples will be collected ten times; the time between samples will be one year for all sites except LaSelva and Luquillo which will collect samples every three months. There will be four replicates for each species, site and time. In addition to the standard litters, each site will be represented by a "wildcard" litter which appears at one site for each sample collection. The purpose of the wildcard species is to verify the predictions from the standard species. There will be four replicates for each wildcard species, site and time. METHODS: Litter Collection Each site was responsible for collecting the litter used in the experiments. For most sites, the leaf litter was collected directly from senesecent plants or as freshly fallen litter. Green leaves were collected from the Jornada, San Diego, Luquillo, and LaSelva sites. All leaf litter except, Drypetes glauca which was oven dried at 40 C to prevent decay, was air dried prior to shipment to Oregon State University. Fine roots (<2 mm diameter) were collected by two methods: tropical hardwood (Drypetes glauca) and pine (Pinus elliotii) fine roots were collected by excavating surface roots and washing. Graminoid roots were collected from material exposed along stream banks. Graminoid and pine roots were air dried, whereas the tropical hardwood roots were oven dried at 40 C to prevent decomposition. In the case of the LaSelva site, the litter was sterilized after the bags were filled to kill all invertebrates, fungi, and virus prior to shipment. Sterilization was conducted at the Battelle National Laboratory by exposing the litter to 20 hours of gamma rays with 60Co as the source. The total exposure was 2 Mrad. Bag Design All bags were 20- by 20-cm and filled with 10 g leaves or 5-7 g of fine roots. Each bag was identified with a unique number embossed on an aluminum tag. The bag openings were sealed with six monel staples. The initial air dry weight, calculated oven dry weight, species, site, replicate number for each litterbag were recorded prior to placement in the field. Subsamples of litter material were taken to determine the air dry to oven dry conversion factor and the initial chemistry of the litter. Moisture content of the air dried litter ranged from 2-10% moisture content. Three types of bags were used in this experiment. For the long-term leaf litter experiment the bags had a top mesh of 1 mm and a bottom of 55 micron mesh. The bags used for fine roots were entirely of 55 micron mesh. The bags used in the mesh size effects study had a top of 7 mm mesh and a bottom of 55 micron mesh. Dowels The wooden dowels used in the experiment are made of ramin (Gonystlylus bancannus). This species is a tropical hardwood from southeast Asia. It is not resistant to decay and rated as perishable. The dowels are 13 mm in diameter and 61 cm in length. One half of the dowel is to be embedded vertically into the soil and the other half is to be exposed to aerial conditions. The air dry weight of each dowel was recorded, and a subsample of dowels was measured for diameter, density, air dry moisture content, nitrogen content, and carbon chemistry. In 1994 a second group of wooden dowels was sent out to all LIDET sites. These dowels have a sleeve of 1 mm mesh on the lower 30.5 cm with an attached aluminum tag identical to the tag attached to the upper half of the dowel. A 20 cm section of orange plastic flagging is sewn into the top corner of the mesh sleeve. Recovery of the initial dowels, particularly the below-ground portion, has been difficult and the marked, tagged sleeve should improve recovery. Sample Placement Samples were placed in the field during fall of 1990, or 1991, by each of the participating sites. Locations were near climatic stations and in areas protected from disturbances that could destroy the litter bags. The locations were also selected to be typical of areas that other intersite decomposition experiments might be conducted. The exact method for placement varied from site to site, but the following standards were applied: 1) Four separate locations were selected to avoid pseudo- replication problems. 2) Each set of bags to be collected was connected by a cord; these sets of bags should be laid out in parallel lines in a random order. 3) Leaf litterbags should be placed so that contact with the underlying litter layer is made. Fine root litterbags will be inserted into the upper mineral soil (humus layer for histosols). A vertical cut with a shovel, the bag inserted the correct depth (0-20 cm), and another cut should be used to press the soil against the bag (Figure 3). 4. Dowels should be installed at the end of the string opposite the fine root bags. The dowels were placed so that 30 cm is exposed to the air and 30 cm is embedded in the soil. Sample Processing Once the litter or dowels are collected they should be oven dried in paper bags at 55oC until the mass is stable. In the case of fine roots and dowels, a rinse with distilled water to remove adhering soil prior to drying is recommended. Any mosses, lichens, fine roots, or other plant parts that have grown into the bags or dowels should also be removed prior to harvesting. Samples will be pooled by species, site, and time for grinding and archiving. A subset of unpooled samples will also be saved to determine the internal variability of pooled samples. Chemical analyses will be performed using two methods. Each pooled sample from each species, site, and time will be analyzed for total nitrogen, lignin, and cellulose using near infrared reflectance spectoscopy (Wessman et al. 1988). Internal variability of samples will be estimated by running replicates of high and low lignin species. Twenty five percent of the pooled samples will also be sampled for Kjeldahl nitrogen, lignin, cellulose, water extractive, non- polar extractive, and ash content using wet chemical methods. Wet chemical methods will then be used to calibrate the near infrared reflectance spectoscopy methods. Wessman, C. A., J. D. Aber, D. L. Peterson, and J. M. Melillo. 1988. Foliar analysis using near infrared reflectance spectroscopy. Can. J. For. Res. 18:6-11 UPDATE HISTORY: March 96: Data has been entered into the appropriate data formats and is fairly complete through year 4. Current work includes development of Near Infrared Reflectance Analysis of samples to determine N content, continuing processing of incoming samples, and reformating and proofing of existing data. COMMENTS: