The litterfall study was designed to assess the quantity of biomass (leaves, twigs, reproductive materials) falling from tree species in different ecosystem types. Three study sites selected were: (1) the pinyon-juniper woodland site near Cerro Montoso on the Sevilleta NWR; (2) the cottonwood forest LTER site along the Rio Grande at Bosque del Apache NWR; and (2) the old-growth spruce-fir-aspen site near South Baldy in the Magdalena Mountains (Cibola National Forest). The study was conducted over two years (1992-1993) to compare litterfall rates and quantities among sites, seasons and years.
To assess differences in rates and quantities of leaf, twig, reproductive parts (nuts, seeds, berries) of litterfall from tree species in various ecosystems studied by the Sevilleta LTER Program.
A total of 120 litterfall baskets were distributed among the 3 study sites. In the Sevilleta's Cerro Montoso site, 30 baskets were placed under juniper trees, and 30 were placed under pinyon trees. At the Bosque del Apache site, 30 baskets were placed in 3 transect lines of 10 baskets each, at 10 meter intervals, through the cottonwood forest. At the Magdalena Mountain site, 30 baskets were placed in 3 transect lines of 10 baskets each, at 10 meter intervals (as in the Bosque site).
Each basket was considered a sample unit.
Frequency of Sampling:
During the same times as arthropod pitfall collections (several times/year)
120 baskets total. Each basket was a rubber basin with a small (5 mm) hole drilled in the bottom to allow rainwater and snowmelt to drain out. Basket dimensions were circular, with a diameter of 41.5 cm at the top rim, tapering inward to a diameter of 35 cm at the basket bottom. The basket height was 12.5 cm.
Litterfall baskets were place under tree canopies to catch falling leaves, twigs, and reproductive parts. In the Bosque del Apache and Magdalena Mountain sites, the baskets were placed systematically in 3 transect lines through the forest (which generally had a closed canopy). In the Pinyon-Juniper site on SNWR, the baskets were placed under individual trees (basket locations were halfway between the trunk and the edge of the canopy) due to the patchiness of tree locations. Hence, the results for this site are for a "per tree" basis, and should be scaled up to reflect different tree densities in various Pinyon-Juniper sites.
Litterfall samples were collected by placing all litter into plastic zip-lock bags, marking each bag with the basket tag number, and taking the bags back to the laboratory. If samples were wet from rain/snowfall, the sample bags were opened and allowed to air-dry for several days. Litter was then sorted by category (leaf, twig, reproductive part, or "miscellaneous" if the part could not be recognized) and by species. The sorted litter was then oven dried at 60 degrees Centigrade for one week, and weighed on a Mettler top-loading balance.
Magdalen Mountains Site, Cibola National Forest:
- Soil: rocky soils, with high organic matter (litter) below tree canopies.
- Slope/Aspect: Various, ranging from flat to 30 degrees. Easterly aspect.
- Vegetation Community: Mixed-species conifer forest with aspens.
- Terrain/Physiography: Mountainous
- Geology/Lithology: Magdalena Mountains, derived from volcanic activity.
- Hydrology - surface/groundwater: Virtually no runoff during storms due to deep litter layer.
- Size: sampling area covered approximately 1 ha
- History (if known): Old growth forest, no logging and no fire history.
- Elevation: 3,243 meters at weather station (station #46).
- Climate (general): A summary of the meteorological data from the Langmuir Laboratory weather station in the Magdalena Mountains is shown below. For further climate details and data, consult the Sevilleta Meteorology databases.