LBA-ECO LC-13 GIS COVERAGES OF LOGGED AREAS, TAPAJOS FOREST, PARA, BRAZIL: 1996, 1998
Entry ID:
LC13TAPAJOS
|
[
Get Data
]
[
Update this Record
]
|
Updating this record requires registration.
|
Summary
Abstract:
We combined a detailed field study of canopy gap fraction with spectral mixture analysis of Landsat ETM+ satellite imagery to assess landscape and regional dynamics of canopy damage following selective logging in an eastern Amazon forest. Our field studies encompassed measurements of ground damage and canopy gap fractions along multitemporal sequences of post-harvest regrowth of 0.5-3.5 yr. Areas ... used to stage harvested logs prior to transport, called log decks, had the largest forest gap fractions, but their contribution to the landscape-level gap dynamics was minor. Tree falls were spatially the most extensive form of canopy damage following selective logging, but the canopy gap fractions resulting from them were small. Reduced-impact logging resulted in consistently less damage to the forest canopy than did conventional logging practices. This was true at the level of individual landscape strata such as roads, skids, and tree falls as well as at the area-integrated scale. A spectral mixture model was employed that utilizes bundles of field and image spectral reflectance measurements with a Monte Carlo analysis to estimate high spatial resolution (subpixel) cover of forest canopies, exposed nonphotosynthetic vegetation, and soils in the Landsat imagery. The method proved highly useful for quantifying forest canopy cover fraction in the log decks, roads, skids, tree fall, and intact forest areas, and it tracked caopy damage up to 3.5 yr post-harvest. Forest canopy cover fractions derived from satellite observations were highly and inversely correlated with field- and satellite-based measurements. A 450-km^2 study of gap fraction showed that approximately one-half of the canopy opening caused by logging is closed within one year of regrowth following timber harvests. This is the first regional-scale study utilizing field measurements, satellite observations, and models to quantify forest canopy damage and recovery following selective logging in the Amazon.
Related URL
Description:
LBA-ECO LC-13 GIS COVERAGES OF LOGGED AREAS, TAPAJOS FOREST, PARA, BRAZIL: 1996, 1998
|
Geographic Coverage
(Click for Interactive Map)
Spatial coordinates
| |
N: -2.25
|
|
S: -3.5
|
|
E: -54.0
|
|
W: -56.0
|
Temporal Coverage
Start Date:
1984-01-01
Stop Date:
1989-12-31
Quality
Samples were obtained from the dust traps by carefully washing the marbles, screen, and pan with distilled water into plastic liter bottles. In the laboratory, the sample was gradually dried at about 35C in large evaporating dishes; coarse organic material is removed during this process. Subsequent analyses on dust samples ... included, in the order they were performed: (1) moisture, (2) organic matter, (3) soluble salts and gypsum, (4) total carbonate (calcite plus dolomite), (5) grain size, (6) major-oxide chemistry, and (7) mineralogy (sand, silt, and clay fractions). The database for any given site commonly contains gaps depending on how far the sample for a particular year could be stretched through the analytical cascade. In some cases, samples from different years at the same site or adjacent sites were combined to obtain enough material for measuring grain size. A sample was commonly retrieved and used in more than one analysis if the first analytical procedure used was non- destructive. These sequential analytical techniques included: (1) Moisture and organic-matter content (Walkley- Black procedure in Black, 1965) were measured on the same split using 0.05 g. (2) The entire sample was used to extract the solution to measure soluble salts (Jackson, 1958) and was then dried and recovered; thus, subsequent analyses were performed on samples without soluble salts. (3) A 0.25-g split was used to analyze total carbonate (Chittick procedure in Singer and Janitzky, 1986). This split, free of carbonate after the analysis, was recovered and used to analyze for major oxides and zirconium. (4) When sufficient sample (0.4g) existed to obtain grain size using the Sedigraph rather than by pipette analysis, the clay and silt fractions were saved and used to analyze mineralogy by X-ray diffraction. Most of the laboratory analyses were performed in the Sedimentation Laboratory of the Institute of Arctic and Alpine Research in Boulder, Colorado, using standard laboratory techniques for soil samples (see Black, 1965, and Singer and Janitzky, 1986) that we adapted for use on very small samples (the non-organic content of a dust sample collected from one trap typically weighs less than 1 g/yr). These adaptations generally result in larger standard errors than normal for the results of different techniques because the amount of sample used is smaller than the recommended amount. The sampling design for this study was not statistically based; rather, sites were chosen to provide data on dust influx at soil- study sites and to answer specific questions about the relations of dust to local source lithology and type, distance from source, and climate. Some sites were chosen for their proximity to potential dust sources of different lithologic composition (for example, playas versus granitic, calcic, or mafic alluvial fans). Other sites were placed along transects crossing topographic barriers downwind from a dust source. These transects include sites east of Tonopah (43-46) crossing the rhyolitic Kawich Range, sites downwind of northern (40, 35, 36) and central Death Valley ( 38, 39, 11-14) crossing the mixed-lithology Grapevine and Funeral Mountains, respectively, and sites downwind of Desert Dry Lake crossing the calcareous Sheep Range (47-50) north of Las Vegas. In addition, some sites were chosen for their proximity to weather stations. Specific locations for dust traps were chosen on the basis of the above criteria plus accessibility, absence of dirt roads or other artificially disturbed areas upwind, and inconspicuousness. The last factor is important because the sites are not protected or monitored; hence, most sites are at least 0.5 mile from a road or trail. Despite these precautions, dust traps are sometimes tampered with, often violently. This is a particular problem in areas close to population centers, and most of these sites (52-55 near Los Angeles and 17-19 and 22 near Las Vegas) have been abandoned. A few other sites, mostly those that appeared to be greatly influenced by nearby farming (20, 21, and 41), were eliminated in 1989. Dust traps were also generally placed in flat, relatively open areas to mitigate wind-eddy effects created by tall vegetation or topographic irregularities. The 55 sites established in 1984 and 1985 were sampled annually through 1989 in order to establish an adequate statistical basis to calculate annual dust flux. Sampling continues at 37 of these sites (many sites now have two or more dust traps) every two or three years as opportunity and funding permit. The most important factors that influenced dust-trap design in this study were: (1) measuring the amount of dust added to soils; (2) sampling on an annual basis; (3) no protection other than being hard to find; and (4) the cost and ready availability of components that might have to be replaced from sources in small towns. The original design consists of a single-piece Teflon- coated angel-food cake pan (see note 1) painted flat black on the outside to maximize water evaporation and mounted on a steel fence post about 2 m above the ground. A circular piece of 1/4-inch- mesh galvanized hardware cloth is fitted into the pan so that it rests 3-4 cm below the rim, and glass marbles fill the upper part of the pan above the hardware cloth. The Teflon coating is non- reactive and adds no mineral contamination to the dust sample should it flake. The hardware cloth resists weathering under normal conditions. The 2-m height eliminates most sand-sized particles that travel by saltation rather than by suspension in air; sand grains are not generally pertinent to soil genesis because they are too large to be translocated downward into soil profiles. The marbles imitate the effect of a gravelly fan surface and prevent dust that has filtered or washed into the bottom of the pan from being blown away. The empty space below the hardware cloth provides a reservoir that prevents water from overflowing the pan during large storms. This basic design was modified in 1986 in two ways. In many areas, the traps became favored perching sites for a wide variety of birds. As a result, significant amounts of non-eolian sediment were locally added to the samples (as much as five times the normal amount of dust at some sites). All dust traps were fitted with two metal straps looped in an inverted basket shape over the top and the top surfaces of the straps were coated with Tanglefoot1. This sticky material never dries (although it eventually becomes saturated with dust and must be reapplied) and effectively discourages birds from roosting. In addition, extra dust traps surrounded by alter- type wind baffles were constructed at four sites characterized by different plant communities. These communities and sites are: blackbrush (Coleogyne ramosissima), creosote bush (Larrea divaricata), and other low brushy plants at sites 1-5 on Fortymile Wash; Joshua tree (Yucca brevifolia), other tall yucca species, and blackbrush at site 18 on the Kyle Canyon fan; pinyon-juniper (Pinus monophylla-Juniperus sp) at site 7 on Pahute Mesa; and acacia (acacia sp), creosote bush, and blackbrush at site 26 near the McCoy Mountains. The wind baffles imitate the effect of ground-level wind speed at the 2-m height of the dust trap and permit comparison of the amount of dust caught by an unshielded trap with the amount that should be caught at ground level where vegetation breaks the wind. See notes in the Attribute_Accuracy_Report regarding combination of samples too small for individual analyses. Generally the data from ICP, oxides, and mineralogy are for combined samples. 
Access Constraints
None
Use Constraints
None
Data Set Progress
COMPLETE
Personnel
Role:
TECHNICAL CONTACT
Phone:
303-236-1270
Fax:
303-236-5349
Email:
mreheis at usgs.gov
Contact Address:
U.S. Geological Survey
MS 980, Box 25046
Denver Federal Center
City:
Denver
Province or State:
CO
Postal Code:
80225-0046
Country:
USA
Role:
DIF AUTHOR
Phone:
(301) 614-6898
Fax:
301-614-5268
Email:
Tyler.B.Stevens at nasa.gov
Contact Address:
NASA Goddard Space Flight Center
Global Change Master Directory
City:
Greenbelt
Province or State:
MD
Postal Code:
20771
Country:
USA
Publications/References
Reheis, M.C., and Kihl, R., 1995, Dust Deposition in Southern Nevada and California, 1984-1989: Relations to Climate, Source Area, and Lithology, Journal of Geophysical Research, v. 100D5, p. 8893-8918.
Extended Metadata Properties
(Click to view more)
Creation and Review Dates
DIF Creation Date:
2003-04-29
Last DIF Revision Date:
2012-12-12
Future DIF Review Date:
2004-04-29
|
[
Update this Record
]
|
Updating this record requires registration.
|
|