USGS Science⌕ Search

SEARCH · USGS Science

Results for “Journal of Forest Science”

Search indexed USGS publications on groundwater, aquifers, geologic maps, mineral resources and earthquakes. Explore source records by subject and place.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 73 records · Page 4Linked to original sources
USGS2016

The automated reference toolset: A soil-geomorphic ecological potential matching algorithm

Ecological inventory and monitoring data need referential context for interpretation. Identification of appropriate reference areas of similar ecological potential for site comparison is demonstrated using a newly developed automated reference toolset (ART). Foundational to identification of reference areas was a soil map of particle size in the control section (PSCS), a theme in US Soil Taxonomy. A 30-m resolution PSCS map of the Colorado Plateau (366,000 km 2 ) was created by interpolating ∼5000 field soil observations using a random forest model and a suite of raster environmental spatial layers representing topography, climate, general ecological community, and satellite imagery ratios. The PSCS map had overall out of bag accuracy of 61.8% (Kappa of 0.54, p < 0.0001), and an independent validation accuracy of 93.2% at a set of 356 field plots along the southern edge of Canyonlands National Park, Utah. The ART process was also tested at these plots, and matched plots with the same ecological sites (ESs) 67% of the time where sites fell within 2-km buffers of each other. These results show that the PSCS and ART have strong application for ecological monitoring and sampling design, as well as assessing impacts of disturbance and land management action using an ecological potential framework. Results also demonstrate that PSCS could be a key mapping layer for the USDA-NRCS provisional ES development initiative.

Soil Science Society of America Journal↗
USGS2009

Development of time series stacks of Landsat images for reconstructing forest disturbance history

Forest dynamics is highly relevant to a broad range of earth science studies, many of which have geographic coverage ranging from regional to global scales. While the temporally dense Landsat acquisitions available in many regions provide a unique opportunity for understanding forest disturbance history dating back to 1972, large quantities of Landsat images will need to be analysed for studies at regional to global scales. This will not only require effective change detection algorithms, but also highly automated, high level preprocessing capabilities to produce images with subpixel geolocation accuracies and best achievable radiometric consistency, a status called imagery-ready-to-use (IRU). This paper describes a streamlined approach for producing IRU quality Landsat time series stacks (LTSS). This approach consists of an image selection protocol, high level preprocessing algorithms and IRU quality verification procedures. The high level preprocessing algorithms include updated radiometric calibration and atmospheric correction for calculating surface reflectance and precision registration and orthorectification routines for improving geolocation accuracy. These automated routines have been implemented in the Landsat Ecosystem Disturbance Adaptive System (LEDAPS) designed for processing large quantities of Landsat images. Some characteristics of the LTSS developed using this approach are discussed.

International Journal of Digital Earth↗
USGS2020

A hybrid approach for predictive soil property mapping using conventional soil survey data

Soil property maps are important for land management and earth systems modeling. A new hybrid point-disaggregation predictive soil property mapping strategy improved mapping in the Colorado River Basin, and can be applied to other areas with similar data (e.g. conterminous United States). This new approach increased sample size ~6-fold over past efforts. Random forests related environmental raster layers representing soil forming factors to samples to predict 15 soil properties (pH, texture fractions, rock, electrical conductivity, gypsum, CaCO3, sodium adsorption ratio, available water capacity, bulk density, erodibility, organic matter) at 7 depths, depth to restrictive layer, and surface rock size and cover. Cross-validations resulted in coefficient of determinations averaging 0.52, with a range of 0.20 to 0.76; and mean absolute errors ranged from 3% to 98% of training data averages with a mean of 41%. Uncertainty estimates were also developed by creating relative prediction intervals (RPIs) for the entire study area, which allow end users to evaluate uncertainty relative to original data distributions. Average error increased with higher RPI values (higher uncertainty), and areas with the highest RPI are consistently under-sampled, suggesting that additional sampling in these areas may improve prediction accuracy. Greater uncertainty was also observed in areas with shale parent materials and physiographic settings uncommon relative to the broader study area.

New Mexico, Colorado, Wyoming, Utah, Nevada, Arizo↗
USGS2025

Resource selection of the southern fox squirrel (Sciurus niger niger) in the coastal plain of Virginia

The southern fox squirrel ( Sciurus niger niger ) is a subspecies of fox squirrel that ranges from southeastern Virginia to northern Florida. Throughout its Southeastern range, southern fox squirrel habitat of natural mixed pine-hardwood forests has been fragmented by agriculture and short-rotation pine plantations. In Virginia, remaining habitat has been transformed by fire suppression on the landscape and has in turn resulted in small, disjunct populations of southern fox squirrels. We sought to identify the home range and resource utilization of southern fox squirrels in the southern Coastal Plain of Virginia. From established nest boxes, we captured, radio collared and tracked four individuals at Big Woods Wildlife Management area and Piney Grove Complex in Sussex County in 2022. We observed an average male 95% and 50% adaptive kernel home range 173.49 ha (SE = 25.73, N = 2) and 40.62 ha (SE = 5.87, N = 2), respectively and an average female 95% and 50% adaptive kernel home range of 28.51 ha (SE = 0.49, N = 2) and 4.71 ha (SE = 0.34, N = 2), respectively. At both the second and third orders of habitat selection, squirrels selected for pine savanna cover types and short fire-return intervals.

Virginia↗
USGS2009

Fire and vegetation history on Santa Rosa Island, Channel Islands, and long-term environmental change in southern California

The long-term history of vegetation and fire was investigated at two locations – Soledad Pond (275 m; from ca. 12 000 cal. a BP) and Abalone Rocks Marsh (0 m; from ca. 7000 cal. a BP) – on Santa Rosa Island, situated off the coast of southern California. A coastal conifer forest covered highlands of Santa Rosa during the last glacial, but by ca. 11 800 cal. a BP Pinus stands, coastal sage scrub and grassland replaced the forest as the climate warmed. The early Holocene became increasingly drier, particularly after ca. 9150 cal. a BP, as the pond dried frequently, and coastal sage scrub covered the nearby hillslopes. By ca. 6900 cal. a BP grasslands recovered at both sites. Pollen of wetland plants became prominent at Soledad Pond after ca. 4500 cal. a BP, and at Abalone Rocks Marsh after ca. 3465 cal. a BP. Diatoms suggest freshening of the Abalone Rocks Marsh somewhat later, probably by additional runoff from the highlands. Introduction of non-native species by ranchers occurred subsequent to AD 1850. Charcoal influx is high early in the record, but declines during the early Holocene when minimal biomass suggests extended drought. A general increase occurs after ca. 7000 cal. a BP, and especially after ca. 4500 cal. a BP. The Holocene pattern closely resembles population levels constructed from the archaeological record, and suggests a potential influence by humans on the fire regime of the islands, particularly during the late Holocene.

California↗
USGS1997

Woody debris decomposition in the Atchafalaya River Basin of Louisiana following hurricane disturbance

The contribution of woody debris to some biogeochemical functions of forested wetlands was examined in the Atchafalaya River Basin in Louisiana following disturbance by Hurricane Andrew. Woody debris decomposition processes were characterized in terms of mass, C, N, and P dynamics. These were compared between different diameters of debris, areas recieving different intensities of disturbance, and between different positions relative to the soil. Disturbance intensity (as defined by canopy closure) had little effect on decomposition processes when compared with soil orientation (i.e., whether in contact with or suspended above the soil). Rates of mass loss varied between 0.055 and 0.068 for suspended and ground-contact coarse woody debris, respectively. Fine woody debris rate coefficients averaged 0.060 and 0.085 for the same respective orientations. In general, woody debris displayed strong source activity for P but a greater tendency toward sink behavior for N. In terms of biogeochemical transformations, these data suggest that woody debris might act as a phosphate source during sheet flow events but could provide short-term retention of inorganic N associated with floodwaters.

Louisiana↗
USGS2012

Strategies for soil quality assessment using VNIR gyperspectral spectroscopy in a western Kenya Chronosequence

Visible and near-infrared reflectance spectroscopy (VNIRS) is a rapid and nondestructive method that can predict multiple soil properties simultaneously, but its application in multidimensional soil quality (SQ) assessment in the tropics still needs to be further assessed. In this study, VNIRS (350–2500 nm) was employed to analyze 227 air-dried soil samples of Ultisols from a soil chronosequence in western Kenya and assess 16 SQ indicators. Partial least squares regression (PLSR) was validated using the full-site cross-validation method by grouping samples from each farm or forest site. Most suitable models successfully predicted SQ indicators (R 2 ≥ 0.80; ratio of performance to deviation [RPD] ≥ 2.00) including soil organic matter (OM LOI ), active C, Ca, cation exchange capacity (CEC), and clay. Moderately-well predicted indicators (0.50 ≤ R 2 < 0.80; 1.40 ≤ RPD < 2.00) were water stable aggregation (WSA), Cu, silt, Mg, pH, sand, water content at permanent wilting point (Θ pwp ), and field capacity (Θ fc ). Poorly predicted indicators (R 2 < 0.50; RPD < 1.40) were EC, S, P, available water capacity (AWC), K, Zn, and penetration resistance. Combining VNIRS with selected field- and laboratory-measured SQ indicator values increased predictability. Furthermore, VNIRS showed moderate to substantial agreement in predicting interpretive SQ scores and a composite soil quality index (CSQI) especially when combined with directly measured SQ indicator values. In conclusion, VNIRS has good potential for low cost, rapid assessment of physical and biological SQ indicators but conventional soil chemical tests may need to be retained to provide comprehensive SQ assessments.

Western Kenya↗
USGS2016

Invasive European bird cherry disrupts stream-riparian linkages: effects on terrestrial invertebrate prey subsidies for juvenile coho salmon

The spread of invasive species in riparian forests has the potential to affect both terrestrial and aquatic organisms linked through cross-ecosystem resource subsidies. However, this potential had not been explored in regards to terrestrial prey subsidies for stream fishes. To address this, we examined the effects of an invasive riparian tree, European bird cherry (EBC, Prunus padus ), spreading along urban Alaskan salmon streams, by collecting terrestrial invertebrates present on the foliage of riparian trees, their subsidies to streams, and their consumption by juvenile coho salmon ( Oncorhynchus kisutch ). Riparian EBC supported four to six times less terrestrial invertebrate biomass on its foliage and contributed two to three times lower subsidies relative to native deciduous trees. This reduction in terrestrial invertebrate biomass was consistent between two watersheds over 2 years. In spite of this reduction in terrestrial prey resource input, juvenile coho salmon consumed similar levels of terrestrial invertebrates in stream reaches bordered by EBC. Although we did not see ecological effects extending to stream salmonids, reduced terrestrial prey subsidies to streams are likely to have negative consequences as EBC continues to spread.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS2009

Sources and transformations of nitrate from streams draining varying land uses: Evidence from dual isotope analysis

Knowledge of key sources and biogeochemical processes that affect the transport of nitrate (NO 3 - ) in streams can inform watershed management strategies for controlling downstream eutrophication. We applied dual isotope analysis of NO 3 - to determine the dominant sources and processes that affect NO 3 - concentrations in six stream/river watersheds of different land uses. Samples were collected monthly at a range of flow conditions for 15 mo during 2004-05 and analyzed for NO 3 - concentrations, ?? 15 N NO3 , and ?? 18 O NO3 . Samples from two forested watersheds indicated that NO 3 - derived from nitrification was dominant at baseflow. A watershed dominated by suburban land use had three ?? 18 O NO3 values greater than +25???, indicating a large direct contribution of atmospheric NO 3 - transported to the stream during some high flows. Two watersheds with large proportions of agricultural land use had many ?? 15 N NO3 values greater than +9???, suggesting an animal waste source consistent with regional dairy farming practices. These data showed a linear seasonal pattern with a ?? 18 O NO3 :?? 15 N NO3 of 1:2, consistent with seasonally varying denitrification that peaked in late summer to early fall with the warmest temperatures and lowest annual streamflow. The large range of ?? 15 N NO3 values (10???) indicates that NO 3 - supply was likely not limiting the rate of denitrification, consistent with ground water and/or in-stream denitrification. Mixing of two or more distinct sources may have affected the seasonal isotope patterns observed in these two agricultural streams. In a mixed land use watershed of large drainage area, none of the source and process patterns observed in the small streams were evident. These results emphasize that observations at watersheds of a few to a few hundred km 2 may be necessary to adequately quantify the relative roles of various NO 3 - transport and process patterns that contribute to streamflow in large basins. Copyright ?? 2009 by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. All rights reserved.

Journal of Environmental Quality↗
USGS2012

Early indications of soil recovery from acidic deposition in U.S. red spruce forests

Forty to fifty percent decreases in acidic deposition through the 1980s and 1990s led to partial recovery of acidified surface waters in the northeastern United States; however, the limited number of studies that have assessed soil change found increased soil acidification during this period. From existing data, it's not clear whether soils continued to worsen in the 1990s or if recovery had begun. To evaluate possible changes in soils through the 1990s, soils in six red spruce (Picea rubens Sarg.) stands in New York, Vermont, New Hampshire, and Maine, first sampled in 1992 to 1993, were resampled in 2003 to 2004. The Oa-horizon pH increased (P < 0.01) at three sites, was marginally higher (P < 0.1) at one site, and lower (P < 0.05) at the New York site. Total C concentrations in Oa horizons decreased (P < 0.05) at sites where the pH increased, but the cause is uncertain. Exchangeable Al concentrations in Oa horizons decreased (P < 0.05) 20 to 40% at all sites except New York, which showed no change. The Al decrease can be attributed to decreased deposition of SO 4 2− , which decreased the mobility of Al throughout the upper soil profile. Results indicate a nascent recovery driven largely by vegetation processes.

Soil Science Society of America Journal↗
USGS2025

Being loud to find a quiet bird: Surveying a secretive tropical avian species

Secretive birds are hard to detect, and thus, likely underestimated when surveyed, potentially preventing measures to protect them. We identified a sampling period and method that would yield the most reliable estimates of population numbers of the secretive Puerto Rican Lizard-Cuckoo ( Coccyzus vieilloti ). We addressed these objectives by comparing point counts (passive) and playback broadcast (active) survey methods from January to December, 2022 at Cambalache State Forest, Puerto Rico. We surveyed 20 stations (radius = 50 m each) between sunrise and 10 am, employing the time-of-detection method. We recorded strong responses from C. vieilloti after birds had been stimulated by playback broadcasts (recapture probabilities), corresponding to a behavioral response (M b ). For example, average capture (p) and recapture (c) probabilities within the peak breeding season for active surveys were 0.23 ± 0.10 and 0.49 ±0.08, respectively. Active surveys yielded higher estimates of C. vieilloti compared to passive surveys. For example, active survey expected population numbers (15.6 ha or area sampled) during peak breeding season were 42.87 ± 12.08 compared to 19.60 ± 2.08 individuals from passive surveys. Coefficients of variation population estimates of active surveys ranged between 10 and 16%, with one exception (28%), well within acceptable levels for wildlife studies. We show that secretive species like C. vieilloti can be reliably surveyed using playback broadcasts. Surveys should be conducted during the peak breeding season when estimates are higher and have better precision. Conducting similar tests on other secretive species could ensure that their status is not mischaracterized and that they receive the benefits of appropriate conservation measures, if warranted.

Cambalache State Forest, Puerto Rico↗
USGS1990

Coal in sub-Saharan-African countries undergoing desertification

Coal has been reported in 11 of the 16 sub-Saharan countries discussed in this appraisal: Mauritania, Senegal, Mali, Niger, Benin, Nigeria, Cameroon, Central African Republic, Sudan, Ethiopia, and Somalia. No coal occurrences have been reported in Gambia, Togo, Burkina, Chad, and Djibouti but coal may be present within these countries because neighboring countries do contain coal-bearing rocks. Most of these countries are undergoing desertification or will in the near future. Wood, directly or in the form of charcoal, constitutes two-thirds of the fuel used in Africa. Destruction of forest and shrub lands for fuel is occurring at an increasing rate because of desertification and increasing energy demands. The decline in biological productivity, coupled with concentration of population in areas where water is available and crops may be grown, leads to increasing shortages of wood for fuel. Part of the present and future energy needs of the sub-Saharan region could be met by use of indigenous coal and peat. Nine sedimentary basins, completely or partially within the sub-Saharan region, have the potential of either coal and/or peat deposits of economic value: 1- Senegal Basin, 2- Taoudeni Basin and Gao Trough, 3- Niger Basin, 4- Chad Basin, 5- Chari Basin, 6- Benue Trough (Depression), 7- Sudan Trough, 8- Plateau and Rift Belt, and 9- Somali Basin. Niger and Nigeria are the only countries in sub-Saharan Africa in which coal is presently being mined as a fuel source for powerplants and domestic use. Peat occurs in the deltas, lower river, and interdunal basin areas of Senegal, Mauritania, and Sudan. Peat can be used as an alternate fuel source and is currently being tested as a soil amendment in the agricultural sector.

Journal of African Earth Sciences↗
USGS2018

Soil property and class maps of the conterminous United States at 100-meter spatial resolution

With growing concern for the depletion of soil resources, conventional soil maps need to be updated and provided at finer and finer resolutions to be able to support spatially explicit human–landscape models. Three US soil point datasets—the National Cooperative Soil Survey Characterization Database, the National Soil Information System, and the Rapid Carbon Assessment dataset—were combined with a stack of over 200 environmental datasets and gSSURGO polygon maps to generate complete coverage gridded predictions at 100-m spatial resolution of six soil properties (percentage of organic C, total N, bulk density, pH, and percentage of sand and clay) and two US soil taxonomic classes (291 great groups [GGs] and 78 modified particle size classes [mPSCs]) for the conterminous United States. Models were built using parallelized random forest and gradient boosting algorithms as implemented in the ranger and xgboost packages for R. Soil property predictions were generated at seven standard soil depths (0, 5, 15, 30, 60, 100, and 200 cm). Prediction probability maps for US soil taxonomic classifications were also generated. Cross validation results indicated an out-of-bag classification accuracy of 60% for GGs and 66% for mPSCs; for soil properties, RMSE for leave-location-out cross-validation was 0.74 ( R 2 = 0.68), 17.8 wt% ( R 2 = 0.57), 12 wt% ( R 2 = 0.46), 3.63 wt% ( R 2 = 0.41), 0.2 g cm −3 ( R 2 = 0.42), and 0.27 wt% ( R 2 = 0.39) for pH, percent sand and clay, weight percentage of organic C, bulk density, and weight percentage of total N, respectively. Nine independent validation datasets were used to assess prediction accuracies for soil class models, and results ranged between 24 and 58% and between 24 and 93% for GG and mPSC prediction accuracies, respectively. Although mapping accuracies were variable and likely lower than gSSURGO in some areas, this modeling approach can enable easier integration of soil information with spatially explicit models compared with multicomponent map units.

Soil Science Society of America Journal↗
USGS2001

Processes regulating watershed chemical export during snowmelt, fraser experimental forest, Colorado

In the Central Rocky Mountains, snowfall dominates precipitation. Airborne contaminants retained in the snowpack can affect high elevation surface water chemistry during snowmelt. At the Fraser Experimental Forest (FEF), located west of the Continental Divide in Central Colorado, snowmelt dominates the annual hydrograph, and accounts for >95% of annual stream water discharge. During the winters of 1989-1993, we measured precipitation inputs, snowpack water equivalent (SWE) and ion content, and stream water chemistry every 7-10 days along a 3150-3500 m elevation gradient in the subalpine and alpine Lexen Creek watershed. The study objectives were to (1) quantify the distribution of SWE and snowpack chemical content with elevation and aspect, (2) quantify snowmelt rates, temperature of soil, snowpack, and air with elevation and aspect, and (3) use change in upstream-downstream water chemistry during snowmelt to better define alpine and subalpine flowpaths. The SWE increased with elevation (P < 0.001) and was greater on NE aspects (P < 0.05). Subalpine soils were unfrozen. Snowmelt occurred throughout winter at low elevation (3150 m), SE aspect stations. By snowpack peak water equivalent (PWE), the snowpack lost about a third (0.24 m) of its moisture. The subalpine snowpack had warm (> - 3??C) temperatures throughout winter which resulted in significant snowpack ion loss. By snowpack PWE in mid May, the snowpack had lost almost half the cumulative precipitation H+, NH4+, and SO42- inputs and a third of the NO3- input. Windborne soil particulate inputs late in winter increased snowpack base cation content. Variation in subalpine SWE and snowpack ion content with elevation and aspect, and wind redistribution of snowfall in the alpine resulted in large year-to-year differences in the timing and magnitude of SWE, PWE, and snowpack ion content. The alpine stream water ion concentrations changed little during snowmelt indicating meltwater passed quickly through surface porous soils and was well mixed before entering the stream. Conversely, subalpine stream water chemistry was diluted during snowmelt suggesting much melt water moved to the stream as shallow subsurface lateral flow. Published by Elsevier Science B.V.

Journal of Hydrology↗
USGS2019

Late-Glacial paleoecology of the Middle Susitna Valley, Alaska: Environmental context for human dispersal

We present here the results of multi-proxy analyses (sediment geochemistry, diatoms, and pollen) from sediment cores collected at four lakes in the middle Susitna Valley, Alaska. These lakes form a transect from the tundra to the boreal forest. The retrieved cores span from ~12,000 cal yr BP to the present, with age control provided by radiometric dates and tephra deposits, some of which are newly identified. Results indicate that deglaciation occurred before 12,000 cal yr BP and that by that time, the lakes were deep, productive, and surrounded by shrub tundra. The lake with the highest sampling resolution indicates a brief climatic reversal ~11,500 cal yr BP with decreased diatom-inferred lake level and lowered lake productivity, and reduced shrub presence. During the early to middle Holocene, all of the sedimentary records provide evidence of climatic amelioration with tree expansion and productive lakes. A middle to late Holocene climatic deterioration with reduced trees and a shallower, less productive lake is also indicated. In addition, the prominent Watana tephra at ~4,000 cal yr BP likely reduced lake productivity and affected the vegetation. Even though the region was relatively productive soon after deglaciation, people did not occupy the region until ~11,000 cal yr BP, about 1000 years later, and then only sparsely. By the middle and late Holocene, the region was more densely populated and this shift in human occupancy presumably reflects changes in resource abundance, especially caribou. Whether the Watana ashfall influenced caribou abundance and thus people, is still under investigation, but given the tephra’s effect on vegetation and lake productivity, it seems likely.

Alaska↗
USGS1996

Exchangeable hydrogen explains the pH of spodosol Oa horizons

The chemistry of extremely acid Oa horizons does not conform to traditional pH, Al, and base saturation relationships. Results from two separate studies of northeastern U.S. forested soils were used to investigate relationships between pH in water or dilute salt solutions and other soil characteristics. In Oa horizons with pH below 4, soil pH in dilute CaCl 2 solution was correlated with exchangeable H + measured either by titration ( r = −0.88, P = 0.0001, n = 142) or by electrode ( r = −0.89, P = 0.0001, n = 45). Exchangeable H + expressed as a percentage of the cation-exchange capacity (CEC) was linear with pH and showed similar slopes for data from both studies. For all samples, pHw = 4.21 − 1.80 × H + /CEC ( R 2 = 0.69, n = 194). The reciprocal of the H + /CEC ratio is base saturation with Al added to the bases. Because of the low pH, exchangeable Al does not appear to behave as an acid. Exchangeable H + remains an operationally defined quantity because of the difficulty in separating exchange and hydrolysis reactions. In a variety of neutral-salt extractants, concentrations of H + were correlated with 0.1 M BaCl 2 -exchangeable H + ( r > 0.91, P = 0.0001, n = 26) regardless of the strength of the extract. Nine successive extractions with 0.33 m M CaCl 2 removed more H + than was removed by single batch extractions with either 1 M KCl or 0.1 M BaCl 2 (average H + of 70, 43, and 49 mmol kg −1 , respectively for 26 samples). The data showed little difference in the chemical behavior of Oa horizons from a variety of geographical sites and vegetation types.

Maine, New Hampshire, New York, Vermont↗
USGS2000

Forest soil chemistry and terrain attributes in a Catskills watershed

Knowledge of soil chemistry is useful in assessing the sensitivity of forested areas to natural and anthropogenic disturbances, but characterizing large areas is expensive because of the large sample numbers required and the cost of soil chemical analyses. We collected and chemically analyzed soil samples from 72 sites within a 214-ha watershed in the Catskill Mountains of New York to evaluate factors that influence soil chemistry and whether terrain features could be used to predict soil chemical properties. Using geographic information system (GIS) techniques, we determined five terrain attributes at each sampling location: (i) slope, (ii) aspect, (iii) elevation, (iv) topographic index, and (v) flow accumulation. These attributes were ineffective in predicting the chemical properties of organic and mineral soil samples; together they explained only 4 to 25% of the variance in pH(w), effective cation-exchange capacity (CEC(e)), exchangeable bases, exchangeable acidity, total C, total N, and C/N ratio. Regressions among soil properties were much better; total C and pH(w) together explained 33 to 66% of the variation in exchangeable bases and CEC(e). Total C was positively correlated with N (r = 0.91 and 0.96 in Oa horizons and mineral soil, respectively), exchangeable bases (r = 0.65, 0.76), and CEC(e) (r = 0.54, 0.44), indicating the importance of organic matter to the chemistry of these acidic soils. The fraction of CEC(e) occupied by H explained 44% of the variation in pH(w). Soil chemical properties at this site vary on spatial scales finer than typical GIS analyses, resulting in relationships with poor predictive power. Thus, interrelationships among soil properties are more reliable for prediction.Knowledge of soil chemistry is useful in assessing the sensitivity of forested areas to natural and anthropogenic disturbances, but characterizing large areas is expensive because of the large sample numbers required and the cost of soil chemical analyses. We collected and chemically analyzed soil samples from 72 sites within a 214-ha watershed in the Catskill Mountains of New York to evaluate factors that influence soil chemistry and whether terrain features could be used to predict soil chemical properties. Using geographic information system (GIS) techniques, we determined five terrain attributes at each sampling location: (i) slope, (ii) aspect, (iii) elevation, (iv) topographic index, and (v) flow accumulation. These attributes were ineffective in predicting the chemical properties of organic and mineral soil samples; together they explained only 4 to 25% of the variance in pHw, effective cation-exchange capacity (CECe), exchangeable bases, exchangeable acidity, total C, total N, and C/N ratio. Regressions among soil properties were much better; total C and pHw together explained 33 to 66% of the variation in exchangeable bases and CECe. Total C was positively correlated with N (r = 0.91 and 0.96 in Oa horizons and mineral soil, respectively), exchangeable bases (r = 0.65, 0.76), and CECe (r = 0.54, 0.44), indicating the importance of organic matter to the chemistry of these acidic soils. The fraction of CECe occupied by H explained 44% of the variation in pHw. Soil chemical properties at this site vary on spatial scales finer than typical GIS analyses, resulting in relationships with poor predictive power. Thus, interrelationships among soil properties are more reliable for prediction.

New York↗
USGS2010

A comparison of litter production in young and old baldcypress (Taxodium distichum L.) stands at Caddo Lake, Texas

Aboveground primary productivity for cypress forests was assessed from measurements of litter production in two age groups and in two hydrological regimes (standing water and free-flowing). Caddo Lake, located in northeast Texas on the Texas-Louisiana border, offered a unique study site since it is dominated by extensive stands composed entirely of Taxodium distichum (L.) Rich, (baldcypress) in different age groups. Young stands (approximately 100 years old) are found along the shoreline and on shallow flooded islands. Old stands (-150 to 300 years old) are found in deeper water where they were continuously flooded. Litter production over three years from October 1998 to September 2001 was measured. Litter consisting of leaves, twigs, bark, reproductive parts, and Tillandsia usneoides (L.) L. (Spanish moss) was collected monthly using 0.5 m 2 floating traps. Tree diameters were measured within 200 m 2 circular plots in each stand. The young stands supported densities greater than 2,000 stems/ha and a mean stand basal area of 72.3 m 2 /ha, whereas old stands supported lower densities of about 500 stems/ha but with a similar mean stand basal area of 73.3 m 2 /ha. There was a significant difference between old and young stands for overall yearly litter production, averaging about 670 g/m 2 /yr in the young stands and 460 g/m 2 /yr in the old stands. Leaves and twigs were significantly greater in the young stands, while reproductive parts were higher in old stands. Litter collections between years or hydrological regimes were not significantly different.

Texas↗