Landtype-forest community relationships: A case study on the Mid-Cumberland Plateau

Relationships between forest communities and landtypes (the most detailed level of a hierarchical land classification system) were determined for the Prentice Cooper State Forest (PCSF), located on the southern tip of Walden Ridge, west of Chattanooga, Tennessee.Four extensive landtypes within the Mullins Cove area of PCSF were sampled: 1) broad sandstone ridges-south aspect (LT-3), 2) north sandstone slopes (LT-5), 3) south sandstone slopes (LT-6), and 4) plateau escarpment and upper sandstone slopes and benches-south aspect (LT-17). Rectangular, 0.04-hectare plots specified sub-plots for sampling overstory, midstory, sapling/shrub, seedling/herb forest strata, and physical site characteristics. Plots (139) were allocated by landtype using a random start with subsequent systematic location.Multivariate statistical techniques were used to 1) examine the distinctness of forest communities occurring among landtypes (discriminant analysis), 2) describe the forest communities occurring within landtypes (cluster analysis), and 3) determine factors controlling the spatial distribution of forest communities on the landscape (factor analysis).Different relative importance values of species among communities along with different community combinations among landtypes resulted in distinct forest vegetation among landtypes.Chestnut oak (Quercus prinus L.), white oak (Quercus alba L.), and shortleaf pine (Pinus echinata Miller) communities occurred on all four landtypes. Scarlet oak (Quercus coccinia Muenchh.) communities occurred on LT-5, LT-6, and LT-17. Black oak (Quercus velutina Lam.) communities occurred on LT-3 and LT-5. Yellow-poplar (Liriodendron tulipifera L.), northern red oak (Quercus rubra L.), and eastern hemlock (Tsuga canadensis (L.) Carr.), communities occurred only on LT-17.Landscape scale factors that varied along an elevation gradient were dominant in controlling spatial distribution of forest communities. Microsite factors were secondary controllers. Specific ecological factors could not be determined by factor analysis.Relatively distinct vegetation occurs among sampled landtypes on the PCSF. This study provides additional evidence that the land classification system divides the Mid-Cumberland Plateau landscape into distinct ecological units.     

Partition Constants and Adsorption/Desorption Hysteresis for Volatile Organic Compounds on Soil from a Louisiana Superfund Site

The adsorption of four volatile organic compounds (1,4-dichloro-benzene, 1,2-dichloroethane, 1,2,2-trichloroethane and 1,1,2,2,-tetrachloroethane) on three soil types from a Superfund site (Petroprocessors Inc) in Baton Rouge, LA was studied with the purpose of obtaining an overall correlation for inclusion in a groundwater transport model being developed for site remediation. The soil-water partition constant, K_d was determined using a standard ASTM procedure (E–1195–87). Using the data for different soil types (fraction organic carbon between 0.11% and 1.13%) and different mineral surface areas (7 to 45 m²/g), the organic carbon contribution (K_oc) and the mineral matter contribution (K_min) to the partition constant were determined. The soils obtained were either from the Pleistocene period or recent shallow deposits at the site. Both log K_oc and log K_min were linearly correlated to log K_ow, the octanol-water partition constant. This data provided the basis for obtaining a general correlation for K_d on different soil types at the site. The predicted values were in agreement with that for a composite soil from the same site. The desorption of compounds from the high clay soil after the 24 hour adsorption period was observed to show a biphasic behavior, namely, an easily desorbed fraction and a desorption resistant fraction. The easily desorbed fraction was found to be satisfactorily predicted using the conventional K_d as obtained from the adsorption experiment. The slowly desorbing fraction had a time constant of several weeks. The concentration in the desorption resistant compartment was found to be dependant on the initial amount of contaminant available for adsorption. The aqueous phase concentration in equilibrium with the desorption resistant fraction was found to be 8 g/L for dichlorobenzene and 12 g/L for dichloroethane.     

EFFECTIVENESS OF TIMBER HARVEST PRACTICES FOR CONTROLLING SEDIMENT RELATED WATER QUALITY IMPACTS1

ABSTRACT: Timber harvest best management practices (BMPs) in Washington State were evaluated to determine their effectiveness at achieving water quality standards pertaining to sediment related effects. A weight‐of‐evidence approach was used to determine BMP effectiveness based on assessment of erosion with sediment delivery to streams, physical disturbance of stream channels, and aquatic habitat conditions during the first two years following harvest. Stream buffers were effective at preventing chronic sediment delivery to streams and physical disturbance of stream channels. Practices for ground‐based harvest and cable yarding in the vicinity of small streams without buffers were ineffective or only partially effective at preventing water quality impacts. The primary operational factors influencing BMP effectiveness were: the proximity of ground disturbing activities to streams; presence or absence of designated stream buffers; the use of special timber falling and yarding practices intended to minimize physical disturbance of stream channels; and timing of harvest to occur during snow cover or frozen ground conditions. Important site factors included the density of small streams at harvest sites and the steepness of inner stream valley slopes. Recommendations are given for practices that provide a high confidence of achieving water quality standards by preventing chronic sediment delivery and avoiding direct stream channel disturbance.     

Monitoring of the Degradation Activities and the Diversity of the Microbial Community Degrading Refinery Waste Sludge

The biodegradation of n-alkanes and branched alkanes from waste sludge were observed in landfarming soils of Motor Oil Hellas (a petroleum refinery) and changes in the bacterial communities in the soils were monitored during the remediation. Bacterial 16S rRNA gene (rDNA)-based community fingerprint patterns were obtained from soil samples by terminal restriction fragment length polymorphism (T-RFLP) analysis. Changes in T-RFLP fingerprints, as well as in the petroleum contaminant composition of the polluted soil, correlated with degradation activities in field tests.     

Persistence and pathways of testosterone dissipation in agricultural soil

The persistence and pathways of dissipation of testosterone in three agricultural soils were examined in laboratory microcosm incubations at different soil moistures (1.7-39%) and temperatures (4-30 degrees C) using (14)C- and (3)H-labeled and unlabeled testosterone. Sterilized loam was also examined to assess possible abiotic pathways. Extractable (14)C decreased rapidly for all three soils at 30 degrees C with times to dissipate 50% of material (DT(50)) ranging from 8.5 to 21 h. Respired (14)CO(2) accounted for approximately 50% of the applied (14)C after 120 h. Androgenic activity of soil extracts declined faster than the extractable (14)C levels demonstrating that testosterone was not being converted to compounds with greater activity. Dissipation rates of nonvolatile, extractable (3)H in loam at 7, 15, and 39% moisture were similar, but the rate in air-dried loam (1.7% moisture) was significantly reduced. High performance liquid chromatography (HPLC) analysis of extracts of (14)C-testosterone-treated loam incubated at 30 degrees C for 6 h revealed that the (14)C was distributed among the remaining testosterone and three major metabolites (4-androstene-3,17-dione, 5alpha-androstane-3,17-dione, and 1,4-androstadiene-3,17-dione), which accounted for 48.7, 23.7, and 9.6% of the remaining (14)C, respectively. Periodic analysis of soil incubated at 23, 12, and 4 degrees C showed that the rates of testosterone dissipation and metabolite appearance and subsequent dissipation were temperature dependent with rates decreasing with decreasing temperature. In sterilized loam, 4-androstene-3,17-dione was the only metabolite detected. We conclude that testosterone is rapidly and thoroughly biodegraded in agricultural soils under a range of conditions typical of a temperate growing season and thus is unlikely to pose a long-term risk to adjacent aquatic environments.     

MODELING NITROGEN TRANSPORT IN THE IPSWICH RIVER BASIN,MASSACHUSETTS, USING A HYDROLOGICAL SIMULATION PROGRAM IN FORTRAN (HSPF)1

ABSTRACT: Increased riverine nitrogen (N) fluxes have been strongly correlated with land use changes and are now one of the largest pollution problems in the coastal region of the United States. In the present study, the Hydrological Simulation Program‐FORTRAN (HSPF) is used to simulate transport of N in the Ipswich River basin in Massachusetts and to evaluate the effect of future land use scenarios on the water quality of the river. Model results show that under a land use change scenario constructed with restrictions from environmental protection laws, where 44 percent of the forest in the basin was converted to urban land, stream nitrate concentrations increased by about 30 percent of the present values. When an extreme land use scenario was used, and 100 percent of the forest was converted to urban land, concentrations doubled in comparison to present values. Model simulations also showed that present stream nitrate concentrations might be four times greater than they were prior to urbanization. While pervious lands with high density residential land use generated runoff with the highest N concentrations in HSPF simulations, the results suggested that denitrification in the riparian zone and wetlands coupled with the hydrology of the basin are likely to control the magnitude of nitrate loads to the aquatic system. The simulation results showed that HSPF can predict the general patterns of inorganic N concentrations in the Ipswich River and tributaries. Nevertheless, HSPF has some difficulty simulating the extreme variability of the observed data throughout the main stem and tributaries, probably because of limitations in the representation of wetlands and riparian zones in the model, where N processes such as denitrification seem to play a major role in controlling the transport of N from the terrestrial system to the river reaches.     

Bioremediation of Stranded Oil on an Arctic Shoreline

The application of slow-release and soluble fertilizers proved to be an effective and environmentally benign way of stimulating oil biodegradation on an Arctic shoreline. Fertilizer application to the surface of the beach delivered nutrients to the oiled sediment beneath the beach surface. There was no significant run-off of this fertilizer to either the nearshore water or to unfertilized plots, and there were no adverse toxicological effects of the fertilizer application. The fertilizer application was followed by an increase in oxygen consumption and carbon dioxide evolution from the beach, increased microbial biomass, and significantly greater biodegradation of oil on the plots that had received fertilizer. The rate of oil biodegradation was approximately doubled over the course of a year by fertilizer applications in the first two months after the spill.Simple test kits proved adequate to monitor the fertilizer-application process in the field in a time frame that would allow the application process to be fine-tuned during treatment on a real spill. Simple test kits and portable instrumentation were useful in demonstrating the initial success of the bioremediation strategy.     

IMPACTS OF CALIFORNIA'S CLIMATIC REGIMES AND COASTAL LAND USE CHANGE ON STREAMFLOW CHARACTERISTICS1

ABSTRACT: To investigate the impacts of urbanization and climatic fluctuations on stream flow magnitude and variability in a Mediterranean climate, the HEC‐HMS rainfall/runoff model is used to simulate stream flow for a 14‐year period (October 1, 1988, to September 30, 2002) in the Atascadero Creek watershed located along the southern coast of California for 1929, 1998, and 2050 (estimated) land use conditions (8, 38 and 52 percent urban, respectively). The 14‐year period experienced a range of climatic conditions caused mainly by El Nino‐Southern Oscillation variations. A geographic information system is used to delineate the watershed and parameterize the model, which is calibrated using data from two stream flow and eight rainfall gauges. Urbanization is shown to increase peak discharges and runoff volume while decreasing stream flow variability. In all cases, the annual and 14‐year distributions of stream flow are shown to be highly skewed, with the annual maximum 24 hours of discharge accounting for 22 to 52 percent of the annual runoff and the maximum ten days of discharge from an average El Nino year producing 10 to 15 percent of the total 14‐year discharge. For the entire period of urbanization (1929 to 2050), the average increase in annual maximum discharges and runoff was 45 m³/s (300 percent) and 15 cm (350 percent), respectively. Additionally, the projected increase in urbanization from 1998 to 2050 is half the increase from 1929 to 1998; however, increases in runoff (22 m³/s and 7 cm) are similar for both scenarios because of the region's spatial development pattern.     

THE PREOPERATIONAL EFFECTS OF A WATER-RESOURCES PROJECT ON PROPERTY PRICES1

ABSTRACT: Residential properties nearby a park-lake system were studied, through time-series, to detect possible changes in the land market during the period between announcement and completion of the impounding reservoir, 1962 to 1973. The time series identifies a period of increases in the values of properties which is concomitant with the announcement of the park-lake. This is followed by a second period characterized by lower prices, which ends in 1970, as construction activities take place. During construction, from 1970 to 1973, property values were found to increase rapidly.     

Predator biomass,prey density,and species composition effects on group size in recruit coral reef fishes

Group incidence and size are described for recruit parrotfishes, wrasses, and damselfishes on Hawaiian reefs over 3 years (2006–2008) at sites spanning the archipelago (20–28°N, 155–177°W). Coral-poor and coral-rich areas were surveyed at sites with both low (Hawaii Island) and high (Midway Atoll) predator densities, facilitating examination of relations among predator and recruit densities, habitat, and group metrics. Predator and recruit densities varied spatially and temporally, with a sixfold range in total recruit densities among years. Group (≥2 recruits) metrics varied with time and tracked predator and recruit densities and the proportion of schooling species. Groups often included heterospecifics whose proportion increased with group size. A non-saturating relationship between group size and recruit density suggests that the anti-predator benefits of aggregation exceeded competitive costs. Grouping behavior may have overarching importance for recruit survival–even at high recruit densities–and merits further study on Hawaiian reefs and elsewhere.