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Cogongrass is a nonindigenous species perceived to threaten native communities of the southeastern United States through modification of species composition and alteration of community processes. To examine how gap size and disturbance type influence the invasion of wet pine savannas by cogongrass, we performed three field experiments to evaluate the...

We estimate the acoustic properties of a crack containing magmatic or hydrothermal fluids to quantify the source properties of long-period (LP) events observed in volcanic areas assuming that a crack-like structure is the source of LP events. The tails of synthetic waveforms obtained from a model of a fluid-driven crack...

Recent work has emphasized development of full‐range water‐retention functions that are applicable under both wet and dry soil conditions, but evaluation of such functions in numerical modeling has been limited. Here we show that simulations using the Rossi‐Nimmo (RN) full‐range function compared favorably with those using the common Brooks‐Corey function...

To reconcile observations of decomposition rates, carbon inventories, and net primary production (NPP), we estimated long-term averages for C exchange in boreal forests near Thompson, Manitoba. Soil drainage as defined by water table, moss cover, and permafrost dynamics, is the dominant control on direct fire emissions. In upland forests, an...

A deep-water ferromanganese crust from a Central Indian Ocean seamount dated previously by 10Be and 230Th(excess) was studied for compositional and textural variations that occurred throughout its growth history. The 10Be/9Be dated interval (upper 32 mm) yields an uniform growth rate of 2.8 ?? 0.1 mm/Ma [Frank, M., O'Nions, R.K.,...

Landsliding in response to rainfall involves physical processes that operate on disparate timescales. Relationships between these timescales guide development of a mathematical model that uses reduced forms of Richards equation to evaluate effects of rainfall infiltration on landslide occurrence, timing, depth, and acceleration in diverse situations. The longest pertinent timescale...

Radio transmitter attachment methodology is important to the design of radio telemetry studies. In 1998, we attached 5 transmitters to a captive population of Western Sandpipers (Calidris mauri) and 7 transmitters to wild Killdeer (Charadriusv ociferus) using a modified version of the Rappole and Tipton (1991) figure-8 leg-loop harness. Captive...

Catchment-scale intensive and extensive research conducted over the last decade shows that our understanding of the biogeochemical and hydrologic processes in subalpine and alpine basins is not yet sufficiently mature to model and predict how biogeochemical transformations and surface water quality will change in response to climatic or human-driven changes...

This paper summarizes terminology and general concepts involved in animal development for the purpose of providing background for the study and understanding of frog malformations. The results of our radiographic investigation of rear limb malformations in Rana pipiens provide evidence that frog malformations are the product of early developmental errors....

Cyanazine and two of its major metabolites, cyanazine amide and cyanazine acid, were measured at trace levels in groundwater using liquid chromatography/atmospheric pressure chemical ionization/mass spectrometry (LC/APCI/MS). Solid-phase extraction was carried out by passing 20 mL of groundwater sample through a cartridge containing a polymeric phase (PLRP-s), with recoveries ranging...

The Stream Segment Temperature Model was used to estimate cumulative effects of large-scale timber harvest on stream temperature. Literature values were used to create parameters for the model for two hypothetical situations, one forested and the other extensively clearcut. Results compared favorably with field studies of extensive forest canopy removal....

High‐altitude watersheds in the Front Range of Colorado show symptoms of advanced stages of nitrogen excess, despite having less nitrogen in atmospheric deposition than other regions where watersheds retain nitrogen. In two alpine/subalpine subbasins of the Loch Vale watershed, atmospheric deposition of NO3− plus NH4+ was 3.2–5.5 kg N ha−1, and watershed...

Low-flying aircraft can affect behavior, physiology, and distribution of wildlife (Manci et al., 1988), and over time, may impact a population by reducing survival and reproductive performance. Thus, it is important to identify the particular aspects of overflights that affect animals so that management strategies can be developed to minimize...

Moment-tensor solutions, estimated using optimal filter theory, are listed for 204 moderate-to-large size earthquakes that occurred during 1998. (C) 2000 Published by Elsevier Science B.V....

Enzyme-linked immunosorbent assay (ELISA) data from surface water reconnaissance were compared to data from samples analyzed by gas chromatography for the pesticide residues cyanazine (2-[[4-chloro-6-(ethylamino)-l,3,5-triazin-2-yl]amino]-2-methylpropanenitrile ) and metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide). When ELISA analyses were duplicated, cyanazine and metolachlor detection was found to have highly reproducible results; adjusted R2s were 0.97 and...

Well-preserved cuticles were isolated from Cordaites principalis (Germar) Geinitz leaf compressions, i.e., foliage from extinct gymnosperm trees Coniferophyta: Order Cordaitales. The specimens were collected from the Sydney. Stellarton and Bay St. George subbasins of the once extensive Carboniferous Maritimes Basin of Atlantic Canada. Fourier transformation of infrared spectra (FTIR) and...

The migration of a patch of prey through a field of relatively stationary predators is a situation that occurs frequently in nature. Making quantitative predictions concerning such phenomena may be difficult, however, because factors such as the number of the prey in the patch, the spatial length and velocity of...

Simulations by global terrestrial biogeochemical models (TBMs) consistently underestimate the concentration of atmospheric carbon dioxide (CO2) at high latitude monitoring stations during the nongrowing season. We hypothesized that heterotrophic respiration is underestimated during the nongrowing season primarily because TBMs do not generally consider the insulative effects of snowpack on soil...

A modification of previously published solutions regarding the spatial variation of hydraulic heads is discussed whereby the semivariogram of increments of head residuals (termed head residual increments HRIs) are related to the variance and integral scale of the transmissivity field. A first‐order solution is developed for the case of a...

Historically, forecast error for returns of sockeye salmon Oncorhynchus nerka to Bristol Bay, Alaska, has been large. Using cross-validation forecast error as our criterion, we selected forecast models for each of the nine principal Bristol Bay drainages. Competing forecast models included stock-recruitment relationships, environmental variables, prior returns of siblings, or...

Sea otters have been an important resource for people living along the North Pacific coast for thousands of years. At least two aspects of the sea otters' natural history have linked them with humans: their pelt and their food habits. Sea otter pelts, arguably the finest in the animal...

Torreya taxifolia is a coniferous tree that is endemic to the 35 km stretch of bluffs and ravines along the east side of the Apalachicola River in northern Florida and adjacent southern Georgia. This formerly locally abundant tree declined during the 1950s and 1960s as a result of disease and...

The Florida torreya (  Torreya taxifolia) is a coniferous tree endemic to a 35-km stretch of bluffs and ravines along the east side of the Apalachicola River in northern Florida and southern Georgia. This formerly locally abundant tree has declined as a result of disease during the 1950s and is on...

We evaluate the empirical and theoretical support for the hypothesis that a large proportion of native species richness is required to maximize ecosystem stability and sustain function. This assessment is important for conservation strategies because sustenance of ecosystem functions has been used as an argument for the conservation of species....