Effects of soil surface shading, mulching and vegetation control on Douglas-fir seedling growth and microsite water partitioning

A two year study with 500 seedlings was conducted in the harsh, drought prone southwest Oregon environment to assess the effects of 12 soil surface shading, mulching and vegetation control techniques on soil temperature and moisture environments and seedling growth. Treatments modified, to various degrees, soil surface temperatures, reduced soil surface evaporation and reduced vegetative competition for water in the seedling root zone. These modified conditions affected seedlings by reducing soil water loss to increase water available for seedling use and adjusting the timing of seedling growth. Seedlings in treatments where competing vegetation was removed had significantly larger final shoot volumes and stem diameters. Soil water loss was significantly less in treatments where soil surface evaporation was controlled by mulching or controlling competing vegetation. Shaded and control treatments used the most water over the season. Soil water loss in treatments with vegetation controlled by herbicide was significantly less than those with vegetation control by scalping which disturbs the soil surface by removing the loose soil and duff layer. Therefore, seedlings grew the most with treatments that elicited the most efficient use of available microsite water either by reducing soil surface evaporation or vegetative competition. Transpiration data supported these conclusions by showing more than twice the water was transpired by competing vegetative species per unit leaf area than by seedlings. In addition, estimates of percent cover by seedlings and all vegetative species occupying the site showed competing vegetation to cover 78.6% of the site compared to 2.4% cover by the seedlings. This illustrates the degree of competition the vegetation gives to the seedling over the whole site even in an environment where water is a limiting resource

Incorporating anthropogenic influences into fire probability models : effects of human activity and climate change on fire activity in California

The costly interactions between humans and wildfires throughout California demonstrate the need to understand the relationships between them, especially in the face of a changing climate and expanding human communities. Although a number of statistical and process-based wildfire models exist for California, there is enormous uncertainty about the location and number of future fires, with previously published estimates of increases ranging from nine to fifty-three percent by the end of the century. Our goal is to assess the role of climate and anthropogenic influences on the state's fire regimes from 1975 to 2050. We develop an empirical model that integrates estimates of biophysical indicators relevant to plant communities and anthropogenic influences at each forecast time step. Historically, we find that anthropogenic influences account for up to fifty percent of explanatory power in the model. We also find that the total area burned is likely to increase, with burned area expected to increase by 2.2 and 5.0 percent by 2050 under climatic bookends (PCM and GFDL climate models, respectively). Our two climate models show considerable agreement, but due to potential shifts in rainfall patterns, substantial uncertainty remains for the semiarid inland deserts and coastal areas of the south. Given the strength of human-related variables in some regions, however, it is clear that comprehensive projections of future fire activity should include both anthropogenic and biophysical influences. Previous findings of substantially increased numbers of fires and burned area for California may be tied to omitted variable bias from the exclusion of human influences. The omission of anthropogenic variables in our model would overstate the importance of climatic ones by at least 24%. As such, the failure to include anthropogenic effects in many models likely overstates the response of wildfire to climatic change

Neoliberal Redistributive Policy: The U.S. Net Social Wage in the 21st Century

In this paper, I examine the trends of fiscal transfers between the state and workers during 1959 - 2012 to understand the net impact of redistributive policy in the United States. This paper presents original net social wage data from and analysis based on the replication and extension of Shaikh and Tonak (2002). The paper investigates the appearance of a post-2001 variation in the net social wage data. The positive net social wage in the 21st century is the result of a combination of factors including the growth of income support, healthcare inflation, neoliberal tax reforms, and macroeconomic instability. Growing economic inequality does not appear to alter the results of the net social wage methodology

Influence of deterministic geologic trends on spatial variability of hydrologic properties in volcanic tuff

Hydrologic properties have been measured on outcrop samples taken from a detailed, two-dimension grid covering a 1.4 km outcrop exposure of the 10-m thick non-welded-to-welded, shardy base microstratigraphic unit of the Tiva Canyon Member of the Miocene Paintbrush Tuff at Yucca Mountain, Nevada. These data allow quantification of spatial trends in rock matrix properties that exist in this important hydrologic unit. Geologic investigation, combined with statistical and geostatistical analyses of the numerical data, indicates that spatial variability of matrix properties is related to deterministic geologic processes that operated throughout the region. Linear vertical trends in hydrologic properties are strongly developed in the shardy base microstratigraphic unit, and they are more accurately modeled using the concept of a thickness-normalized stratigraphic elevation within the unit, rather than absolute elevation. Hydrologic properties appear to be correlated over distances of 0.25 to 0.3 of the unit thickness after removing the deterministic vertical trend. The use of stratigraphic elevation allows scaling of identified trends by unit thickness which may be of particular importance in a basal, topography-blanketing unit such as this one. Horizontal changes in hydrologic properties do not appear to form obvious trends within the limited lateral geographic extent of the ash-flow environment that was examined. Matrix properties appear to be correlated horizontally over distances between 100 and 400 m. The existence and quantitative description of these trends and patterns of vertical spatial continuity should increase confidence in models of hydrologic properties and groundwater flow in this area that may be constructed to support the design of a potential high-level nuclear waste repository at Yucca Mountain

Report on the May-June 2002 Englebright Lake deep coring campaign

This report describes the May-June 2002 Englebright Lake coring project. Englebright Lake is a 14-km-long reservoir on the Yuba River of northern California, impounded by Englebright Dam, which was completed in 1940. The sediments were cored to assess the current conditions in the reservoir as part of the California Bay-Delta Authority’s Upper Yuba River Studies Program. Sediment was collected using both hydraulic-piston and rotational coring equipment mounted on a floating drilling platform. Thirty boreholes were attempted at 7 sites spaced along the longitudinal axis of the reservoir. Complete sedimentary sections were recovered from 20 boreholes at 6 sites. In total, 335 m of sediment was cored, with 86% average recovery. The core sections (each up to 1.5 m long) were processed using a standard set of laboratory techniques, including geophysical logging of physical properties, splitting, visual descriptions, digital photography, and initial subsampling. This report presents the results of these analyses in a series of stratigraphic columns. Using the observed stratigraphy as a guide, several series of subsamples were collected for various sedimentologic, geochemical, and geochronological analyses. The results of laboratory analyses of most of these subsamples will be presented in future reports and articles

Erosion of refugia in the Sierra Nevada meadowsnetwork with climate change

Climate refugia management has been proposed as a climate adaptation strategy in the face of global change. Key to this strategy is identification of these areas as well as an understanding of how they are connected on the landscape. Focusing on meadows of the Sierra Nevada in California, we examined multiple factors affecting connectivity using circuit theory, and determined how patches have been and are expected to be affected by climate change. Connectivity surfaces varied depending upon the underlying hypothesis, although meadow area and elevation were important features for higher connectivity. Climate refugia that would promote population persistence were identified from downscaled climate layers, based on locations with minimal climatic change from historical conditions. This approach was agnostic to specific species, yielding a broad perspective about changes and localized habitats. Connectivity was not a consistent predictor of refugial status in the 20th century, but expected future climate refugia tended to have higher connectivity than those that recently deviated from historical conditions. Climate change is projected to reduce the number of refugial meadows on a variety of climate axes, resulting in a sparser network of potential refugia across elevations. Our approach provides a straightforward method that can be used as a tool to prioritize places for climate adaptation.This work was primarily supported by a grant from the California Landscape Conservation Cooperative (80250-BJ127) to TLM, CM, and SRB, along with funding from the U.C. Berkeley Initiative in Global Change Biology to SRB and an NSF Bioinformatics Postdoctoral Research Fellowship to TLM. We thank Eric Berlow, Bob Westfall, Connie Millar, Sarah Stock, and David Wright for analytical input. We thank J.Z. Drexler and at least two anonymous reviewers for comments that improved earlier drafts

Role of Second-Trimester Genetic Sonography After Down Syndrome Screening

To estimate the effectiveness of second-trimester genetic sonography in modifying Down syndrome screening test results

Down syndrome serum screening also identifies an increased risk for multicystic dysplastic kidney, two-vessel cord, and hydrocele

The FASTER trial compared 1st and 2nd trimester screening methods for aneuploidy. We examined relationships between maternal serum markers and common congenital anomalies in the pediatric outcome data set of 36,837 subjects

Preconceptional Folate Supplementation and the Risk of Spontaneous Preterm Birth: A Cohort Study

In an analysis of a cohort of pregnant women, Radek Bukowski and colleagues describe an association between taking folic acid supplements and a reduction in the risk of preterm birth