Paleoclimate records from glacial Indian and Pacific oceans sediments document millennial-scale fluctuations of subsurface dissolved oxygen levels and denitrification coherent with North Atlantic temperature oscillations. Yet the mechanism of this teleconnection between the remote ocean basins remains elusive. Here we present model simulations of the oxygen and nitrogen cycles that...
The first three years of SeaWiFS data (1997-2000) provide the most complete quantification to date of chlorophyll seasonal variability along the full latitudinal extent of the four major eastern boundary currents (EBCs). Comparisons to previously published chlorophyll seasonal climatologies deduced from the relatively sparse coverage provided by the Coastal Zone...
During the summers of 1987 and 1988, 77 near-surface satellite-tracked drifters were deployed in or near cold filaments near Point Arena, California (39ºN), and tracked for up to 6 months as part of the Coastal Transition Zone (CTZ) program. The drifters had large drogues centered at 15 m, and the...
The concept of sustainable resource management can be applied at multiple scales.
Monitoring is an essential component of sustainable natural resource management
schemes, and as we begin to confront the need to manage natural resources at the
global scale, the importance of monitoring at the global scale is also growing....
Over the last three decades the first-order correlation in morphology and orientation of seamount trails
has been called upon to support the concept of a ‘‘fixed’’ Pacific hot spot frame of reference and to explain
the Hawaii-Emperor bend (HEB) by a dramatic change in Pacific plate motion. In this paper,...
Research has found an upward trend in impulse buying in general, and impulse buying is frequently foreseen among mall shoppers. Impulse purchases account for over $4 billion in annual sales in the U.S. (Mogelonsky, 1998). Retailers have found that over 50 percent of mall shoppers purchase on impulse (Nichols et...
Persistent, long‐lived, stationary sites of excessive mantle melting are called hotspots. Hotspots leave volcanic trails on lithospheric plates passing across them. The global constellation of fixed hotspots thus forms a convenient frame of reference for plate motions, through the orientations and age distributions of volcanic trails left by these melting...
Intraexciton transitions in semiconductor quantum wells are modulated by strong and tunable few-cycle terahertz pulses. Time-resolved terahertz-pump and optical-probe measurements demonstrate that the 1s heavy-hole and light-hole exciton resonances undergo large-amplitude spectral modulations when the terahertz radiation is tuned near the 1s–2p intraexciton transition. The strong nonlinear optical transients exhibit...
We used reverse time capture-mark-recapture models to describe associations between rate of population change (λ) and climate for northern spotted owls (Strix occidentalis caurina) at six long-term study areas in Washington and Oregon, USA. Populations in three of six areas showed strong evidence of declining populations, while populations in two...
In the Sierra Nevada, distributions of forest tree species are largely controlled by the soil-moisture balance. Changes in temperature or precipitation as a result of increased greenhouse gas concentrations could lead to changes in species distributions. In addition, climatic change could increase the frequency and severity of wildfires. We used...
Nitrogen is a limiting resource in many temperate forests and nitrogen-fixing plants are usually limited to the early stages of post-disturbance succession. In fire-dependent Sierra Nevada forests, however, Ceanothus cordulatus is relatively abundant even in old-growth forest conditions which are at least partly maintained by fire. We conducted a field...
Studies of the effects of climate change on forests have focused on the ability of species to tolerate temperature
and moisture changes and to disperse, but they have ignored the effects of disturbances caused by climate change
(e.g., Ojima et al. 1991).Yet modeling studies indicate the importance of climate effects...
Western United States forest wildfire activity is widely thought to have increased in recent decades, yet neither the extent of recent changes nor the degree to which climate may be driving regional changes in wildfire has been systematically documented. Much of the public and scientific discussion of changes in western...
Understanding the relative influence of fuels and climate on wildfires across the Rocky Mountains is necessary to predict how fires may respond
to a changing climate and to define effective fuel management approaches to controlling wildfire in this increasingly populated region. The idea
that decades of fire suppression have promoted...
Soil respiration is a major pathway for carbon cycling in terrestrial ecosystems yet little is known about its response to natural and
anthropogenic disturbances. This study examined soil respiration response to prescribed burning and thinning treatments in an old-growth, mixed-conifer
forest on the western slope of the Sierra Nevada Mountains....
Mechanical thinning and prescribed fire are widely used to restore western forests after a century of fire suppression, yet we know little about
how these treatments affect understory communities where plant diversity is highest. We followed understory plants and environmental factors in
old-growth, Sierran mixed conifer for two pre-treatment and...
Fire suppression has increased fuel loads and fuel continuity in mixed-conifer ecosystems, resulting in forest structures
that are vulnerable to catastrophic fire. This paper models fire behaviour in a mixed-conifer forest and investigates how
silvicultural and fuels treatments affect potential fire behaviour. The computer program FARSITE was used to spatially...
Successful fire exclusion in the 20th century has created severe fire problems across the West. Not every forest is at risk of
uncharacteristically severe wildfire, but drier forests are in need of active management to mitigate fire hazard. We summarize a
set of simple principles important to address in fuel...
Mortality patterns in an old-growth, mixed-conifer forest, in the absence of wildfire, were investigated at the Teakettle Experimental Forest from 2000 to 2002. We tested the hypothesis that after a century of fire suppression, pathogen- and insect-associated mortality (between episodic droughts) would be significantly greater on ingrowth trees (i.e., smaller-diameter,...
Despite its widespread use, forest health is frequently used without a clear definition, making its application to forest management difficult. Where the term has been defined (McIntire 1988, Monnig and Byler 1992, USDA Forest Service 1992, USDA Forest Service I993a), alternative definitions and viewpoints of forest health have not been...