Treesearch

Russian boreal forests have an annual wildfire activity averaging 10 to 20 million ha, which has increased in recent years. This wildfire activity, in response to changing climate has the potential to significantly affect the carbon storage capacity of Siberian forests. A better understanding of the effect of fire on soil respiration rates in the boreal forest of Siberia is important. Fire can change the rate of soil respiration by reducing soil moisture and organic matter, increasing surface temperature, and reducing soil microbial populations to varying degrees, based on fire intensity....

Mortality and reduced growth rates due to raking accumulated basal duff were evaluated for old, large-diameter ponderosa and Jeffrey pine trees on the Lassen National Forest, California. No fire treatments were included to isolate the effect of raking from fire. Trees were monitored annually for 5 years after the raking treatment for mortality and then cored to measure basal area increment. Results showed that raking basal duff and litter to mineral soil from the bole out to 60 cm had no effect on basal area increment or mortality for 5 years posttreatment. Results are pertinent to...

Throughout Earth’s history fire has been a major disturbance factor in many terrestrial ecosystems. Fire is man’s first tool. It was used for a host of cultural purposes to modify stand structure and species composition as well as landscape pattern and process. Changes in climate and land use are leading to changes in vegetation and the frequency and severity of modern fire disturbances. As a major determinant of historic vegetation structure and species composition it is appropriate to consider using fire as a restoration tool. The ecologically principaled, safe, effective use of fire in...

Climate change presents significant risks to our nation’s natural and cultural resources. Although climate change was once believed to be a future problem, there is now unequivocal scientific evidence that our planet’s climate system is warming (IPCC 2007a). While many people understand that human emissions of greenhouse gases have significantly contributed to recent observed climate changes, fewer are aware of the specific impacts these changes will bring. This document is part of a series of bio-regional summaries that provide key scientific findings about climate change and impacts to...

We report on the development of an accurate, portable, dynamic calibration system for volatile organic compounds (VOCs). The Mobile Organic Carbon Calibration System (MOCCS) combines the production of gas-phase VOC standards using permeation or diffusion sources with quantitative total organic carbon (TOC) conversion on a palladium surface to CO2 in the presence of oxygen, and the subsequent CO2 measurement. MOCCS was validated using three different comparisons: (1) TOC of high accuracy methane standards compared well to expected concentrations (3% relative error), (2) a gas-phase benzene...

The Fire INventory from NCAR version 1.0 (FINNv1) provides daily, 1 km resolution, global estimates of the trace gas and particle emissions from open burning of biomass, which includes wildfire, agricultural fires, and prescribed burning and does not include 5 biofuel use and trash burning. Emission factors used in the calculations have been updated with recent data, particularly for the non-methane organic compounds (NMOC). The resulting global annual NMOC emission estimates are as much as a factor of 5 greater than some prior estimates. Chemical speciation profiles, necessary to allocate...

We report the construction of a database of infrared spectra aimed at detecting the gases emitted by biomass burning. The project uses many of the methods of the Pacific Northwest National Laboratory (PNNL) infrared database, but the selection of the species and special experimental considerations are optimized. Each spectrum is a weighted average derived from 10 or more individual measurements. Each composite has a spectral range from ≤600 to ≥6500cm−1 with an instrumental apodized resolution of 0.11cm−1. The resolution was chosen to bring out all spectral features, but recognizing that...

This study evaluated the short-term effects of thinning methods for pinyon pine woodlands at two sites in the southwestern Great Basin. Both cut/pile/burn and mastication treatments were equally effective at reducing the target fuels which were mature, live pinyon trees. Application costs though differed substantially, with the cut/pile/burn technique being less expensive. Thinning treatments increased the abundance of herbaceous vegetation, although in some cases the strength of the increase was constrained by the level of pre-treatment tree dominance. Increases in perennial grass cover...

Ecosystems are not static, having evolved with disturbances such as fire, windstorms, floods, disease, and animal activity. The natural variability imposed by such disturbances must be included when defining sustainability goals. One approach is to target the historic range of variability (HRV), determining if current management maintains the ecosystem within its HRV. Tree cores; stand age; stable isotopes; ancient packrat middens; museum collections; and sediment records of charcoal, pollen, testate amoebae, or animal hair can provide data for reconstructing the HRV.

Biomass burning (BB) is the second largest source of trace gases and the largest source of primary fine carbonaceous particles in the global troposphere. Many recent BB studies have provided new emission factor (EF) measurements. This is especially 5 true for non methane organic compounds (NMOC), which influence secondary organic aerosol (SOA) and ozone formation. New EF should improve regional to global BB emissions estimates and therefore, the input for atmospheric models. In this work we present an up-to-date, comprehensive tabulation of EF for known pyrogenic species based on measuremen...