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 United States wildfire has focused instead on the effects of 19th- and 20th-century land-use history. We compiled a comprehensive database of large wildfires in western United States forests since 1970 and compared it with hydroclimatic and land-surface data. Here, we show that large wildfire activity increased suddenly and markedly in the mid-1980s, with higher large-wildfire frequency, longer wildfire durations, and longer wildfire seasons. The greatest increases occurred in mid-elevation, Northern Rockies forests, where land-use histories have relatively little effect on fire risks and are strongly associated with increased spring and summer temperatures and an earlier spring snowmelt.

/pdf/warming-and-earlier-spring-increase-western-u-s-forest-33qvd39h8z.pdf

Warming and Earlier Spring Increase Western U.S. Forest Wildfire Activity

There is a special reason for reviewing this book at this time: it is the 50th edition of a compendium that is known and used frequently in most chemical and physical laboratories in many parts of the world. Surely, a publication that has been published for 56 years, withstanding the vagaries of science in this century, must have had something to offer. There is another reason: while the book is a standard fixture in most chemical and physical laboratories, including those in medical centers, it is not as frequently seen in the laboratories of physician's offices (those either in solo or group practice). I believe that the Handbook can be useful in those laboratories. One of the reasons, among others, is that the various basic items of information it offers may be helpful in new tests, either physical or chemical, which are continuously being published. The basic information may relate

Handbook of Chemistry and Physics

Fire is a worldwide phenomenon that appears in the geological record soon after the appearance of terrestrial plants. Fire influences global ecosystem patterns and processes, including vegetation distribution and structure, the carbon cycle, and climate. Although humans and fire have always coexisted, our capacity to manage fire remains imperfect and may become more difficult in the future as climate change alters fire regimes. This risk is difficult to assess, however, because fires are still poorly represented in global models. Here, we discuss some of the most important issues involved in developing a better understanding of the role of fire in the Earth system.

/pdf/fire-in-the-earth-system-481yvwaoo1.pdf

Fire in the Earth System

Many physical, chemical, mineralogical, and biological soil properties can be affected by forest fires. The effects are chiefly a result of burn severity, which consists of peak temperatures and duration of the fire. Climate, vegetation, and topography of the burnt area control the resilience of the soil system; some fire-induced changes can even be permanent. Low to moderate severity fires, such as most of those prescribed in forest management, promote renovation of the dominant vegetation through elimination of undesired species and transient increase of pH and available nutrients. No irreversible ecosystem change occurs, but the enhancement of hydrophobicity can render the soil less able to soak up water and more prone to erosion. Severe fires, such as wildfires, generally have several negative effects on soil. They cause significant removal of organic matter, deterioration of both structure and porosity, considerable loss of nutrients through volatilisation, ash entrapment in smoke columns, leaching and erosion, and marked alteration of both quantity and specific composition of microbial and soil-dwelling invertebrate communities. However, despite common perceptions, if plants succeed in promptly recolonising the burnt area, the pre-fire level of most properties can be recovered and even enhanced. This work is a review of the up-to-date literature dealing with changes imposed by fires on properties of forest soils. Ecological implications of these changes are described.

/pdf/effects-of-fire-on-properties-of-forest-soils-a-review-1ymllzm5e7.pdf

Effects of fire on properties of forest soils: a review

https://bio.uib.no/te/papers/Grimm_2010_The_ODD_protocol_.pdf

The ODD protocol: A review and first update

Perspective: Prescribed Fire Is Not the Issue

Learning by doing: education in ecological restoration at Northern Arizona University.

(Please note, this is an abstract only) Land managers frequently thin small-diameter trees and apply prescribed fire to reduce fuel loads and restore ecosystem structure, function, and process in forested areas. There is increasing concern that disturbances associated with these management practices can facilitate nonnative plant invasions. Bromus tectorum is an annual grass from the Mediterranean region. It has invaded large areas of the Interior West and has become the dominant species in many of these areas. In 2003, a ponderosa pine ecological restoration site on Mt. Trumbull in the Uinkaret Mountains of northern Arizona experienced a large increase in Bromus. Thinning and burning projects had been conducted on this site since 1996. Bromus frequency increased on the thinned and burned plots by six-fold between 1996 and 2003. While Bromus also increased on thinned plots that were not burned and the untreated control plots, the frequency of Bromus was significantly lower than on the thinned and burned plots. There were two additional factors that may have influenced the Bromus invasion. In 2002, the region experienced the most extreme drought recorded in the past 100 years. Substantial rainfall returned to the area in September 2002, coincident with the timing of Bromus germination. Additionally, cattle were reintroduced to the study area in July 2002 after a five year hiatus in grazing. We present data that suggest the interaction of prescribed fire, small-diameter tree thinning, cattle grazing, and drought were the primary causes of the spread of Bromus.

https://www.fs.fed.us/rm/pubs/rmrs_p051/rmrs_p051_192.pdf

Cheatgrass encroachment on a ponderosa pine ecological restoration project in northern Arizona, U. S. A.

In this paper, we describe several long-term studies in the ponderosa pine (Pinus ponderosa) forests of the American Southwest, focusing on the unique insights and contributions of these studies. Many of the studies that we discuss were established by staff from the Fort Valley Experiment Station (FVES; http://www.rmrs.nau.edu/fortvalley/).

Long-term vegetation studies in the southwest

Ecosystem stability has been of increasing interest in the past several decades as it helps predict the consequences of anthropogenic disturbances on ecosystems. Species may exhibit stability through compensation, with greatly fluctuating populations year to year but a consistent density response over time. Stability is increased when species with similar functional roles compensate for one another by responding differently to environmental change. In restoration projects, the objective is to restore stability by altering ecosystem composition, structure, and function to resemble natural (‘‘reference’’) conditions. We assessed the success of ecological restoration treatments by examining the structural and functional responses of the small mammal community before and after treatment, and compared to reference conditions. We used Royle density models to examine the responses of eight species of small mammals to restoration (thinning) treatments in ponderosa pine forests to determine if the community maintained total density, biomass, and function (represented by ectomycorrhizal fungi dispersion) after disturbance. Community composition differed in each of 6 years following treatment, but total density and biomass remained constant, suggesting the community is a stable prey base for predators. In addition, goldenmantled ground squirrels (Spermophilus lateralis) and gray-collared chipmunks (Tamias cinereicollis) appeared to play a similar role in dispersing ectomycorrhizal fungi across different forest structures. Both total species density and biomass were greater after thinning than in unthinned stands, and were similar to reference stands. These results suggest that although species composition changes from year to year after disturbance, restoration treatments can maintain ecosystem stability in terms of small mammal community-level properties.

https://esajournals.onlinelibrary.wiley.com/doi/pdf/10.1890/ES12-00143.1

W. Wallace Covington

Papers

Perspective: Prescribed Fire Is Not the Issue

Learning by doing: education in ecological restoration at Northern Arizona University.

Cheatgrass encroachment on a ponderosa pine ecological restoration project in northern Arizona, U. S. A.

Long-term vegetation studies in the southwest

Small mammal community maintains stability through compensatory dynamics after restoration of a ponderosa pine forest