Postfire Mortality Of Ponderosa Pine And Douglas Fir

This review focused on the primary literature that described, modeled, or predicted the probability of postfire mortality in ponderosa pine (Pinus ponderosa) and Douglas-fir (Pseudotsuga menziesii). The methods and measurements that were used to predict postfire tree death tended to fall into two general categories: those focusing on measuring important aspects of fire behavior, the indirect but ultimate cause of mortality; and those focusing on tissue damage due to fire, the direct effect of fire on plant organs. Of the methods reviewed in this paper, crown scorch volume was the most effective, easiest to use, and most popular measurement in predicting postfire mortality in both conifer species. In addition to this direct measure of foliage damage, several studies showed the importance and utility of adding a measurement of stem (bole) damage. There is no clear method of choice for this, but direct assessment of cambium condition near the tree base is widely used in Douglas-fir. Only two ponderosa pine studies directly measured fine root biomass changes due to fire, but they did not use these measurements to predict postfire mortality. Indirect measures of fire behavior such as ground char classes may be the most practical choice for measuring root damage. This review did not find clear postfire survivability differences between the two species. The literature also does not show a consistent use of terminology; we propose a standard set of terms and their definitions.

This is a print on demand edition of a hard to find publication. This report synthesizes the literature and current state of knowledge pertaining to re-introducing fire in stands where it has been excluded for long periods and the impact of these introductory fires on overstory tree injury and mortality. Only forested ecosystems in the United States that are adapted to survive frequent fire are included. Treatment options that minimize large-diameter and old tree injury and mortality in areas with deep duff and methods to manage and reduce duff accumulations are discussed. Pertinent background information on tree physiology, properties of duff, and historical versus current disturbance regimes are also discussed. Charts and tables.

Douglas-fir has life history traits that greatly enhance resistance to injury from fire, thereby increasing post-fire survival rates. Tools for predicting the probability of tree mortality following fire are important components of both pre-fire planning and post-fire management efforts. Using data from mixed-severity wildfire in Montana and Wyoming, Hood and Bentz (2007) developed models for predicting the probability of Douglas-fir mortality and Douglas-fir bark beetle attack based on fire injury and stand characteristics. This guide is based on information in Hood and Bentz (2007) and is intended for use in development of post-fire management and prescribed burn plans. Included are descriptions of both models and variables that significantly influence post-fire Douglas-fir mortality and bark beetle attack. A supplemental field guide provides photographs of a range of levels for each fire-related injury and descriptions for measuring each characteristic in the field. Also provided are discussions on how to interpret Douglas-fir mortality and bark beetle attack models for use in management decision-making regarding wild and prescribed fires in the Northern Rocky Mountains.

Many coniferous species have life history traits and characteristics that greatly enhance their resistance to injury from fire, thereby increasing post-fire survival rates. Douglas-fir (Pseudotsuga menziesii (Mirbel) Franco), for example, is known for its fire tolerance, in large part, due to thick insulating bark that develops with age and protects the inner cambium from heat injury. Mortality following fire, however, depends not only on tree species, but also on type and degree of fire-caused injuries, initial tree vigor, and post-fire environment. These same factors may also influence timing of tree death, which can be delayed as long as 4 years post-fire. Within a few months to a few years following fire, bark and wood boring beetles may preferentially attack, and wood deterioration caused by staining, decay pathogens, and/or checking can occur. Parker and others provide an extensive review of interactions between insects and fire (prescribed and wildfire) in coniferous forests of interior western North America. Development of management plans immediately following fire, therefore, can be difficult due to the timing and uncertainty of many interacting factors. Reliable estimates of post-fire Douglas-fir mortality, predicted from field-based characterizations of fire injury, would greatly facilitate informed post-fire management, including salvage, following both mixed-severity wildfires and applications of prescribed fire. Prediction of fire- and beetle-caused delayed tree mortality is also an important component in the development of prescribed burn plan objectives. Managers must know what fire intensity levels are needed to accomplish mortality related objectives. Also, in adaptive management, a key part to determining if burn objectives were met is installation of monitoring plots. By revisiting prescribed burns and monitoring fire effects, future burn prescriptions can be adjusted to better achieve desired results. To do this, field crews must be able to accurately assess post-fire tree injury and the potential for delayed mortality. Fire behavior and effects models, such as the First Order Fire Effects Model (FOFEM) and BehavePlus, are available for use in predicting post-fire tree mortality. The tree mortality model in these software packages is based on models developed by Ryan and Reinhardt (1988) and Ryan and Amman (1994). However, this tree mortality model was developed from data for several different tree species. More importantly, this model does not fully account for bark beetle effects on post-fire tree mortality. Douglas-fir bark beetles (Dendroctonus pseudotsugae Hopkins Coleoptera: Curculionidae, Scolytine) are highly attracted to fire-injured Douglas-fir and can cause significant tree mortality, apart from fire injuries alone. If Douglas-fir beetle populations are a concern following fire, it is important to characterize the fire-related tree injuries most conducive to beetle attack and successful brood production and survival. Hood and Bentz (2007) developed a model to predict the probability of Douglas-fir mortality and one to predict the probability of Douglas-fir beetle attacks within 4 years post-fire based on data collected from three mixed-severity wildfires in western Montana and Wyoming. The intent of this guide is to facilitate use of these models in post-fire management and prescribed burn planning. We note that ecological and economic constraints make forest management following wildfire a complex task. Our models are meant to be used as part of a multidisciplinary strategy aimed at maximizing benefits to post-fire ecological communities and forest management. Following a brief description of the two models, variables significant in predicting post-fire Douglas-fir mortality and Douglas-fir beetle attack are described.