David Ganz

Graduate Student Researcher-

Lab of  Dr. Donald Dahlsten
Department of Environmental Science Policy and Management
Insect Biology Division, 201 Wellman Hall #3112
U.C. Berkeley- College of Natural Resources

Berkeley, CA 94720

My Publication List

Two of my recent studies:
Fire Mitigation in Strawberry Canyon
GIS Lab Work

RESEARCH PROSPECTUS

Measuring Fire Intensities and Severity from Prescribed Fires and the Extent of Tree Mortality from Bark Beetles In Sierra Nevada East Side Pine Ecosystems

Abstract

Due to a prolonged absence of periodic low-intensity burning in the Sierra Nevada East Side Pine ecosystems, changes in species composition and stand structure have predisposed these forests to extensive insect and disease attack -- as well as to severe stand replacement wildfires. In some areas 75 to 100 years of effective fire control has altered the historical fire regime thus resulting in unusual amounts of fuel and stand conditions. These areas are then susceptible to unusual fire behavior.

Prescribed fire is seen as the management tool to help remediate the current problems of poor forest health and extensive high-risk fire behavior characteristics. The potential for prescribed fire to physically alter these characteristics may cause significant tree mortality from the burn itself as well as subsequent mortality to bark beetles in the years to come. This study plan provides an experimental design for measuring the extent of beetle-induced mortality from different prescribed fires in the Sierra Nevada East Side Pine ecosystems of Northern California. Special attention will be given to the role of fire in predisposing trees to beetle attack through direct effects on the bark and cambium. The goal is to provide forest managers in this region with an idea of the severity of tree mortality associated with prescribed fires burned under a wide variety of environmental and fuel conditions. The study will address the concern for increased use of this management tool and provide research findings with direct implications for managing land for reintroducing fire into the ecosystem.

I. Problem Statement

In the Sierra Nevada of California, fire has been an important evolutionary factor in the development of East Side Pine ecosystems (Biswell 1972, Jepson 1925, Wright 1978, SNEP 1996). Due to successful fire suppression over the last century, much of the Sierra Nevada is overstocked with trees, and as a result riddled with disease and insect problems (SNEP 1996). During this last decade, drought-induced stresses on vegetation coupled with the drying of dead fuels has left many of these forests in a high fire risk. As a result, the Forest Service is looking to use prescribed fire as a tool to reduce the fire hazard and improve the physiological condition of the ecosystem. Jack Ward Thomas, former Chief of the USDA Forest Service, has asked the agency to "increase mechanical and prescribed fire treatments to 3,000,000 acres per year in fire dependent ecosystems by the year 2005" (USDA Forest Service, "Course to the Future: Positioning Fire and Aviation Management", May 1995). This new policy has led to a significant scientific commitment to understanding the impacts of prescribed fire operations. Nevertheless, the general public continues to see fire as a primary cause of tree mortality and habitat loss. The use of prescribed fire has increased the concerns about the detrimental impacts of fire on tree vigor, especially when it potentially predisposes large trees to bark beetle attacks. In order for this new policy to be implemented, more scientific information is needed on the effects of using this management tool on the ecosystem.

In the same manner that a management tool has the potential to increase tree vigor and site productivity (site quality), it also has the potential to reduce it through misapplication and site degradation. Prescribed fires have been shown to have such a potential. Growth losses on commercial tree species have been reported in response to fire stress. These losses are usually attributed to root, cambial and crown damage, leading to a decline in the physiological condition or vigor of the tree (Hare 1961, Wright and Bailey 1982). Other potential sources of losses may be attributed to fuel consumption of organic material and topsoil loss through the process of erosion (Agee 1973). Bark beetles have been shown to selective in their colonization of host trees, with the respect the species and the vigor of the tree (Moeck et al.1981). Fire has been found to be an abiotic agent that potentially weakens trees and predisposes them to beetle attack (Miller and Patterson, 1927; Hall and Eaton, 1961; Furniss, 1965; Swain, 1968; Gara et. al.,1984). There is also evidence suggesting that there is a direct correlation between Dendroctonus and Ips attacks and the extent of fire damage on lodgepole pine in Oregon (Geiszler et al. 1984). However, little has been published on the effect of different types of prescribed fire on tree vigor and subsequently on bark beetle and natural enemy populations. This study is designed to determine the extent of change in tree vigor from different prescribed fires and the potential for "primary attraction" of bark beetles and the development of outbreaks.

II. Objectives

The main objective of this study is to measure the effects of different fire intensities from prescribed fires on tree vigor and its susceptibility to beetle attack on two study sites in the Northern Sierra Nevada of California. The two study sites are located in the Tahoe Basin and Blacks Mountain Experimental Forest. Measurements of the change in cambium activity will be used to calculate the extent of burn damage on mixed conifer species from the fire treatments while stand and fuel parameters will be measured before and after the treatments to characterize fire severity. Fireline intensity will be measured by taking videos of flame lengths during the burn. Bark beetles will be monitored for their response to seasonal fire treatments (fall versus spring) and for three years after the burns. In addition, the proposed research will evaluate the current Wagner guidelines for predicting tree mortality after fire. Success of this study will be measured by its implications for land managers like the Forest Service, who are planning on using prescribed fire as a management tool and are concerned about bark beetle attacks, as there is the potential for prescribed fires to perpetuate insect problems in the East Side Pine ecosystem of the Sierra Nevada. Scientific findings will be peer reviewed and sent to scientific journals for publication and then distributed to forestry extension services, collaborating government agencies, and interested private companies.

III. Hypothesis

Low intensity prescribed fire does not produce enough heat to predispose trees/stands to bark beetle attack but high intensity burns result in significant stand damage (both initially by fire and secondly by susceptibility to beetle kill in following seasons). The higher temperatures make trees more susceptible to beetle attack though natural enemies are not deterred by fire and come in preventing outbreak populations from building up. Damage to a stand is likely to be directly correlated to its pre-fire stocking density. Here are the factors and variables which will be considered in proving or disproving this hypothesis (including sources for methodology):

1) STAND STRUCTURE & COMPOSITION

a) Density measures: Trees/acre, basal area, Reineke SDI

b) Age and growth measures: MAI, DBH, height, volume

c) Species composition: overstory and understory

d) Site Quality

i. Topography: slope ,aspect, drainage

ii. Climate: precipitation and temperature data
iii. Soil properties: soil moisture, texture, and nutrient levels

2) FIRE SEVERITY AND INTENSITY

a) Organic Layer: duff depth before and after the burn

b) Fuel Loading: fuel size class before and after burn

c) Flame Length: during the burn itself

d) Photo interpretation: during the burn itself

e) Bark and Crown Scorch: indirect measures of fire behavior

3) TREE VIGOR AND SUSCEPTIBILITY

a) Percentage of live crown: LCR, needle loss, discoloration

b) Photosynthetic activity: chlorophyll fluorescence, reflectance

c) Cambial Damage (Graeme Berlyn, personal communication)

d) Success rate of bark beetle attack

e) Tree vigor index- BA/SA (Waring et al. 1980)

An alternative hypothesis is that prescribed burning does contribute to significant tree mortality and host tree susceptibility even with low intensity prescribed fire in the East Side Pine ecosystem of the Sierra Nevada . This alternative indicates that measures should be taken to minimize the use of prescribed burning in areas where tree mortality is not a preferred outcome (for instance private industry).

IV. Methods

Design and Analysis for Characterizing Stand Structure and Fire Intensities:

In order to control these factors and variables to reduce the amount of experimental variability, prescribed fire sites for the treatments and controls have been carefully chosen. The two sites are exclusively in East Side pine stands with variations in stand structure and fuel loadings. These variations have been measured using fixed area plot sampling system, in which overstory and understory is inventoried and marked for further study. Age and growth measures has been performed on a subset of the overstory trees. Site quality has been evaluated for the growth potential based on existing site information.

To characterize the fire severity and severity, data has been collected using a variety of methods depending on the fire scientist administering the controlled burn. Flame length during the burn is commonly used as an indication of intensity. Fuel consumption is also a commonly used method for measuring severity. Spikes have been driven flush with the top of the duff and the exposed length and distance to mineral soil measured after burning according to the method described by Beaufait et al. (1977). This has also been done surrounding individual trees to evaluate the smoldering effect from heavy duff accumulation around the base. Fuel loading has been measured using transect planes (Brown 1974) and fuel consumption calculated by remeasuring fuels along each transect plane. With information from temperature-measuring systems such as these, it should be feasible to predict an association between the intensity of the fire, the amount of fuel consumed and the fire effects. By collaborating with fire scientists, I hope to get consistent measures of fire intensity to make such predictions.

Design and Analysis for Characterizing Tree Vigor:

The concept of tree vigor and vitality is difficult, if not impossible, to determine unambiguously. However, good growth is usually considered a sign of good vitality and correspondingly reduced growth a sign of decreased vitality. For the purpose of this study, stand vigor has been defined as the stand's physiological capacity to metabolize, respire and produce net photosynthetic gain (in growth and in storage).

Vigor can be used as an index of productivity which is traditionally measured with LCR, MAI and PAI. Tree vigor indices (Waring et al. 1980) have been developed to determine vigor based on a simple physiologic process. A stand that has high vigor will have high levels of productivity and higher increments of growth. Stands with trees with high live crown ratios will have more photosynthetic surface area and thus more photosynthetic capacity. This results in more carbohydrates to distribute for such things as storage, seed production, and stem volume growth. Stands of high vigor will also be more adept in fighting off insect and disease problems as they develop. Healthy trees in unburned treatments (controls) will be used to compare the effects of different fire intensities on cambial activity (within same species, dbh classes and LCR). The ability of the cambium to transport materials necessary for growth and maintenance may be altered by the heat of a prescribed fire. Tetrazolium salts will be used to determine enzyme activity within the cambium and then analyzed quantitatively with an image analysis system (Graeme Berlyn, personal communication). With information from growth and vigor measures, I hope to find a correlation between the intensity of the fire, the vigor of the residual trees and the susceptibility of a forest stand to bark beetle attack.

Design and Analysis for Determining Host Selection Behavior and Their Associates:

At a 1989 work conference, Ken Raffa writes "the role of active tree physiology in beetle chemical communication also requires more attention" and "an improved understanding of tree defense systems and beetle behavioral responses to host condition should lead to effective management tactics, both for prediction and prevention" (Work Conference: Attraction and Dispersal of Pine Bark Beetles and Their Associates, Mountain Lake, Virginia, October 1989). Prescribed fire allows for careful study of tree physiology and host selection because even controlled disturbance can potentially predispose trees. We are able to set up equipment to study when and where these effects lead to bark beetle behavioral response.

Seasonality of prescribed burning will be evaluated as it has been noticed in the field to be a critical factor for predisposing trees to bark beetle attack. Though attack densities may be evaluated through entry holes, brood survival will not be determined by this study as this would involve cutting into the cambium thus preventing any physiological response by the tree. Previous studies with the red turpentine beetle (Dendroctonus valens) have shown green infested trees which continue to live many years after the fire and initial attack. This type of information (seaonality of burns, timing of attack, successful attack rates, tree survival rates) along with the tree physiology study should give researchers and managers a better understanding of tree defense systems and beetle behavioral responses to host condition.

V. References

AGEE, J.K., 1973. Prescribed fire effects on physical and hydrologic properties of mixed-conifer forest floor and soil. Water Resources Center, University of California, Davis, 1973
BEAUFAIT, W.R., HARDY, C.E., FISCHER, W.C., 1977. Broadcast burning in larch-fir clearcuts: The Miller Creek-Newman Ridge Study. USDA For. Serv. Res. Pap.- Intermountain For. and Range Exp. Stn., Ogden, Utah. 53 pp.
BERLYN, GRAEME 1996. Personal communication. Tree Physiology Professor, Yale School of Forestry and Environmental Studies, New Haven, CT.
BISWELL, H.H. 1972. Fire ecology in ponderosa pine-grassland. pp. 69-96 in Proc. Tall Timbers Fire Ecology Conf. Tall Timbers Res. Stn., Tallahassee, FL.
BROWN, J.K. 1974. Handbook for inventorying downed woody material. USDA For. Serv. Gen. tech. Rpt.- Intermountain For and Range. Exp. Stn., Ogden, Utah. 24 pp.
FURNISS, M. M., 1965. Susceptibility of fire-injured Douglas-fir to bark beetle attack in southern Idaho. Journal of Forestry 63:8-11
GARA, R. I., LITTKE W.R., AGEE , J.K., GEISZLER, D.R., STUART, J.D., and DRIVER, C.H., 1984. Influence of fires, fungi and mountain pine beetles on development of a lodgepole pine forest in South- Central Oregon. Proceedings in Lodgepole Pine: the species and its management. Wash. St. University, Spokane, Washington
HALL, R. C., and C.B. EATON, 1961. Trials with lindane for protecting fire-injured trees from insects. USDA FOr. Serv. Pacific Southwest For. Rge. Exp. Sta. Rept. 19 pp.
HARE, R.C., 1961. Heat effects on living plants. USDA For. Serv. Occ. Pap.S-183 Southern For. Exp. Sta., New Orleans, LA
JEPSON, W.L.1925. Floering plants of California. Assoc. Student store, Univ. of California., Berkeley, CA 1238 pp.
MAARIT, K., NIEMELA, P. and ANNILA, E., 1996. Vitality and bark beetle resistence of fertilized Norway spruce. Forest Ecology and Management 84:149-157
MILLER, J.M., and J.E. PATTERSON, 1927. Preliminary studies on the relation of fire injury to bark beetle attack in western yellow pine. J. Agric. Res. 34:597-613
MOECK,H.A., WOOD, D.L., and LINDAHL, K.Q, Jr., 1981. Host selection behavior of bark beetles (coleoptera:Scolytidae) attacking Pinus ponderosa, with special emphasis on the Western Pine beetle, Dendroctonus brevicomis. Journal of Chem. Ecol. 7:1 pp.49-83
RAFFA, K.R., 1989. Critical Needs in Understanding Bark Beetle Biology and Management: Host Susceptibility & Host Selection in Work Conference: Attraction and Dispersal of Pine Bark Beetles and Their Associates, Mountain Lake, Virginia, October 1989
SACKETT, S.S., and S.M. HAASE, 1992 Measuring soil and tree temperatures during prescribed fires with thermocouple probes. USDA For.Serv. Gen. Tech. Rep. Pacific SouthWest Exp. Sta.-Gen. Tech. Rep. 131. Albany, CA, 15 pp.
SNEP. 1996. Sierra Nevada Ecosystem Project. Volume 2: Chapter Four. Wildland Resources Center, Report No. 38. University of Califonia, Davis.
SWAIN, K.M. 1968. Protecting ponderosa pine from bark beetle attack by use of lindane-water emulsion spray. USDA For. Serv. Div. Timber Management Rept.,13 pp.
USDA Forest Service, "Course to the Future: Positioning Fire and Aviation Management", May 1995. USDA Forest Service Position Statement, Washington D.C.
WARING, R.H., THIES, W.G., and MUSCATO, D. 1980. Stem growth per unit leaf area; a measure of tree vigor. Forest Science, 26 112-117
WRIGHT, H.A. and A.W. BAILEY, 1982. Fire Ecology: United States and southern Canada. John Wiley and Sons. New York. 501 pp.
WRIGHT, H. A. 1978. The effect of fire on vegetation in ponderosa pine forest. Texas Tech Univ. Range and Wildlife Inf. Ser. No. 2, Publ. no. T-9-199. 21pp.
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