© The Regents of the University of California, (2004) (last updated 23 Feb. 2005)
Dr. Donald L. Dahlsten passed away on 3 Sept. 2003. Please see the UC Berkeley press release.
A giant sequoia tree was planted in Don's honor by his grandchildren on the Berkeley campus between Wellman Court and Tolman Hall:
Click here to see a picture gallery celebrating Don's last 25 years
The focus of research in Don's laboratory was on the development of ecologically sensitive methods for controlling insects that feed on forest trees and trees in urban environments. The studies were primarily field oriented in order to gain insight into the ecological mechanisms and trophic interactions so that the control strategies can be implemented. Most of this work was with insects that either parasitize or prey on tree feeding insects but we also worked with some species of insectivorous birds and their effects on the forest ecosystem.
CLASSES
PROJECTS:
|
|
Insectivorous Birds In the Forest Ecosystem / Wildlife Studies |
|
|
|
|
|
|
Native Bark Beetles, their Natural Enemies, and Fire / Insect Interactions |
|
|
Dr.
Donald L. Dahlsten, Professor
David
L. Rowney, Biostatistician (daver@berkeley.edu)
Dr. Robert Zuparko,
Post Doc. Researcher (bz@ nature.berkeley.edu)
Dr. Bruce Jennings,
Post Doc. Researcher
Graduate Students:
Kyle Apigian (kapigian@hotmail.com)
Angelica Herrera (gelica@pw.usda.gov)
Deanna Simon (dsimon@nature.berkeley.edu)
Chris Solek (csolek@nature.berkeley.edu)
Other links:
to UCB Biological Control page
The objective of this study was to develop an integrated pest management program for the elm leaf beetle. This insect is one of the top three insects of importance in urban environments in the United States. We have developed monitoring and timing techniques using degree days but we have been only partially successful in developing control techniques. We worked in Sacramento, a city with 4000 elms, and evaluated the use of a bacterial insecticide and the introduction of a warm weather adapted egg parasitoid from Spain. Other strains of these egg parasitoids have been released for several years with little success.
We studied native bark beetle species and their natural enemies. Bark beetles are the most important forest pests in California. We studied the natural enemy complexes of these beetles for many years and carried experiments to identify the mechanisms that bark beetle parasites and predators use to locate their hosts.
Fire/Bark Beetle Research: 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. The lab, in cooperation with the U. S. Forest Service, Pacific Southwest Region, measured the extent of beetle-induced mortality from different prescribed fires in the East-side pine ecosystem of Northern California. Special attention was given to the role of fire in predisposing trees to beetle attack and the effect of fire on tree physiology. The goal of our work was 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. This addresses the concern for increased use of this management tool and provide findings with direct implications for managing land for reintroducing fire into the ecosystem.
The lab also contributed to the Fire and Fire Surrogate study at U. C. Blodgett Research Forest. We monitored numbers of ground-dwelling arthropods monthly through the summer season on plots with mechanical thinning, prescribed fire, a combination of both, and no treatment.
To study insectivorous birds we used nesting boxes in forest environments. The goal is to determine
the impact that secondary cavity nesting birds have on forest insect pests. We used video and movie cameras to identify prey items. We also studied the reproductive biology of the mountain chickadees, chestnut- backed chickadees and pygmy nuthatches. The impact of predators, such as weasels, bears, squirrels, and snakes on these birds in nesting boxes was studied as well. We are evaluating ways to limit predation on nests, such as installation of metal bands below the nest boxes on trees.
Effects of Sudden Oak Death on wildlife. As part of the Sudden Oak Death Project we monitored bird populations using census points and nest boxes, small mammals using live traps, and reptiles/amphibians using cover boards in plots with and without active SOD infections in norhern California.
Effects of Biological Control of Tamarisk on bird populations. This new study in cooperation with the USDA will monitor birds using census points and nest boxes in riparian plots with and without introduced biological control agents on tamarisk, an invasive exotic invader plant species.
Effects of Riparian Woodland Management for Control of Pierce's Disease
on vertebrates: In 1997 a study was initiated to study management techniques
in riparian woodlands to control Pierce's disease. These techniques involve
manipulation of vegetation in riparian corridors between fields of grapevines.
Management of riparian woodlands to reduce the incidence of Pierce's disease
in neighboring fields must also meet requirements to maintain good habitat for
wildlife and fish. We are studying the effect that the experimental treatments
have on the vertebrates (birds, mammals, reptiles and amphibians) in these riparian
areas. We use a number of procedures to accomplish this: bird and mammal census
from fixed spots for fixed time periods; spring survey of nests; observations
of animals using artificial nest boxes; predator activity at nest boxes; live
trapping of small mammals; photographic surveys using cameras activated by light
beam interruption; and monitoring of flat plate shelters for reptiles and
amphibians. These procedures are concentrated in the spring-early summer during
nesting season, but are continued less intensively through 
the
entire year.
Argentine Ants and Urban Tree Dwelling Homopterans
This study determined relationships between food source stress (primarily tree dwelling Homopterans), environmental conditions, and home invasions by Argentine ants (Linepithema humile).
