Submitted by Robert Mathiasen, Jerry
Beatty, and Katy Marshall
I. TAXONOMY, HOSTS, AND DISTRIBUTION
1. Our work on the taxonomic status of the shore pine dwarf
mistletoe is continuing. More
specimens of male plants of western hemlock dwarf mistletoe were collected from
several populations throughout Oregon and Washington in early August and
additional morphological measurements completed.
We have started analysis of the shore pine dwarf mistletoe data and hope
to draft a manuscript this winter. (R.
Mathiasen, Northern Arizona University, Flagstaff, AZ; E. Wass, Canadian Forest
Service, PFC, Victoria, B.C.; R. S. Smith, Grand Forks, B.C.)
2. Further observations of the phenology of Hawksworth=s
dwarf mistletoe (A. hawksworthii) will
be made in early November 2000 in Belize. (R.
Mathiasen, Northern Arizona University, Flagstaff, AZ;)
3. Another population of the Honduran dwarf mistletoe (A.
hondurense) was discovered on Pinus
tecunumanii in October 1999 in Celaque National Park near Gracias,
Department Lempira, Honduras. This
is only the fourth location reported for this dwarf mistletoe from Honduras, but
specimens deposited at the Standley Herbarium at Zamorano, Honduras indicate it
also occurs in other areas of Celaque National Park. (R. Mathiasen, Northern
Arizona University, Flagstaff, AZ; J. Melgar, ESNACIFOR, Siguatepeque, Honduras;
C. Parks, PNWRS, LaGrande, OR; and J. Beatty, WTCFID, FI&D, Region 6, Sandy,
OR)
4.
Our field observations and molecular analysis have confirmed that the
black dwarf mistletoe (A. nigrum) populations in Chiapas, Mexico are actually Honduran
dwarf mistletoe (A. hondurense). This
extends the distribution of this dwarf mistletoe from Honduras into southern
Mexico and indicates that it probably occurs in Guatemala. (R. Mathiasen and S.
Sesnie, Northern Arizona University, Flagstaff, AZ; D. Nickrent, Southern
Illinois University, Carbondale, IL; C. Parks, PNW Research Station, LaGrande,
OR; and J. Beatty, WTCFID, FI&D, Region 6, Sandy, OR)
5. Male plants of Arceuthobium
globosum ssp. grandicaule
measuring over 81 cm in height were discovered on Pinus rudis in the Sierra de los Cuchumatanes near Chemal in western
Guatemala in March 2000. Female
plants measuring over 66 cm in height have been discovered in the same
populations. These represent the
largest dwarf mistletoe plants discovered thus far in the Universe. Frank
Hawksworth=s
previous maximum plant height for this dwarf mistletoe was 70 cm.
More trophy size dwarf mistletoe hunting in Guatemala is scheduled for
August 2001. (R. Mathiasen and S.
Sesnie, Northern Arizona University, Flagstaff, AZ; C. Parks, PNW Research
Station, LaGrande, OR; and J. Beatty, WTCFID, FI&D, Region 6, Sandy, OR)
6. A review of the hosts and geographic distribution of Arceuthobium
oxycedri was completed and submitted to the Journal of Plant Pathology.
Following several updates in host nomenclature, 15 taxa of Juniperus,
2 Chamaecyparis, 5 Cupressus,
and 1 Thuja are reported as hosts.
Juniper dwarf mistletoe is reported from 28 countries across northern
Africa, western Europe, the Balkans, Russia and other former Soviet Republics,
the Near East, the Indian subcontinent, and western China. Previous reports from
Bhutan and Hungry are corrected; and reports for Portugal, Armenia, and
Afghanistan are questioned. Although not supported by valid reports, the
mistletoe is suspected to occur in Nepal and Bhutan. (B. Geils, RMRS, Flagstaff,
AZ; W. Ciesla, Fort Collins, CO; R. Adams, Gruver, TX)
II.
PHYSIOLOGY AND ANATOMY
1. A series of experiments under environmentally controlled
conditions (greenhouse and growth chamber) are being established to investigate
the effects of reduced light and moisture on host physiology and mistletoe
latency. The subject mistletoes are southwestern dwarf mistletoe, Douglas-fir
dwarf mistletoe, lodgepole pine dwarf mistletoe, and hemlock dwarf mistletoe.
Results of the study are hoped to provide a better understanding of host and
pathogen responses following partial cutting and parameter estimates for a
mistletoe simulation model. (B. Geils, RMRS, Flagstaff, AZ; T. Kolb, Northern
Arizona University, Flagstaff, AZ)
III.
LIFE CYCLES
1.
We continued our study of the sex ratio of Chihuahua pine dwarf mistletoe
(A. gillii) in southern Arizona.
We sampled additional A. gillii
populations in the Santa Catalina, Huachuca, Santa Rita, and Chiricahua
Mountains in 2000. So far the sex
ratio of all the populations we have sampled is essentially 1:1. (R. Mathiasen and C. Daugherty, Northern Arizona University,
Flagstaff, AZ; and D. Russell, Bureau of Land Management, Grants Pass, OR)
IV. HOST-PARASITE RELATIONS
No
submissions.
V.
EFFECTS ON HOSTS
No
submissions.
VI.
ECOLOGY
1. A preliminary study was completed on trophic interactions in
dwarf mistletoe infested ponderosa pine communities of the Colorado Front Range.
The objective of this work conducted by Kalian Mooney, University of
Colorado, was to evaluate the importance of trophic cascades and other
interactions among predators and herbivores of southwestern dwarf mistletoe.
The important bird predators were chickadees and nuthatches; ants and
spiders were identified as the important arthropod predators; and the
lepidopteron Dasypyga alternosquammella
as the principle herbivore. Based on differences between trees with or without
bird enclosure, birds appeared to reduce the numbers of all insects (ants only
marginally) and reduce the number of cursorial spiders (but not web spiders).
Together birds and arthropod predators significantly reduced the
population of herbivores. Although 36% to 39% of shoots had been fed upon, there
was no significant difference in the amount of remaining mistletoe between
predator-free and predator-exposed branches. Life history data and parasitoids
were collected for D. alternosquammella. An
increase in the probability of herbivory was related to greater host branch
diameter and greater mistletoe shoot size.
An expanded study is being established to further explore 1) the
interactions among birds, ants, and spiders as competitors and predators, 2) the
indirect effects of predators and direct effects of herbivores on mistletoe
fitness, and 3) the influence of host branch morphology (including brooming) on
the abundance of predators, herbivores, and herbivory. (B. Geils, RMRS,
Flagstaff, AZ; Kailan Mooney and Yan Linhart, University of Colorado, Boulder,
CO)
2.
We are conducting a study to compare bird diversity in dwarf mistletoe
infested and uninfested ponderosa pine stands in northern Arizona. The objective of this research is to determine the
relationship between avian relative abundance and species diversity, and
infestation by Southwestern dwarf mistletoe (A.
vaginatum subsp. cryptopodum) in
ponderosa pine forests of northern Arizona.
We hypothesize that birds occur in greater abundance and with wider
species diversity in stands that are infested with dwarf mistletoe compared to
similar uninfested stands. The
fixed radius point-count method is being used to determine an index of relative
avian abundance and species diversity within stands of varying mistletoe
infestation severity. Twenty 80
acre study sites have been selected in pure pine forests west of the San
Francisco Peaks in the Coconino National Forest.
Five study sites in each of the following classes were selected: 1)
severely infested (mean DMR > 2.0); 2)
moderately infested (mean DMR 1.1-2.0); 3) lightly infested (mean DMR
0.1-1.0); and 4) uninfested (mean DMR 0). Eight
point-count stations have been established within each stand.
Birds were sampled at each point count station 6 times in 1999, and 6
times in 2000. Detailed stand
characterization is being completed in 40 1/10-acre plots within each stand.
Each tree encountered is being rated for dwarf mistletoe infection using
Hawksworth’s dwarf mistletoe rating, Tinnin’s broom volume rating, % volume
broomed, and an absolute broom volume rating.
In addition, ground cover, shrub/sapling cover, canopy structure, and
coarse woody debris data are being collected to identify potential covariates.
It is our goal to quantify how several avian species respond to different
levels of dwarf mistletoe infestation and to recommend what levels of mistletoe
infestation might be most beneficial to birds. (T. Parker, R. Mathiasen, and C.
Chambers, Northern Arizona University, Flagstaff, AZ)
3. We are investigating bird and mammal use of Douglas-fir dwarf
mistletoe-induced witches' brooms in the Southwest. This research will aid managers in determining which broom
and tree characteristics are important for wildlife habitat.
There are two phases of the study. The
first phase is a comparison of wildlife use in broomed and unbroomed trees.
Three stands were selected on the San Francisco Peaks on the Coconino
National Forest in Northern Arizona. We
laid out 4x4 grids (each point 80.5m apart) in each stand and systematically
selected pairs of broomed and unbroomed trees (based on diameter at breast
height) at each point to climb. We climbed trees in these stands in the fall of
1998 and 1999. Thus far, we have
found significantly more use in the broomed trees versus the unbroomed trees.
Due to what appears to be preferential use of broomed trees by birds and
mammals in these areas, a second phase was added to the study in order to
increase the scope of inference. During
the summer of 1999, 5 transects on 4 national forests in Arizona and New Mexico
were randomly selected. Fifteen
broomed trees (5 trees in 3 diameter classes) on each transect were
systematically selected and climbed to examine for wildlife use. We have
finished collecting all field data and we are now analyzing it. (S. Hedwall, C.
Chambers, R. Mathiasen, Northern Arizona University, Flagstaff, AZ; B. Geils,
RMRS, Flagstaff, AZ; M. Fairweather, FHP, R3, Flagstaff, AZ; and C. Parks, PNWRS,
LaGrande, OR)
4.
We have started a study to examine wildlife use of witches' brooms in
ponderosa pine in northern Arizona. The
first field season (2000) involved locating study sites and selecting sample
trees. This is a continuation of work on wildlife use of witches'
brooms in Douglas-fir. (G. Garnett,
R. Mathiasen, and C. Chambers, Northern Arizona University, Flagstaff, AZ)
5. I am continuing to study the growth of infected Douglas-fir
trees in a thinned stand in the Okanogan forest. The trees ranged from 2.5 to 15
cm dbh at the time the study was initiated. The study is in its thirteenth
season. I plan to initiate a study
of the pattern of development of brooms in Douglas-fir and ponderosa pine. This
will be the first season for that work. Sharon
Stanton is studying the effects of brooming, as distinct from DMR, on the growth
of ponderosa pine. That work should be completed by the end of this year.
Some papers we have published or are working on include: 1. Tinnin and
Forbes. 1999. Red squirrel nests in witches' brooms in Douglas-fir trees.
Northwestern Naturalist 80:17-21; 2. Tinnin, Parks, and Knutson. 1999. Effects
of Douglas-fir dwarf mistletoe on trees in thinned stands in the Pacific
Northwest. Forest Science 45:359-365; 3. Parks et al. 1999. Wildlife use of
dwarf mistletoe brooms in Douglas-fir in Northeast Oregon. Western Journal of
Applied Forestry 14:100-105; 4. Tinnin. 2001. Effect of dwarf mistletoe on bole
taper and volume in young Douglas-fir. Western
Journal of Applied Forestry (in press); 5. Godfree. 2000. Lodgepole pine dwarf
mistletoe in central lodgepole pine stands: effects on crown architecture, host
tree population dynamics, canopy structure and understory composition. Doctoral
Dissertation. (Near completion). (B. Tinnin, Portland State University,
Portland, OR)
VII.
GENETICS
1. The Central Zone Genetic Resource Program in Region 5, USDA Forest Service initiated a test dwarf mistletoe inoculation on one block of our resistance test plantation. The primary intent of the inoculation was to evaluate seed retention on the seedlings that were covered with bird netting, covered with bridal veil, or uncovered, and to evaluated germination from two different inoculation times. Some seedlings were inoculated in December while others were inoculated in March. Seed retention results were 65% for uncovered seedlings, 68% for seedlings covered with bird netting, and 75% for seedlings covered with bridal veil. The lower percentage for uncovered seedlings was attributed to the small size of several of the seedlings, either in a tendency to loose the seed more easily or in the difficulty to relocate the seed. This trend was seen on small seedlings that were covered as well. Of the retained seed, 14% from the March inoculation and 13% from the December inoculation appear to have germinated. The overall germination rate for total seed placed was 9%. These results are tentative at this time. A more thorough evaluation is planned. (D. Ringnes, USDA Forest Service, Camino, CA)
2. Selected lodgepole pine trees from the Colorado State Forest
Service seed production area (near Michigan Reservoir) were identified in 1971
as apparently having above-average growth, form, and mistletoe resistance.
Half-sib seedlings from 11 putatively-resistant trees were compared to seedlings
from 5 putatively-susceptible trees (from an infested, natural stand at Pingree
Park) in an inoculation trial conducted on the Fraser Experimental Forest. The
trial consisted of 5 seedlings per source, out planted in 1984, and inoculated
in 1988 and 1990. By 1999, mistletoe shoots had appeared on at least one
seedling from each putatively-resistant source; only one putatively-susceptible
source included no visibly infected seedlings. New infections appeared each year
since 1992; 33% of all surviving seedlings were infected. The long incubation
period for lodgepole pine dwarf mistletoe observed in this field study is
consistent with expectations and is attributed to the short growing season at
Fraser. (B. Geils, RMRS, Flagstaff, AZ; G. Fechner and J. Sprackling, RMRS, Fort
Collins, CO)
VIII.
MANAGEMENT
1. Our dwarf mistletoe suppression program is on the skids these
days. We do not have any
suppression projects because of cuts in suppression funding and because dwarf
mistletoe projects get lower priority than our bark beetle projects.
Permanent plot-wise, we have a good system of plots in place, and I
expect we will begin to harvest some useful data from these plots in about 2-5
years. The Targhee National Forest
plots are being used by Brian Geils in his efforts to update the Dwarf Mistletoe
model linked to the Forest Vegetation Simulator (formerly Prognosis).
Otherwise we don't have anything to report. (J. Hoffman, FHP, Region 4
Boise, ID; J. Guyon, FHP, Region 4, Ogden, UT)
2. We continue to fund Dwarf Mistletoe Suppression projects but
the emphasis has changed over the last 10 years.
Although we still have projects that are tied directly to treating a
specified number of acres on a few sites, we are also partially funding projects
at a much broader scale, such as ecosystem management projects that have dwarf
mistletoe management concerns. These
projects encompass analysis and treatment of sites within an area of 10,000 or
more acres. (M. Fairweather, FHP, Region 3, Flagstaff, AZ)
3. A project involving the use of prescribed burning to control dwarf mistletoe in a non-commercial forest was completed on the San Carlos Reservation. Preliminary results indicate some mortality and lower broom die-back. Victoria Wesley, Forest Health specialist for the tribe is the project leader and we will be working together to provide the results from this project. (M. Fairweather, FHP, Region 3, Flagstaff, AZ)
4.
Project title: Management of Dwarf Mistletoes by Biological and Genetic Control
Methods.
Research
Objectives: the overall objectives of the project is to survey and collect
fungal hyperparasites and to investigate their potential use as biological
control agents for dwarf mistletoes. Currently the focus of this research
program is on biological control of western hemlock and lodgepole pine dwarf
mistletoes. Most recently, research efforts are underway to explore the use of
genetic control method for management of western hemlock dwarf mistletoe.
Research
progress:
In vitro
germination and development of western hemlock dwarf mistletoe (Arceuthobium
tsugense subsp. tsugense) – A
novel procedure for in vitro culture
of western hemlock dwarf mistletoe was developed for the first time. A factorial
experiment evaluated the effects of media (Harvey’s medium (HM) and modified
White’s medium (WM), temperature (15°
C and 25°
C), presence or absence of light, and plant growth regulators (the auxin 2,4-D)
and the cytokinin (BAP) at varying concentrations (0.001 mg/l to 1.00 mg/l).
Seeds explants germinated in less than one week in culture and produced radicles.
Optimal conditions for radicle elongation were WM at 20°
C in the presence of light and without plant growth regulators. Some of the
radicles split at the tip to yield callus while others swelled to become
spherical holdfasts. Holdfasts were also produced at the tips of radicles, and
callus arose from split holdfasts. Factors that positively influenced holdfast
production were Harvey’s medium, light, and 2-4-D at 1 mg/l. Callus
development from split radicles and split holdfasts was optimal on WM with 0.5
mg/l 2,4-D and 1 mg/l BAP at 20°
C in the dark. The tissue culture procedure will be useful for studying genetic
resistance and the physiological and biochemical mechanisms of the host-parasite
interactions, as well as, to screen naturally occurring hyperparasites fungi for
their potential use as biological control agents against dwarf mistletoes.
Histopathological
investigation of the infection of germinated seeds and callus of western hemlock
dwarf mistletoe by Nectria neomacrospora
(Anamorph: Cylindrocarpon cylindroides)
and Colletotrichum gloeosporioides in
dual culture- the selection of these
two hyperparasitic candidate fungi was based on their performance as promising
biological control agents under field conditions. The potential use of these two
fungi was evaluated for their pathogenicity on germinated seeds and callus grown
in vitro. Mistletoe seeds were germinated on Harvey’s tissue culture medium
in one half of a petri plate while the other half contained water agar on which
the fungal growth was initiated from mycelial plug. Callus tissue was initiated
on Harvey’s medium or White’s modified medium, challenged with fungi on
Harvey’s medium (Cylindrocarpon
cylindroides) or modified White’s medium (Colletotrichum gloeosporioides), as fungal growth rates were found
to be moderate on these media. Mistletoe tissue were prepared for light
microscopy at various days post-contact with fungi. In seeds, both endosperm and
radicle were colonized, and cushion development, cell wall degradation, and
intercellular and intacellular colonization was evident. Cells infected with Cylindrocarpon
cylindroides were disorganized and appeared plasmolysed. The in
vitro screening method developed in this investigation was useful to elucidate
host-pathogen interactions and was sensitive enough to show that Cylindrocarpon
cylindroides was more aggressive at colonization than Colletotrichum
gloeosporioides.
Field
trials continue monitoring of the field trials which were initiated in 1997 on
the potential use of Cylindrocarpon
cylindroides and Colletotrichum
gloeosporioides as potential biological control of western hemlock dwarf
mistletoe.
Exploring
the use of genetic resistance strategy for management of western hemlock dwarf
mistletoe- early results suggests levels of resistance to western hemlock dwarf
mistletoe within western hemlock clones in conifer plantations in British
Columbia. An understanding of the mechanisms involved and factors influencing
resistance to western hemlock dwarf mistletoe will support the selection and
breeding the host plants which are more resistant to infection. Research
objectives include: 1) utilization of in
vitro (tissue culture) system already developed at Dr. Shamoun’s lab as a
rapid screening method for resistance in western hemlock populations to western
hemlock dwarf mistletoe; 2) elucidation and characterization of inheritance of
resistance in hemlock populations to western hemlock dwarf mistletoe. To date,
we have planted 300 young seedlings of western hemlock representing 50
provenance under greenhouse conditions. These young seedlings will be infected
with seeds of western hemlock dwarf mistletoe in October, 2000. The experiment
will be monitored in the next 1-3 years for selection different resistance
traits to western hemlock dwarf mistletoe. This research venture is a
collaborative research effort with Charlie Cartwright- Hemlock breeder, BC
Ministry of Forests.
Biological
control of lodgepole pine dwarf mistletoe- this project is part of a Ph.D. work
conducted by Tod Ramsfield who is working under the direction of Drs. Bart van
der Kamp and Simon F. Shamoun. To date, we have achieved : 1) continue
collection of the potential candidate hyperparasite Colletotrichum
gloeosporioides from lodgepole pine dwarf mistletoe. A total of 91 pure
cultures were preserved at the fungal culture collection of Dr. Shamoun’s
lab.; 2) inoculated 36 lodgepole pine seedlings with A. americanum seeds under outside conditions at the Pacific Forestry
Centre. Also inoculated 31 lodgepole pine seedlings with A.
americanum under shadehouse conditions; 3) established a partial shoot
removal trail in Lytton, BC where treatments were no shoots removed, ¼, ½, ¾,
and all shoots removed and shoots cut in half to determine how A.
americanum responds to stress; 4) during the summer, 2000, a field trial was
established to assess the efficacy of the formulated C. gloeosporioides on A.
americanum at Lytton, BC; 5) sample tree canopy to observe the distribution
of C. gloeosporioides at different canopy levels of lodgepole pine trees;
6) projected work will explore the role of Colletotrichum
in the endophytic system, using culture technique, microscopy and DNA markers.
Publications:
1) Deeks, S., Shamoun, S.F. and Punja, Z. 1999. Tissue culture of parasitic flowering plants: methods and applications in agriculture and forestry. In Vitro Cell. Dev. Biiol.- Plant 35: 369-381.
2) Kope, H. and Shamoun, S.F. 2000. Mycoflora associates of western hemlock dwarf mistletoe plants and host swellings collected from southern Vancouver Island, British Columbia. Canadian Plant Disease Survey 80: 144-147.
3) Deeks, S., Shamoun, S.F. and Punja, Z. 2000. In Vitro germination and development of western hemlock (Arceuthobium tsugense subsp. tsugense). Plant Cell, Tissue and Organ Culture (In press)
4) Deeks, S., Shamoun, S.F. and Punja, Z. 2000. A histopathological study of infection of germinated seeds and callus of western hemlock dwarf mistletoe by Cylindrocarpon cylindroides and Colletotrichum gloeosporioides in dual culture. Canadian Journal of Plant Pathology (In press)
5) Completion of M.Sc. thesis by S.J. Deeks at Simon Fraser University- Tissue culture of western hemlock dwarf mistletoe and its application to studies on biological control. This work was conducted at the Pacific Forestry Centre under the supervision of Drs. Simon F. Shamoun and Zamir K. Punja (SFU)
Poster
presentations at the joint meeting of the Canadian Phytopathological Society and
the Pacific Division of the American Phytopathological Society- June 18-21,
2000, Victoria, BC, Canada:
1) Deeks, S., Shamoun, S.F. and Punja, Z. 2000. The application of in vitro culture of western hemlock dwarf mistletoe to studies on biological control
2) Ramsfield, T., Shamoun, S.F. and van der Kamp, B. 2000. Factors related to seed production by lodgepole pine dwarf mistletoe.
A
proposal has been accepted by I.U.F.R.O. to establish a new working group on
“Parasitic Flowering Plants in Forests”. Dr. Simon Francis Shamoun has been
selected as a Coordinator for this group. If any one is interested to join this
working group, please, contact Dr. Shamoun at the following e-mail address:
SShamoun@PFC.Forestry.CA ; Phone: (250) 363-0766; Fax: (250) 363-0775. (S.
Shamoun, Pacific Forestry Centre, Victoria, B.C.)
IX.
SURVEYS
1. We are currently working up data and preparing a manuscript
on spatial patterns of hemlock dwarf mistletoe in the old-growth forest of the
T.T. Munger Research Natural Area (RNA), Gifford Pinchot National Forest.
We DMR'd all western hemlock and true fir trees > 5 cm on a 12 ha
mapped plot (3,516 trees) surrounding the canopy crane.
We are now running spatial statistics (Ripley's K) on the data to
determine negative and positive association between infected and uninfected
trees, DMR 1 and DMR 6 trees, and trees with their highest rating in the upper
third versus all infected hemlock. We
also hope to develop some novel ways to determine whether non-hosts are playing
a role in the shape of the infection centers.
Figure 1 shows our 12ha map of the infection centers.
In this portion of the RNA, there are clearly delineated infection
centers, with two small, isolated infection centers in the lower left-hand side.
The nearest infected tree to these centers in over 30 meters away, and
therefore, we hypothesize that bird-transported seed began the center!
Other
projects at the WRCCRF include a senior thesis project by Morgan Dutton from
University of Washington entitled: An analysis of western hemlock response to
hemlock dwarf mistletoe. This work
was done with Tom Hinckley at UW, and involved an investigation of foliage
morphology, nitrogen status, isotopic C, chlorophyll content, and effect on
height growth. The major affect of mistletoe seems to be on nitrogen content of
infected branches, as height, and other foliage characteristics were not
significantly different between infected and uninfected branches.
Percent nitrogen levels in uninfected foliage samples averaged 1.06%,
significantly higher than infected foliage which averaged 0.80%.
Morgan sampled foliage from 3 locations on each branch, apex (A), middle
(B), and base (C) of branches. Infected
branches were A: 0.68%, B: 0.69%, C: 1.03%.
Uninfected branches were A: 1.08%, B: 1.06%, C: 1.05%.
She feels that the branch autonomy theory, i.e. branches are fairly
isolated from the main tree, explains the lack of effect on whole tree
characteristics. The very wet
location (100 inches precipitation) may prevent a huge drought effect on the
trees, and this also limits the effect of mistletoe on whole tree
characteristics.
We
also DMR'd all hemlock and true firs > 45.7 cm dbh on 104, one-acre plots
which form stepped strips in the T.T. Munger RNA (2,089 trees).
We then took average DMR for each 1 acre plot.
Before we can proceed with any more analysis, we have to go out and GPS
the plots, so that is our summer project this year. Future work on this data set will include analysis of the
relation of DMR and growth increment for western hemlock. (D. Shaw, E. Freeman,
J. Chen, and D. Braun, Wind River Canopy Crane Research Facility, Carson, WA)
X.
MODELING
1. In 2000, we began our first 10-year remeasurement of plots
established under the Pest Trend Impact Plot System. Data analysis will be forthcoming. Many more plots will be remeasured in the next couple of
years. (M. Fairweather, FHP, Region 3, Flagstaff, AZ)
2. Recently several industrial companies proposed to limit sizes
of clearcuts in coastal forests of British Columbia, and to emphasize
silviculture systems that retain many live trees in harvested areas. These new
practices raised concerns that the resulting forest conditions will encourage
spread of hemlock dwarf mistletoe (Arceuthobium
tsugense) and increase future impacts of the parasite on trees, stands and
forests. New strategies are needed to suppress parasitic effects of dwarf
mistletoe where forests are managed for timber production, or to sustain forest
conditions associated with infestations that are desired for wildlife habitat
and other amenities. A detailed model of dwarf mistletoe spread developed by the
US Forest Service is being tested for BC conditions. It was attached both to a
version ("Pacific Northwest" variant) of the US tree growth model
"Forest Vegetation Simulator" (FVS) which models growth effects in
complex (multi-age, -species) stands, and to the ministry Tree and Stand
Simulator (TASS) for detailed, spatial growth projections of relatively simple
stands. Further model development and evaluation of projections are planned for
actual forest conditions and/or data. A working group of government and industry
co-operators and interested specialists (including scientists, managers and
other interested persons) provides input and advice. Please contact J. Muir for further information and
opportunities to participate. (J. Muir, BC Ministry of Forests, Victoria, B.C.)
3. Work continues on development, documentation, and evaluation
of the spatial-statistical model for spread and intensification of dwarf
mistletoe. Characteristics of the pattern of tree distribution (stem clumpyness)
and spatial autocorrelation of DMR (infection patchyness) were examined using
data from the Grand Canyon dwarf mistletoe control study. Parameter values for
stem clumpyness and infection patchyness were computed for a 10-acre,
stem-mapped plot (and portions of that plot); changes in these parameters over
time were also determined. Model behavior in terms of long-term changes in DMR,
DMI, and percent infected were compared against observed data using levels of
stem clumpyness and infection patchyness consistent with those determined for
the plot. Additional mapped data are being analyzed to explore change in these
parameters as stands develop, variation by host and stand type, and sensitivity
to measurement errors. The spatial-statistical model has been fit and tested
against two versions of the Forest Vegetation Simulator (FVS) to test it with
data for ponderosa pine in the Southwest and for western hemlock in British
Columbia. FVS is a stand-average, distant-independent model. Future work is
planned to fit this mistletoe spread and intensification model to the TASS
program for simulating the growth of individual, mapped trees. (B. Geils, RMRS,
Flagstaff, AZ; D. Robinson, ESSA, Vancouver, BC; J. Smith, Northern Arizona
University, Flagstaff, AZ; J. Muir, BC Min. of Forests, Victoria, BC)
4.
Work continues on improvement and validation of the Dwarf Mistletoe
Impact Model (DMIM), widely available to users of FVS. An enhancement of a
former release of the DMIM demonstrated more realistic predictions of mistletoe
spread from overstory to understory trees. Data from numerous long-term studies
in the western US regions provided an opportunity to update the empirical spread
and intensification functions in the DMIM for additional host species and to
compare results from simulations to actual observations. These studies include
data for ponderosa pine in the Pacific Northwest, Rocky Mountain, and
Southwestern Regions, fir in the Pacific Southwest Region, western larch in the
Northern Region, and lodgepole pine in the Intermountain and Rocky Mountain
Regions. Although some studies were established more recently, many span several
decades and represent a variety of stand types and management histories. The
project is a collaboration of Forest Health Protection staff from each western
region, Forest Health Technology Enterprise Team, and the Rocky Mountain
Research Station; the project is expected to be complete in 2001 with revision
of the model. (B. Geils, RMRS, Flagstaff, AZ and 14 others)
5.
Efforts are underway to adapt survey procedures to use GPS technology,
and to update the DMLOSS and JPINE simulation programs to use the GPS survey
data and information in the provincial database managed with ArcView. (F. Baker,
Utah State University, Logan, UT)
6.
A paper discussing 40 years of dwarf mistletoe spread and intensification
in a regenerating black spruce stand is in the final drafts for the Northern
Journal of Applied Forestry. For
the first 30 years A. pusillum killed
some trees, but the number of infected trees remained constant. In the last 10 years, however, the number of infected trees
has increased greatly, and mortality centers free of host trees are becoming
defined. Very little of the stand
will survive a normal 90 year rotation. (F. Baker, Utah State University, Logan,
UT)
XI.
MISCELLANEOUS
1. A database catalog for the Forest Pathology Herbarium-Fort Collins, mistletoe collection has been developed. With completion of the monograph by Hawksworth and Wiens, the mistletoe collection they assembled is to be transferred to the University of California (western North American species) and to the Smithsonian Institution (other species). Preliminary to that transfer, however, it is necessary to have a complete and current catalogue of specimens and process for identifying sheets by collector, host, collection site and for tracking annotation history and disposition. In the near future, the Forest Pathology Herbarium-Berkeley, mistletoe collection may be added, and the catalog published. (B. Geils and R. Galliano-Popp, RMRS, Flagstaff, AZ)