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BEN # 111




BBBBB    EEEEEE   NN   N             ISSN 1188-603X
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BBBBB    EEEEE    NN N N             BOTANICAL
BB   B   EE       NN  NN             ELECTRONIC
BBBBB    EEEEEE   NN   N             NEWS

No. 111                              August 26, 1995

aceska@freenet.victoria.bc.ca        Victoria, B.C.
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 Dr. A. Ceska, P.O.Box 8546, Victoria, B.C. Canada V8W 3S2
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THE DECLINE OF PACIFIC MADRONE: SYMPOSIUM SYNOPSIS
From: Clement W. Hamilton and Paul West c/o <pwest@eskimo.com>

[Copyrighted  material released with the authors' permission for
      posting on BEN.]

The past several years has seen increasing interest, on the part
of the horticultural public as well as landscape  professionals,
in the health of the Pacific madrone, Arbutus menziesii. Several
general  trends  --  such  as  the  desire for more broad-leaved
evergreens in urban  landscapes,  the  growing  appreciation  of
native  plants  of  ornamental  and  ecological  value, and ever
augmented plant-physiological  stress  due  to  urbanization  --
converge  on  the  madrone. People are almost unanimous in their
praise of the tree's desirability for urban landscapes, and also
unanimously puzzled about what might be causing its  decline  in
urban areas of the Pacific Northwest.

The  symposium  on  "The  Decline  of  Pacific  Madrone: current
theories and research directions" was held at the University  of
Washington  Center  for Urban Horticulture April 28, 1995. About
200 researchers, professionals, and interested citizens gathered
to share their knowledge and perspectives. They sought to deter-
mine whether any common understandings could be reached and what
future research might be of greatest help to  the  madrone.  Two
questions  underlay the twelve presentations and ensuing discus-
sions: 1) What are the nature  and  causes  of  the  decline  of
Arbutus   menziesii   in   urban  environments  of  the  Pacific
Northwest? and 2) How can the madrone be  propagated,  restored,
and managed in urban landscapes?

This  symposium  was  initiated  by a group of Seattle community
activists who had been witnessing the  gradual  demise  of  many
formerly  handsome  madrones along Magnolia Bluff. In 1994, they
won special funding to determine how to reverse this decline  as
mitigation  for  the West Point sewage treatment plant at nearby
Discovery Park. Save Magnolia's Madronas, as they  called  them-
selves,  recognized  that  the  madrone's decline was widespread
throughout the Seattle area, and that  research  was  needed  to
better under stand the causes of decline.

At  the  beginning  of  the  symposium, Christopher Chappell and
Gregory Ettl spoke of the natural context of the madrone,  Chap-
pell noting the apparent importance of fire in the establishment
and   persistence   of   plant  associations  in  which  madrone
predominates. Fairly dry, sunny sites with shallow, well drained
soil seem to be prime madrone habitat.

Richard Hunt considered that a particular growth  characteristic
of  the  madrone  actually  may accelerate its decline. When the
tree becomes stressed, it flowers more prolifically,  an  evolu-
tionary  strategy  to  continue its lineage despite its possibly
impending death. That  excessive  flowering,  however,  detracts
from  the  resources  to put into new terminal shoot growth, and
the tree produces fewer new leaves. As flowering  increases  and
leaf  production  declines, the tree may begin to lack the vigor
necessary t o defend itself against the canker-causing  diseases
described by Hunt and by Ralph Byther.

Dana  Bressette  and  Clement  Hamilton  have  been sampling in-
dividual madrone trees west  of  the  Cascades,  recording  site
conditions  and  grading  tree health. Their preliminary results
suggest that two characteristics correlate with  decline:  tall,
single-stemmed  growth  habit  and  thin  bark.  This implicates
exposure of the stem as a primary  causative  factor.  Bressette
noted  also  that  she  witnessed bark exfoliation more often on
south sides of samples, possibly implicating sun exposure  as  a
direct  cause  of decline. Their observations complement a model
of stand decline that A.B. Adams has proposed. He noted that the
trees studied in the landscaped area of Magnolia Bluff exhibited
more dieback and canker than do the trees in the natural setting
of nearby Thorn dyke Park. This led  him  to  posit  a  positive
feedback  process whereby the disturbance and exposure caused by
landscape development causes a stress response in the tree, such
as exfoliation of the bark. This may then predispose the tree to
infection by pathogens, which accelerates the  decline.  As  the
tree  canopy  dies  back  and individual trees are lost, the ex-
posure of the  stand  further  increases,  thus  augmenting  the
potential for general decline.

Trees are dying, but these are typically remnant trees of former
forest  stands  that  have not been able to adjust to changes --
usually clearing -- in the environment around them. In contrast,
young, vigorous madrone trees  can  be  seen  growing  up  along
highways,  in  parking lot medians, and in other stressful urban
situations. It appears, therefore, that madrones can thrive in a
wider variety of conditions than found in its usual habitat,  if
they  are  established  as  juveniles  within those same growing
conditions. Madrones have been witnessed growing at the edges of
wetlands, in irrigated turf, and under  closed  conifer  canopy,
for  instance.  This perspective holds promise that madrones can
find new niches in many parts of the urban landscape.

This hope is fueled by  great  evidence  that  madrones  can  be
readily  propagated  from  seed.  The  work of Ray Maleike, Rita
Hummel, Diana Privett, and Rico  Gonzclez  indicates  that  con-
tainer  production  is within reach using standard nursery prac-
tices. Another challenge is transferring  the  plants  from  the
nursery  into  the  landscape.  Thus  far,  the  work of Hummel,
Privett, Gonzclez, and Tony Shoffner has focused on establishing
1- to 3-gallon sized material.  Because  madrone  exhibits  sen-
sitivity  to  transplanting,  smaller  material  offers more im-
mediate potential. Working with small material presents  special
challenges  to  the  landscape manager, however, requiring extra
protection in environments with heavy traffic, careful  monitor-
ing  for pests (notably slugs and root weevil), and allowing the
juvenile bushy habit and low branching to prevail  in  order  to
protect the trunk. The challenge does not end with establishment
of  the  trees,  as Phil Coker points out; proper arboricultural
treatment depends on  understanding  the  physiology  of  mature
trees.

At  the  close  of  the  symposium,  participants discussed over
twenty areas of research that  could  benefit  madrones  in  the
future,  among  them  the  following: 1) systematic study of the
canker-causing organisms; 2) genetic  study  of  disease  resis-
tance,  coupled  with  a  program of selecting, propagating, and
introducing desirable plants; 3)  exploring  the  possible  sig-
nificance  of  mycorrhizal  associations;  4) trial plantings in
different types of urban site; 5) determining the size and  area
of  minimum  viable populations in urban greenbelts; and 6) com-
parative study of different  approaches  to  pruning  and  other
arboricultural practices.

Seldom does one plant species, outside of agriculture or produc-
tion  forestry,  arouse  such  a  high  degree of concern as has
Arbutus menziesii. The contributors to  this  volume  hope  that
their  work  has helped lay a significant foundation for a heal-
thier future for the Pacific madrone.

Proceedings from the symposium will be published this  fall  and
will  be  available  from  the  Center  for  Urban Horticulture,
University of Washington GF-15, Seattle WA 98195, for $15 US.


CAREX PRAIREA IN MONTANA
From: Toby Spribille
      </S=T.SPRIBILLE/OU1=R01F14D03A@mhs-fswa.attmail.com>

The recent exploration of the calcareous wetlands in the Tobacco
Valley in northwest Montana has resulted in numerous new records
for the region and an interesting overview of  bryophyte  diver-
sity  in  an  otherwise  poorly-known area. One of the most sig-
nificant finds to date is the discovery of Carex  prairea  Dewey
in  two  marl  fens  near  the  village of Trego in the northern
Salish Mountains. This species is very rare in the west, and  is
present  in  British Columbia only in the Fraser Plateau region.
Phytogeographically, it can be regarded  as  a  northeast  North
American  element  at  its  western  periphery; its discovery in
northwest  Montana  represents  a  range  extension  south  from
central B.C. and west from the northern Great Plains.

The  plant  was first brought to my attention by Jack Triepke, a
botanist on the Fortine Ranger District, who collected it  in  a
large  marl  fen/Betula  glandulosa  carr.  It  was subsequently
collected in another fen in the vicinity. At the latter site  it
was  the  dominant  cover, forming extensive hummocks with Carex
gynocrates. The seeping water had a pH of 7.2.

In addition to the Carex, many other rare or infrequent  species
were  discovered  in  the  second  fen. These include the mosses
Scorpidium cossoni, Meesia triquetra  and  Catascopium  nigritum
and  the rare lichen Cetraria sepincola, known from only a hand-
ful of collections south of the Canadian border. It was found to
be locally common on twigs of Betula glandulosa.

Voucher specimens  of  Carex  prairea:  MONTANA;  FLATHEAD  CO.:
      Collins Fen, Lime Creek, 25. July 1995, J. Triepke FJT025;
      Magnesia  Creek,  abundant  in  rich  fen,  21. June 1995,
      Spribille 3355; same location,  1.  Aug.  1995,  Spribille
      3902; specimens to be deposited at COLO, MICH, MONTU.


ALIEN SPECIES IN HAWAII - DATABASE OF DATA SOURCES
From: Philip A. Thomas - National Biological Service
      Haleakala Field Station <halesci@hawaii.edu>

I  am working on a project sponsored by the Research Corporation
of the University of Hawaii to compile a database of sources  of
information  RE: alien species in Hawaii. I would be very inter-
ested to hear from anyone who has any  kind  of  data  on  alien
species  (plants, animals, etc.) which occur in Hawaii. Data can
be field notes,  electronic  databases,  incidental  or  spatial
observations, etc. I would appreciate any information.

Please  respond  to  me directly with a brief description of the
data that you have/know about, or  if  you  would  like  further
details about this project.

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