[APWG] INFO: Prescribed Fire and Weed Control

[Olivia Kwong]

I've removed the attachment because it was exceedingly large (1.5 megs). 
If you're interested in a PDF of the report (about 360kb), just reply to 
me and I'll send it to you.

---------- Forwarded message ----------
From: Luna Latimer Lake <latimerl at onid.orst.edu>
To: apwg at lists.plantconservation.org
Date: Tue, 31 Jan 2006 14:33:42 -0800
Subject: Prescribed Fire and Weed Control
Forwarded message:


Facinating and NEW  on-the-ground-relevent final report on the study we
requested from Peter Rice and Mick Harrington to determine if we should
burn and spray OR spray and burn to optimize fire benefits and weed
control.  Also great info on whether weed spraying shifts a plant 
community toward or away from Potential Natural Community as defined by 
Muggler and Stewart.  Share with your weed and fire management peers.

(See attached file: 2005Fire&WeedsFHPfinal.doc)

Summary conclusion of the burn / spray question (my bolding for emphasis 
on this question):

The low severity early spring burns implemented in this study did not
affect weed abundances during the period of response measurement. Target
weed abundance on burn only plots did not differ from target weed 
abundance on the check plots. Nor did including a spring burn in 
combination with herbicide application alter weed abundance relative to 
plots that been only sprayed. However it should be recalled that spraying 
efficacy was very high.  Weed suppression, as measured by canopy cover, 
approached one hundred percent in most cases for one to three years for 
all the target weeds except leafy spurge.

      The spring burning did suppress rough fescue canopy cover in the
first growing season following the burn at the Bison Range site. Many of
the rough fescue plants at this site were one foot or more in diameter and
the bunch bases contained large amounts of decadent flammable material in
addition to the perennating buds. There was a trend for perennial grass
growth to be retarded in blocks 1 and 2 at the Blue Mountain site in the
growing season immediately after burning. The perennial grasses in these
two Blue Mountain blocks are primarily native bunchgrasses that are
susceptible to fire injury. Rough fescue, Idaho fescue, and bluebunch
wheatgrass were codominants and had 22% combined canopy cover at the
initiation of the experiment, while the introduced rhizomatous grasses had
less than 0.3% canopy cover. The initial suppression effect of burning on
native bunchgrass regrowth at these two sites was not observed in
subsequent growing seasons. The abundance of perennial grasses was not
affected by the burning at the two other sites. Cheatgrass and other 
annual bromes abundance was not influenced by these spring prescribed 
burns at any of the four sites.

      The community composition of plots that were sprayed was similar but
distinct from check plots at all four sites. At three sites the 
composition of plots that were just burned did not differ from the check 
plots and plots that included burning in addition to spraying was similar 
to plots that had been just sprayed. A burn influence on overall community
composition was observed only at the rough fescue dominated Bison Range
site and that affect was limited to the growing season immediately after
the spring burn.

      Prior to treatments the species composition at these four sites
differed considerably from their respective Mueggler and Stewart habitat
type definition plots. The herbicide spraying made the species composition
more similar to the potential natural communities for the plots that still
had remnant habitat type indicator bunchgrasses. The sprayed plots that
responded with progression towards the habitat type definitions were at 
the Bison Range and in several blocks at the Blue Mountain and North Hills
sites. The three Blue Mountain plots that had co-dominant introduced
rhizomatous grass species, the fifth block in the North Hills which was
dominated by introduced rhizomatous grasses, and the Henry Creek site 
which was lacking in indicator bunchgrass species went on floristic 
trajectories that will not lead to the habitat type definition even with 
spraying. Adding a burn to the spray treatment did not increase the 
progression towards the potential natural communities, nor did burning 
alone foster that restoration goal. In fact burning at the Bison Range 
site was retrogressive relative to the habitat type definition.

Andy Kulla
Missoula Ranger District
Bldg. 24A, Fort  Missoula
Missoula, MT 59804
(406) 329-3962
----- End forwarded message -----


Luna Latimer Lake

(530) 469-3216
Mid Klamath Watershed Council
Orleans/Somes Bar Fire Safe Council
latimerl at onid.orst.edu