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Preservation of a Rare Annual Grass,
Puccinellia parishii, in Native American
Agricultural Fields
M. Tremble and B. Hevron 1
Abstract ~ Parish alkali grass, Puccinellia parishii, is a rare annual grass
known from seven small populations. Two populations are known from
southern California, six from northeastern Arizona, and one from
southwestern New Mexico. All populations are known from saline, perennial
springs or cienegas, a habitat type that is rapidly disappearing throughout
the southwest. The largest population is found in Pasture Canyon on the
Navajo Nation. The canyon has been farmed by native americans for over
400 years. P. parishii will soon be proposed as Endangered under the
Endangered Species Act and Pasture Canyon may be designated as critical
habitat. We have initiated a research project, of which one objective is to
determine sustainable agricultural practices that will preserve this species.
Fifteen Navajo and Hopi farmers have answered questionnaires regarding
historical and current agricultural activities. This information includes
methods of plowing, crops, water diversions, fertilizers, herbicides and
burning. We will also collect data on population biology of this rare grass.
Data collected will include seedbank density, seed dormancy, seedling
emergence, and the environmental variables that regulate these factors. An
ecological model and management plan will be developed in order to
preserve the species and the cultural practices of the native american
farmers.
Efforts to conserve biodiversity, particularly in North America
have focused on "naturnl" rather than non-native or artificial
ecosystems (Katz, 1991). At least 95% of the terrestrial
environment is affected by human activities, including
agriculture; and terrestrial habitats provide over 98% of human
food (paoletti et. al, 1992). The concept of "naturalness" may
sometimes stand in the way of conserving biodiversity (Wedin,
1992). Anthropogenic landscapes may be managed for high
biodiversity. For example, the ancient grassland communities of
Europe have a high species richness that often reach 30-40
species per meter (Bakker, 1989).
In another study, the number of arthropod species in soil and
litter in a forest and com ecosystem were compared and found
to be nearly equivalent (paoletti et. al, 1988). There are fanning
systems which favor sustained biodiversity. These include
minimum or no tillage, a mosaic landscape structure, biological
pest control, polyculture, and rotation (paoletti et. al, 1992). It
has also been pointed out that biodiversity conservation and the
objectives of sustainable agriculture are economically
compatible (Altieri et. al, 1987). More research is needed to
compare agroecosystems to undistUIbed ecosystems.
In comparison to Europe, however, North American efforts
to preserve biodiversity and make agriculture more sustainable
have not been connected~ this may due to the fact that those
wolking on sustainable agriculture have emphasized ecosystem
functions such as reducing erosion or restoring hydrologic
regimes whereas conservation biologists have focused on
fragmentation of communities or preservation of threatened
species (Wedin, 1992). The lesson from European grassland
conservation efforts is that "until we realize that fmding
sustainable agricultural practices and conserving threatened
grassland biodiversity are intertwined problems, we may not fInd
a solution to either" (Wedin, 1992).
1 Co ordin a torlEcologist,
~ndow
Navajo Natural Heritage Program,
Rock, AZ,: and Botanist, Navajo Natural Heritage Program ..
354
Silver City; and 3) The Tuba City area of the western Navajo
Nation and the Hopi Tribe (map. Fig. 1). An uncertain locality
based on a 1948 collection from the northern Navajo Nation has
oot been relocated despite several attempts. The Tuba City
populations were only recently discovered (Hevron, 1991).
The largest population of the grass near Tuba City occurs in
Pasture Canyon which is farmed by Navajos and Hopis. The
Southern California populations occur in an area of considerable
population growth and on Department of Defense land. The New
A long tenn objective of our research project will be an
attempt to fmd sustainable agricultural practices that will
preserve and enhance populations of a rare annual grass,
Puccinellia parishii. This species is found exclusively associated
with saline springs and cienegas, habitats which are threatened
throughout the western United States. P. parishii is only known
from seven smaIl populations in: 1) Southern California in the
vicinity of San Bernardino and Edwards Air Force Base; 2)
Southwestern New Mexico approximately 30 miles south of
!
\
\
\,'- _--';
..
Figure 1. -
Distribution of Pucinellia parlshll in Pasture Canyon.
355
The Navajo Natural Heritage Program has commenced a
research project on the distribution and biology of P.puccinellia
in Pasture Canyon. The three objectives are: a management plan
to protect the rare annual grass; a special management area in
which the biodiversity of the wetlands are enhanced, restored,
and conselVed; and introduction of Puccinellia parishii into
fallow plots in the upper canyon.
There are two main elements of the study. One is gathering
cultural information from the fanners on their farming practices
and their knowledge of the canyon's historical condition Some
results of a questionnaire circulated among fanners are as
follows.
1) There are 34 fields, 14 of which are farmed by
Navajos, and 20 of which are farmed by Hopis.
2) Many plots are farmed by several families or
individuals. One plot is farmed by 10 people.
3) Most people indicated that the plots would be passed
on to younger family members, but they were
aware that the younger p~ople were not very
interested in farming.
4) Among the current farmers, the farming tenure in
Pasture Canyon ranges from 10 to 51 years.
5) Many farmers do not farm in certain years because
the road is impassable or the fields remain too wet
to plow. Some farmers pump water from their field
in the springtime.
6) The earliest plowing time is in April and the latest is
. in July.
7) The crops include blue, white and yellow com,
several types of squash, watermelons, cantaloupes,
sweet corn, varieties of chili, tomato, cucumber,
zucchini, onions, and several varieties of beans.
8) While plots were historically plowed using horses,
increasingly modem techniques are being utilized.
Deep disc plowing is the preferred cultivation
method over the rototiller or spade.
9) Fertilizer and hetbicide applications are now more
common.
10) Many farmers bum their fields in order to control
weeds.
11) Farmers have observed many changes in Pasture
Canyon over their lifetime. These include more
weeds, bigger sand dunes, greater vandalism, more
livestock in the fields, more water and fewer plants,
and fewer cottonwoods. One farmer stated that the
com does not grow as high as it once did.
12) Most farmers would like to see better management
efforts by the tribal and federal governments to
resolve some of these problems.
The second part of the study is collecting biological and
ecological infonnation. Soil samples have been collected from
all known populations, including Pasture Canyon. The soils were
analyzed for the following parameters: pH, water soluble salts
(EC), calcium, magnesium, sodium, sodium adsOIption ratio
(SAR), camonate, cation exchange capacity (CEC), sulfate,
Mexico population is on land owned by the Phelps-Dodge
mining corporation Clearly threatened, the USFWS is proposing
that Parish alkali grass be listed as Endangered under the
Endangered Species Act. This paper will concentrate on research
conducted in Pasture Canyon
This rare alkali grass grows in three patches in Pasture
Canyon 1\vo of these patches are in agricultural fields which
are plowed and planted with crops each year. Pasture Canyon,
nearly four miles in length, is bordered by sheer Navajo
sandstone walls that exceed 100 feet in height. A perermial
stream flows through the canyon and is fed by an extensive
chain of springs and seeps. The ~anyon has been known as a
oasis in the middle of barren rimrock and sand dunes for at least
three hundred years. Use ofPas~ Canyon by Navajo and Hopi
fanners may antedate the Spanish invasion (Gregory, 1916). The
canyon has been formally divided into a northern Nav~o section
and a southern Hopi section.
The crops grown in Pasture Canyon have significant cultural
and economic value. Many of the plant crops are varieties
indigenous to the Hopi lands. oraoout 150 indigenous species,
144 plants were used for food or religious ceremonies (Gregory,
1916). We have obselVed Navajos collecting medicinal plants
in the canyon Much of the Hopi culture and religion is based
upon com which is the predominant crop grown in Pasture
Canyon Some Hopi fanners have stated that they depend upon
the crops for income and food. Most of the Navajo traditional
use area of the canyon, approximately one-half of the area is
essentially fallow, whereas the Hopi use area is largely farmed.
Modem farming techniques are increasingly preferred over
traditional techniques. Commercial fertilizer and hetbicides are
sometimes applied. Modem farming techniques appear to allow
invasion of weedy species which may be altering the competitive
relationship of Puccinellia within the plant community. The
weedy invasive Polygonum sp. has fonned a dense ground cover
in one Puccinellia population, most likely in response to deep
disc plowing.
It is possible to reconstruct the historic landscape ecology of
the Canyon The pre-historic vegetation was probably a dense
cover of familiar marsh plants, Typha, Scirpus, Juncus, and
Trig/ochin, with saltgrass Distich/is on the drier margins. Today
there are small remnants of this native vegetation in fallow fields
and along the margins of other fields. There are no records of
the past abundance and distribution of Puccinellia in Pasture
Canyon. None of the Nav~os or Hopis interviewed have
recognized the grass. Several farmers have asked "what is this
plant good for?"
In 1915, Pasture Canyon contained three lakes. One of these
was a 15 acre reservoir fonned by a dam while the other two
lakes were fonned by encroachment of wind-blown sand
(Gregory, 1916). Since that time floods have undoubtedly altered
the alluvium geometry, and attempts have been made to prevent
sand from encroaching upon the canyon floor. In addition, a
ditch has been constructed to channel the spring flow along the
sides of the canyon wall. In the winter this water and melted
snow inundate portions of the canyon floor.
356
Another hypothesis is that however modern fanning
techniques may be incompatible with this rare annual grass.
Deep disc plowing as well as fertilizer and heIbicide applications
may represent significant threats. Increases in fertilizer and
heIbicides have greatly increased productivity of grasslands;
however this management has also led to a shatp decrease in
species diversity (Wedin, 1992).
We also postulate that inundation of the fields may be
significant for two reasons. Due to the inundation, a late plowing
schedule (the latest plowing being in July) may allow
Puccinellia to complete its life cycle. Extensive pumping of the
fields could jeopar4ize these populations of Puccinellia by
altering soil chemistry. Winter rains and snowmelt may push
alkalinity ions deeper into the soil column, resulting in a lower
EC of the soil moisture and the surface; Puccinellia genninates
and grows during the spring when the soil is moist and the ECls
are low. As the moisture decreases seasonally, the salts move
up in the soil column and thereby prohibit Puccinellia from
extracting moisture, in which ~ase, the annual grass may die
(Griggs, F. Thomas, personal communication). Alternatively,
inundation may create high turnover in the seed bank by causing
anaerobic conditions. Wet meadows are sensitive to hydrologic
changes brought about by drainage of agricultural land (Baker,
1987). If the peaty soils of the meadow dry out, then turnover
of nitrogen increases significantly; this compounds the
eutrophication caused by fertilization
In addition to testing these hypotheses, we are also examining
management options whereby land users are compensated for
practicing ecologically sound and sustainable agricultural
practices. It is hoped that both the Navajo and Hopi tribes can
sustain their traditional farming and preserve Puccinellia parishii
at the same time.
selenium, % sand, % silt, % clay, and texture. PreliminaIy
analysis indicates no significant differences between sampling
sites with Puccinellia and those without. Gennination studies
using seeds and soils from Pasture Canyon have been initiated
at the Flagstaff Atboretum, a Center for Plant Conservation
cooperator. Initial studies indicate that the annual grass grows
better in moister soils (Machiniski, 1993). However, these initial
studies utilized commercial potting soil and the seeds were
planted in the late summer. This study may indicate that
photoperiod and soil chemistIy are as important factors as the
period of inundation.
With the cooperation of two fanners, seven exclosures were
set up in two populations of the annual grass. However, the
tenure of one field changed before the field was plowed; the
new land user removed the exclosures. Two exclosures remain
in the other field. We will be examining the effects of this no
plowing regime on these Puccinellia populations next year.
Photos were taken from established points in order to monitor
land use and periods of water inun4ation In addition, seeds were
collected from all Arizona populations in 1993 for more
gennination studies and genetic analysis.
Studies are planned to test several hypotheses. One hypothesis
is that plowing represents a distuIbance that allows Puccinellia
to persist. DistuIbance is important in maintaining species
diversity in grasslands (Bazzaz, 1983). Restoration of locally
extinct forbs have failed when seeds have simply been added
unless a distwbance has been created by grazing or some other
process (Wedin, 1992). A heterogeneous matrix of species may
coexist longer than when they occur in extensive monoclonal
populations. Loss of environmental fluctuations in dune
grasslands results in vegetation succession and dominance of
perennial species (Van Andel et. al, 1991). Most annuals are
adapted to environmental fluctuations. For instance we have
been studying an annual saltplant, Proatriplex pleiantha, that
relies upon the occasional year when precipitation is abundant
enough to se a good seed crop. During dry years, the populations
of the species are extremely small.
An alternative hypothesis is that plowing is a threat to this
rare annual grass. In a study of the effects of tillage and mulch
on the emergence and survival of weeds in corn, it was
concluded that tillage had a consistent effect on annual weed
species that maintain a soil seed bank; that is no tillage improved
emergence and survival of the weeds (Mohler and Calloway,
1992). A model of the effects of tillage on the emergence of
weed seedlings indicates that no tillage will have more seedlings
than tillage in the first year following input of seeds to the soil,
but no tillage will have fewer seedlings in later years unless
innate or induced dormancy is high or seed survival near the
soil SUIface is very good. No tillage or minimum tillage will
have more seedlings perennially if seed return is allowed. It
would appear that cases in which the persistence of seeds
increases with depth are annual grasses with laIge short lived
seeds (Mohler, 1992).
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