Vegetation and Habitat Along the Gila River

Kelly Kindscher, Associate Scientist, Kansas Biological Survey, University of Kansas, 2101 Constant Avenue, Lawrence, KS  66047; Email:  Kindscher@KU.edu

Abstract 

            As part of a biodiversity study, 49 riparian sites along the Gila River were sampled to document the presence and abundance of many rare birds, reptiles, and amphibians and to specifically examine their habitat which is the topic of this paper.  During the summer of 2006, a team of researchers recorded all the plant species, their percent cover, and the number and size of the woody species from three 25 m plots at each of the sites. Data from this project demonstrate upstream (sites in the vicinity of the Gila Hot Springs) are different than downstream (near the towns of Gila and below) with upstream sites having more species/plot, less bare ground, more total plant cover and more wetland species.  These data are important for providing a baseline for possible in-stream flow alterations or climate change. 

Introduction

This project was undertaken to document the presence and abundance of many rare species and their habitat along the upper reaches of the Gila River in southwest New Mexico.  This paper discusses the vegetation and habitat data collected during the first year of the study—2006.  Collection of these data is urgently needed to provide baseline documentation of wildlife habitat before potential changes to the river occur. Such changes include in-stream flow alteration and climatic changes. Baseline documentation before these changes occur will provide necessary information for management opportunities to restore and improve habitat.   Decisions based on good data are essential for public discourse and sound management practices.  We believe that the lack of current data is a problem that we can help resolve to benefit the conservation of these bird, reptile, and amphibian species and the potential conservation and restoration of their habitat.  One of the rarest birds, the federally endangered willow flycatcher, Empidonax trailii, has been documented to have the largest number of territories along this stretch of the Gila River (U.S. Fish and Wildlife Service 2002).  However, the status of most other species of concern and their habitat along the Gila River is not well documented.

            Although it is beyond the scope of the project, but an important aspect of it, we permanently marked 49 locations along the Gila River with Global Positioning System (GPS) coordinates so that they can be re-sampled in the future to determine longer-term trends and also to establish a baseline data set that can be used to evaluate change in conservation status of these species in the event that conservation, restoration, or hydrological changes are made to these habitats. 

Methods:

Study Area

Fieldwork for this study of birds, amphibians, reptiles and their habitat along the Gila River took place in Grant and Catron Counties, New Mexico, from near the towns of Red Rock, Gila, and Cliff upstream to the town of Gila Hot Springs and up the Middle and West Forks beyond the Gila Cliff Dwellings National Monument lands (see Figure 1).

Methodology

Because of our experience in other large-scale projects (Kindscher et al. 1998, Norris and Farrar 2001, Saveraid et al. 2001, Debinski et al. 1999), we were able to establish a robust methodology for a large-scale project in the Gila watershed.  We focused primarily on two categories of sites--upstream sites (higher elevation sites nearer the town of Gila Hot Springs and the Gila Cliff Dwelling National Monument) and downstream sites (lower elevation sites nearer to the towns of Gila and Cliff and down to Red Rock, New Mexico; Figure 1).    Lands in the study area and owned and managed by the Gila National Forest, Gila Cliff Dwellings National Monument, the State of New Mexico, Bureau of Land Management, the Nature Conservancy, and private property owners.  All sites were selected randomly within riparian areas and were separated by at least ½ mile to ensure independence.

Vegetation of the area was characterized by three circular plots at each site.  Each plot was a 0.10 hectare area (18-m radius area) and was sampled for all overstory and understory species. We determined cover values for all plant species, and we will collect voucher specimen during year two of our fieldwork which we will deposit in the Dale A. Zimmerman Herbarium at Western New Mexico University and the Ronald L. McGregor Herbarium at the University of Kansas. 

We recorded data in every survey plot for the following habitat attributes (modified from Rice et al. 1984): the diameter at breast height (dbh) of the four largest trees, the foliage density of the ground layer (density of the foliage from the ground to 0.6 m), foliage density of the under story (1.5 m–3.0 m), the foliage density of the over story (from 3.0 m to the canopy), the foliage height diversity, and the number of trees in the plot with dbh >

All data was collected on a fieldwork form, copied, and entered into an Excel spreadsheet at the University of Kansas. 

Results:

For the 147 plots along the river a total of 399 plant species were found.  The riparian area contains forests dominated by Fremont’s cottonwood, narrow leaf cottonwood, Goodding’s willow, and rabbitbrush (Table 1 and 2).   In addition there are open areas of grasslands and savanna and other areas of sand and gravel bars.  Significant differences were found between bare ground and dominant species upstream and downstream.   Upstream areas had more species 47.3 per plot compared to downstream sites with on 32.1 species.  Upstream sites had less bare ground with total plant cover, including canopy overlap of 99.8% compared to downstream sites with 62.8 percent.  Vegetation differences were illustrated by the fact that bare ground had the highest cover class of any plant or category at downstream sites.  Also more wetland species, those classified as wetland obligate speices by the US Fish and Wildlife Service, were found in upstream plots. 

Non-native species are of concern in riparian habitats in the Southwest.  Tamarisk has become a species of concern in the southwestern United States as this exotic species tends to use considerable amounts of water in riparian areas and crowds other species out.

Whiteman (2006) found salt cedar along much of the Gila River and mapped its locations.  Our results indicate that only 14 of the lower 72 plots had tamarisk cover, with the highest percentage being only 2% of the cover of any plot and most plots having only a trace. For the upper plots (those above Turkey Creek), we only found 4 of our 75 plots had tamarisk, also with the cover less than 2% in all plots.  So overall, only 12 percent of our plots had tamarisk cover and the greatest percentage was 2% in any of these plots.   A higher percentage of cover was found for the exotic sweet clover, which made extensive stands along middle portions of the river.

Gila River Riparian Plot Data for July 2006

Bare Ground	Bare Ground	40.42
Populus fremontii	Fremont cottonwood	12.59
Salix gooddingii	Gooddings willow	6.85
Baccharis salicifolia	mules fat	2.97
Salix exigua	sandbar willow	1.99
Platanus wrightii	Arizona sycamore	1.96
Ericameria nauseosa	rubber rabbitbrush	1.50
Hymenoclea monogyra	burrobrush	1.48
Salix irrorata	sandbar willow	1.29
Water	Water	0.88
Melilotus albus	white sweetclover	0.72
Acer negundo	boxelder	0.53
Sporobolus contractus	spike dropseed	0.49
Rumex crispus	curly dock	0.43
Aristida divaricata	poverty threeawn	0.39
Salsola tragus	prickly Russian thistle	0.38
Cynodon dactylon	bermudagrass	0.38
Prosopis glandulosa	honey mesquite	0.36
Artemisia carruthii	Carruth's sagebrush	0.31
Amaranthus palmeri	pigweed	0.31
Boerhavia erecta	erect spiderling	0.28

Table 1.  Upland plots—species cover summed from 75 plots at 25 sites, located from Grapevine Campground at the forks of the Gila upstream to along the Middle and West Fork above the Cliff Dwellings.

Gila River Riparian Plot Data for July 2006

Bare Ground	Bare Ground	23.88
Ericameria nauseosa	rubber rabbitbrush	8.88
Populus angustifolia	narrowleaf cottonwood	8.46
Salix irrorata	sandbar willow	6.08
Alnus incana	mountain alder	4.05
Artemisia carruthii	Carruth's sagebrush	3.56
Acer negundo	boxelder	3.36
Melilotus albus	white sweetclover	2.67
Populus acuminata	lanceleaf cottonwood	2.58
Platanus wrightii	Arizona sycamore	2.46
Populus fremontii	Fremont cottonwood	1.57
Pinus ponderosa	ponderosa pine	1.24
Vitis arizonica	canyon grape	1.19
Juniperus scopulorum	Rocky Mountain juniper	1.07
Mirabilis longiflora	sweet four oclock	1.01
Juniperus monosperma	oneseed juniper	1.00
Sporobolus contractus	spike dropseed	0.96
Brickellia floribunda	Chihuahuan brickellbush	0.95
Parthenocissus vitacea	thicket creeper	0.92
Juniperus deppeana	alligator juniper	0.88
Bouteloua gracilis	blue grama	0.79

Table 2. Table 1.  Downstream plots—species cover summed from 72 plots at 24 sites, located from Turkey Creek downstream to below Red Rocks, New Mexico.

Discussion

The Gila River in southwest New Mexico is still a free-flowing river and is dominated by stands of native riparian species.   Although there are some patches of exotic species, such as sweet clover and salt cedar, for the most part, the cover in overwhelmingly dominated by native species and is relatively good condition. 

Our data will be archived and will be useful for conservation work, planning for restoration, and management of the river’s vegetation  and will be important baseline data for any proposed actions that will change the hydrology of the river through proposed water development projects.  In addition, our data can be important for documenting and studying the habitat of rare and common species of plants, birds, and other animals, and also for the management of exotic species.  Because there are differences along the river in the vegetation due to the hydrology, geology and past land management practices, we intend to collect more data and make our interpretation of them available for review, provide and discussion.  Our data will be available to other researcher and the public through the first authors web site:

http://www.kbs.ku.edu/people/staff_www/kindscher/facweb_kindscher.htm

Acknowledgements 

I would like to thank Quinn Long, Maggie Riggs, Hillary Loring, Bernadette Kuhn, Sarah March for help in the field data collection and species identification, Jessica Dean and Bernadette Kuhn for data entry, to Craig Freeman and Caleb Morse for botanical identifications of specimen, and Bill Norris, Randy Jennings, and Roland Shook for collaborating on the project.  In addition, I would like to thank the New Mexico Game and Fish for funding and most importantly, the property owners-- Gila National Forest, Gila Cliff Dwellings National Monument, the State of New Mexico, Bureau of Land Management, the Nature Conservancy, and private property owners—for giving us permission to collect this data. 

Literature Cited:

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Norris, W.R. and D.R. Farrar. 2001. A method for the rapid survey and natural quality evaluation of forests in the Central Hardwoods region. Natural Areas Journal 21:313-323.

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US Fish and Wildlife Service. 2002.  Southwestern Willow Flycatcher Recovery Plan.  Albuquerque, New Mexico.

Whiteman, K.E. (2006) Distribution of salt cedar (Tamarix  L.) along an unregulated river in Southwestern New

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Fig 1.  Study Sites Along the Gila River.