Cuatro Ciénegas Arundo
Eradication Plan – September 1, 2005
Arundo Eradication Plan: Cuatro Ciénegas, Coahuila, Mexico
Suzanne McGaugh, Iowa State University, EEOB
Dean Hendrickson, University of Texas-Austin, Texas Memorial Museum
Gary Bell, The Nature Conservancy, New Mexico, Conservation Science
Tom Dudley, University of California Santa Barbara, Marine Science Institute
Kelly Lyons, Trinity University, Department of Biology
Valeria Souza, Instituto de Ecología de la UNAM
Lucas McEachron, Florida State University,
With participation of persons attending the Taller sobre de Arundo sponsored by The Nature Conservancy and Pronatura, including representatives from Desuvalle, A.C., Universidad Iberoamericana, Instituto de Ecología de la UNAM (IE/UNAM), CONANP, University of Texas, Iowa State University, Florida State University, the community of Cuatro Ciénegas, PRONATURA-Noreste, and The Nature Conservancy.
Recently, a number of wetlands and rivers in Cuatro Ciénegas, Coahuila, Mexico have become infested with an alien weed species known as Giant Reed (Arundo donax). Public and private agencies with ownership and/or management responsibilities share a common concern in dealing with the immediate threats of excessive transpiration of water, wild fires, and loss of habitat that are commonly associated with this species.
The focus of this management plan is the eradication and long-term management of Giant Reed in the Cuatro Ciénegas Natural Protected Area. Secondary objectives include revegetation of key areas where aesthetics and/or lack of recovery by native vegetation requires habitat enhancement.
The valley of Cuatro Ciénegas, in Coahuila, México, is ranked among the world’s most unique ecosystems. Harboring over 70 endemic species, its endemism is higher than any other place in North America (Stein et al. 2000). Much of the valley’s biotic diversity is associated with a diverse complex of hundreds of geothermal springs, lakes and streams that exhibit extreme temperature and water chemistry variation often over very small spatial scales. Many of the species are classified as endangered or threatened by the Mexican government and the Convention on International Trade of Endangered Species (CITES). The extreme fragility of the ecosystem resulted in it being declared a National Protected Area (Secretaria de Desarrollo Social 1994). However, continued threats to biodiversity include water exploitation, exotic species’ invasions, industrial development, and rapidly increasing tourism and population growth.
Over the last five decades, the Cuatro Ciénegas valley has attracted many researchers with interest in long term conservation of the area. At the recent Cuatro Ciénegas researcher's meeting, ‘Congreso de Investigadores de Cuatro Ciénegas,’ direct conservation concerns of valley were addressed, and the growing invasion of Arundo donax, the Giant Reed, climbed near the top of this list. In addition, in the reexamination of invasive species by Programa de Especies Invasoras de México, organized by Conocimiento y Uso de la Biodiversidad (CONABIO), A. donax is now considered as one of the top threats to native ecosystems. This bamboo-like, perennial grass is a notoriously aggressive threat to warm freshwater ecosystems (Polunin and Huxley 1987). Establishing by rhizomes, it spreads clonally and quickly displaces native vegetation (Khudamrongswat et al. 2004). Arundo donax is placed among the fastest growing terrestrial plants in the world (nearly 10 cm/ day (Dudley 2000)), and, per unit of biomass, it is reported to use three times more water than native vegetation in a southern Californian riparian system (Else 1996). Complete homogenization of habitats by Giant Reed sets the stage for substantial modification of physical and chemical characteristics of an ecosystem including accelerating fire cycles and enhanced flooding events (i.e. Bell 1997; Dudley 2000). Currently, management authorities in the United States are spending large amounts of money attempting to control invasions in California (Dudley 2000). Establishment of new populations of Giant Reed occurs readily through movement of rhizomes and stems downstream of established populations. Fortunately, no caryopses have been found among Giant Reed populations of the Cuatro Ciénegas valley (Lyons pers comm., Eguiarte et al. presentation 2005). As such, spread, and therefore management, of Giant Reed in the Cuatro Ciénegas valley is essentially an intra-basin and downstream phenomenon. In the Cuatro Ciénegas Protected Area, new populations are also established where heavy machinery is used to dredge canals for water management (pers. obs. Lyons, Bell, Hendrickson and McGaugh). Therefore, containment of the species in this region will also require education regarding the movement of rhizomes and stem parts on the tires of land-moving machinery.
Concerns over the invasion of Giant Reed led The Nature Conservancy and Pronatura Noreste to sponsor the Arundo Control Symposium in Cuatro Ciénegas during June 2005. As indicated in the minutes of that symposium (Appndix 1), representatives from the community of Cuatro Ciénegas, four agencies, and five universities addressed steps needed for eradication. Experts agreed that, currently, the invasion is manageable. Due to the aggressive nature of the plant and the high conservation priority of the region, the consortium determined that immediate action is necessary to minimize the cost and ecosystem impact incurred by any delay in management of Giant Reed.
At the end of the Arundo Control Symposium in Cuatro Ciénegas in June 2005, all present agreed to collaborate to achieve the following goals by the dates indicated:
Conduct experiments investigating impact of herbicide on the stromatolites (summer and fall 2005).
Develop an operating plan of action and costs, detailing application procedures, the spatial sequence of application, mechanisms to reduce re-invasions, and subsequent monitoring (September 2005).
Enact a public awareness campaign on the negative impacts of the Arundo in the town of Cuatro Ciénegas and surrounding ejidos (September 2005).
Implement local eradication and control measures of Giant Reed in CC Protected Area after safety experiments are completed.
Progress to date (1 September 2005)
Conduct experiments investigating impact of herbicide on the stromatolites (summer and fall 2005) – Funds remaining in the Arundo Workshop project were sufficient to fund laboratory experiments that began at UNAM in August of 2005. Field trials are planned for November 2005. (Valeria Souza, pers. comm.).
Develop an operating plan of action and costs, detailing application procedures, the spatial sequence of application, mechanisms to reduce re-invasions, and subsequent monitoring (September 2005) - This document (finalized on Sept 1, 2005) constitutes the first draft of such a plan. Simultaneous with the release of this document, and complementing it, web pages (see http://www.desertfishes.org/cuatroc/organisms/non-native/arundo/Arundo.html) were published that further explain and justify the urgency of moving forward with an Arundo control project in Cuatro Ciénegas. Also simultaneously, we announced the availability of new email discussion list, CCArundo@lists.cc.utexas.edu. All participants at the summer Arundo workshop have been subscribed to this list, and subscription is open to any interested person (see http://www.desertfishes.org/cuatroc/list.php to subscribe). We hope that this use of this list by all interested persons will facilitate finalization of this plan and implementation of control efforts.
Enact a public awareness campaign on the negative impacts of the Arundo in the town of Cuatro Ciénegas and surrounding ejidos (September 2005) - The web page mentioned in item 2 (above) provides basic information about Arundo and attempts to explain specifically the risk that this plant represents for the future biological integrity and human economy of the Cuatro Ciénegas region. It is made available via the web with the intent of facilitating development of public education projects. An obvious first step would be translation of the web page to Spanish. We welcome volunteers to do that.
Implement local eradication and control measures of Giant Reed in CC Protected Area after safety experiments are completed – We provide this draft as the first step toward finalizing a plan and implementing eradication and control measures. We feel that it is now important that future progress toward this goal be locally managed and welcome offers from other individuals to take charge of coordinating the rapid review, finalization and implementation of a plan.
Considerations for local control and possible eradication of Arundo in the CC Protected Area, included manual removal, fire and herbicide application. Members of the Consortium and Preserve staff were universally chemical-adverse, preferring removal of Arundo through non-chemical, mechanical methods; however, we ultimately determined that this would not be an effective approach for Arundo.
In California, a great effort in time and money has been expended in developing effective procedures for Arundo removal. Unfortunately, management techniques such as manual and mechanical removal in addition to fire, implemented in the Santa Ana and Santa Margarita and River basins, have proven ineffective and result in extensive collateral damage to ecosystems (Bell 1993, 1997). Since Arundo propagates readily from small fragments of rhizome and stem, manual or mechanical removal often results in dispersal of plant propagules. Root and rhizome masses are easily left behind and accidentally moved to new locations. In addition to these downfalls, manual eradication is expensive. For example, the price for only the above ground biomass cutting (not including removal from the site) has been reported at $5000 USD per acre (Bell 1993). Finally, due to the sensitive nature of the CC Preserve ecosystems we also wish to avoid disturbance of the hardened calcareous soils. Disturbance results in substantial changes to the local hydrology and may create yet more microhabitat for Arundo and other non-indigenous invasive species that respond positively to disturbance.
Fire, by itself, likewise is not a solution. While fire effectively removes all above ground biomass, Arundo regenerates substantially more quickly after fire (see Fig 1.) and rapidly outgrows native species that may have otherwise taken root in a burned-over site. Fire events, thus, tend to push wetland communities to monocultures of Giant Reed with little or no additional plant species diversity (Bell 1993).
Treatment of Arundo with a wetland-approved herbicide containing glyphosate has provided direct, effective control of the plant without high risk of reinfestation or dispersal of biomass, and thus the invasion (Bell 1997). Due to its effectiveness, glyphosate can be applied in fine sprays limiting exposure to other plants and animals. In addition, glyphosate is appropriate for environmentally sensitive areas because its bioavailability is diminished quickly after application, and it has been formulated for use in aquatic environments. Although this method is putatively the most flexible, efficient and has been widely accepted elsewhere, application of herbicide must be approached with caution.