Lilaeopsis schaffneriana spp. recurva
|Listed||January 6, 1997|
|Description||Herbaceous, semiaquatic perennial plant with slender, erect leaves that grow from creeping rhizomes.|
|Habitat||Periphery of the wetted channel, or in small openings in the understory.|
|Threats||Loss of habitat due to groundwater pumping; competition from non-native plants.|
|Range||Arizona; Sonora, Mexico|
Lilaeopsis schaffneriana spp. recurva (Huachuca water-umbel) is an herbaceous, semiaquatic perennial plant with slender, erect leaves that grow from creeping rhizomes. The leaves are cylindrical, hollow with no pith, and have septa (thin partitions) at regular intervals. The yellow-green or bright green leaves are generally 0.04-0.12 in (1-3 mm) in diameter and often 1-2 in (2.5-5 cm) tall, but can reach up to 8 in (20 cm) tall under favorable conditions. Three to ten very small flowers are borne on an umbel that is always shorter than the leaves. The fruits are globose, 0.06-0.08 in (1.5-2 mm) in diameter, and usually slightly longer than wide. The species reproduces sexually through flowering and asexually from rhizomes, the latter probably being the primary reproductive mode. An additional dispersal opportunity occurs as a result of the dislodging of clumps of plants, which then may re-root in a different site along aquatic systems.
Lilaeopsis schaffneriana spp. recurva was first described by A.W. Hill in 1926 based on the type specimen collected near Tucson in 1881. Hill applied the name Lilaeopsis recurva to the specimen, and the name prevailed until Affolter revised the genus in 1985. Affolter applied the name L. schaffneriana ssp. recurva to plants found east of the continental divide.
Huachuca water-umbel has an opportunistic strategy that ensures its survival in healthy riverine systems, cienegas, and springs. In upper watersheds that generally do not experience scouring floods, Huachuca water-umbel occurs in microsites where interspecific plant competition is low. At these sites, Huachuca water-umbel occurs on wetted soils interspersed with other plants at low density, along the periphery of the wetted channel, or in small openings in the understory. The upper Santa Cruz River and associated springs in the San Rafael Valley, where a population of Huachuca water-umbel occurs, is an example of a site that meets these conditions. The types of microsites required by Huachuca water-umbel were generally lost from the main stems of the San Pedro and Santa Cruz Rivers when channel entrenchment occurred in the late 1800's. Habitat on the upper San Pedro River is recovering, and Huachuca water-umbel has recently re-colonized small reaches of the main channel.
In stream and river habitats, Huachuca water-umbel can occur in backwaters, side channels, and nearby springs. After a flood, Huachuca water-umbel can rapidly expand its population and occupy disturbed habitat until interspecific competition exceeds its tolerance. This response was recorded at Sonoita Creek in August 1988, when a scouring flood removed about 95% of the Huachuca water-umbel population. One year later, Huachuca water-umbel had re-colonized the stream and was again codominant with watercress. The expansion and contraction of Huachuca water-umbel populations appears to depend on the presence of refugia where the species can escape the effects of scouring floods, a watershed that has an unaltered hydrograph, and a healthy riparian community that stabilizes the channel. Two patches of Huachuca water-umbel on the San Pedro River were lost during a winter flood in 1994 and had still not re-colonized that area as of May of 1995, demonstrating the dynamic and often precarious nature of occurrences within a riparian system.
Density of Huachuca water-umbel plants and size of populations fluctuate in response to both flood cycles and site characteristics. While the extent of occupied habitat can be estimated, the number of individuals in each population is impossible to determine because of the intermeshing nature of the creeping rhizomes and the predominantly asexual mode of reproduction. A population of Huachuca water-umbel may be composed of one or many individuals.
Huachuca water-umbel has been documented from 22 sites in the Arizona counties of Santa Cruz, Cochise, and Pima counties, and in adjacent Sonora, Mexico, west of the continental divide. The plant has been extirpated from six of the 22 sites. The 16 extant sites occur in the major watersheds of the San Pedro River, Santa Cruz River, Rio Yaqui, and Rio Sonora. Nine Huachuca water-umbel populations occur in the San Pedro River watershed in Arizona and Sonora, on sites owned or managed by private landowners, Fort Huachuca Military Reservation, the Coronado National Forest, and the Bureau of Land Management's Tucson District. Two extirpated populations in the upper San Pedro water-shed occurred at Zinn Pond in St. David and the San Pedro River near St. David. Cienega-like habitats were probably common along the San Pedro River prior to 1900, but these habitats are now largely gone. Surveys conducted for wildlife habitat assessment have found several discontinuous clumps of Huachuca water-umbel within the upper San Pedro River where habitat was present in 1996 prior to recent flooding. The four Huachuca water-umbel populations in the Santa Cruz watershed probably represent very small remnants of larger populations, which may have occurred in the extensive riparian and aquatic habitat formerly along the river.
Two Huachuca water-umbel populations occur in the Rio Yaqui watershed. The species was recently discovered at Presa Cuquiarichi in the Sierra de los Ajos, several miles east of Cananea, Sonora. The species remains in small areas in Black Draw, Cochise County, Arizona. Transplants from Black Draw have been successfully established in nearby wetlands and ponds. Recent renovation of House Pond on private land near Black Draw extirpated the Huachuca water-umbel population. A population in the Rio San Bernardino in Sonora was also recently extirpated. One Huachuca water-umbel population occurs in the Rio Sonora watershed at Ojo de Agua, a cienega in Sonora at the headwaters of the river.
Introduction of Huachuca water-umbel into ponds on the San Bernardino National Wildlife Refuge appears to be successful. Huachuca water-umbel was transplanted in 1991 from Black Draw into new ponds and other Refuge wetlands. Transplants placed in areas with low plant density expanded rapidly, naturally colonizing in 1992 a pond created the year before. However, as plant competition increased around the perimeter of the pond, the Huachuca water-umbel population decreased. This response seems to confirm observations made by scientists that other species will out-compete Huachuca water-umbel.
One of the biggest threats to Huachuca water-umbel is the ever-increasing amount of groundwater pumping that is occurring along the San Pedro river, especially in the areas around Sierra Vista, Fort Huachuca, Huachuca City, and Hereford-Palominas. Excessive groundwater usages along other riverine habitats are also substantial threats to this taxon. Flows in certain reaches of the Santa Cruz River were perennial until groundwater pumping caused the water table to drop below the streambed. Recovery of perennial flow in the Santa Cruz River and of Huachuca water-umbel near Tucson is unlikely, given the importance of groundwater for the metropolitan area.
Groundwater pumping in Mexico threatens populations of Huachuca water-umbel on both sides of the border. South of the San Bernardino National Wildlife Refuge, groundwater is being pumped to irrigate farmlands in Mexico, and this pumping threatens to dry up the springs and streams that support several listed endangered fish and a population of Huachuca water-umbel. The large copper mine in Sonora at Cananea pumps groundwater for processing and support services. Although little is known about how groundwater pumping near Cananea may affect the spring at Ojo de Agua de Cananea, it is likely that overdrafts would decrease springflow or dewater the spring, extirpating the Huachuca water-umbel population. The spring at Ojo de Agua de Cananea is also the main source of municipal water for the town of Cananea. This water diversion, particularly if increased, may adversely affect Huachuca water-umbel. In the past, large contaminant spills from the mine have occurred, resulting in fish kills for many miles of the San Pedro River in Mexico and the United States.
The effects of such spills on Huachuca water-umbel are unknown, but could be detrimental. Reaches of many southern Arizona rivers and streams have been channelized for flood control purposes, which disrupts natural channel dynamics and promotes the loss of riparian plant communities. Channelization modifies the natural hydrograph above and below the channelized reach, which may adversely affect Huachuca water-umbel. Channelization will continue to contribute to riparian habitat decline. Additional channelization will accelerate the loss and degradation of Spiranthes and Huachuca water-umbel habitat. Dredging extirpated Huachuca water-umbel at House Pond, near the extant population in Black Draw. The Huachuca water-umbel population at Zinn Pond in St. David near the San Pedro River was probably lost when the pond was dredged and deepened. This population was last documented in 1953.
Livestock grazing potentially affects Huachuca water-umbel at the ecosystem, community, population, and individual levels. Cattle generally do not eat Huachuca water-umbel because the leaves are too close to the ground, but they can trample plants. Huachuca water-umbel is capable of rapidly expanding in disturbed sites and could recover quickly from light trampling by extending undisturbed rhizomes. Light trampling also may keep other plant density low, providing favorable Huachuca water-umbel microsites. Well-managed livestock grazing and Huachuca water-umbel are compatible. The fact that Huachuca water-umbel and its habitat occur in the upper Santa Cruz and San Pedro river systems in the San Rafael Valley attests to the good land stewardship of past and current landowners.
Poor livestock grazing management can destabilize stream channels and disturb cienega soils, creating conditions unfavorable to Huachuca water-umbel, which requires stable stream channels and cienegas. Such management can also change riparian structure and diversity, causing a decline in watershed condition. Poor livestock grazing management is widely believed to be one of the most significant factors contributing to regional channel entrenchment in the late 1800s. Livestock management in Mexico has severely degraded riparian areas along Black Draw and its watershed. The degraded habitat most likely contributed to the severity of a destructive scouring flood on San Bernardino Creek in 1988, which extirpated two patches of Huachuca water-umbel. Overgrazing is occurring immediately adjacent to the San Bernardino National Wildlife Refuge and has destabilized the channel of Black Draw. A headcut moving upstream threatens to undermine the riparian area recovery that has occurred since the refuge was acquired. The refuge is implementing management to avoid the destructive effects of downstream grazing. Stream headcutting threatens the Huachuca water-umbel at Los Fresnos cienega in Sonora. Erosion is occurring in Arroyo Los Fresnos downstream from the cienega and the headcut is moving upstream. The causes of this erosion are uncertain, but are presumably livestock grazing and roads in this sparsely populated region. If the causes of this erosion are left unchecked and headcutting continues, it is likely that the cienega habitat will be lost within the foreseeable future. The loss of Los Fresnos cienega may extirpate the Huachuca water-umbel population there.
Sand and gravel mining along the San Pedro, Babacomari, and Santa Cruz rivers in the United States has occurred and probably will continue, although no mining occurs within the San Pedro Riparian National Conservation Area. Sand and gravel operations remove riparian vegetation and destabilize the system, which could cause Huachuca water-umbel population and habitat losses upstream or downstream from the mining. These mines also pump groundwater for processing purposes, and could locally affect groundwater reserves and perennial stream baseflow. Groundwater has been used since 1983 to wash sand and gravel mined near the Babacomari River, 0.5 mi (0.8 km) west of Highway 90. This activity could affect at least one Spiranthes population.
Rural and urban development, road building and maintenance, agriculture, mining, and other land disturbances that degrade watersheds can adversely affect Huachuca water-umbel. Increased runoff rates and erosion in the Sierra Vista subwatershed may lead to more frequent "flash" floods and much greater deposition of sediment in the San Pedro River. This increased hydrologic instability would be detrimental to Huachuca water-umbel, which does not tolerate high levels of disturbance or channel instability. Flash floods could also scour existing Huachuca water-umbel out of the system, and further floods could occur with a frequency or intensity that would not allow refugia sites for subsequent Huachuca water-umbel recolonization.
These development activities are common in the middle Santa Cruz basin but much less prevalent in the San Pedro basin. For this reason, conservation and recovery of the middle Santa Cruz River is unlikely, though it is still possible in the upper San Pedro watershed, given region-wide planning decisions favorable to good watershed management. Increased development in the upper San Pedro Valley, including the expansion of existing cities and increased rural building, will likely increase erosion and have other detrimental watershed effects. Watershed-level disturbances are few in the upper Santa Cruz and Black Draw drainages.
Irrigated farm fields were present in the Black Draw watershed, but these were abandoned when FWS acquired the area as a refuge. The fields are returning to natural vegetation. The San Rafael Valley, which contains portions of the headwaters of the Santa Cruz and San Pedro rivers, is well-managed, and currently undeveloped, with few watershed-disturbing activities. However, there is potential for commercial development in the San Rafael Valley and resulting watershed effects.
Riparian areas and cienegas offer oasis-like living and recreational opportunities for residents of southern Arizona and northern Sonora. Riparian areas and cienegas such as Sonoita Creek, the San Pedro River, Canelo Hills cienega, and the perennial creeks of the Huachuca Mountains receive substantial recreational visitation, and this is expected to increase with an increasing southern Arizona population. While well-managed recreational activity is unlikely to extirpate Huachuca water-umbel populations, severe impacts in unmanaged areas can compact soils, destabilize stream banks, and decrease riparian plant density, including densities of Huachuca water-umbel.
Bermuda grass may directly compete with Huachuca water-umbel in certain microsites. Watercress (Rorippa nasturtium-aquaticum ) is another non-native plant now abundant along perennial streams in Arizona. It is successful in disturbed areas and can form dense monocultures that can out-compete Huachuca water-umbel populations.
Two populations of Huachuca water-umbel have been lost from unknown causes. Despite the presence of apparently suitable conditions, the species has not been observed at Monkey Spring near Sonoita Creek since 1965. Huachuca water-umbel was collected in 1958 just off Highway 80 in deep water along the San Pedro River near St. David, but neither the plant nor the habitat exists there any longer.
Conservation and Recovery
The largest area currently available for recovery of Huachuca water-umbel is the San Pedro River along the perennial reach from Hereford to about 4 miles north of Charleston. Whether or not the species can recover there depends largely on future perennial surface flows in the river and a natural, unregulated hydrograph. Perennial flow in the upper San Pedro River is derived from precipitation runoff and interflow through the unsaturated soil horizon, and baseflow in the form of groundwater flow from deep regional aquifers and a shallower floodplain aquifer. Groundwater pumping has increased dramatically since the early 1960s but could be reduced by water conservation, watershed management, effluent recharge or other measures to reduce water use or increase recharge. Such measures are being developed and implemented, including development of a Surface Water Plan and Effluent Recharge Plan, and adoption of water conservation measures by the City of Sierra Vista; and implementation of water conservation measures, enhancement of mountain front recharge, effluent recharge, and other actions by Fort Huachuca. However, these measures may not be adequate to balance use with recharge, halt the eventual interception of the river by cones of depression, and ultimately, maintain baseflow throughout the upper San Pedro River Fort Huachuca also relies on a well and springs in Garden Canyon. These diversions and pumping could de-water the stream and damage or destroy the Huachuca water-umbel population in the canyon, particularly during below-average rainfall periods. The City of Sierra Vista is exploring means for implementing conservation and habitat restoration actions for Huachuca water-umbel and other rare plants.
U. S. Fish and Wildlife Service. 15 May 2000. "Lilaeopsis schaffneriana ssp. recurva Huachuca water-umbel." America's National Wildlife Refuges. http://refuges.fws.gov/nwrsfiles/wildlifemgmt/speciesaccounts/plants/water_umbel.html.