This file was created by scanning the printed publication. Errors identified by the software have been corrected; however, some errors may remain. Arroyo-Riparian Shrub Diversity Along a Transition Zone Between the Sacramento Mountains and Tularosa Basin, New

Joneen S. Cockman Rex Pieper Dennis Clason

Abstract-Four arroyos were examined in the Sacramento Moun­ The importance of arroyo-riparian or ephemeral drain­ tains of to determine type differences and describe ages for birds has been well documented (Carothers and vegetation diversity of the main channel relative to the surrounding others 1974; Carothers and Johnson 1975; Finch 1989; watershed. Arroyos were selected to represent foothills and a Reichenbacker 1984). Floral structure variables such as submesa. Univariate analyses were conducted on shrub, half-shrub, patchiness, volume, and foliage height diversity were found grass, and forb functional groups. Each group responded to different to be not independent of one another (Anderson and Ohmart effects depending on the response variable (cover, density, diver­ 1980). Instead, variable complexes were identified as well as sity). However, nonsignificant interactions were masked by the fact ties between bird use and time of year. that response variables (especially diversity) were comprised of different depending on the location of the arroyo in foothill Research Purpose ______or submesa types. Obligate and exclusive species were identified. At this time, environmental regulations do not protect arroyo habitat. Data are needed to support management It has been suggested that arroyos in the southwestern decisions related to environmental quality. are of recent origin, and are a feature of Interest and concern for the protection of wetlands has accelerated erosion on once-uniform grasslands and cienegas increased since the inception ofthe National Environmental (Cooke and Reeves 1976; Bryan 1925). Antevs (1952) bor­ Policy Act (NEPA) of 1969. Four Federal agencies provide rowed the term "wadis" from Israeli and Egyptian literature regulating authority for wetlands. These are the U.S. Army to describe ephemeral drainages that are not features of Corps of Engineers (USACE), the Environmental Protection man-caused erosion. These drainages are limited to the Agency (EPA), the U.S. Fish and Wildlife Service (USFWS), headwaters of valleys, occur in moist areas, and are limited and the Natural Resources Conservation Service (NRCS). in size. The typical drainage described by Antevs is 3.6 Each agency provides a different definition of a wetland meters deep, 15 meters wide, and .8 km long. The drainages depending on the agency's function. However, all agencies of this study more closely resemble Antev's description of a include in their definition three basic elements: hydrology, "wadis." vegetation, and soil characteristics (Mackenthun and Classification ofriparian communities has been conducted Bregman 1992). by Pase and Layser 1977; Freeman and Dick-Peddie 1970; The USEPA and USACE have adopted the definition of Anderson and Ohmart 1980). Apache plume (Fallugia wetland from the Clean Water Act Section 404 (Mackenthun paradoxa) has been described as the most commonly found and Bregman 1992): riparian species in New Mexico, with more than 80% of the Those areas that are inundated or saturated by surface or arroyos in a southern New Mexico study containing this groundwater at a frequency and duration sufficient to support, shrub (Browning 1989). Littleleafsumac (Rhus microphylla) and that under normal circumstances do support, a prevalence and cutleafbricklebush ( laciniata) were listed as of vegetation typically adapted for life in saturated soil condi­ tions. Wetlands generally include swamps, marshes, bogs and close associates in areas of approximately 1,500 meters ele­ similar areas. vation. Burrobush (Hymenoclea monogyra) was listed as an associated species in washes at lower elevations (Browning It is important to note that this definition identifies 1989). The four arroyos described in this report resemble saturated soil conditions and a prevalence of vegetation closely the Apache plume series described by Browning suited to saturated soils. The presence of indicator species (1989) and also contain Burrobush at lower elevations. such as cattails that grow only in saturated conditions has been used to identify wetlands. Arroyos and wadis do not contain saturated soil conditions In: Barrow, Jerry R.; McArthur, E. Durant; Sosebee, Ronald E.; Tausch, Robin J., comps. 1996. Proceedings: shrubland ecosystem dynamics in a and do not qualify as a wetland by the USEPA definition. changing environment; 1995 May 23-25; Las Cruces, NM. Gen. Tech. Rep. However, they do support species that will grow on no INT-GTR-338. Ogden, UT: U.S. Department of Agriculture, Forest Service, other site. They also support a variety ofwildlife species and Intermountain Research Station. Joneen S. Cockman and Rex Pieper are Research Assistant and Professor appear to be critical habitat. of Range Science, Department of Animal and Range Sciences; Dennis Clason However, little research has been done to quantify plant or is Professor, Department of Experimental Statistics, New Mexico State animal species occurring in the arroyos. Studies are needed University, Las Cruces, NM 88003.

230 to test if the arroyo does support unique species or a higher The annual average rainfall for the area is about 30 cm. diversity compared to the adjacent watershed. However, there is a rain shadow between the submesa and The purpose of this research is to describe and quantify foothill. No rain gauge data are available to quantify the vegetation along ephemeral drainages in the Sacramento difference between sites. However, a difference in vegeta­ Mountains of southern New Mexico. The study will provide tion between the sites suggests that the foothill area receives baseline data to facilitate management decisions pertaining much greater rainfall. Also, many people who have worked to NEPA compliance. The focus of the study is to test for in the area and have observed the weather pattern agree vegetation differences between foothill and submesa ar­ that thunderstorms build up over the Sacramento Moun­ royos. It also examines the main channel relative to adjacent tains and flow south over the foothills. They have observed vegetation types, and adds to our knowledge of these impor­ torrential rainfall in the foothills while the submesa area tant habitats in the Southwest. receives little or no rainfall. This pattern appears to be a frequent occurrence. Soils of the area are dominated by rock outcrop and Study Area ______limestone hills. Gravelly alluvium is prevalent on the lower slopes. Narrow bands of alluvial soil line the arroyos. Of The study area contains four arroyos particular to the particular interest is a major separation in soil classification research and one major drainage that connects the four between the foothill and submesa areas. The submesa is (fig. 1). The area occupies approximately 13,000 hectares mapped in southern desert soils while the foothill is mapped and is used jointly by the Bureau of Land Management as a in soils from the neighboring mesic region. This is a transi­ grazing allotment and a wilderness study area. It is also tion zone between the true desert soils and cooler plains designated military ground, identified as McGregor Range, soils. a portion of the Fort Bliss military establishment. Located at the southern tip of the Sacramento Mountains, the area is approximately 16 air km northeast from the Methods ______village of Orogrande, NM, and 112 km northeast from EI Paso, TX. Elevation ranges from 1,200 meters to 1,600 Site Selection meters. Two of the arroyos (Indy and Carly) are located in a foothill area. The headwaters of these arroyos originate at Field reconnaissance using soil maps and aerial photos was approximately 1,800 meters, and the tailwaters drain into conducted prior to selecting study sites. Two similar arroyos Culp Canyon at approximately 1,670 meters. The other two (Indy and Carly) were selected in a foothill area (fig. 1). Two arroyos (Alien Temple and Four Bucks) are located on a more (Alien Temple and Four Bucks) were selected within a submesa. Their headwater originates at the j unction ofCulp submesa area. The submesa is positioned between an upper Canyon at approximately 1,500 meters, and they drain into mesa with sharp vertical boundary and the Tularosa Basin. the Tularosa Basin at approximately 1,370 meters. The land is hummocky and slopes gently between the mesa and basin. The foothill arroyos flow into a major drainage (Culp Canyon), and the submesa arroyos originate from Culp Canyon. The foothill arroyos are about 2.4 km in length. They range from 3-15 meters wide. The submesa arroyos are approximately 11 km long, and range from 2-30 meters wide. All arroyos range from 0.5-3 meters deep. Sample locations were selected along each arroyo at head­ water, midwater, and tailwater locations (upper, middle, and lower elevations) (fig. 2). An attempt was made to identify all vascular plant species in the study area. too immature to identify were catalogued, and phenology was recorded. These plants were collected again when ma­ ture specimens were available. Vouchers were collected from as many species as possible to aid in accurate identifi­ cation. This paper provides results pertaining to two shrubby functional groups, half-shrubs and shrubs. The half-shrub group contains cacti because cacti were infrequent and low in number in the study area. This was done to follow their presence rather than delete them from analyses. Similarly, Figure 1-Location of arroyos in a 13,000 ha BLM the large shrub group includes trees because trees were grazing allotment. Indy and Carly arroyos are located in infrequent in the study area. a foothill area. The headwater portions of these arroyos originate at approximately 1,800 meters and drain into Culp Canyon at about 1,670 meters. The headwaters Response Variables of Four Bucks and Alien Temple arroyos originate in Culp Canyon at about 1,500 meters. They drain into the Cover, density, and presence of all vascular plant species Tularosa Basin at about 1,370 meters. They are lo­ were measured for the greater study. This paper is limited cated on a submesa. Sample locations are marked on to a discussion of diversity based on species richness which each arroyo at lower, middle, and upper elevations. is derived from presence data. Belts with six replicate Scale: grids represent 1 mile x 1 mile.

231 I MlDW. TER PLOTS

Figure 2-Sample locations were selected along each arroyo at headwater, midwater, and tailwater locations corresponding to upper, middle, and lower elevations. Alluvium, flank, and upland plots are paired by northwest and southeast exposure. The main channel plots are singular and contribute to an unbalanced treatmentstruc­ ture. Alluvium is missing at headwater locations, which also contributes to an unbalanced treatment structure.

subplots were used to facilitate data gathering. Obligate Table 1-Response of species richness to treatment effects. species are also discussed. Functional group Effect

Shrubs and trees Elevation x position 0.0343 NW exposure Analyzing an Unbalanced Treatment OF = 5, error = 16 0.0056 SE exposure Structure Half-shrub and cacti Elevation x position 0.0425 NW exposure OF = 5, error = 16 0.1813 SE exposure Two features of the experimental design are unbalanced and required that separate tests be conducted to facilitate one overall F -test in the analyses of variance. First, by nature of the arroyos, alluvium positions are absent from headwater zones (fig. 2). This required significance levels to elevation with an increase in species richness moving away be extracted from a series ofthree tests: a test with the whole from the main channel. A similar response was seen for the arroyo, a test with no alluvium, and a test with no upper middle elevation positions. That is, species richness was elevation. Second, the main channel belts are singular in an greater at the highest elevation in the main channel. It elevation zone where alluvium, flank, and upland belts are decreased in the main channel with a decrease in elevation paired by northwest and southeast exposure. So, two sepa­ rate tests were run to facilitate this imbalance (1) the main channel-v- northwest exposure and (2) the main channel-v­ 12 southeast exposure. A total of six F -tests were conducted to 'E Q) facilitate the unbalanced data. CIl 10 ~ 0.. 8 I- r- f- CIl .S! Analyses of Species Richness () 6 - l- I- - - f- '- f- '---- c.Q) (f) 4 ~ r- - - l- I- - - f- r- - - Univariate analyses were conducted using SAS General 0 2 f-- f- - - l- f- . - - f- f- - i--- Linear Models (GLM) procedure. Data were averaged across zci 0 ~ -r - species within a functional group. Appropriate error terms L-M L-A L-F L-U M-M M-A M-F M-U U-M U-F U-U were selected for nested and crossed sampling structure. ELEVATION * POSITION The analyses of variance for species richness is presented in 1_ NW-MC !ill SE-MC 1 table 1. Figure 3-Half-shrubs and cacti were most sensi­ Half-Shrubs and Cacti tive to an elevation x position effect for species richness. Elevation = lower (L). middle (M), and Univariate analyses for the species richness ofhalf-shrubs upper (U). Position = main channel (M). alluvium and cacti was most sensitive to an elevation x position effect (A), flank (F), and upland (U). NW-MC = main channel and poSitions with a northwest facing expo­ (northwest exposure Pr > F = 0.0425, southeast exposure Pr sure. SE-MC = main channel and positions with a > F =0.1813). The submesa and foothill types were averaged southeast facing exposure. Standard error for all in figure 3. The least species richness was seen at the lowest treatments (NW-MC = 1.016, SE-MC =0.973).

232 along the drainage channel. However, species richness "in­ per belt to 10.5 species per belt. The main channel position creased while moving perpendicular away from the main produced the highest species richness of shrubs and trees channel and ascending along the position gradient from with each elevation zone. This increase is probably due to the alluvium to flank to upland. This relationship was seen in presence of true obligate riparian species as well as faculta­ the lower and middle elevation zones. However, the upper tive species that also occur on other positions. Significant elevation zone showed a decrease in species richness moving comparisons are presented in tables 3a and 3b. away from the main channel. Species richness ranged from a low of 5.5 species per belt to a high of 11 species per belt. Significant comparisons are presented in tables 2a and 2b. Obligate Species ______Obligate riparian and upper watershed species were iden­ Shrubs and Trees tified in separate analyses for the foothill and submesa types (table 4). In the foothill, species were combined from both Analyses of species richness for shrubs and trees were Indy and Carly arroyos. Data included all species recorded most sensitive to an elevation x position effect (northwest in cover, density, and presence records. Data were sorted by exposure Pr > F = 0.0343, southeast exposure Pr > F = position across all elevation zones. Thus, the species list for 0.0056). Differences between northwest and southeast expo­ a position represents the full length of an arroyo from sure can be seen within elevation zones (fig. 4), suggesting headwater to tailwater. Submesa data were handled the an elevation x exposure interaction. However, exposure data same way by combining observations from Alien Temple and are from separate tests, and comparisons between expo­ Four Bucks arroyos. sures are speculative. Significant changes in species rich­ Riparian obligate species were identified by selecting ness across position can be seen within the lower and upper species that were found in the main channel or alluvium elevation zones. Species richness ranged from 4.25 species positions but did not occur in other positions. The procedure

Table 2a-Significant comparisons for species richness of half-shrubs and cacti. Data are for the main channel and positions on the northwest exposure.

L-MC L-A L-F L-U M-MC M-A M-F M-U U-MC U-F u-u L-MC L-A L-F L-U M-MC M-A M-F M-U U-MC U-F U-U H: LS mean (i) = LS mean (j). Pr> T = 0.05.

Table 2~Significant comparisons for species richness of half-shrubs and cacti. Data are for the main channel and positions on the southeast exposure.

L-MC L-A L-F L-U M-MC M-A M-F M-U U-MC U-F U-U L-MC L-A L-F L-U M-MC M-A M-F M-U U-MC U-F U-U H: LS mean(i) = LS mean (j). Pr > T =0.05.

233 E 12.------~ recognizes the alluvium. position as an integral part of the ~ 10+------­ riparian channel. In the submesa type, it functions as a flood ~ ~ 8 plain for the collection of soil and debris from the main Q) channel during heavy rainfall events. In the foothill type, it .~ 6 functions as a flood plain for the collection of material from the (J') 4 (5 main channel, and it collects runoff from lateral drainages. ci 2 Upper watershed obligate species were identified as those Z 0 species recorded on flank or upland positions but not re­ L-M L-A L-F L-U M-M M-A M-F M-U U-M U-F U-U ELEVATION * POSITION corded elsewhere. 1_ NW-MC _ SE-MC 1 Shifting of Obligate Species Between Figure 4-Shrubs and trees were most sensitive to an Types elevation x position effect for species richness. Eleva­ tion = lower (L), middle (M), and upper (U). Position = Some shifting of obligate species occurred between the main channel (M), alluvium (A), flank (F), and upland foothill and submesa types. For example, David's mint (U). NW-MC = main channel and positions with a (Salvia davidsonii) was a riparian obligate species in the northwest facing exposure. SE-MC = main channel and positions with a southeast facing exposure. Stan­ foothill type, but occurred as an upper watershed species in dard error for all treatments (NW-MC = 0.764, SE­ the submesa type. Apache plume occurred as an obligate MC = 0.714). riparian species in the submesa type, but was not obligate in the foothill type because it occurred in the riparian zone as well as the flanks and uplands. The foothill type is mesic enough throughout the watershed to support it in many

Table 3s-Significant comparisons for species richness of shrubs and trees. Data are for the main channel and positions on the northwest exposure.

L-MC L-A L-F L-U M-MC M-A M-F M-U U-MC U-F u-u L-MC L-A L-F L-U M-MC M-A M-F M-U U-MC U-F U-U H: LS mean(i) = LS meanG). Pr> T = 0.05.

Table 3b-Significant comparisons for species richness of shrubs and trees. Data are for the main channel and positions on the southeast exposure.

L-MC L-A L-F L-U M-MC M-A M-F M-U U-MC U-F U-U L-MC L-A L-F L-U M-MC M-A M-F M-U U-MC U-F UU H: LS mean(i) = LS meanG). Pr > T = 0.05.

234 Table 4-Species obligate to the riparian zone or upper watershed. The test with all 4 arroyos produced among riparian obligate species 47 forbs, 9 grasses, one half-shrub, 6 shrubs, Shrubs and trees Half-shrubs and cacti and one tree species. The same test produced among upper Foothill riparian species watershed obligate species 6 cacti, 16 forbs, 3 grasses, 1 half­ None shrub, and 5 shrub species. These lists are larger than those ** produced for either the foothill or submesa types alone. This Cercocarpus montanus var. glaber is a reflection in the shift in species composition between the Condalia ericoides * two arroyo types. Garrya ovata subsp. goldmanii It is interesting to note certain characteristics of indi­ Rhus trilobata x microphylla vidual obligate species relative to the overall vegetation Celtis laevigata var. reticulata** story. The main channel position is filled with woody vegeta­ Foothill upper watershed species tion. Yet, the only obligate riparian half-shrub is burrobush. Brickellia petrophila Choisya dumosa Similarly, the submesa type uplands are dominated by half­ Fouquieria splendens * shrubs, but no obligate half-shrubs were recorded there. Isocoma wrightii No obligate cacti were recorded for the riparian corridor. Mimosa borealis Most cacti in the study area occupy rocky habitat in upland Yucca torreyi * positions. Trees were scattered and infrequent in the study Coryphantha strobiliformis Coryphantha vivipara** area. Most occurr~nces were in the foothill type. Sugar Echinocereus spp. hackberry (Celtis laevigata) was the only obligate ripanan Echinocereus Lloydii tree. However alligator juniper (Juniperus deppeana), one­ seed juniper (J. monogyra), pinyon pine (Pinus edulis), and Submesa riparian species oak (Quercus spp.) occurred infrequently in the foothill type. Brickellia laciniata** Hymenoclea monogyra Chilopsis linearis Obligate riparian shrubs for the whole study area are Fallugia paradoxa * limited to Guadalupe brickellia (Brickellia brachyphylla), Celtis laevigata var. reticulata** cutleaf brickelbush, desert willow (Chilopsis linearis), smooth mountain mahogany (Cercocarpus montanus var. glaber), Submesa upper watershed species Baccharis pteronioides * Coryphantha macromeris Mexican silktassel (Garrya ovata subsp. goldmanii), and Ceanothus greggii Coryphantha vivipara** hybrid sumac (Rhus trilobata xmicrophylla). The first three Chrysothamnus pulchellus * Mammillaria lasiacantha shrubs are completely senescent and easily recognizable as Conda/ia ericoides * riparian species. The latter three species may not be obligate Oasylirion spp. * riparian species in all habitats. Three species of mountain Coldenia greggii mahogany are recognized in the Trans Pecos region (Powell *Lost as an obligate species when analyses combines foothill and submesa 1988). Two of the three species occur in this study. Shaggy arroyo types. mountain mahogany (C. m. var .paucidentatus) occurs through­ "'Also occurs in submesalfoothill arroyos. out the foothill type. Smooth mountain mahogany has a tree­ like growth form in the main channel where it occurs infrequently. But, it has been reported to grow in upland positions in Brewster County (Powell 1988). Ma­ locations. David's mint was well represented on the foothill hogany are important browse plants. They are senescent but main channel. However, its occurrence in the submesa type lose their leaves slowly. Mexican silktassel is evergreen. It was infrequent, and it probably occupies a mesic microsite. is known to grow in upland positions where there is ample Shifting of obligate species probably occurs as elevation water concentrated by runoff such as in the Organ Moun­ descends to other type locations. For example, neither little tains. Little leaf sumac and large leaf sumac both occurred leaf sumac or large leaf sumac (Rhus trilobata) were identi­ throughout the study area. It appears that it could be fied as obligate riparian or obligate upper watershed species. capable of growing in other positions. Sumac are also impor­ (One exception occurred where a peculiar specimen thought tant browse plants. Like mahogany, they are senescent but to be a hybrid of the two shrubs occupied the main channel.) lose their leaves slowly. Because of the features of the latter Both the foothill and submesa types are mesic enough three species, their identification as true obligate riparian throughout the watershed to support these shrubs in most species is questionable. positions. However, this might change if the arroyos posi­ tioned at lower elevations in the desert floor of the Tularosa Basin were examined. Both sumacs probably occur as obli­ References gate riparian species on the desert floor. ------.....------Anderson, B.W. and R.D. Ohmart. 1980. Designing and developing a predictive model and testing a revegetated riparian community Species Obligate to all Four Arroyos for southwestern birds (Lower River Valley). In: USDA Forest Service General Technical Report INT US Intermountain Obligate species were identified in a separate analyses Forest and Range Experiment Station. Ogden, Utah, The Sta­ tion. Sept. 1980. (86) p. 434-450. that combined all four arroyos. The procedure follows that Antevs, Ernst. 1952. Arroyo-cutting and filling. The Journal of described above. A few species that were obligate in separate Geology 6:375-385. submesa and foothill analyses were no longer obligate when Browning, John M. 1989. Classification of Riparian Plant Commu­ all four arroyos were combined (table 4). nities in New Mexico. Unpublished Master's Thesis. New Mexico State University, Las Cruces.

235 Bryan, Kirk. 1925. Date of channel trenching (arroyo cutting) in the Mackenthun, Kenneth M. and Jacob I. Bregman. 1992. Environ­ arid southwest. Science 62:338-344. mental Regulations Handbook. Lewis Publishers, Boca Raton, Carothers, S.W., RR Johnson and S.W. Aitchison. 1974. Popula­ Ann Arbor, London. tion structure and social organization of southwestern riparian Pase, C.P., and E.F. Layser. 1977. Classification of riparian habitat birds. American Zoologist 14:97-108. in the southwest. In: Importance, preservation and management Carothers, S.W., and RR Johnson. 1975. Water management of riparian habitats: A symposium. P. 5-9. USDA Forest Service practices and their effects on nongame birds in range habitats. P. General Technical Report RM-43. Rocky Mountain Forest and 210-222. In: Proceedings of the Symposium on Management of Range Experiment Station, Fort Collins, Colorado. Forest and Range Habitats for Nongame Birds. USDA Forest Powell, A. Michael. 1988. Trees and Shrubs of Trans-Pecos Texas Service General Technical Report No.1. Washington D.C. (Including Big Bend and Guadalupe Mountains National Parks). Cooke, Ronald U. and Richard W. Reeves. 1976. Arroyos and Big Bend Natural History Association, Inc. Big Bend National Environmental Change in the American South-West. Clarendon Park, TX. Press, Oxford. Reichenbacker, F.W. 1984. Ecology and evolution of southwe stem Finch, D.M. 1986. Similarities in riparian bird communities among riparian plant communities. Desert Plants 6:15-23. elevational zones in southeastern Wyoming. P. 105-110. In: SAS Institute Inc. 1990. SAS Procedures Guide, Version 6, Third Proceedings, Wyoming Water 1986 and Streamside Zones Con­ Edition. SAS Institute, Cary, NC. ference: Proceedings: Wyoming's water doesn't wait while we Soil Conservation Service. 1981. Soil Survey of Otero Area, New debate: Casper, Wyoming, April 28-30, 1986/sponsored by Mexico (Parts of Otero, Eddy, and Chaves Counties). USDA Soil Wyoming Water Resource Center and UW Agric. Ext. Serv., Conservation Service and Forest Service in cooperation with the Univ. WY. Laramie, WY: The Center (1986) p105-110. New Mexico State University Agricultural Experiment Station. Freeman, C.E. and W.A. Dick-Peddie. 1970. Woody riparian vegeta­ tion in the Black and Sacramento mountain ranges, southern New Mexico. Southwest Naturalist 15:145-164.

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