Origin of Soil Mounds Associated with Clumps of Ribes Velutinum

Origin of Soil Mounds Associated with Clumps of Ribes velutinum

Item Type text; Article

Authors Saunders, D. V.; Young, J. A.; Evans, R. A.

Citation Saunders, D. V., Young, J. A., & Evans, R. A. (1973). Origin of soil mounds associated with clumps of Ribes velutinum. Journal of Range Management, 26(1), 30-31.

DOI 10.2307/3896878

Publisher Society for Range Management

Journal Journal of Range Management

Download date 24/09/2021 18:06:32

Item License http://rightsstatements.org/vocab/InC/1.0/

Version Final published version

Link to Item http://hdl.handle.net/10150/647307 horizon there may be fractured granite or relatively deep beds of coarse decom- posing granite. At Granite Mountain we excavated 10 Ribes clumps; eight clumps with mounds Origin of Soil Mounds Associated and two clumps without mounds. Trenches were dug across the clumps with Clumps of Ribes velutinuvn to a depth of 1.5 m. The occurrence of whorls of growth on Ribes stems, changes of soil texture and structure, evidence of rodent activity, and charcoal and organic DALE V. SAUNDERS, JAMES A. YOUNG, AND RAYMOND A. EVANS matter accumulations were recorded in stratigraphic sequence. Depth control was Highlight: The mounds of soil associated with multi-stem clumps of Ribes velutin- maintained with the aid of a level and urn Greene are apparently the result of rodent activity and are not remnant erosion sur- rod. faces. The development of the mounds is a dynamic response to stand renewal by Soil samples were obtained from the burning. Rodents apparently are attracted by the increase in annuals, especially downy mbunds and from the soil surface be- brome, which occurs after fire. The protection of the spiney clumps of resprouting tween the mounds. These samples were Ribes provides a safe place for the rodents to build their dens. analyzed for texture, pH, organic matter, nitrate-nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, and cation Range managers must continually (Erodium cicutarium (L.) L’Her.). On the exchange capacity. make decisions on the condition and north slopes, succession in the herbaceous In addition to studies at Granite trend of rangelands. The soil mounds vegetation has largely passed from downy Mountain, 10 Ribes clumps were inves- associated with multiple-stem shrubs have brome to Sandberg bluegrass (Pea sand- tigaged at each of two more recent wildfire areas. Red Rock Summit, 40 km been employed to judge gross trend bergii Vasey). The mounds are associated with Ribes north of Reno, was burned in 1968; changes on the basis that the height of velutinum Greene clumps. The Ribes Silver Knoll, 20 km north of Reno, was the mound reflects the amount of soil clumps are largely, but not entirely, burned in 1970. The soils and physiog- erosion that has occurred on the site. located on north-facing slopes. Not every raphy of both of these sites were very Ellison (1954), investigating the subalpine clump of Ribes is growing on a mound, similar to Granite Mountain. Plant cover vegetation of the Wasatch Plateau, des- The root sprouting shrub, desert peach at Red Rock Summit was dominated by cribed Ribes growing on mounds as the (Prunus andersonii Gray), forms dense downy brome. The Silver Knolls burn had only vegetation on high-elevation steep clumps on both north and south slopes a very sparce plant cover composed of slopes. He suggested that in this situation but is not associated with mounds. forbs with the beginning of a population the mounds represented the original soil The soils in the study area are largely buildup of downy brome. mollic haplargrids derived from decom- At all locations, the density of shrubs surface because the texture, structure, posing granite. The surface soil has a was determined on 10 plots 10 m by 10 and organic matter content of the surface sandy-loam texture and at about 3 dm in m in dimension. The herbaceous vegeta- soil of the mounds reflected a more mesic depth grades into a well developed clay- tion was sampled using the step-point condition than was currently found be- loam horizon. Underlying the developed method of Evans and Love (1957). tween the mounds. Our purpose was to investigate the development of soil mounds associated with clumps of Ribes. PresentStems \ \ Methods We excavated a series of Ribes mounds on Granite Mountain, located 50 km north of Reno, Nevada. The mounds were located in a series of plant communities at an elevation from 1650 to 1800 m. The area was burned in a wildfire in 1950. The vegetation is now dominated by green rabbitbrush (Chrysothamnus viscidiforus [Hook.] Nutt.). There is considerable re-invasion of big sagebrush (Artemisia tridentata Nutt.). The herbaceous vegetation on south-facing slopes is dominated by downy brome (Bromus tectorum L.) and redstem filaree

The authors are, respectively, undergrad- uate research assistant, Renewable Natural Re- sources Center, College of Agriculture, and range scientists, Agricultural Research Service, U. S. Department of Agriculture, University of Nevada at Reno. The study represents cooperative investiga- tiOns of the Agr. Res. Serv., U. S. Dep. Agr., and the Agricultural Experiment Station, Uni- versity of Nevada, Reno. (University of Nevada Fig. 1. Cross-section view of typical Ribes mound showing root system and evidence of rodent Journal Series No. 204.) activity.

30 JOURNAL OF RANGE MANAGEMENT 26(l), January 1973 6 Results buried but continued to grow to regain Table 2. Comparison of surface 15 cm of In all of the mounds excavated at the surface. The stems and roots hold the soil between and on Ribes mounds. mound in place. Unfortunately, it was Granite Peak, there was abundant evi- Soil Between On dence of rodent activity. Tunnels 10 to impossible to determine annual growth characteristics mounds mounds 30 cm in diameter extended to 1.5 m rings in these stems. At about the same level as the whorl Texture (%) below the soil surface. Seed caches were >2mm 19.4 11.5 found in hollows 3 to 4 dm in diameter. of growth, an organic or charcoal horizon <2mm 62.6 70.5 These caches contained from 5 to 10 could be traced through the mound (Fig. Silt 15.0 14.5 liters of caryopses of downy brome. The 1). Viewed in cross section, this horizon Clay 3.0 3.5 caryopses appeared to have been stored appeared to be a continuation of the soil Cation exchange capacity 7 7 for a considerable period for the lemmas surface on either side of the mound. The &q/l 00 g) and paleae had separated from the re- organic matter consisted of decomposed Organic matter (%) 2.4 2.6 downy brome caryopses and herbage. The mainder of the caryopses and the Available nutrients caryopses would not germinate. occasional charcoal horizons which re- NO @pm N) 2 5 When the vegetation of this com- placed the organic layer appeared to be P @pm) 105 290 Ca (meq/l 00 g) munity is dominated by annuals, there is the remains of woody material. 3.6 - 0.6 Mg (meq/lOO g) In two clumps of Ribes without 4.4 1.0 a great deal of collection and caching of S @pm) 8 12 downy brome caryopses by rodents of mounds which were excavated at Granite the family Heteromyidae, especially Peak, no evidence of rodent activity was Dipodomys sp. and Perognathus sp. found. The soil profile under the mounds (LaTourrette et al., 1971). At the current appeared to be a continuation of that Significance of Ribes Mounds stage of succession of the Granite Peak found on either side of the clump. No to Management vegetation, the coIlectors of downy evidence of burned stems was found in In this situation the mounds associated brome caryopses appear to be gone; and these clumps, which apparently were with clumps of Ribes appear to be a the extensive dens in the Ribes mounds established after the fire. product of rodent activity and cannot be are inhabited by a variety of rodents, At Silver Knolls one year after the used to determine rates of soil movement reptiles, and insects. vegetation was consumed in an intense in long-term erosion. In other environ- All of the characteristics noted were wildfire, the herbaceous vegetation was ments, the mounds may be remnant not evident in every mound, but enough dominated by forbs (Table 1). The Ribes surfaces left by erosion, but they should of the features were always present to crowns were completely consumed by the always be checked for rodent activity and provide a stratigraphic sequence (Fig. 1). fire, but shrubs were sprouting in whorls signs of buried surface horizons. Besides the universal occurrence of from the burned stems. There was no The mound building may have a long rodent tunnkls in the mounds, burned evidence of mounds or of rodent activity. term influence on site quality. The soil on Ribes stems were located well below the Three years after burning at the Red the mounds has been influenced by surface of the mounds (Fig. 1). Around Rock Summit site, the plant community rodent activity (Table 2). Available nutri- the burned stems there were whorls of was dominated by downy brome (Table ents, especially phosphorous and potas- stems which had extended up through the 1). The Ribes clumps had resprouted with sium, were higher in the soil of the mound to provide the aerial portion of stem heights of 2 to 3 dm. There was mounds compared to adjacent soil. Or- the shrub. The stems extended laterally considerable rodent activity associated ganic matter, soil texture, and cation from the whorl and had roots at their with these clumps and mounds appeared exchange capacity were not affected by nodes. Apparently, aerial stems were to be under construction. the mound building process. Leaf fall from the shrubs and protection from Table 1. Frequency (%) and cover (%) of herbaceous vegetation grazing of the associated herbaceous veg- and shrub density (per 100 sq. m) at three locations. etation by the dense mass of spines of the Measurement Silver Red Rock Granite Ribes clump may account for these and species Knolls Summit Peak differences. The Ribes clumps severely limit forage Frequency and browse production and utilization on Bromus tectorum 14 64 22 Sisymbrium altissimum 25 these sites. The use of fire or herbicides Erodium cicutarium 11 to control this species must take into Descurainia pinnata 2 4 9 account the protection the mounds pro- Mentzelia albicaulis 52 vide for the sprouting Ribes crowns. Lomatium Gmbyi 16 Leptodactylon pungens 3 3 I Balsomorhiza sagittata 1 Literature Cited Poa Sandbergii 3 43 Ellison, L. 1954. Subalpine vegetation of the Stipa occidentalis 2 8 5 Wasatch Plateau, Utah. Ecol. Monogr. Stipa thurberiana 1 2 3 24:89-184. Cover 6.0 14 7.7 Evans, R. A., and R. M. Love, 1957. The step-point method of sampling -- practical Density A tool in range research. J. Range Manage. Chrysothamnus viscidiflorus 6 7 10:208-212. Artemisia tridentata 2 5 LaTourrette, J. E., J. A. Young, and R. A. Ribes velutinum 2 1 2 Evans. 1971. Seed dispersal in relation to Prunus Andersonii 1 1 1 rodent activities in seral big sagebrush com- Tetradymia canescens 2 1 munities. J. Range Manage. 24 : 118-l 20.

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