Earl F. Aldon

Effects of organic amendments on soil biota on a degraded rangeland.

Rehabilitation of degraded rangeland requires rebuilding the soil, including soil biota. In this study wheat straw, bark and wood chips, and dried municipal sludge were placed on native range plots in northcentral New Mexico. Organic amendments had little or no effects on decomposition of straw, litter respiration, soil respiration, biomass of soil microflora, and populations of most of the soil biota in the second year of the study. The differences in soil nematode and microarthropod population densities and straw decomposition occurred only in the bark and wood chip mulched plots in year 1. The absence of differences in year 2 may have been the result of below-average rainfall. The wood chip bark mulch was visibily present at the end of year 2 but the other mulches were not. There may be long-term benefits from application of recalcitrant mulches like wood chips and bark, but the less recalcitrant mulching materials like straw and low application rates of sludge produce no measurable benefit.

Characterizing gene responses to drought stress in fourwing saltbush (Atriplex canescens (Pursh.) Nutt.)

New techniques in molecular biology can be used to characterize genes whose expression is induced by drought stress. These techniques can be used to understand responses of range plants to environmental stresses at the biochemical and molecular level. For example, they can be used to characterize genes that respond to drought stress conditions in the native shrub Atriplex canescens (Pursh.) Nutt. Complementary DNA (cDNA) libraries constructed from drought-induced messenger RNA (poly A+ RNA) were used to characterize genes which are associated with the stress response. A cDNA library from A. canescens was prepared. This library from stressed shrubs was differentially screened with radiolabeled cDNA probes from stressed and nonstressed shrubs, and apparent drought-induced clones were identified. This is the first report of molecular characterization of drought responsive genes in four-wing saltbush. The identification of genes specific to responses to drought stress could provide a basis for understanding drought tolerance in this important range species.

Influence of vesicular-arbuscular mycorrhizal fungi on the nodulation and growh of subclover.

This study was initiated to determine the itiuence of vesiculararbuscular mycorrhizal (VAM) fungi on a rhizobhun-legume interaction. Inoculation of subclover with Glomus fascicddus resulted in 2 times as many rhizobium nodules on roots as on nonmycorrhizal controls. Inocuhtion with Glomus mosseue resulted in 1.4 times greater nodule formation compared to the noninoculated controls. Plants inoculated with G. mosseue + G. fusckulatus had 1.9 times more nodules than the controls. Furthermore, inoculation with G. fasciculatus or G. mosswe+ G. fasciculatus resulted in shoot weights and total plant weights nearly double that of the controls. The conclusion is that inoculation with the correct VAM fungal species is as important as the selection of the rhizobium species for subclover growth and development. The increased demand for energy resources has resulted in large tracts of arid and semiarid rangelands being disturbed by the quest for coal and oil shale. Both the 1972 federal mining law and state regulations require the reclamation of these lands to acceptable standards for forage and wildlife habitat. Western rangelands are generally deficient in nitrogen and phosphorus throughout their soil profiles; as a result, standard rehabilitation operations must use large applications of these inorganic fertilizers to establish site productivity (Bauer et al. 1978). However, the costs of fertilizer often exceed the actual benefits derived from their use in reseeding projects in arid locations. Abbott and Robson studied the growth of subterranean clover inoculated with two types of vesicular arbuscular endophytes and compared them with that of noninoculated plants at 5 levels of applied superphospate in a high phosphate fixing soil. A greater growth response of plants inoculated with a fungus resembling G. mosseue was associated with a greater amount of mycorrhizal roots. Responses in nodulation closely paralleled responses in growth. This study was initiated to determine the potential of using existing biological systems in place of expensive fertilizer applications for site rehabilitation. Legumes will, with associated rhizobium, fix large quantities of nitrogen; this association might be useful as a biological system for supplying nitrogen. However, the legume-rhizobium interaction requires relatively high levels of phosphorus (van Schreven 1958). Since vesicular-arbuscular mycorrhizal (VAM) fungi increase the uptake of phosphorus by their host plants, a study was initiated to determine the influence of VAM fungis on a rhizobium-legume assoc

Vegetative propagation of desert saltgrass rhizomes.

tion under low phosphorus conditions. The use of mist chambers for root studies Authors arc. respectively, associate professor, graduate research assistant, and former student. Debartment of Ranne Manaeement. Humboldt State Universitv. Arcata, Califorttia 45521, and projecy leader, ‘kocky ‘Mountain Forest and Ran& Experiment Station. Albuquerque,, New Mexico 87106. William Beavis is presently a research assistant. Iowa State Untversity, Ames Xl01 I. This research was funded by the Rocky Mountain Forest and Range Experiment Station, at the Station’s Research Work Unit in Albuquerque, incooperation with the University of New Mexico. Station headquarters is in Fort Collins. in cooperation with Colorado State University. Manuscript received December 4. 1981. avoids the confounding effects of edaphic factors (Graham et al. 1976). Materials and Methods Spores of Glomus mosseae (Nichol. and Gerd.) Gerdemannand Trappe and Glomusfascicuhtus (7haxter sensu Gerdemann) Gerdemann and Trappe, collected in the state of Washington, were multiplied in pot culture on wheat (Graham et al. 1976). Spores were extracted by wet sieving and decanting (Gerdemann and Nicholson 1963) and stored in Ringer’s solution (Daniels and Graham 1976) for about 3-5 months before use. Seeds of subclover (Trifolium subterranean L. cv. Mount Barker) were surface disinfected in a 0.5% sodium hypochlorite solution and rinsed 5 times in sterile, distilled water. The moistened seeds were inoculated with a commercial preparation of Rhizobium trifolii (Dungeard) by placing them in the preparation and thoroughly coating each seed. The inoculated seeds were then planted in 3-inch pots containing a 1 to I mixture (vol/vol) of sterile autoclaved sand and vermiculite. When the seedlings reached the two-leaf stage, they were carefully tapped out of the pots, and the roots were rinsed free of sand and vermiculite with tap water. The seedlings were then placed in 3-inch pots with one root subtended through a l/2-inch hole drilled in the base of each pot. One to 3 lateral roots were left confined within the pot. The confined roots were covered with l/2-inch of moistened vermiculite, and the potted plants were then placed in a misted-root culture chamber (Hansen et al. 1979). The roots were sprayed continuously with a fine mist of a 40-fold dilution of a modified Hoaglands number 2 solution to allow healing of any abrasions on the roots (Graham et al. 1976). After 7 days, the vermiculite covering the confined roots was carefully rinsed out of the pots with tap water. Roots of the plants used for controls were recovered with moistened vermiculite and placed back on the misted-root chambers. Plants for the VAM fungi treatments were inoculated by placing lo-15 spores of each selected VAM fungal species directly on the rootlets confined within the pot. The inoculated roots were covered with moistened vermiculite, and the pots again placed in the root-chamber and misted with the same diluted Hoglands solutions (available phosphorus maintained at 10e6 M concentration). Treatments, in addition to the R. trifolii inoculation already done, were (1) control-no VAM inoculation; (2) G. mosseae; (3) G. fasciculatus; (4) G. mosseae -IG.fascicularus-inoculated with 15 spores each of the VAM fungi G. mosseae and G. fasciculatus. All root lengths were measured every 2 weeks until all of the plants were harvested 12 weeks following inoculation, when the following data were also collected: Number of nodules/root system, root dry weight, shoot dry weight, and total plant dry weight. Presence of VAM mycelium was determined by trypan blue staining techniques. Two completely randomized blocks of 92 plants/block were used, which represents a total of 23 plants per treatment, replicated twice. 576 JOURNAL OF RANGE MANAGEMENT 36(5), September 1963

Ground‐dwelling arthropods of the Rio Puerco watershed, New Mexico

Highlight: Desert saltgrass is a potential candidate for mine spoil-bank revegetation in much of the semiarid West. Laboratory studies showed optimum temperature for growth to be 25 to 30°C. No clear relationship was found between length of a rhizome section and its capacity to sprout. In desiccation experiments, onenode segments lost water more quickly than did two-node sections. A marked reduction in rhizome sprouting occurred when moisture bsses exceeded 35% of the initial weight. One-node rhizomes stored in polyethylene bags of temperatures of 2 and 10°C had sprouting percentages in excess of 65% after 28 days.

Vegetation changes as a result of soil ripping on the Rio Puerco in New Mexico.

Abstract One of the most important components of a terrestrial ecosystem is the ground‐dwelling arthropods, which play a functional role as general detritivores and predators. Because of their sensitivity to rangeland deterioration, a study on the abundance of the ground‐dwelling arthropods was undertaken in four different habitats of the Rio Puerco Watershed in New Mexico. Thirty‐two traps (768 trap nights) were placed in each of four habitats: grama grassland, sagebrush, shrubland, juniper grassland, and pine woodland. There were more genera of ants in the juniper grassland habitat than in the other habitats. Fieldcrickets, Gryllus sp., were most abundant in the grama grassland and entomobryid collembolans were most abundant in juniper grassland and pine woodland habitats. Despite differences in species composition, the ground‐dwelling arthropod fauna was dominated by detrivorous forms in every habitat.

Stocking rangelands on the Rio Puerco in New Mexico.

Man’s activity has a tremendous impact on the environment. Often a single goal in land treatment results in many subtle effects that are not readily discernible until some time later, sometimes with disastrous consequences. Soil ripping, for instance, a form of deep plowing to break up soil, effectively reduces surface runoff and erosion from semi-arid watersheds (Hickey and Dortignac, 1964). But what is the effect of this treatment on the vegetation growing on treated areas? The effect of soil ripping on the vegetation of one large area was investigated over a period of 15 years.

Establishing alkali sacaton on harsh sites in the Southwest.

Stocking levels, utilization percentages, and perennial grass forage production were recorded from 1958 through 1969 on the San Luis Experimental Watersheds in the Rio Puerto Basin, 58 miles northwest of Albuquerque, New Mexico. Over two-thirds of the 3,900,OOO acres of the Rio Puerto is composed of rangelands similar to those in the experimental watersheds. From 12 years of data on part of the watershed, we have developed tables to use as guidelines for stocking semidesert ranges in central New Mexico, where summer deferment is practiced. These are applicable on semidesert ranges found on most of the Rio Puerto drainage. The portion of the watershed used for this study is a 525-acre experimental range unit, pasture II, in the transition zone between woodland and semidesert grassland (Aldon, 1964). Cattle grazed the area each year from November 1 through April 30. Principal forage species, in descending order of cattle preference (Aldon and Garcia, 1967), are alkali sacaton (Sporobollcs airoides (Torr.) Torr.), galleta (Hilaria jamesii (Torr.) Benth.), and blue grama (Bouteloua graciks (H.B.K.), Lag. ex Steud.).

Endomycorrhizal (Vesicular Arbuscular) Associations of Some Arid Zone Shrubs

Alkali sacaton (Sporobolus airoides (Torr.) Torr.) is a valuable plant on flood plains in the semidesert vegetation type of the Southwest (Aldon 1964). On badly eroded sites, remnant plants have effectively lowered sediment losses and provided valuable forage when managed properly (Aldon and Garcia, 1967). Establishing the plant on bare areas through reseeding has been difficult. Seeding has been attempted countless times by land managers with little success. Seed germination would be sporadic, and subsequent seedling mortality sometimes complete. Reasons for these difficulties became apparent during intensive investigations with the seeds and seedlings of this plant. From these investigations a series of steps was prepared outlining the establishment requirements for individual plants under ideal conditions. The validity of each step was tested in the field under difficult conditions.