Nancy Shaw

Assessment of Range Planting as a Conservation Practice

ABSTRACT Natural Resource Conservation Service Range Planting — Conservation Practice Standards provide guidelines for making decisions about seedbed preparation, planting methods, plant materials selection, seeding rate, seeding depth, timing of seeding, postplanting management, and weed control. Adoption of these standards is expected to contribute to successful improvement of vegetation composition and productivity of grazed plant communities. Also expected are some specific conservation effects, such as improved forage for livestock; improved forage, browse, or cover for wildlife; improved water quality and quantity; reduced wind or water erosion; and increased carbon sequestration. The success of specific conservation practices and the magnitude of conservation effects are highly dependent on ecological-site characteristics, the initial degree of deviation from desired site characteristics, and weather, all of which are highly variable in both time and space. Previous research has produced few studies directly linking range planting conservation practices to conservation effects. Assessment of conservation effects attributed to rangeland planting practices must, therefore, be separated into two components: 1) evidence of the degree to which specific management practices have been shown to result in desirable vegetation change and 2) evidence supporting positive conservation effects of alternative vegetation states. The aggregate literature generally supports both 1) the existing conservation practice recommendations for rangeland seeding and 2) the inherent assumption that if these practices are successful, they will result in beneficial conservation effects. High spatial and temporal variability in these systems, however, may limit the success of generic or prescriptive management practices. Current conservation practice recommendations could be improved by incorporating more direct linkages to the ecologically based technical literature, more up-to-date information on adaptive management strategies in highly variable rangeland systems, and integration of monitoring strategies designed to directly test the efficacy of specific conservation practices.

Environmental regulation of dormancy loss in seeds of Lomatium dissectum (Apiaceae)

BACKGROUND AND AIMS Lomatium dissectum (Apiaceae) is a perennial, herbaceous plant of wide distribution in Western North America. At the time of dispersal, L. dissectum seeds are dormant and have under-developed embryos. The aims of this work were to determine the requirements for dormancy break and germination, to characterize the type of seed dormancy, and to determine the effect of dehydration after embryo growth on seed viability and secondary dormancy. METHODS The temperature requirements for embryo growth and germination were investigated under growth chamber and field conditions. The effect of GA(3) on embryo growth was also analysed to determine the specific type of seed dormancy. The effect of dehydration on seed viability and induction of secondary dormancy were tested in seeds where embryos had elongated about 4-fold their initial length. Most experiments examining the nature of seed dormancy were conducted with seeds collected at one site in two different years. To characterize the degree of variation in dormancy-breaking requirements among seed populations, the stratification requirements of seeds collected at eight different sites were compared. KEY RESULTS Embryo growth prior to and during germination occurred at temperatures between 3 and 6 degrees C and was negligible at stratification temperatures of 0.5 and 9.1 degrees C. Seeds buried in the field and exposed to natural winter conditions showed similar trends. Interruption of the cold stratification period by 8 weeks of dehydration decreased seed viability by about 30 % and induced secondary dormancy in the remaining viable seeds. Comparison of the cold stratification requirements of different seed populations indicates that seeds collected from moist habitats have longer cold stratification requirements that those from semiarid environments. CONCLUSIONS Seeds of L. dissectum have deep complex morphophysiological dormancy. The requirements for dormancy break and germination reflect an adaptation to trigger germination in late winter.

Impact of Native Grasses and Cheatgrass (Bromus tectorum) on Great Basin Forb Seedling Growth

Abstract Re-establishing native communities that resist exotic weed invasion and provide diverse habitat for wildlife are high priorities for restoration in sagebrush ecosystems. Native forbs are an important component of healthy rangelands in this system, but they are rarely included in seedings. Understanding competitive interactions between forb and grass seedlings is required to devise seeding strategies that can enhance establishment of diverse native species assemblages in degraded sagebrush communities. We conducted a greenhouse experiment to examine seedling biomass and relative growth rate of common native forb species when grown alone or in the presence of a native bunchgrass or an exotic annual grass. Forb species included bigseed biscuitroot (Lomatium macrocarpum [Nutt. ex Torr. & A. Gray] J.M. Coult. & Rose), sulphur-flower buckwheat (Eriogonum umbellatum Torr.), hoary aster (Machaeranthera canescens [Pursh] Gray), royal penstemon (Penstemon speciosus Douglas ex Lindl.), and Munros globemallow (Sphaeralcea munroana [Douglas ex Lindl.] Spach ex Gray); and neighboring grass species included bottlebrush squirreltail (Elymus elymoides [Raf.] Swezey), Sandberg bluegrass (Poa secunda J. Presl); and cheatgrass (Bromus tectorum L.). Forbs and grasses were harvested after 6, 9, or 12 wk of growth for biomass determination and calculation of relative growth rates (RGR) of forbs. Neither bunchgrass reduced biomass of any forb. RGR was reduced for royal penstemon when grown with either native grass and for Munros globemallow when grown with bottlebrush squirreltail. Although only assessed qualitatively, forbs with vertically oriented root morphologies exhibited no reduction in RGR when grown with native grasses, compared to forbs with dense lateral branching, similar to the root morphology of native grasses. Biomass of forbs was reduced by 50% to 91% and RGR by 37% to 80% when grown with cheatgrass. Understanding native forb interactions with native grasses and cheatgrass will aid land managers in selecting effective seed mixes and making better use of costly seed.

Germination and seedling establishment of spiny hopsage in response to planting date and seedbed environment.

Reestablishment of spiny hopsage (Grayia spinosa [Hook.] Moq.) in the shrub steppe requires development of appropriate seeding technology. We examined the effect of planting date and seedbed environment on germination and seedling establishment of 2 seed sources at 2 southwestern Idaho sites. Seedbeds were prepared by rototilling. In 1987-88, seeds collected in 1986 were drilled at 66 viable seeds m-1 of row at Birds of Prey in late fall, winter, and early spring and at Reynolds Creek in late fall, early spring, and late spring. Seeds collected in 1986 and 1988 were broadcast at 400 viable seeds m(-2) at both sites in late fall, early spring, and late spring 1988-89. Seeds in nylon bags were also planted at each site in late fall, winter, and early spring in 1987-88 and in late fall, winter, early spring, and late spring in 1988-89. On each succeeding planting date and in early summer, 5 bags of each seed source from each of the earlier planting dates were recovered. Water content, viability, and germination were compared among seeds from previous plantings and control seeds stored in the laboratory. Each year, first-year seedling establishment at both sites was favored by late fall compared to other planting dates. In 1988, seedlings established only from late fall plantings at a density of 1 m(-2) st each site. In 1989, late fall planting at the 2 sites increased seedling establishment 6 (51 vs 8 m(-2)) and 20 (41 vs 2 m(-2)) times compared to early spring planting. Germination was generally greater for seeds incubated at field sites compared to controls. Germination total and rate increased 6-11 times and 13 days from late fall 1987 to early spring 1988, 1-6 times and 4 and 9 days from winter 1988 to early spring 1988, 17 times and 10-11 days from late fall 1988 to winter 1989, and 4-7 times and 11 days from winter 1989 to early spring 1989. Late fall or early winter planting is essential to permit early spring germination when surface soils are moist.

Genetic and environmental effects on seed weight in subspecies of big sagebrush: applications for restoration

The sagebrush steppe is a patchwork of species and subspecies occupying distinct environmental niches across the intermountain regions of western North America. These ecosystems face degradation from disturbances and exotic weeds. Using sagebrush seed that is matched to its appropriate niche is a critical component to successful restoration, improving habitat for the threatened greater sage-grouse and other species. The need for restoration is greatest in basin habitats composed of two subspecies: diploid basin big sagebrush (A. tridentata subsp. tridentata) and tetraploid Wyoming big sagebrush (subsp. wyomingensis). In this study we assess seed weights across five subspecies-cytotype groups of big sagebrush and examine the genetic and environmental components. Our goal is to determine if seed weight can be used as a diagnostic test for subspecies and seed certification. Seed weight was measured from 55 wild collections and from progeny derived from these collections and grown in two common gardens. A linear mixed-effect model showed 91% of the variation in seed weight is explained by genetic, genetic × environment and environmental effects (conditional R2 = 0.91). Moreover, genetic effects alone, subspecies-cytotype groups, explained 39% of the variation (marginal R2 = 0.39). Of the five subspecies-cytotype groups, most had overlapping weights using conservative 99% confidence intervals. However, diploid tridentata and wyomingensis had non-overlapping 99% confidence intervals. To demonstrate the application of seed weighing to assess the subspecies purity of commercial seed lots, we compared confidence intervals of tridentata and wyomingensis developed from the experimental data to seed weights of commercial lots. The results showed that only 17% of the commercial seed lots certified as wyomingensis had mean seed weights that fell within the confidence intervals for this subspecies. The remaining lighter seed lots (83%) matched weights of tridentata. While restoring sagebrush ecosystems is a multifaceted problem, a fundamental component to restoration is ensuring the appropriate seed is used. We found seed weight is principally affected by genetic factors, with limited environmental effects. Seed weighing is an effective application to assess subspecies purity of wyomingensis and tridentata seed and could be used as a certification step for evaluating commercial collections used in restoration.

Seed biology of rush skeletonweed in sagebrush steppe.

Rush skeletonweed (Chondrilla juncea L.) is an invasive, herbaceous, long-lived perennial species of Eurasian or Mediterranean origin now occurring in many locations throughout the world. In the United States, it occupies over 2.5 million ha of rangeland in the pacific Northwest and California. Despite the ecological and economic significance of this species, little is known of the ecology and life history characteristics of North American populations. The purpose of this study was to examine seed germination characteristics of 2 populations of rush skeletonweed in Idaho. Seeds from rush skeletonweed plants in southwestern Idaho were collected during the 1994 and 1995 growing seasons. Mature seeds were harvested on 6 dates between early July and early October 1994, and on 5 dates between early July and late September 1995. Fresh seeds from each harvest period were measured to determine seed weight, total germination, rate of germination, and viability (tetrazolium staining [TZ]) of non-germinating seeds. An aliquot of seeds collected in 1994 was also stored for 1 year to examine the effects of seed storage on germination. In southwestern Idaho, rush skeletonweed produces seeds continuously from mid-July through October. Seeds were capable of immediate germination without scarification or wet prechilling. Total germination generally ranged from 60 to 100% throughout the entire seed production period. Germination was also rapid, reaching 50% of total germination in less than 12 days. In general, germination was higher at the lower incubation temperature regime (20/10 degrees C), perhaps reflecting origins of this species in Mediterranean winter rainfall regions. The TZ testing indicated that 30 to 60% of non-germinating seeds were viable, suggesting that seeds may persist in the soil seed bank. Up to 60% of seeds remained viable following 1 year of storage. Stored seeds generally exhibited higher germination rates (average = 90%) than fresh seeds (average = 67%), indicating possible dormancy and afterripening effects. Germination characteristics of this species are consistent with those of other invasive alien species, and favor rapid population growth leading to community dominance. DOI:10.2458/azu_jrm_v53i5_liao

Irrigation to Enhance Native Seed Production for Great Basin Restoration

ABSTRACT: Native shrublands and their associated grasses and forbs have been disappearing from the Great Basin as a result of grazing practices, exotic weed invasions, altered fire regimes, climate change and other human impacts. Native forb seed is needed to restore these areas. The irrigation requirements for maximum seed production of four key native forb species (Eriogonum umbellatum, Lomatium dissectum, Penstemon speciosus, and Sphaeralcea grossulariifolia) were studied at the Oregon State University Malheur Experiment Station beginning in 2005. Species plots were supplied with 0, 100, or 200 mm of subsurface drip irrigation per year using a randomized complete block design with four replications. Irrigation in each plot was divided into four equal increments applied between bud and seed set with timing dependent upon the flowering and seed set phenology of each species. Seed was harvested in each year of production through 2011, and the optimal irrigation rate was determined by regression. The four native forb species differed in their responses to irrigation. Lomatium dissectum seed yields were optimized with 140 mm of irrigation. Eriogonum umbellatum seed yields were optimized with 173 to 200 mm of irrigation in dry years and progressively less to no irrigation in the wettest year. Penstemon speciosus seed yields were optimized with 107 mm of irrigation in dry years and were reduced by irrigation in wet years. Sphaeralcea grossulariifolia seed yields did not respond to irrigation. Water requirements of these species are low, and these results can be used by seed growers to produce native forb seed more economically.

Integrated reclamation: Approaching ecological function?

Attempts to reclaim arid and semiarid lands have traditionally targeted plant species composition. Much research attention has been directed to seeding rates, species mixes and timing of seeding. However, in order to attain functioning systems, attention to structure and process must compliment existing efforts. We ask how to use a systems approach to enhance reclamation success. Using a case study example, we discuss ways to target key drivers that return the functional and dynamic nature of western wildlands. Integration of a multitude of abiotic (soil stability, hydrology and nutrient cycling) and biotic processes (plant functional traits, species turnover and regeneration, and wildlife interactions) into reclamation planning will be crucial to uniting research with management experience. Long-term monitoring coupled with tools to unify diverse datasets will be key to future management decisions. Reclamation is constrained by our inability to unify varied experiences with documented evidence. Research should assist managers with integrating spatial and temporal variability of ecosystem processes into long-term management planning. Using an integrated approach, we can more fully comprehend reclamation within the context of ecosystem function. An integrated knowledge base should serve as a communication tool and facilitate more sustainable landscape solutions.

Managing Intermountain rangelands - improvement of range and wildlife habitats: proceedings; 1981 September 15-17; Twin Falls, ID; 1982 June 22-24; Elko, NV

The proceedings summarizes recent research and existing literature pertaining to the restoration and management of game and livestock ranges in the Intermountain Region. Improved plant materials and planting practices are emphasized. The series of 28 papers was presented at the Restoration of Range and Wildlife Habitat Training Sessions held in Twin Falls, Idaho, September 15-17, 1981 and in Elko, Nevada, June 22-24, 1982.

Spiny hopsage fruit and seed morphology

Rangeland seedings of spiny hopsage (Grayia spinosa [Hook.] Moq.) may be made with either bracted utricles or seeds. Problems have resulted from inconsistent use of terminology describing these 2 structures and the fact their germination and seedling emergence is not the same with similar environmental conditions and seeding techniques. We examined the flower, fruit, and seed morphology of spiny hopsage microscopically to resolve these discrepancies and provide a basis for discussing the functional roles of bracted utricle and seed components. The spiny hopsage fruit is a utricle consisting of a single disk-shaped seed contained within a thin pericarp. The utricle is enclosed in 2 papery bracteoles. Failure to recognize the obscure pericarp plus inaccurate use of terminology appear responsible for confusion in the literature. The presence and condition of seed and fruit structures can affect seeding requirements and embryo response to environmental conditions. Consequently, accurate identification of all structures associated with the fruit or seed combined with a review of seed biology and seedling establishment literature is essential for designing effective wildland seeding practices.