• Clubmoss effects on plant water status and standing crop

      Colberg, T. J.; Romo, J. T. (Society for Range Management, 2003-09-01)
      Clubmoss (Selaginella densa Rydb.), a low growing, vascular cryptogam forms carpet-like mats that cover up to 80% of the ground in the Northern Mixed Prairie. Many range managers believe clubmoss competes with grasses for water or intercepts precipitation and negatively affects plant water relations and productivity. The objective of these studies was to test the hypothesis that precipitation has greater effects on leaf xylem water potentials (Leafxwp) and plant productivity than clubmoss. Studies examined the effects of clubmoss on Leafxwp of Junegrass (Koeleria cristata Pers.) and blue grama (Bouteloua gracilis [HBK.] Lag.), and productivity of forbs and graminoids by: 1) irrigating or reducing precipitation relative to natural precipitation; 2) removing clubmoss relative to clubmoss present, and; 3) irrigating with 0.0 to 25 mm of water when clubmoss was present or removed. Leafxwp of Junegrass and blue grama were unaffected by clubmoss through the growing season (P = 0.33), but Leafxwp were lowest (P or = 0.05) when precipitation was reduced relative to the control and when irrigating. Standing crop of forbs was similar in the control and clubmoss removal treatment (P = 0.22) and among precipitation treatments (P = 0.13), averaging 28 g m-2 (SE = 2.2). Graminoid standing crop was unaffected by clubmoss (P = 0.35) and was greatest (P = 0.02) when irrigated (74 g m-2), intermediate in the control (53 g m-2), and least (36 g m-2) with reduced precipitation (SE = 8.7). Clubmoss did not affect (P = 0.70) total standing crop; total standing crop declined from 102 g m-2 when irrigated to 76 g m-2 in the control, and 69 g m-2 (SE = 9.0) with reduced precipitation. Clubmoss had no influence (P = 0.06) on Leafxwp when irrigated with 0 to 25 mm of water. The decline in Leafxwp from 1 to 7 days after irrigation was the product of the interacting effects of the amount of water applied and days after irrigation (P = 0.03). More than 10 mm of irrigation water were required to impart a significant increase (P < 0.05) in Leafxwp. The hypothesis that clubmoss reduces productivity of associated plants in the Northern Mixed Prairie by increasing water stress is rejected. Similarly clubmoss does not reduce plant water stress or increase production. Precipitation amounts overshadow any effects clubmoss has on Leafxwp and plant production. Range managers in the Northern Mixed Prairie may want to consider maximizing the effectiveness of precipitation in this water-limited environment instead of focusing on reducing or attempting to eliminate clubmoss.
    • Comparison of 2 techniques for monitoring vegetation on military lands

      Prosser, C. W.; Skinner, K. M.; Sedivec, K. K. (Society for Range Management, 2003-09-01)
      The U.S. Army is responsible for preparing a well-trained combat force while maintaining the ecological diversity and integrity of the lands it manages. The ability to efficiently collect data that accurately capture plant community diversity and percent composition is imperative to proper monitoring and land management of military lands. To ensure that the dual goals of military training and land stewardship are met on an army-wide basis, the U.S. Army Land Condition-Trend Analysis (LCTA) Program was developed. The LCTA Program specifies the Army's standard methodology for the collection, analysis, and reporting of natural resource data used for land inventory and monitoring. However, the LCTA sampling technique was developed in Colorado and Texas and little information is available on whether these methods are suitable for vegetation inventory and monitoring in other grassland ecosystems. This study compares LCTA measures of species richness and composition with quadrat sampling in the transitional area between the tall- and mixed-grass prairies of Camp Gilbert C. Grafton (South Unit) in North Dakota. Species richness was 67% higher when sampling with quadrats than using the LCTA technique, suggesting that LCTA samples did not detect a third of the plants present. Compared with the quadrat technique, LCTA samples overestimated the community contribution of Bouteloua gracilis (H.B.K.) Lag. ex Steud. (blue grama) and underestimated proportions of forbs and sedges. Moreover, LCTA samples are labor intensive and time consuming to collect. Other sampling methods may be needed to detect shifts in species composition towards a less desirable plant community or decreases in biodiversity that may be due to land-use. Thus, it is important for Camp Gilbert C. Grafton (South Unit) to re-evaluate the current standard methodology for monitoring the impacts of military training. Since military installations are located in many different ecosystems, it may be necessary for other installations to likewise examine the usefulness of LCTA techniques in their ecosystems.
    • Observation: Leafy spurge control in western prairie fringed orchid habitat

      Kirby, D. R.; Lym, R. G.; Sterling, J. J.; Sieg, C. H. (Society for Range Management, 2003-09-01)
      The western prairie fringed orchid (Platanthera praeclara Sheviak and Bowles) is a threatened species of the tallgrass prairie. Invasion by leafy spurge (Euphorbia esula L.) is a serious threat to western prairie fringed orchid habitat. The objectives of this study were to develop a herbicide treatment to control leafy spurge while sustaining western prairie fringed orchid populations and to evaluate the soil seedbank composition of leafy spurge-infested sites to guide long-term management strategies. Quinclorac (3,7-dichloro-8-quinolinecarboxylic acid), imazapic {(+/-)-2-[4,5-dihydro-4-methyl-4-(1-methylethyl)-5-oxo-1H-imidazol-2=yl]-5-methyl-3-pyridinecarboxylic acid}, and glyphosate [N-(phosphonomethyl)glycine] plus 2,4-D (2,4-dichlorophenoxy acetic acid) were applied in the fall for 2 consecutive years, and changes in leafy spurge cover, density, yield, and herbaceous yield were assessed. In a separate study, quinclorac, imazapic, and glyphosate plus 2,4-D were each fall-applied to 12 western prairie fringed orchids and assessed for reoccurrence and density of orchids 1-year after treatment. Quinclorac and imazapic, but not glyphosate plus 2,4-D, reduced leafy spurge cover, density, and yield without causing deleterious effects to associated native herbaceous cover and yields. Western prairie fringed orchid reoccurrence and density were unaffected by any herbicide 1 year after treatment. Soil cores were removed in spring and fall following the first year herbicide treatment, washed and placed in trays. Seedlings were allowed to germinate for 16 weeks in the greenhouse. Over 50 plant species were identified in the soil seedbank, of which approximately 60% were early seral species indicative of disturbance. Given the dominance of leafy spurge in the seed bank, a long-term management program to control this noxious species is warranted. Although these results are promising, longer-term studies need be conducted to ensure that repeated herbicide treatments do not harm the western prairie fringed orchid.