Investigation,evaluation, and priority ranking of natural areas

Texas experience suggests that amateur naturalists will be heavily involved in preliminary ecological surveys of natural areas, hence a simple key for identification of community-types is presented. Line intercept transects are suggested for amateur use in providing standardised quantitative data on the physiognomy of natural areas. A scheme for the evaluation of each area utilises the weighted values of climax condition, educational suitability, species significance, community representation, and human impact through multiplicative scoring to give a natural area score. With the weighted values-multiplicative scoring scheme, natural areas are clearly distinguished in priority for acquisition.     

Effect of distribution and concentration of topically applied neonicotinoid insecticides in buffalograss,Buchloe dactyloides,leaf tissues on the differential mortality of Blissus occiduus under field conditions

BACKGROUND: Neonicotinoid insecticides are generally efficacious against many turfgrass pests, including several important phloem‐feeding insects. However, inconsistencies in control of western chinch bugs, Blissus occiduus, have been documented in field efficacy studies. This research investigated the efficacy of three neonicotinoid insecticides (clothianidin, imidacloprid and thiamethoxam) against B. occiduus in buffalograss under field conditions and detected statistically significant differences in B. occiduus numbers among treatments. A subsequent study documented the relative quantity and degradation rate of these insecticides in buffalograss systemic leaf tissues, using HPLC. RESULTS: Neonicotinoid insecticides initially provided significant reductions in B. occiduus numbers, but mortality diminished over the course of the field studies. Furthermore, while all three neonicotinoids were present in the assayed buffalograss leaf tissues, imidacloprid concentrations were significantly higher than those of clothianidin and thiamethoxam. Over the course of the 28 day study, thiamethoxam concentrations declined 700‐fold, whereas imidacloprid and clothianidin declined only 70‐fold and 60‐fold respectively. CONCLUSIONS: Field studies continued to verify inconsistencies in B. occiduus control with neonicotinoid insecticides. This is the first study to document the relative concentrations of topically applied neonicotinoid insecticides in buffalograss systemic leaf tissues. Copyright © 2012 Society of Chemical Industry     

Vegetation,Hydrologic, and Erosion Responses of Sagebrush Steppe 9 Yr Following Mechanical Tree Removal

Land managers across the western United States are faced with selecting and applying tree-removal treatments on pinyon (Pinus spp.) and juniper (Juniperus spp.) woodland-encroached sagebrush (Artemisia spp.) rangelands, but current understanding of long-term vegetation and hydrological responses of sagebrush sites to tree removal is inadequate for guiding management. This study applied a suite of vegetation and soil measures (0.5 ? 990 m²), small-plot rainfall simulations (0.5 m²), and overland flow experiments (9 m²) to quantify the effects of mechanical tree removal (tree cutting and mastication) on vegetation, runoff, and erosion at two mid- to late-succession woodland-encroached sagebrush sites in the Great Basin, United States, 9 yr after treatment. Low amounts of hillslope-scale shrub (3 ? 15%) and grass (7 ? 12%) canopy cover and extensive intercanopy (area between tree canopies) bare ground (69 ? 88% bare, 75% of area) in untreated areas at both sites facilitated high levels of runoff and sediment from high-intensity (102 mm ? h^? 1, 45 min) rainfall simulations in interspaces (~ 45 mm runoff, 59 ? 381 g ? m^? 2 sediment) between trees and shrubs and from concentrated overland flow experiments (15, 30, and 45 L ? min^? 1, 8 min each) in the intercanopy (371 ? 501 L runoff, 2 342 ? 3 015 g sediment). Tree cutting increased hillslope-scale density of sagebrush by 5% and perennial grass cover by twofold at one site while tree cutting and mastication increased hillslope-scale sagebrush density by 36% and 16%, respectively, and perennial grass cover by threefold at a second more-degraded (initially more sparsely vegetated) site over nine growing seasons. Cover of cheatgrass (Bromus tectorum L.) was < 1% at the sites pretreatment and 1 ? 7% 9 yr after treatment. Bare ground remained high across both sites 9 yr after tree removal and was reduced by treatments solely at the more degraded site. Increases in hillslope-scale vegetation following tree removal had limited impact on runoff and erosion for rainfall simulations and concentrated flow experiments at both sites due to persistent high bare ground. The one exception was reduced runoff and erosion within the cut treatments for intercanopy plots with cut-downed-trees. The cut-downed-trees provided ample litter cover and tree debris at the ground surface to reduce the amount and erosive energy of concentrated overland flow. Trends in hillslope-scale vegetation responses to tree removal in this study demonstrate the effectiveness of mechanical treatments to reestablish sagebrush steppe vegetation without increasing cheatgrass for mid- to late-succession woodland-encroached sites along the warm-dry to cool-moist soil temperature ? moisture threshold in the Great Basin. Our results indicate improved hydrologic function through sagebrush steppe vegetation recruitment after mechanical tree removal on mid- to late-succession woodlands can require more than 9 yr. We anticipate intercanopy runoff and erosion rates will decrease over time at both sites as shrub and grass cover continue to increase, but follow-up tree removal will be needed to prevent pinyon and juniper recolonization. The low intercanopy runoff and erosion measured underneath isolated cut-downed-trees in this study clearly demonstrate that tree debris following mechanical treatments can effectively limit microsite-scale runoff and erosion over time where tree debris settles in good contact with the soil surface.