No abstract

As valuation of ecosystem goods and services derived from ecological processes becomes increasingly important in environmental decision-making, the need to quantify how restoration activities influence ecosystem function has grown more urgent, particularly within income-generating or subsistence-providing landscapes where economic needs and biodiversity goals must be balanced. However, quantification of restoration effects is often hindered by logistical issues, which include (1) the difficulty of systematically monitoring responses over large areas and (2) lack or loss of comparison sites necessary for assessing treatment effect. We explored the use of remote sensing to quantify the effects of native grass seeding and prescribed burns on ecosystem forage provisioning services within a California (U.S.A.) rangeland landscape. We used Landsat time series to monitor forage (green biomass) dynamics within 296 ha of treatment areas-distributed throughout a 36-km 2 watershed-for 6 years and to identify post hoc comparison areas when a priori comparisons were lacking. Remote sensing analysis documented gains and losses in forage provisioning services due to restoration efforts and provided critical information for adaptive management. Our results demonstrate the degree to which invaded grasslands can be resistant to change and suggest that increasing the functional complexity of restoration mixes might help increase forage availability and reduce opportunities for weed reinvasion.

Native perennial bluegrasses are common and persistent in the understory steppe vegetation of western North America. The agamospermous Poa secunda Presl. complex circumscribes a number of commonly recognized forms including big bluegrass (P. ampla Merr.), canby bluegrass (P. canbyi Scribn.), and sandberg bluegrass (P. sandbergii Vasey). Poa fendleriana (Steudel) Vasey is a dioecious, morphologically distinct bluegrass species that is also native to western North America. The amplified fragment length polymorphism (AFLP) method was used to analyze genetic variation within and among cv. Canbar canby bluegrass, cv. Sherman big bluegrass, two allopatric natural populations of sandberg bluegrass, and one natural germplasm source of P. fendleriana Results indicate that Sherman and Canbar are comprised of one or several fixed genotypes, respectively, that are related to sandberg bluegrass. Although several fixed genotypes were also detected within the two natural sandberg bluegrass populations, high levels of genetic diversity were present in the agamospermous sandberg populations and dioecious P. fendleriana population. Patterns of AFLP variation in P. secunda are consistent with facultative apomixis and outcrossing mode of reproduction. Moreover, population differentiation between the two highly diverse natural sandberg bluegrass populations, collected from sites nearly 600 km apart, is very low (GS = 0.14) and reflect a high degree of gene flow. However, the AFLP profiles of Canbar canby bluegrass and Sherman big bluegrass were distinct from sandberg bluegrass. The P. secunda complex, as a group, was clearly distinguishable from P. fendleriana Thus, DNA fingerprinting was used to characterize naturally diverse bluegrass germplasm sources that may be used for large‐scale revegetation efforts across the western USA.

Revegetation of disturbed semiarid lands requires rapid stabiliza-Ratzlaff, 1989; Asay et al., 2001). Although introduced tion of ecological process and soil resources. Introduced species have been widely adopted because the slow establishment of native species grasses have effectively stabilized thousands of hectares frequently results in poor ecosystem recovery and further site degrada-in the western USA and Canada, concerns have been tion. Little research has documented the managerial possibilities and raised about their effects on soil resources and structure species interactions associated with simultaneously establishing native (Elliott and White, 1987; Doormaar et al., 1995; Chrisand introduced grasses on semiarid lands. We conducted a 3-yr experitian and Wilson, 1999) and the persistence of low biologment at Fort Carson, CO, to evaluate if seven native perennial grasses ical diversity where they are planted (Wilson, 1989). would coexist with either Russian wildrye [Psathyrostachys juncea Low diversity may be a result of depleted seedbanks of (Fisch.) Nevski], crested wheatgrass (Agropyron sp.), or Siberian native species (Hassan and West, 1986; Humphrey and wheatgrass [A. fragile (Roth) Candargy] after simultaneous seeding. Schupp, 2001) or lower seed predation and greater seed Five grass mixes, each comprised of the seven natives and one introduced grass, and a standard military seed mix (mostly native grasses carryover from year to year of introduced grasses comwith a small introduced species component) were evaluated by compared with native grasses (Pyke, 1990). Not too surprisparing percentage ground cover of individual species. Predominance ingly, secondary succession does not transition from of crested and Siberian wheatgrass cover resulted in significantly lower dominance held by introduced perennial grasses or invanative grass and weed abundance. In contrast, Russian wildrye and sive annual grasses without an ample and mobile seed military treatments had lower introduced grass cover and high weed supply of native perennial species (Hironaka and Tisabundance, but much higher native grass cover. However, weed cover dale, 1963). However, Cox and Anderson (2004) dedecreased to Ͻ5% in all treatments during the experiment. Western scribed an "assisted succession" process in which rangewheatgrass [Pascopyrum smithii (Rydb.) A. Lö ve] was responsible for Ͼ80% of the native species cover in the military treatment for lands infested with an invasive annual grass were restored all 3 yr, whereas the Russian wildrye treatments had a more balanced to native sagebrush-grassland steppe species through mix of several native species. These results provide insights into manathe sequential process of establishing an introduced gerial considerations for revegetation and weed control for frequently grass, disturbance, and finally seeding adapted native disturbed rangelands and suggest that some introduced grasses may grasses, forbs, and shrubs. coexist with native grasses.

‘Snowstorm’ (Reg. No. CV‐8, PI 666938) forage kochia [Bassia prostrata (L.) A.J. Scott; syn. Kochia prostrata (L.) Schrad.] was released on 22 Mar. 2012 by the USDA‐ARS and the Utah Agricultural Experiment Station. Snowstorm was evaluated as OTVSEL and Otavny‐select and was developed as a synthetic cultivar using two cycles of recurrent selection for stature, forage production, and adaptation to semiarid environments. Snowstorm was compared with the standard forage kochia cultivar, Immigrant, and other ARS experimental forage kochia populations. Research has shown that Immigrant can increase rangeland productivity three‐ to sixfold and provides critical protein (>70 g kg−1) during the fall and winter for livestock and wildlife; however, Immigrant is easily covered by snow because of its short stature. In field comparisons with Immigrant, Snowstorm was similar to Immigrant in establishment and adaptation on semiarid rangelands but was 64% taller (77 versus 47 cm), produced 68% more forage (2526 versus 1504 kg ha−1), and had a 22% higher protein content (79 versus 65 g kg−1) and 4% higher digestibility (674 versus 648 g kg−1) (P ≤ 0.05). Furthermore, DNA fingerprinting showed that Snowstorm, Immigrant, and experimental populations were genetically unique and distinct from each other. Snowstorm is named for its ability to extend the grazing season into the fall and winter and because it provides ranchers and land managers a new, taller, more productive, more nutritious forage kochia cultivar capable of increasing carrying capacity and nutritional content of fall and winter grazinglands, including locations where snow cover had limited forage kochia use in the past.