Reed canarygrass (Phalaris arundinacea L.) is a dominant perennial grass species in many sedge meadows and wet prairies. Efforts to control this species with herbicides have had limited short-term success, partly because reed canarygrass resurges from its rhizomes whenever applications are suspended. A system of apical dominance may operate in reed canarygrass rhizomes, resulting in a persistent rhizome bud bank that must be depleted in order to achieve effective, long-lasting control of this species. Pretreatments that overcome apical dominance may predispose reed canarygrass to more effective herbicidal control. I tested whether coupling pretreatment tillage or pretreatment plant growth regulator (PGR) application to herbicide application would result in greater reed canarygrass control compared to herbicide application alone. Three treatments were tested: (1) Sethoxydim (Vantage®) application only (standard method control), (2) Tillage followed by Vantage® application, and (3) Plant Growth Regulator application (2:1 (a.i.) Cycocel®/Proxy®) followed by Vantage® application. Tillage-Vantage® treatments had a larger effect on reed canarygrass suppression and native species abundance than the other two treatments, and these effects persisted into the subsequent growing season after treatments were discontinued. Coupling PGR pretreatments with herbicide application reduced reed canarygrass stem density 26% greater than herbicide application only. Tillage and PGR pretreatments have potential for enhancing the effects of Vantage®herbicide on reed canarygrass.

The spatial dynamics of black-tailed prairie dog (Cynomys ludovicianus) colonies affect the utility of these environments for other wildlife, including the endangered black-footed ferret (Mustela nigripes). We used location data of active and inactive black-tailed prairie dog burrows to investigate colony structure, spatial distribution, and patch dynamics of two colonies at ferret recovery sites. We used kernel-based utilization distributions (UDs) of active and inactive burrows from two time periods (six and 11 years apart) as the basis for our analysis. Overall, the total extent of our prairie dog colonies changed little over time. However, within colonies, areas with high densities of active and inactive prairie dog burrows formed patches and the distribution of these patches changed in size, shape, and connectivity over time. At the Conata Basin site, high-density active burrow patches increased in total area covered while decreasing in connectivity as they shifted towards the perimeter of the colony over time. At the UL Bend site, we observed a similar but less pronounced shift over a longer period of time. At both sites, while at a large scale it appeared that prairie dogs were simply shifting areas of activity towards the perimeter of colonies and abandoning the center of colonies, we observed a dynamic interaction between areas of active and inactive burrows within colonies over time. Areas that previously contained inactive burrows tended to become active, and vice versa, leading us to hypothesize that there are shifts of activity areas within colonies over time as dictated by forage availability. The spatial dynamics we observed have important implications for techniques to estimate the suitability of ferret habitat and for the management of prairie dog colonies. First, fine-scale techniques for measuring prairie dog colonies that account for their patchy spatial distribution are needed to better assess ferret habitat suitability. Second, the shift of high-density areas of active prairie dog burrows, likely associated with changes in vegetation, suggests that through the management of vegetation we might be able to indirectly improve habitat for ferrets. Finally, we found that prairie dog distributions within a colony are a naturally dynamic process and that management strategies should consider the long-term value of both active and inactive areas within colonies.

Navajo Point, on the southeast tip of the Kaiparowits Plateau, supports Pinus edullis Engelm. var edulis-Juniperus osteosperma (Torrey) Little (piñon-juniper) woodlands undisturbed by large wildfires in the recent past. We developed a fire history and characterized the current fuel structure and plant biodiversity in the piñon-juniper woodlands on Navajo Point. Using a combination of 18 stand ages, stand structural characteristics classified from satellite imagery, and line intercept sampling, we determined that it would take 400–600 years to burn a cumulative area equal in extent to Navajo Point. Despite a long history of livestock grazing and fire suppression policies, the woodlands on Navajo Point still retain most of their primeval character. Specifically, the landscape patch mosaic on Navajo Point has not been fundamentally altered by 20^th century fire exclusion. We conclude that the old-growth woodlands that cover at least half of Navajo Point are a natural and ecologically significant component of this ecosystem, resulting from the combination of the area's soils, climate, and inherently infrequent disturbance regime. Today, the rich understory supports 207 plant species of which only 6% are exotic. Despite the current pristine character of this woodland, the greatest potential threat comes from Bromus tectorum L. (cheatgrass), which occurs intermittently throughout the area. If expansion occurs, this flashy fuel (which has no native counterpart) could significantly shorten the centuries-long fire cycle that has allowed for the development of the biologically rich woodland on Navajo Point.

Identifying the mechanisms that drive invasions of open habitats by woody species is critical for preserving diverse savannas. Trees can promote the establishment of bird-dispersed woody plant species in savannas by reducing dispersal limitation. Previous work in wet pine savannas has shown that densities of bird-dispersed shrubs are higher and species richness of herbaceous species, most of which are not bird-dispersed, is lower in areas near trees. To test the hypothesis that shrub seedling density in wet pine savannas was limited by dispersal and thus the availability of perches for seed-dispersing birds, seed traps and artificial perches were placed near and away from pines. To measure fire-induced mortality of trees and shrubs, Pinus elliottii juveniles and shrub seedlings that had emerged during a fire-free interval were quantified before and after fires. Trees provided perches for birds that dispersed shrubs, thereby reducing dispersal limitation of shrubs. Significantly more seeds of the shrubs, Ilex glabra and I. vomitoria, were encountered in seed traps at the bases of P. elliottii than in areas away from trees in two consecutive years. Seedlings of woody species with fleshy fruits occurred more frequently at the bases of artificial perches than away from perches, and the effect of the perches on seedling density was greater away from trees. Eight- and nine-year periods without fire were not long enough for the majority (>99%) of post-fire recruits of P. elliottii to grow large enough to survive growing-season fires. A small but greater fraction of shrub seedlings (10%) survived the fires. We argue that periodic fires are sufficient to preclude further invasion of wet pine savannas by P. elliottii, expansion of shrub thickets, and associated declines in plant diversity.

We compared the native bees visiting the flowers of three species of invasive plants, saltcedar (Tamarix spp.) and white and yellow sweet clover (Melilotus albus, M. officinalis), with those visiting seven concurrently blooming native plant species in mid-summer at three sites in Capitol Reef National Park, Utah. Overall, as many total species of bees visited the flowers of the three invasive plant species as visited the seven natives. On average, invasive species were visited by twice as many bee species as were natives. With a single exception, visitors of invasives were generalist bees, rather than specialists. Colletes petalostemonis, the only native legume specialist recorded, was an abundant forager on the flowers of both species of Melilotus, demonstrating that at least some specialist bees will move to invasive plants that are closely related to their usual hosts. Species abundant on the flowers of invasives tended to collect both pollen and nectar, suggesting that bees are using pollen of Tamarix and Melilotus to provision their offspring. We argue that invasives with entomophilous flowers are unlikely to either facilitate the reproduction of uncommon native plants or consistently compete with them for pollinators. Rather, they are likely, over time, to selectively increase the carrying capacity and population size of native bees, specifically generalists, and specialists of closely related plant species.

Seed dormancy and seed longevity partially determine the crucial stages of germination and establishment of seedlings for rare Cactaceae in arid environments. We studied the effect of seed age and seed dormancy on germination and seedling establishment of an endangered species of cactus (Mammillaria huitzilopochtli) from Oaxaca, Mexico, in controlled and natural conditions. Germination experiments were conducted in greenhouse conditions and seedling survival was assessed in controlled and natural areas. We found that M. huitzilopochtli has non-dormant seeds and that germination occurred during the first seven days after sowing for seeds less than one year old (x = 90%). Germination decreased with time, which indicated that this species might be able to form a transient seed bank (maximum one year old). Scarification treatments in M. huitzilopochtli did not interact with seed age response and did not enhance germination percentages, asserting that seeds are nondormant. When compared with other species of the same genus inhabiting the same region, we conclude that dormancy in cacti is probably more related to environmental heterogeneity than to phylogenetic constraints. Similar to the majority of cacti species, seedlings of M. huitzilopochtli only established in shade conditions. The seeds and seedling traits of this endangered species must be taken into account for conservation programs. Because few seeds were produced yearly, no seeds could be stored at room conditions for long time periods (> 2 yr) and seedling survival was low (mean = 13.75%).

The Nebraska Sandhills are a unique and valuable grassland resource within the Great Plains with a long history of grazing. In 1926, a vegetation study was established at the Nebraska National Forest Bessey Ranger District to investigate plant community changes in response to heavy grazing. At the time, heavy grazing was being used to shift the grassland plant community dominance from Schizachyrium scoparium (Michx.) Nash (little bluestem) to Bouteloua hirsuta Lag. (hairy grama) in order to create a natural firebreak to protect the adjacent forest from wildfires. Species frequencies were collected from 48, 1-m² permanent plots in 1926, 1927, 1929, 1931, 1938, 1948, and 1979 to 2004. We evaluated long-term vegetation dynamics by investigating the influence of summer grazing and precipitation on the plant community using Detrended Correspondence Analysis (DCA) and correlations. We determined that grazing had more influence on the plant community than precipitation, with the DCA axis 1 representing a grazing intensity gradient and the DCA axis 2 representing an equilibrium – non-equilibrium gradient. Heavy grazing coupled with drought reduced frequency of most species, but did not cause a permanent change in plant community composition. Improved management of the Sandhills, together with the inherent stability of the grassland, will continue to protect this landscape from severe degradation and erosion.

Many different methods of synthesizing and analyzing environmental monitoring data exist. Given the diversity of current environmental monitoring projects, and the large number of scientists and policy-makers involved, there is a critical need for a universal format that both summarizes data sets and indicates any potential need for management action. Control charts, originally developed for industrial applications, represent one way of doing this. Control charts indicate when a system is going ‘out of control’ by plotting through time some measure of a stochastic process with reference to its expected value. Control charts can be constructed for many different types of indicators, whether univariate or multivariate. Control charts are simple to interpret, and can easily be updated whenever additional data become available. The relative risks of Type I (i.e., concluding meaningful change has occurred when actually it has not) and Type II (i.e., concluding meaningful change has not occurred when in fact it has) errors are intuitive and easily adjusted, and one may define a threshold for action at any desired level. Control charts may often be more informative than traditional statistical analyses such as regressions or parameter estimation with confidence intervals. The primary challenge in most situations will be determining a stable or baseline state for the ecological indicator in question.

The Columbia Bottomlands, a Southern floodplain forest formation on the upper Texas coast, historically covered over 283,000 ha but has since been reduced to 25% of its former extent. The importance of this regional ecosystem as critical stopover and staging habitat for Nearctic-Neotropical migratory landbirds gave rise to the Columbia Bottomlands Conservation Plan, an active land acquisition and conservation program administered by the U.S. Fish and Wildlife Service and its governmental and non-governmental partners. The Plan seeks to establish an integrated network of protected tracts as representative examples of the regional landscape, and thus conserve ecosystem integrity, function, heterogeneity, and biological diversity. We describe the Conservation Plan and its progress to date, and we summarize data on the plant composition of a typical preserved tract. Vegetation sampling at the Dance Bayou Unit, a mature forest remnant, revealed a mosaic of species composition across habitats varying in microtopography, soil type, and flooding pattern. The Dance Bayou study is a formative step in developing guidelines for future plant inventories, for site characterization in aid of land acquisition, and for restoration targets. As threats from urban development accelerate, intensified efforts may be needed to reach the Conservation Plan goal of protecting 10% of the original ecosystem extent.

The historical Ballona Wetlands in coastal Los Angeles County were once one of the most significant coastal wetland systems in southern California, but were greatly reduced in extent and ecological function by the mid-1900s. Starting around 1900, the Ballona area saw the near-complete elimination of two major vegetation types (riparian scrub and freshwater marsh), and during the early 1960s, it experienced the loss of most of its tidal salt marsh to a major development, Marina del Rey. Attempts to recreate lost habitat, all since 1990, have achieved mixed results in terms of restoring lost natural communities, including birds. Of the 38 bird species known to have been extirpated from the valley as breeding or winter resident species since 1900, only 11 have become reestablished. Remarkably, all of the reestablished species are characteristic of a single, recently-restored habitat type, freshwater wetland. By contrast, species dependent on other native habitats of the area (notably grassland, coastal scrub, and salt marsh) have registered only extirpations, with essentially no reestablishment despite recent habitat restoration. Though some of these extirpated species no longer occur in coastal Los Angeles County, those that do should be afforded special consideration in future restoration efforts.