Lora B. Perkins

Soil conditioning and plant–soil feedbacks affect competitive relationships between native and invasive grasses

Abstract Understanding how competition from invasive species and soil conditions individually and interactively affect native performance will increase knowledge of invasion dynamics and can be used to improve the success of restoration plans. This study, conducted in Reno NV, USA, uses a two-phase plant–soil feedback experiment coupled with a target-neighbor competition design to examine the individual and interactive effects of both soil conditions and invasive neighbors on native performance. Study species include invasive species (Bromus tectorum and Agropyron cristatum) and native species (Elymus elymoides and Pseudoroegneria spicata). Results indicate that both plant performance and competitive interactions were influenced by species-specific soil conditioning. Specifically, invasive B. tectorum generated a larger competitive effect on natives than invasive A. cristatum; however, only A. cristatum conditioned soil in a manner that increased competitive effects of conspecifics on natives. Native P. spicata was relatively unaffected by soil conditioning and conversely, E. elymoides was strongly affected by soil conditioning. Few previous studies have examined soil conditioning and the interaction of soil conditioning and neighbor effects that both are potentially important mechanisms in structuring plant communities and influencing plant invasion.

Invasion syndromes: hypotheses on relationships among invasive species attributes and characteristics of invaded sites

As invasion science accepts that there is no single causal factor for biological invasion, the identification of groups of traits that are often associated, or “syndromes”, is a logical move forward. Invasion syndromes are proposed to identify suites of site conditions (biotic and environmental) that render a site vulnerable to invasion by different types of invaders. This paper proposed four invasion syndromes which relate invader attributes (competitive ability, niche construction, phenotypic plasticity, and phenological niche separation) to the biotic characteristics (biodiversity and enemies) and environmental conditions (resource abundance and fluctuation) of invaded sites. The four invasion syndromes described in this paper are a development of hypotheses of how the many factors that influence species invasion might be associated. Invasion Syndrome 1 proposes that sites with relatively high resource abundance and high diversity should be vulnerable to invasion by species with high competitive ability. Invasion Syndrome 2 hypothesizes that sites with relatively low resource abundance and low diversity should be vulnerable to invasion by species with niche construction ability. Invasion Syndrome 3 postulates that sites with moderate or fluctuating resources and moderate diversity should be vulnerable to invasion by species with high phenotypic plasticity. Invasion Syndrome 4 hypothesizes that species introduced into a site where it has phenological niche separation from natives will not have to contend with interference from the biotic community at a site (diversity or natural enemies) and may invade where ever site environmental conditions suit its life history. Further work is needed to support, contradict, or refine these hypotheses and almost certainly will identify more invasion syndromes.

Diversity of free-Living nitrogen fixing Streptomyces in soils of the badlands of South Dakota

Biological Nitrogen Fixation is critical for ecosystem productivity. Select members of Bacteria and Archaea express a nitrogenase enzyme complex that reduces atmospheric nitrogen to ammonia. Several nitrogen fixing bacteria form symbiotic associations with plants, but free-living diazotrophs also contribute a substantial amount of nitrogen to ecosystems. The aim of this study was to isolate and characterize free-living diazotrophs in arid lands of South Dakota Badlands. Samples were obtained from sod tables and the surrounding base in spring and fall. Diazotrophs were isolated on solid nitrogen free medium (NFM) under hypoxic conditions, and their16S rRNA and nifH genes sequenced. nifH was also amplified directly from soil DNA extracts. The 16S rRNA gene data indicated a diversity of putative free-living diazotrophs across 4 phyla (Actinomycetes, Proteobacteria, Bacteroidetes, and Firmicutes), but ∼50% of these clustered with Streptomyces. These Streptomyces isolates grew in liquid NFM in an ammonia-depleted environment. Only 5 of these yielded a nifH gene product using the PolF/PolR primer set. Four of these aligned with nifH of the cyanobacteria Scytonema and Nostoc, and the other one aligned with nifH of Bradyrhizobium. Six selected Streptomyces isolates, three of which were nifH positive by PCR, all indicated 15N2 incorporation, providing strong support of nitrogen fixation. All nifH amplicons from soil DNA extract resembled Cyanobacteria. This is the first known report of diazotrophic Streptomyces, other than the thermophilic, autotrophic S. thermoautotrophicus. nifH genes of these Streptomyces were related to those from Cyanobacteria. It is possible that the cyanobacteria-like nifH amplicons obtained from soil DNA were associated with Streptomyces.

Invasive earthworms in a Northern Great Plains prairie fragment

Although ample research exists on the ecological impacts of earthworm invasion in the Great Lakes region and northern hardwood forests, little data is available on the presence, distribution, and impact of earthworms in the prairies of the Northern Tallgrass Prairie. Sampling in a Northern Tallgrass Prairie fragment yielded three species of invasive earthworms occupying three different functional groups: surface and litter dwellers (epigeic), subsurface horizontal burrowers (endogeic), and deep vertical bore inhabitants (anecic). This research note illustrates the presence of non-native and potentially invasive earthworms in Northern Tallgrass Prairie.

Are Bison Intermediate Feeders? Unveiling Summer Diet Selection at the Northern Fringe of Historical Distribution

ABSTRACT Bison (Bison bison) were historically distributed throughout North America with the northern edge of the distribution occurring in north-central Manitoba and surrounding provinces. Despite bison occupying the boreal zone of North America, little is known of their forage selection patterns of herbaceous plant material when occupying pastures within a densely forested aspen ecosystem. In 2015 we initiated a study to examine forage selection patterns for bison among and within summer months (June–August). We hypothesized that vegetative composition of bison diets would be consistent with availability, would shift with forage availability, and would predominately consist of grass and sedge species. We opportunistically collected adult female bison fecal samples (N = 99) and identified forage composition using the DNA barcoding method. We estimated availability of forage to the lowest taxonomical level possible using a modified Daubenmire frame. Overall, bison diets were composed of 44.3% grass, 37.7% forb, 16.3% browse, and < 2% sedge and rush. Forage availability comprised 51.2% grass, 28.3% forb, 11.0% sedge, and 7.6% rush. All analyses indicated that use and availability for grass, forb, sedge, and rush differed (P ≤ 0.05) throughout the summer. Grass and forbs were important dietary components for bison, comprising > 80% of bison diets. However, bison selected for these two dietary components independently as the summer progressed. Our results indicate that these bison consume a large portion (∼54.0%) of low-cellulose, high cell-soluble forages to meet their dietary needs. This suggests that bison may be or become intermediate foragers and are more like elk (Cervus elapus) than domestic cattle or sheep when inhabiting forested systems at the northern edge of their historical distribution. Herd managers and biologists should be cognizant of the importance of eudicots for bison and adopt a management plan that promotes a spatially heterogenous vegetative schematic.

Capturing Neonatal Bison With a Net Gun From a Utility Terrain Vehicle

Abstract Monitoring neonatal bison Bison bison for daily survival is difficult without a proper technique to effectively capture and safely handle neonates. Currently, we are not aware of an effective method to capture neonatal bison. In May 2015, we initiated a study on Olsons Bison Conservation Ranches, Pine River, Manitoba, Canada, to evaluate a new approach to effectively capture and handle neonate bison. We captured bison neonates by using a modified .308 caliber net gun deployed from a utility terrain vehicle. We successfully captured and radio-tagged 10 male and 16 female neonate bison in 37 attempts (70.3% success). Over a period of 4 d, 16.0 labor h were spent pursuing and handling neonates, with an average capture rate of one bison neonate for every 0.6 labor h. Average handling time of bison neonates was 3.7 ± 1.6 min and ranged from 1.0 to 7.5 min. Results of our study indicate that our approach was effective and efficient for capturing and handling bison neonates safely. No injuries or captu...

Plant-Derived Smoke Influences Germination of Native and Invasive Plant Species

©2017 by the Board of Regents of the University of Wisconsin System. Plant-Derived Smoke Influences Germination of Native and Invasive Plant Species Joe Bennett (corresponding author: Department of Natural Resource Management, South Dakota State University, Brookings, SD 57007, jrbennett@ndow.org) and Lora Perkins (Department of Natural Resource Management, South Dakota State University, Brookings, SD).

Weed Establishment and Persistence after Water Pipeline Installation and Reclamation in the Mixed Grass Prairie of Western North Dakota

Weeds in reclamations interfere with success by: 1) competing with desirable species seeded during revegetation; 2) preventing recolonization of reclamations by native species; and 3) reducing the integrity of landscapes by expanding from reclamations into adjacent, intact areas. In the Bakken oilfield of western North Dakota, dispersed reclamation activity and increased traffic may provide many opportunities for weeds to spread. To determine the potential for disturbance and reclamation to increase resident weed populations and introduce new weed species, we tracked twenty-one weed (non-native/ruderal/invasive) species over a four-year period after the installation of a 1.8 km livestock water pipeline and subsequent land reclamation on a historic ranch in western North Dakota. We included areas of historic (early 20th century homestead) and recent (prairie dog town) landscape disturbances and tracked weed frequency and density in the disturbed pipeline and in the directly adjacent intact prairie. Most of the weeds in the pipeline were non-persistent populations of naturalized species. Our data show that although naturalized weeds may respond positively to disturbance, they can quickly return to pre-disturbance levels. However, disturbance may have resulted in the introduction of one new noxious weed, Hyoscyamus niger (black henbane). Agropyron cristatum (crested wheatgrass), an invasive, non-native perennial grass that reduces native plant diversity and forage value, was also introduced. This study demonstrates the importance of prevention of weed dispersal during disturbance and reclamation, contamination-free seed sources, and post-reclamation follow up to control any weeds that may have been introduced as a result of pipeline development.

Conversion of Smooth Brome (Bromus inermis) to Switchgrass (Panicum virgatum) on Untilled Prairie in Northwest Iowa

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Evaluation of Five Herbicide Treatments to Control Yellow Toadflax (Linaria vulgaris)

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