Native Plant Initiative Newsletter, Fall 2019

https://openprairie.sdstate.edu/nativeplant_news/1001/thumbnail.jp

Native Plant Initiative Newsletter, Spring 2019

https://openprairie.sdstate.edu/nativeplant_news/1000/thumbnail.jp

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

Annual Cover Crops Do Not Inhibit Early Growth of Perennial Grasses on a Disturbed Restoration Soil in the Northern Great Plains, USA

In agricultural, rangeland, and forest system revegetation projects, cover crops are used for competitive exclusion of weeds and to stabilize soil. Within revegetation projects, annual or short-lived perennial grasses are often sown at the same time as the perennial grasses that are the desired species for long-term landscape rehabilitation. When cover crops are utilized to control weeds, the same principle of competitive exclusion may apply to sown perennial grasses. In this project, we tested if an annual grass cover crop reduces the early stage performance of sown perennial grasses. We conducted four experiments to evaluate the effects of annual cover crops on perennial grasses. The experiments included ex situ growth chamber experiments in two soil types, an agronomic soil, and soil collected from a revegetation project in a trenched water pipeline in western North Dakota. We also performed two in situ experiments where the presence of annuals was manipulated. Annual cover crops only reduced perennial grass biomass ex situ in the agronomic soil. The disturbed pipeline soil was high in sulfur and sodium. Even when this soil was fertilized, annual cover crops did not reduce sown perennial performance. In stressful environments, or when there is natural microenvironmental variability, annual cover crops do not appear to be costly for the early-stage establishment of more long-term, desirable species

Invasive Grasses Consistently Create Similar Plant-soil Feedback Types in Soils Collected from Geographically Distant Locations

Aims Plants of similar life forms and closely related species have been observed to create similar types of plant–soil feedbacks (PSFs). However, investigations of the consistency of PSFs within species have not yielded clear results. For example, it has been reported that species create different types of PSFs in their native and introduced ranges. The aim of this project is to examine if four species create similar PSF types from soils collected from widely distributed areas within their introduced range. The soil for this project was collected from three areas in western North America. With this design, we aim to determine species- and site-specific ability to create PSFs and if the type of PSF created is consistent in all soil from all three collection areas. The species examined are Agropyron cristatum, Centaurea solstitialis, Poa pratensis and Taeniatherum caput-medusae. Methods We used three-field collected soils (from northern Nevada, western Montana and eastern Montana) in a two-phase greenhouse experiment to quantify the type of PSFs created by four invasive species. The first phase was a conditioning phase wherein each invasive species created species-specific changes to the soil. The second phase of the experiment was the response phase wherein both the conditioning species and a native phytometer were grown in the conditioned soil and in unconditioned (control) soil. The final aboveground biomass was used to evaluate the effect of conditioning and to determine the type of PSF created by each invasive species. Important Findings Our results suggest that three of our four study species did show consistency in relation to PSF. Two species A. cristatum and T. caputmedusae consistently created PSF types that benefit conspecifics more than heterospecifics (and thus are ‘invasive’ PSF types) and P. pratensis consistently exhibited no, or ‘neutral’, feedbacks. The fourth species (C. solstitialis) was inconsistent: in one soil, no feedback was created; in other soil, an invasive PSF was created and in the last soil, a feedback that relatively benefited the native phytometer was created. Thus, PSFs appear to uniformly contribute to the success of two species (A. cristatum and T. caput-medusae) but not C. solstitialis nor P. pratensis

Looking to the Future: Key Points for Sustainable Management of Northern Great Plains Grasslands

The grasslands of the northern Great Plains (NGP) region of North America are considered endangered ecosystems and priority conservation areas yet have great ecological and economic importance. Grasslands in the NGP are no longer self-regulating adaptive systems. The challenges to these grasslands are widespread and serious (e.g. climate change, invasive species, fragmentation, altered disturbance regimes, and anthropogenic chemical loads). Because the challenges facing the region are dynamic, complex, and persistent, a paradigm shift in how we approach restoration and management of the grasslands in the NGP is imperative. The goal of this article is to highlight four key points for land managers and restoration practitioners to consider when planning management or restoration actions. First, we discuss the appropriateness of using historical fidelity as a restoration or management target because of changing climate, widespread pervasiveness of invasive species, the high level of fragmentation, and altered disturbance regimes. Second, we highlight ecosystem resilience and long-term population persistence as alternative targets. Third, because the NGP is so heavily impacted with anthropogenic chemical loading, we discuss the risks of ecological traps and extinction debt. Finally, we highlight the importance of using adaptive management and having patience during restoration and management. Consideration of these four points will help management and restoration of grasslands move toward a more successful and sustainable future. Although we specifically focus on the NGP of North America, these same issues and considerations apply to grasslands and many other ecosystems globally

Hydromulch tackifier and sucrose effects on microbial nitrogen and Bromus tectorum biomass

There is growing interest in using nutrient manipulations to control invasive plants such as Brornus lectorurn L. (cheatgrass). Both labile (sucrose) and recalcitrant (straw and sawdust) carbon sources are added to the soil surface to reduce plant available soil N via soil microbial immobilization. However, the application rates used in previous research can be very high and application techniques are labor intensive. The goal of this research was to determine if established hydrornulching technology could be adapted to nutrient-manipulation-based restoration projects to lower costs. Hydromulching is an established technology for treating large areas on a landscape. It requires the use of a tackifier to adhere the treatment to the soil surface. Three tackifiers are available commercially; guar, psyllium, and polyacrylamide (PAM). Tackifiers are long chain carbon compounds that could induce the same soil responses as other recalcitrant carbon compounds. The objectives of this study were to investigate: 1) whether tackifiers alone or combined with two levels of a labile carbon source (sucrose) decreased cheatgrass biomass; 2) whether the tackifiers differed in their ability to reduce cheatgrass biomass; 3) the degree to which nitrogen immobilization occurs in soil under each tackifier; and each sucrose treatment; and 4) whether treatments affected cheatgrass emergence. Research was conducted in a glasshouse. Cheatgrass biomass was negatively correlated with soil microbial N, although cheatgrass and microbial N responded to different treatments. Cheatgrass biomass was not effected by any of the tackifiers. even though soil microbial N was. None of the treatments had any effect on cheatgrass emergence. If our results are supported in field experiment, hydrornulching technology may easily be adapted to nutrient manipulation based restoration projects considerably lowering costs

Invasion Triangle: An Organizational Framework for Species Invasion

Species invasion is a complex, multifactor process. To encapsulate this complexity into an intuitively appealing, simple, and straightforward manner, we present an organizational framework in the form of an invasion triangle. The invasion triangle is an adaptation of the disease triangle used by plant pathologists to help envision and evaluate interactions among a host, a pathogen, and an environment. Our modification of this framework for invasive species incorporates the major processes that result in invasion as the three sides of the triangle: (1) attributes of the potential invader; (2) biotic characteristics of a potentially invaded site; and (3) environmental conditions of the site. The invasion triangle also includes the impact of external influences on each side of the triangle, such as climate and land use change. This paper introduces the invasion triangle, discusses how accepted invasion hypotheses are integrated in this framework, describes how the invasion triangle can be used to focus research and management, and provides examples of application. The framework provided by the invasion triangle is easy to use by both researchers and managers and also applicable at any level of data intensity, from expert opinion to highly controlled experiments. The organizational framework provided by the invasion triangle is beneficial for understanding and predicting why species are invasive in specific environments, for identifying knowledge gaps, for facilitating communication, and for directing management in regard to invasive species

Seed Source May Determine Field-Specific Germination and Emergence: The Source by Planting Environment Interaction

Farm environmental conditions and management practices can result in within-cultivar differences in seed quality and lead to transgenerational plasticity (farm-specific effects on offspring, or TGP) that affect germination and emergence in transplant fields. We used three perennial bunchgrasses, [green needlegrass (Nassella viridula) ‘Lodorm’, slender wheatgrass (Elymus trachycaulus) ‘Pryor’, and bluebunch wheatgrass (Pseudoregneria spicata) prevariety registered germplasm P-7] to determine if seeds exhibited TGP. We also determined if TGP was affected by the interaction between production farms and planting environments (farm × environment interaction, or context-dependent TGP), using four laboratory temperature regimes to test germination response and four field environments to test emergence response in 2013. We stored seeds in four different environments for 10 mo before repeating the experiment to test if recent seed storage conditions mitigated TGP. Contextdependent TGP affected emergence for Pryor and Lodorm both years, however, only Pryor exhibited context-dependent TGP for germination in 2013. Sources with low germination and emergence in the field were less likely to exhibit context-dependent TGP. Some transplant fields did not show differences among sources, but in other transplant fields, emergence increased as much as 24% depending on farm source. The effect of recent seed storage conditions, significant only for Pryor, was opposite for germination and emergence, with room-temperature stored seeds exhibiting the highest emergence and lowest germination. Context-dependent TGP in emergence could not be predicted by our coarse information regarding seed production environments and storage conditions or by germination in the lab. Nonetheless, context-dependent TGP significantly determined emergence in two of the three study species. Mechanisms underlying this phenomenon need further study to understand potential benefits and pitfalls for producers and seed buyers

Bacteria isolated from parasitic nematodes - a potential novel vector of pathogens?

Bacterial pathogens are ubiquitous in soil and water - concurrently so are free-living helminths that feed on bacteria. These helminths fall into two categories; the non-parasitic and the parasitic. The former have been the focus of previous work, finding that bacterial pathogens inside helminths are conferred survival advantages over and above bacteria alone in the environment, and that accidental ingestion of non-parasitic helminths can cause systemic infection in vertebrate hosts. Here, we determine the potential for bacteria to be associated with parasitic helminths. After culturing helminths from fecal samples obtained from livestock the external bacteria were removed. Two-hundred parasitic helminths from three different species were homogenised and the bacteria that were internal to the helminths were isolated and cultured. Eleven different bacterial isolates were found; of which eight were indentified. The bacteria identified included known human and cattle pathogens. We concluded that bacteria of livestock can be isolated in parasitic helminths and that this suggests a mechanism by which bacteria, pathogenic or otherwise, can be transmitted between individuals. The potential for helminths to play a role as pathogen vectors poses a potential livestock and human health risk. Further work is required to assess the epidemiological impact of this finding