Invasive Grass Species Research Articles

Phenology forecasting models for detection and management of invasive annual grasses

AbstractNon‐native annual grasses can dramatically alter fire frequency and reduce forage quality and biodiversity in the ecosystems they invade. Effective management techniques are needed to reduce these undesirable invasive species and maintain ecosystem services. Well‐timed management strategies, such as grazing, that are applied when invasive grasses are active prior to native plants can control invasive species spread and reduce their impact; however, anticipating the timing of key phenological stages that are susceptible to management over vast landscapes is difficult, as the phenology of these species can vary greatly over time and space. To address this challenge, we created range‐wide phenology forecasts for two problematic invasive annual grasses: cheatgrass (Bromus tectorum), and red brome (Bromus rubens). We tested a suite of 18 mechanistic phenology models using observations from monitoring experiments, volunteer science, herbarium records, timelapse camera imagery, and downscaled gridded climate data to identify the models that best predicted the dates of flowering and senescence of the two invasive grass species. We found that the timing of flowering and senescence of cheatgrass and red brome were best predicted by photothermal time models that had been adjusted for topography using gridded continuous heat‐insolation load index values. Phenology forecasts based on these models can help managers make decisions about when to schedule management actions such as grazing to reduce undesirable invasive grasses and promote forage production, quality, and biodiversity in grasslands; to predict the timing of greatest fire risk after annual grasses dry out; and to select remote sensing imagery to accurately map invasive grasses across topographic and latitudinal gradients. These phenology models also have the potential to be operationalized for within‐season or within‐year decision support.

Monitoring invasive exotic grass species in ecological restoration areas of the Brazilian savanna using UAV images

Identifying and monitoring invasive exotic grasses (IEG) is critical for the ecological restoration of grasslands and savannas, as they are the main barrier to the successful recovery of native grasslands and savannas. The integration of high-resolution remote sensing data, acquired through UAVs (Unmanned Aerial Vehicles), with machine learning algorithms is advancing restoration monitoring. The present study aimed to estimate IEG cover and identify plots with different invasive species dominance in ecological restoration areas in the Brazilian savanna. For ground truth, species cover estimates were carried out in plots through point-line intercept sampling. Then, the areas were classified according to the dominance of each invasive species (>40% vegetation cover) or of a mix of native species. A multispectral camera onboard a UAV was used to acquire images in the visible to near-infrared spectrum. From the images, vegetation indices and texture metrics were derived as predictor variables. The Random Forest (RF) algorithm was used to estimate the percentage of invasive species cover and to classify plots in terms of species dominance. The final RF regression for invasive species cover percentage presented an R2 of 0.71 and selected the blue band, NIR and Ratio Vegetation Index (RVI) as the most important variables. The overall accuracy of plot classification according to species dominance was 84%. The most prominent predictors were the Green Chlorophyll Index (GCI), the atmospherically resistant vegetation index (ARVI), and the RVI. The structural and photosynthetic characteristics of exotic and native species influenced the spectral responses. In conclusion, multispectral images acquired with UAV can be used to estimate the proportion of invasion in restoration sites and to map areas dominated by different invasive grass species in grasslands and savannas. This is a useful tool for evaluating restoration success and can help indicate areas that require management interventions.

First Report of a 'Candidatus Phytoplasma sacchari'-Related Strain Associated with Yellowing and Decline of Silver Bluestem in Texas, U.S.A.

Silver bluestem [Bothriochloa laguroides (DC.) Herter] is a warm-season grass native to Texas. This perennial grass plays a crucial role in maintaining ecological balance and supporting wildlife in the region. In September 2022, while investigating the ecological impact of invasive grass species on a grassland located near Pipe Creek (TX), B. laguroides plants were observed showing symptoms that included yellowing of the blades and occasionally brown discoloration of the midveins and stems (Fig. S1). Disease incidence was estimated as 2% of silver bluestem plants in the 2 hectares surveyed. To investigate the possibility of a phytoplasma association with the symptoms, four symptomatic and four asymptomatic leaf samples were collected for further study. Total DNA was extracted from leaf midribs using a DNeasy Plant Mini Kit (Qiagen). The DNA extracts were tested using a phytoplasma-specific quantitative PCR assay (Hodgetts et al. 2009), which identified two out of the four symptomatic B. laguroides samples as positive for phytoplasmas. A semi-nested PCR assay for amplification of the 16S rRNA gene fragment was then performed on these samples with primers P1/16S-SR followed by P1A/16S-SR (Deng, and Hiruki 1991; Lee et al. 2004), and two additional housekeeping genes (tuf and secA) were amplified as previously described (Makarova et al. 2012; Hodgetts et al. 2008; Bekele et al. 2011). All amplicons of the expected size, 1.5 kb (16S rRNA), 0.4 kb (tuf) and 0.6 kb (secA), were purified and bi-directionally sequenced using primers from each gene second round PCR amplification. Analysis of the sequences derived from the three gene fragments revealed no variation between the two plant samples and confirmed they originated from a phytoplasma, termed strain TXSB-2 (Texas Silver Bluestem). Sequences from a single B. laguroides plant DNA extract were deposited in GenBank with accession numbers OR711913 (16S rRNA), OR709687 (tuf) and OR709688 (secA). A BLAST search of the 16S rRNA gene sequence from TXSB-2 against the NCBI nucleotide database, showed 99.58% sequence identity with an unclassified phytoplasma clone 139-1 from a leafhopper collected in Australia (MW281491) (Fig. S2). The partial nucleotide sequence of the tuf and secA genes showed 90.60% and 89.78% similarity, respectively, to the corresponding genes in 'Ca. P. sacchari' strain SCWL1 (CP115156) associated with sugarcane in China. The iPhyClassifier, an interactive online tool for phytoplasma identification and classification (Zhao et al. 2009), was used to determine the 'Candidatus Phytoplasma' species affiliation and group/subgroup classification status of this phytoplasma strain. The result showed that the TXSB-2 16S rDNA shared 98.94% sequence identity with that of the 'Ca. P. sacchari' reference strain (GenBank accession: MN889545), indicating TXSB-2 is a 'Ca. P. sacchari'-related strain. The result from virtual restriction fragment length polymorphism (RFLP) analysis of the 16S rDNA F2nR2 fragment revealed that TXSB-2 possessed a collective RFLP pattern that is distinct from the reference patterns of all established phytoplasma ribosomal subgroups and is proposed as the representative strain of a new subgroup designated as 16SrXI-H. 'Candidatus Phytoplasma sacchari' has been reported associated with sugarcane grassy shoot disease, which is considered among the most damaging diseases of sugarcane across parts of Southeast Asia and India (Kirdat et al. 2021). The same phytoplasma was recently confirmed infecting sorghum in India (Nithya et al. 2024). To our knowledge, this is the first report of a 'Ca. P. sacchari'-related strain infecting B. laguroides in the United States. Moreover, B. laguroides is a new host for strains related to 'Ca. P. sacchari'. Further investigation is required to elucidate the prevalence of this disease in the area, its natural vectors, and the potential consequences arising from this novel phytoplasma strain within its ecosystem in Texas.

Plant networks are more connected by invasive brome and native shrub facilitation in Central California drylands

Dominant vegetation in many ecosystems is an integral component of structure and habitat. In many drylands, native shrubs function as foundation species that benefit other plants and animals. However, invasive exotic plant species can comprise a significant proportion of the vegetation. In Central California drylands, the facilitative shrub Ephedra californica and the invasive Bromus rubens are widely dispersed and common. Using comprehensive survey data structured by shrub and open gaps for the region, we compared network structure with and without this native shrub canopy and with and without the invasive brome. The presence of the invasive brome profoundly shifted the network measure of centrality in the microsites structured by a shrub canopy (centrality scores increased from 4.3 under shrubs without brome to 6.3, i.e. a relative increase of 42%). This strongly suggests that plant species such as brome can undermine the positive and stabilizing effects of native foundation plant species provided by shrubs in drylands by changing the frequency that the remaining species connect to one another. The net proportion of positive and negative associations was consistent across all microsites (approximately 50% with a total of 14% non-random co-occurrences on average) suggesting that these plant-plant networks are rewired but not more negative. Maintaining resilience in biodiversity thus needs to capitalize on protecting native shrubs whilst also controlling invasive grass species particularly when associated with shrubs.

Phytochemical screening and allelopathic potential of phytoextracts of three invasive grass species

Undoubtedly, it is important to remain vigilant and manage invasive grasses to prevent their spread and mitigate their negative impact on the environment. However, these aggressive plants can also play a beneficial role in certain contexts. For example, several invasive grasses provide valuable forage for livestock and have disease control potential. Therefore, a research experiment was conducted to explore the pros and cons of this approach, not only for surrounding vegetation but also for human and animal disease control. The study is primarily focused on developing livestock feed, plant-derived herbicides, and an understanding of the phytotoxic effects of invasive species. All plant parts of Cenchrus ciliaris L., Polypogon monspeliansis L., and Dicanthium annulatum (Forssk.) Stapf, were tested for their phyto-chemical screening, proximate, and toxicity analysis which was caused by the methanolic extract of these grass species. Qualitative phytochemical screening tests were performed for proximate composition analysis and toxicity assessment essays. The phytochemical analysis revealed the positive results for alkaloids, flavonoids, coumarins, phenols, saponins, and glycosides, while negative for tannins. Comparison of proximate analysis intimated maximum moisture (10.8%) and crude fat (4.1%) in P. monspeliensis, whereas maximum dry matter (84.1%), crude protein (13.95%), crude fiber (11%), and ash (7.2%) in D. annulatum. Five (10, 100, 500, 100, 10,000 ppm) and three (10, 1000, 10,000 ppm) different concentrations of methanolic extract prepared from C. ciliaris, P. monspeliansis, and D. annulatum were used respectively for root inhibition and seed germination essay. Furthermore, three different concentrations (10, 30, 50 mg) of plant fine powder were used for sandwich method test. There was a significant decline in the growth rate of experimental model radish seeds (P > 0.005), and results from sandwich method tests showed suppressed growth of root hairs, inhibiting the anchoring of the radish seed. In comparison, results manifest that; P. monspeliansis indicated an upsurge of inhibition (66.58% at 10,000 ppm), D. annulatum revealed soar germination (75.86% in controlled conditions), and C. ciliaris exhibited dramatic shoot up of inhibition because of sandwich method test (14.02% at 50 mg). In conclusion, although grasses are toxic, it is important to consider the beneficiary account.

Predicting the range expansion of invasive alien grasses under climate change in the Neotropics

A diverse group of invasive grasses from tropical and subtropical Africa and Asia has spread throughout the Neotropics over the last decades. Despite their strong ecological impact, current and future distribution patterns of these grasses in the region according to climate change is poorly investigated. We chose ten high potential invasive grass species and used ecological niche modeling to project their geographic distribution within the Neotropics under four climate change scenarios (current, SSP1-2.6, SSP3-7.0 and SSP5-8.5 for 2100). Current climatically suitable areas for these invasive species were estimated to account for 51.3% of the Neotropics. Projections of future climatically suitable areas ranged between 47.0% and 57.6%, depending on the climate scenario. Range retractions are projected for Melinis repens and Urochloa decumbens regardless of the SSP scenario, while Arundo donax, Hyparrhenia rufa and Melinis minutiflora are expected to expand their range in all SSP scenarios. Currently, these ten invasive species have suitable areas that greatly overlap in dry regions of the Neotropics, mainly in the savannas of Central Brazil and Central America. However, a reduction in species overlap and a geographical expansion towards wetter regions is expected under the SSP1 and SSP3 scenarios, and towards drier regions under the SSP5 scenario.

Mechanical and biotic reclamation strategies for a post‐mine temperate grassland

AbstractGlobal energy production is in high demand and is expanding its development into new landscapes, including grasslands. This expansion has intensive impacts on aboveground and belowground components of grasslands which need to be addressed during reclamation to promote long‐term ecological integrity. This study was conducted to ascertain how alternative reclamation practices may improve soil structure (i.e., compaction) while aiding in the creation of conditions that are conducive to both the establishment and continued growth of native grassland plant species. The grassland was reclaimed with different combinations of seeding mixtures (grass or grass and forb), ripping techniques (subsoil ripping or topsoil ripping), and the integration of mulch into the soil profile. Year, seed mixtures, and ripping techniques and their interactions significantly affected community composition and species diversity. Topsoil‐ripping and grass‐forb treatment had a higher association with native, perennial grasses while subsoil‐ripping and grass treatment favor more short‐lived species. Similar trends persisted across penetration resistance and soil moisture readings where topsoil‐ripping and grass‐forb treatment were different from subsoil‐ripping and grass treatments (p ≤ 0.10). Additionally, Kentucky bluegrass, an invasive grass species, increased by 76% over 1 year and was more common in the topsoil‐ripping and grass‐forb treatments. While early in the reclamation process, results suggest topsoil‐ripping and grass‐forb treatment are promising combination reclamation practices that can establish a native grassland community and initiate the improvement of compacted soil conditions.

Effects of salt stress on interspecific competition between an invasive alien plant Oenothera biennis and three native species.

Biological invasions and soil salinization have become increasingly severe environmental problems under global change due to sea-level rise and poor soil management. Invasive species can often outcompete native species, but few studies focus on whether invasive alien species are always superior competitors under increasing stressors. We grew an invasive grass species, Oenothera biennis L., and three native grass species (Artemisia argyi Lévl. et Vant., Chenopodium album L., and Inula japonica Thunb.) as a monoculture (two seedlings of each species) or mixture (one seedling of O. biennis and one native species seedling) under three levels of salt treatments (0, 1, and 2 g/kg NaCl) in a greenhouse. We found that invasive O. biennis exhibited greater performance over native C. album and I. japonica, but lower performance compared to A. argyi, regardless of the soil salinity. However, salinity did not significantly affect the relative dominance of O. biennis. Interspecific competition enhanced the growth of O. biennis and inhibited the growth of I. japonica. Although O. biennis seedlings always had growth dominance over C. album seedlings, C. album was not affected by O. biennis at any salt level. At high salt levels, O. biennis inhibited the growth of A. argyi, while A. argyi did not affect the growth of O. biennis. Salt alleviated the competitive effect of O. biennis on I. japonica but did not mitigate the competition between O. biennis and the other two native species. Therefore, our study provides evidence for a better understanding of the invasive mechanisms of alien species under various salinity conditions.

A Robust Process to Produce Lignocellulosic Nanofibers from Corn Stover, Reed Canary Grass, and Industrial Hemp.

The use of agricultural waste biomass for nanocellulose production has gained interest due to its environmental and economic benefits compared to conventional bleached pulp feedstock. However, there is still a need to establish robust process technologies that can accommodate the variability of waste feedstocks and to understand the effects of feedstock characteristics on the final nanofiber properties. Here, lignocellulosic nanofibers with unique properties are produced from various waste biomass based on a simple and low-cost process using mild operating conditions. The process robustness is demonstrated by diversifying the feedstock, ranging from food crop waste (corn stover) to invasive grass species (reed canary grass) and industrial lignocellulosic residues (industrial hemp). This comprehensive study provides a thorough examination of the influence of the feedstocks' physico-chemical characteristics on the conversion treatment, including process yield, degree of delignification, effectiveness of nanofibrillation, fiber morphology, surface charge, and density. Results show that nanofibers have been successfully produced from all feedstocks, with minor to no adjustments to process conditions. This work provides a framework for future studies to engineer nanocellulose with specific properties by taking advantage of biomass feedstocks' intrinsic characteristics to enable versatile applications.

Harnessing Ecosystem Services from Invasive Alien Grass and Rush Species to Suppress their Aggressive Expansion in South Africa

Invasive alien species are regarded as one of the major driving forces of species extinction worldwide. To counteract the invasion’s spread and minimize species extinction risk, countries like South Africa are devoted to halting human-induced invasion using various means. The failed efforts to halt the invasion spread have forced South African scientists to start considering social controlling mechanisms, including utilization of these species without propagation as one of the alternatives. It is within this context that this review was aimed at making an inventory of invasive grass species that provide ecosystem services in South Africa. The required data were gathered through rigorous literature surveys and analysis. A total of 19 invasive alien grass and rush species, from 15 genera and two families that are associated with provision of ecosystems services, were documented. The reported species are associated with the provision of nine ecosystem services. The current study argued that although these species are associated with some ecosystem services, they can also threaten the ecological integrity of the ecosystems if not properly managed. Insights about ecosystem services associated with invasive alien grass and rush species are significant in balancing the complex environmental issues and livelihood requirements in rural South Africa.

Potential phytoremediation of Pampa biome native and invasive grass species cohabiting vineyards contaminated with Cu in Southern Brazil.

The objectives were (a) to evaluate whether grasses native to the Pampa biome, Axonopus affinis Chase, Paspalum notatum Flüggé and Paspalum plicatulum Michx, and the invasive grass Cynodon dactylon (L.). Pers have the potential to phytoremediate soil contaminated with Cu (0, 35 and 70mg Cu kg-1); (b) assess whether the growth of these species is compromised by the excess of Cu available in the soil; and (c) determine the impact of excess Cu on the physiological responses of the studied species. C. dactylon presented the best performance in soil contaminated with 35mg of Cu kg-1. In C. dactylon, the concentrations of chlorophyll b and carotenoids increased, as did the photosynthetic rate and plant growth. Phytotoxic effects of Cu in soil contaminated with 70mg of Cu kg-1 were more severe on A. affinis and led to plant death. The other species presented reduced photosynthetic and growth rates, as well as increased activity of antioxidant enzymes such as superoxide dismutase and guaiacol peroxidase. This very same Cu level has decreased photosynthetic pigment concentrations in P. notatum and P. plicatulum. On the other hand, it did not change chlorophyll a and b concentrations in C. dactylon and increased carotenoid concentrations in it. High values recorded for Cu bioaccumulation-in-grass-root factor, mainly in P. plicatulum, have indicated that the investigated plants are potential phytostabilizers. High C. dactylon biomass production-in comparison to other species-compensates for the relatively low metal concentration in its tissues by increasing metal extraction from the soil. This makes C. dactylon more efficient in the phytoremediation process than other species.

From germination to seedling development: the effects of smoke on a native and an invasive grass species of the Cerrado

AbstractThe Brazilian Cerrado, a Neotropical savanna, is a fire-prone ecosystem where the ground layer biomass consists mainly of graminoids. However, as for other savannas, the effects of fire cues (such as smoke) on Cerrado grasses do not present a clear pattern, either for germination or seedling development. Smoke can stimulate different stages of the plant life cycle, which can alter the community and invasion processes. So far, most research on the subject focuses on germination, not addressing post-germinative phases, a sensitive stage of plant development. Here, we investigated the effect of smoke on a native (Echinolaena inflexa) and an invasive (Urochloa decumbens) grass species common in the Cerrado. We analysed germinative parameters and seedling mass and length after exposing the seeds to dry smoke for 5, 10, 15 or 20 min. Seedling development was assessed by measuring shoot and root systems after cultivating germinated seeds for 3, 7 or 15 d. Smoke did not affect germination percentages. However, fumigation reduced the mean germination time of both species and the germination onset of E. inflexa. U. decumbens had higher length values in all periods of cultivation, whereas mass values only surpassed that of E. inflexa at 15 d. Smoke exposure reduced the aboveground length of 7-d seedlings of U. decumbens, and mass of 15-d plants of both species. Also, smoke enhanced the root investment of the native and invasive species in different cultivation periods. Therefore, studying post-germinative parameters on seedling development may bring further insights into the smoke effects.

Plant growth promoting strain Bacillus cereus (RCS-4 MZ520573.1) enhances phytoremediation potential of Cynodon dactylon L. in distillery sludge

Elevated levels of physico-chemical pollution including organic pollutants, metals and metalloids were detected in distillery sludges despite of the anaerobic digestion treatment prior to disposal. The concentrations of the metals were (in mg kg−1): Fe (400.98 ± 3.11), Zn (17.21 ± 0.54), Mn (8.32 ± 0.42), Ni (8.00 ± 0.98), Pb (5.09 ± 0.43), Cr (4.00 ± 0.98), and Cu (3.00 ± 0.10). An invasive grass species, Cynodon dactylon L., demonstrated its ability to remediate the distillery waste sludge (DWS) in the field study. All the physico-chemical parameters of the sludge significantly improved (up to 70–75%) in the presence of Cynodon dactylon L. (p < 0.001) than the control with no plant growth. The highest phytoremediation capacity was associated with the uptake of Fe in the root and shoot. Sludge samples collected near the rhizosphere also showed lower amount of organic compounds compared to control sludge samples. Metal resistant Bacillus cereus (RCS-4 MZ520573.1) was isolated from the rhizosphere of Cynodon dactylon L. and showed potential to enhance the process of phytoremediation via plant growth promoting activities such as production of high level of ligninolytic enzymes: manganese peroxidase (35.98 U), lignin peroxidase (23.98 U) and laccase (12.78 U), indole acetic acid (45.87(mgL−1), phosphatase activity (25.76 mg L−1) and siderophore production (23.09 mg L−1). This study presents information on the performance of Cynodon dactylon L., an abundant invasive perennial grass species and its associated plant growth promoting rhizobacteria demonstrated good capacity to remediate and restore contaminated soil contained complex organic and inorganic pollutants, they could be integrated into the disposal system of distillery sludge to improve the treatment efficiency.

Biology and Management of Torpedograss (Panicum repens) in Ornamental Landscape Planting Beds

Torpedograss is one of the most invasive perennial grass species in Florida landscapes. This new 5-page publication of the UF/IFAS Environmental Horticulture Department was written for green industry professionals and others to aid in the identification and management of torpedograss in landscape planting beds. Written by Yuvraj Khamare, Candice Prince, and Chris Marble.https://edis.ifas.ufl.edu/ep615

Pollinator-friendly flora in rangelands following control of cheatgrass (Bromus tectorum): a case study

AbstractInvasive winter annual grasses, such as cheatgrass (Bromus tectorumL.) are considered serious threats to regional biodiversity. Pollinator populations that depend on the native flora are likely to be negatively impacted as these native species may be displaced by the invasive grass species. Colonization by cheatgrass is also predicted to increase risk of wildfires, as dead plant parts provide fuel in the already dry and arid regions of the western United States. Biocontrol, grazing, prescribed burning, or use of broad-spectrum nonselective herbicides have been suggested as possible means to controlB. tectorum. Efficient control may facilitate regrowth of native flora that could in turn support other ecosystem functions. Reporting our findings as a case study, we describe here the results of the application of a preemergent herbicide, indaziflam, that limits germination ofB. tectorumseeds. Herbicide was applied to the study locations during the months of December 2016, January 2017, and February 2017. The data reported here on the diversity of flowering plants were collected between May through September 2018. Herbicide-treated plots showed an increase in diversity and abundance of flowering plants compared to the untreated control within two seasons after cheatgrass control was implemented, suggesting that effective reduction of the population of the invasive annual cheatgrass may help facilitate the growth of native forbs. Further studies are necessary to understand mechanisms that facilitate reestablishment of native flowering species, the long-term consequences of reducing invasive annual grasses and to document any residual effects of the herbicide on ground-nesting pollinators.

The human–grass–fire cycle: how people and invasives co‐occur to drive fire regimes

Invasive grass species can alter fire regimes, converting native terrestrial ecosystems into non‐native, grass‐dominated landscapes, creating a self‐reinforcing cycle of increasing fire activity and flammable grass expansion. Analyses of this phenomenon tend to focus on the ecology and geography of the grass–fire cycle independent of human activities. Yet people introduce non‐native grasses to new landscapes (eg via agriculture), facilitate their spread (eg via road networks), and are a primary source of ignition (eg via debris burning). We propose a new framework for this phenomenon that explicitly recognizes the important role of anthropogenic activities in the human–grass–fire cycle. We review links between land use and invasive species as well as ignitions, with a particular focus on the spatial and temporal co‐occurrences of these activities to show that these two drivers of wildfires are inextricable. Finally, management strategies that could mitigate impacts are discussed.

Streetlights positively affect the presence of an invasive grass species.

Anthropogenic disturbances associated with urban ecosystems can create favorable conditions for populations of some invasive plant species. Light pollution is one of these disturbances, but how it affects the growth and establishment of invasive plant populations is unknown. Cheatgrass (Bromus tectorum) is a problematic invasive species where it has displaced native grassland communities in the United States, but to our knowledge, there have been no studies of the ecological factors that affect cheatgrass presence in urban ecosystems. We conducted field surveys in urban alleys in Denver, Colorado, to compare the presence of cheatgrass at sites with and without artificial light at night (hereafter artificial light) from streetlights. These streetlights are mounted on utility poles, which cause ground disturbance when installed in alleys; we were able to test the independent effect of poles on cheatgrass establishment because not all poles have streetlights on them. We found that cheatgrass was positively associated with the presence of streetlights and to a lesser extent poles. In addition to cheatgrass, we also found that other plants were positively associated with the presence of both poles and streetlights. Our results suggest that artificial light may benefit the occurrence of cheatgrass and other plant species in urban settings. While invasive populations of cheatgrass in wild habitats attract the most attention from managers, we suggest more consideration for this grass in urban environments where its growth and establishment benefit from anthropogenic changes.

New records of alien and potentially invasive grass (Poaceae) species for southern Africa

Background: The grasses (Poaceae) of the Flora of Southern Africa (FSA) region (i.e. Botswana, Eswatini, Lesotho, Namibia and South Africa) are relatively well documented, for both native and non-native species. Visiting taxonomic expertise nevertheless reveals new FSA and in-country records, particularly of non-native species. Such records provide an opportunity for improving biosecurity relating to potentially invasive but hitherto undetected non-native Poaceae in the FSA region.Objectives: To improve floristic data for non-native Poaceae occurring in theFSA region.Method: Field collections were made, herbarium collections, databases and relevant literature were studied.Results: New records are presented for non-native grasses that were encountered as locally common populations in the Drakensberg Mountain Centre of Floristic Endemism (DMC, Lesotho and South Africa). Festuca rubra and Agrostis capillaris are newly reported for sub-Saharan Africa and southern Africa and are also the first verified specimens reported for the African continent, with previous reports from northern-most Africa (Morocco, Algeria and/or Tunisia) uncertain. Jarava plumosa, introduced from South America and previously known for the whole of Africa from a single population in the Western Cape, South Africa, is newly reported from the border between the Eastern Cape, South Africa and Lesotho. The ecological implications, including the potential to become invasive, are discussed for each species, with taxonomic notes given to help differentiate them from closely resembling taxa.Conclusion: These new records of alien grass species raise concerns over their potential ecological impact, particularly as they are found in an area of conservation importance. Future efforts to monitor their distribution are of importance.

Gatekeepers of transformation: private landowners evaluate invasives based on impacts to ecosystem services

AbstractBiological invasions are not new, yet the anthropogenic drivers of global change have produced unprecedented ecological novelty through the expansion of invasive species. Private landowners play an important role in determining the trajectory of ecological transformations driven by invasives. Using the northern Great Plains of the USA as a case study, we examined private landowners' role as gatekeepers for an invasive species. We employed a factorial vignette survey experiment to understand how the impacts of an unnamed invasive grass modeled on Kentucky bluegrass (Poa pratensis L.) were related to landowners' acceptance of the species. We also explored the relationship between landowners' acceptance of the invasive grass and their management intention to reduce/control the species. Each landowner evaluated multiple vignettes that randomly varied based on how a novel grass species expanding in rangelands would affect provisioning services (season of forage availability, forage quality, forage quantity), regulating services (floral resources for pollinators, water infiltration and availability), and supporting services (grassland bird diversity, grass diversity). Acceptability was strongly associated with landowners' management intentions, and the status of all seven services was related to acceptability. Reductions to any ecosystem service reduced the acceptability of the invasive grass species; however, only increases in forage quality, forage quantity, and water regulation were related to increased acceptability of the invasive. Scenario modeling shows that landowners displayed greater sensitivity to losses in a suite of ecosystem services than to equivalent gains. Scenarios specific to ecosystem service trade‐offs and Kentucky bluegrass invasion indicate that ecological losses may need to be severe before individual landowners change their management practices to reduce/control the species. Given the high thresholds for individual behavioral change, engaging private landowners in collaborative management efforts, whether to control an invasive grass or guide management toward co‐existence, may be helpful to conserve desired biodiversity and the flow of ecosystem services from northern Great Plains grasslands.

Arthropod Assemblages in Invasive and Native Vegetation of Great Salt Lake Wetlands

Wetlands provide essential habitat for shorebirds, songbirds, and waterfowl. Invasive species can disrupt trophic interactions within wetlands by altering the arthropod assemblages on which birds rely. An invasive grass species, Phragmites australis (common reed), has invaded wetlands across North America, including those surrounding the Great Salt Lake, Utah, U.S.A. Phragmites outcompetes native vegetation and alters habitat for resident and migratory birds, yet how Phragmites affects arthropod assemblages is unclear. To address these knowledge gaps, this study investigated how arthropod assemblages differ between native and invasive vegetation in Great Salt Lake wetlands. We examined the arthropod assemblages found within three native habitats as well as in Phragmites-invaded areas. There were few differences in arthropod assemblages between Phragmites and two native habitats (hardstem bulrush, Schoenoplectus acutus and alkali bulrush, Bolboschoenus maritimus). Arthropod assemblages differed between Phragmites and the native Salicornia rubra (pickleweed), which differed markedly from the other plant species in structure, biomass, and related site conditions. Identifying how arthropods interact with Phragmites and native vegetation is critical to recognizing how to effectively manage wetlands for bird habitat. By gaining an understanding of these relationships, arthropod biomass, abundance, diversity, and assemblage composition could serve as assessment metrics for determining wetland management success.