Plant Community Responses to Bison Reintroduction within Montana\u27s Northern Great Plains

In western North America, the rapid loss of native grazers, abiotic disturbance processes (e.g., fire), and human-driven land conversion or degradation have resulted in steadily declining biodiversity and rangeland health. Keystone species restoration and their potential to increase rangeland health are common justifications for bison (Bison bison L.) reintroduction projects throughout North America\u27s Great Plains. Similarly, many other conservation groups also justify the removal of livestock from traditionally cattle-grazed rangelands by citing potential increases in rangeland health or community dynamics following years of heavy use by cattle. Our objective was to assess how ten-years of bison reintroduction and livestock removal influence plant community dynamics in the mixed-grass prairie compared to cattle-grazed rangeland. We compared our treatments to each other, and to a predicted historic climax plant community (HCPC) by collecting plant species incidence, abundance, height, and bare ground data at 10 different sampling sites across each of our treatments, all within a common ecological site. We found that bison exhibited mixed keystone effects ten-years post-reintroduction. In support of their keystone role, we observed higher species richness and compositional heterogeneity (beta-diversity) in our bison-grazed treatment than either our cattle-grazed (p = 0.01 and p = 0.03 respectively) or livestock removal (p = 0.007 and p = 0.002 respectively) treatments. We also found that bison reintroduction outperformed cattle-grazing or livestock removal in moving plant communities toward a predicted HCPC-state, being not significantly different in forb composition (bootstrap resampling, p \u3c 0.0001, nboot = 1,000) and abundance (LSM, t = 1.80, p = 1.80, df = 19), bare ground cover (t = -0.36, p = 0.73, df = 4), and abundance of grasses and sedges (t = -1.73, p = 0.12, df = 19). Bison reintroduction areas were also lower in noxious weed abundance compared to cattle-grazed (t = 1.80, p = 0.042, df = 27) and livestock removal (t = 2.88, p = 0.0039, df = 27). Bison may show some of their predicted keystone effects after ten-years, and we suggest that their reintroduction may be a useful to restoring and conserving the Northern Great Plains mixed-grass prairie ecosystem

Grassland heterogeneity and pyric herbivory: Implications for ungulate movement, biodiversity conservation, and rangeland productivity in the Anthropocene

How to simultaneously manage grasslands for sustained livestock productivity and biodiversity conservation is a persistent dilemma for rangeland ecologists and conservationists. Moreover, climate change and invasive species are recognized as potential threats to many grassland management and conservation objectives. Pyric herbivory – the recoupling of fire and grazing – promotes grassland heterogeneity that is critical to meeting biodiversity, livestock, and invasive species objectives. While fire and physical landscape characteristics (i.e., slope, elevation, aspect, etc.) significantly affect ungulate behavior, it remains unknown how their movement changes with the ambient landscape (i.e., weather, diurnal cycles, seasonal rhythms). The feedbacks between ungulate movement and landscape characteristics – particularly those driven by fire – can also have significant effects on plant communities. However, how feedbacks between invasive species, fire timing, and management (e.g., herbicide, or the interactive effects of fire and herbicide) affect plant dynamics and livestock production remains unknown. Extant knowledge is restricted to studies at small scales unrepresentative of large complex grasslands. Therefore we conducted four distinct studies across grasslands managed with pyric herbivory: two addressing how seasonal, diurnal, and meteorological patterns (e.g., temperature) affect bison movement patterns; and two investigating how invasive species and management approaches aimed at their reduction affect livestock productivity and grassland plant assemblages at multiple scales (0.1m2 – >10^6 m2). We found that bison movements change with season and time of day, and are most affected by air temperature compared to other weather parameters. We also determined that invasive species management may not increase livestock production or biodiversity across large grasslands (i.e., >300 ha), and relationships between invasive species abundance and plant diversity changed with scale. Scale is regarded as a central problem in ecology, and therefore managers should be cautious when applying results from small scale studies to large landscapes. Moreover, landscape heterogeneity is well documented as fostering biodiversity maintenance and ecological resiliency. Therefore, heterogeneity – and processes that promote it – will be critical to conserving grassland biodiversity and function throughout the Anthropocene

A plea for scale, and why it matters for invasive species management, biodiversity and conservation

Invasive species are suspected to be major contributors to biodiversity declines worldwide. Counterintuitively, however, invasive species effects are likely scale dependent and are hypothesized to be positively related to biodiversity at large spatial scales. Past studies investigating the effect of invasion on biodiversity have been mostly conducted at small scales (\u3c100 m2) that cannot represent large dynamic landscapes by design. Therefore, replicated experimental evidence supporting a negative effect of invasive plants on biodiversity is lacking across many landscape types, including large grasslands. We collected data across eight large (333–809 ha) grassland landscapes managed with pyric herbivory—that is the recoupling of fire and grazing—to test how an invasive legume Lespedeza cuneata affected plant and bird communities at spatial grains ranging from 0.1 m2 to \u3e3,000,000 m2. Lespedeza cuneata invasion effects on grassland plant diversity and composition changed with scale, being negative at small spatial grains (0.1 m2) and neutral or positive at large spatial grains (\u3e3,000,000 m2). Lespedeza cuneata abundance did not significantly affect bird diversity at any spatial grain measured. Lespedeza cuneata may negatively affect biodiversity if abundances are greater than those observed in this study. However, previous research suggests that Lespedeza cuneata may not be capable of exceeding 20% canopy cover across large landscapes (\u3e400 ha). Control and eradication strategies can be costly and are fraught with risk. If data do not clearly support a negative Lespedeza cuneata abundance–biodiversity relationship, and if invasion is spatially limited across large landscapes, ongoing control and eradication efforts may be unwarranted and ineffective. Synthesis and applications: Invasive species effects gleaned from small-scale studies may not reliably predict their effects at larger scales. Although we recognize the importance of small-scale studies in potentially isolating individual mechanisms, management strategies based solely on results from small-scale studies of invasion are unlikely to increase or conserve biodiversity across large landscapes. Rather, processes that generate landscape heterogeneity—like pyric herbivory—are probably more important for promoting biodiversity across all scales. Scale is a central problem in ecology, and defining scale in management objectives is essential for effective biodiversity conservation

Towards Prioritizing Documentation Effort

Programmers need documentation to comprehend software, but they often lack the time to write it. Thus, programmers must prioritize their documentation effort to ensure that sections of code important to program comprehension are thoroughly explained. In this paper, we explore the possibility of automatically prioritizing documentation effort. We performed two user studies to evaluate the effectiveness of static source code attributes and textual analysis of source code towards prioritizing documentation effort. The first study used open-source API Libraries while the second study was conducted using closed-source industrial software from ABB. Our findings suggest that static source code attributes are poor predictors of documentation effort priority, whereas textual analysis of source code consistently performed well as a predictor of documentation effort priority

Bison movements change with weather: Implications for their continued conservation in the Anthropocene

Animal movement patterns are affected by complex interactions between biotic and abiotic landscape conditions, and these patterns are being altered by weather variability associated with a changing climate. Some animals, like the American plains bison (Bison bison L.; hereafter, plains bison), are considered keystone species, thus their response to weather variability may alter ecosystem structure and biodiversity patterns. Many movement studies of plains bison and other ungulates have focused on point-pattern analyses (e.g., resource-selection) that have provided information about where these animals move, but information about when or why these animals move is limited. For example, information surrounding the influence of weather on plains bison movement in response to weather is limited but has important implications for their conservation in a changing climate. To explore how movement distance is affected by weather patterns and drought, we utilized 12-min GPS data from two of the largest plains bison herds in North America to model their response to weather and drought parameters using generalized additive mixed models. Distance moved was best predicted by air temperature, wind speed, and rainfall. However, air temperature best explained the variation in distance moved compared to any other single parameter we measured, predicting a 48% decrease in movement rates above 28°C. Moreover, severe drought (as indicated by 25-cm depth soil moisture) better predicted movement distance than moderate drought. The strong influence of weather and drought on plains bison movements observed in our study suggest that shifting climate and weather will likely affect plains bison movement patterns, further complicating conservation efforts for this wide-ranging keystone species. Moreover, changes in plains bison movement patterns may have cascading effects for grassland ecosystem structure, function, and biodiversity. Plains bison and grassland conservation efforts need to be proactive and adaptive when considering the implications of a changing climate on bison movement patterns

Short interfering RNA induced generation and translation of stable 5' mRNA cleavage intermediates

Sequence-specific degradation of homologous mRNA is the main mechanism by which short-interfering RNAs (siRNAs) suppress gene expression. Generally, it is assumed that the mRNA fragments resulting from Ago2 cleavage are rapidly degraded, thus making the transcript translation-incompetent. However, the molecular mechanisms involved in the post-cleavage mRNA decay are not completely understood and the fate of cleavage intermediates has been poorly studied. Using specific siRNAs and short-hairpin RNAs (shRNAs) we show that the 5′ and 3′ mRNA cleavage fragments of human papilloma virus type 16 (HPV-16) E6/7 mRNA, over-expressed in cervical malignancies, are unevenly degraded. Intriguingly, the 5′ mRNA fragment was more abundant and displayed a greater stability than the corresponding 3′ mRNA fragment in RNAi-treated cells. Further analysis revealed that the 5′ mRNA fragment was polysome-associated, indicating its active translation, and this was further confirmed by using tagged E7 protein to show that C-terminally truncated proteins were produced in treated cells. Overall, our findings provide new insight into the degradation of siRNA-targeted transcripts and show that RNAi can alter protein expression in cells as a result of preferential stabilization and translation of the 5′ cleavage fragment. These results challenge the current model of siRNA-mediated RNAi and provide a significant step forward towards understanding non-canonical pathways of siRNA gene silencing

Using airborne and DESIS imaging spectroscopy to map plant diversity across the largest contiguous tract of tallgrass prairie on earth

Grassland ecosystems are under threat globally, primarily due to land-use and land-cover changes that have adversely affected their biodiversity. Given the negative ecological impacts of biodiversity loss in grasslands, there is an urgent need for developing an operational biodiversity monitoring system that functions in these ecosystems. In this paper, we assessed the capability of airborne and spaceborne imaging spectroscopy (also known as hyperspectral imaging) to capture plant α-diversity in a large naturally-assembled grassland while considering the impact of common management practices, specifically prescribed fire. We collected a robust insitu plant diversity data set, including species composition and percent cover from 2500 sampling points with different burn ages, from recently-burned to transitional and pre-prescribed fire at the Joseph H. Williams Tallgrass Prairie Preserve in Oklahoma, USA. We expressed in-situ plant α-diversity using the first three Hill numbers, including species richness (number of observed species in a plant community), exponential Shannon entropy index (hereafter Shannon diversity; effective number of common species, where species are weighed proportional to their percent cover), and inverse Simpson concentration index (hereafter Simpson diversity; effective number of dominant species, where more weight is given to dominant species) at four different plot sizes, including 60 m × 60 m, 120 m × 120 m, 180 m × 180 m, and 240 m × 240 m. We collected full-range airborne hyperspectral data with fine spatial resolution (1 m) and visible and near-infrared spaceborne hyperspectral data from DESIS sensor with coarse spatial resolution (30 m), and used the spectral diversity hypothesis— i.e., that the variability in spectral data is largely driven by plant diversity—to estimate α-diversity remotely. In recently-burned plots and those at the transitional stage, both airborne and spaceborne data were capable of capturing Simpson diversity—a metric that calculates the effective number of dominant species by emphasizing abundant species and discounting rare species—but not species richness or Shannon diversity. Further, neither airborne nor spaceborne hyperspectral data sets were capable of capturing plant α-diversity of 60 m × 60 m or 120 m × 120 m plots. Based on these results, three main findings emerged: (1) management practices influence grassland biodiversity patterns that can be remotely detected, (2) both fine- and coarse-resolution remotely-sensed data can detect the effective number of dominant species (e.g., Simpson diversity), and (3) attention should be given to site-specific plant diversity field data collection to appropriately interpret remote sensing results. Findings of this study indicate the feasibility of estimating Simpson diversity in naturally-assembled grasslands using forthcoming spaceborne imagers such as National Aeronautics and Space Administration’s Surface Biology and Geology mission

Optical and Infrared Photometry of the Unusual Type Ia Supernova 2000cx

We present optical and infrared photometry of the unusual Type Ia supernova 2000cx. With the data of Li et al. (2001) and Jha (2002), this comprises the largest dataset ever assembled for a Type Ia SN, more than 600 points in UBVRIJHK. We confirm the finding of Li et al. regarding the unusually blue B-V colors as SN 2000cx entered the nebular phase. Its I-band secondary hump was extremely weak given its B-band decline rate. The V minus near infrared colors likewise do not match loci based on other slowly declining Type Ia SNe, though V-K is the least ``abnormal''. In several ways SN 2000cx resembles other slow decliners, given its B-band decline rate (Delta m_15(B) = 0.93), the appearance of Fe III lines and weakness of Si II in its pre-maximum spectrum, the V-K colors and post-maximum V-H colors. If the distance modulus derived from Surface Brightness Fluctuations of the host galaxy is correct, we find that the rate of light increase prior to maximum, the characteristics of the bolometric light curve, and the implied absolute magnitude at maximum are all consistent with a sub-luminous object with Delta m_15(B) ~ 1.6-1.7 having a higher than normal kinetic energy.Comment: 46 pages, 17 figures, to be published in Publications of the Astronomical Society of the Pacifi

A systematic review of the neutrophil to lymphocyte and platelet to lymphocyte ratios in patients with lower extremity arterial disease

Summary: Background: Lower extremity arterial disease (LEAD) is caused by atherosclerotic plaque in the arterial supply to the lower limbs. The neutrophil to lymphocyte and platelet to lymphocyte ratios (NLR, PLR) are established markers of systemic inflammation which are related to inferior outcomes in multiple clinical conditions, though remain poorly described in patients with LEAD. Material and methods: This review was carried out in accordance with PRISMA guidelines. The MEDLINE database was interrogated for relevant studies. Primary outcome was the prognostic effect of NLR and PLR on clinical outcomes following treatment, and secondary outcomes were the prognostic effect of NLR and PLR on disease severity and technical success following revascularisation. Results: There were 34 studies included in the final review reporting outcomes on a total of 19870 patients. NLR was investigated in 21 studies, PLR was investigated in two studies, and both NLR & PLR were investigated in 11 studies. Relating to increased levels of systemic inflammation, 20 studies (100%) reported inferior clinical outcomes, 13 (92.9%) studies reported increased disease severity, and seven (87.5%) studies reported inferior technical results from revascularisation. Conclusions: The studies included in this review support the role of elevated NLR and PLR as key components influencing the clinical outcomes, severity, and success of treatment in patients with LEAD. The use of these easily accessible, cost effective and routinely available markers is supported by the present review